Showing papers in "Animal Science in 1996"
TL;DR: The data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain.
Abstract: Thirty-two piglets weaned at 28 days of age were used to test the hypothesis that maintenance of nutrition after weaning would prevent the normal decline in villous height and increase in crypt depth and hence preserve the structure and function of the small intestine. Piglets were allocated to one of four treatments at weaning: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets offered ewes' fresh milk; and (4) piglets offered ewes' fresh milk plus 20 g t-glutamine per I. Piglets in treatments (3) and (4) were offered ewes' fresh milk every 2 h in a feeding schedule that increased from 1·2 I per piglet on the 1st day after weaning to 2·4 I on days 4 and 5. On the 5th day all piglets were killed and samples of small intestine were taken for histological and biochemical examination. Feeding ewes' milk or ewes' milk plus 20 g L-glutamine per I maintained (P > 0·05) villous height and crypt depth compared with piglets killed at weaning. In contrast, piglets given a dry starter diet had shorter villi (P 0·05) in their intestinal mucosa. Piglets given the starter diet proportionately grew from 0·49 to 0·62 more slowly (P 0·05), but consumed proportionately 0·30 less energy (P 0·05). Significant correlations existed between voluntary food intake and villous height at the proximal jejunum for piglets given the starter diet and ewes' milk (P < 0·05 and P = 0·073, respectively). In turn, villous height was significantly correlated (r = 0·78 to 0·87, P < 0·05) with the rate of body-weight gain after weaning in these two groups. For piglets offered ewes' milk plus glutamine, an increase in DM intake was associated only with increases in crypt depth (P < 0·01). These data show that the structure and function of the small intestine can be preserved when a milk diet is given after weaning, and suggest an association between food intake and villous height in determining post-weaning weight gain.
228 citations
TL;DR: Investigation of the relative effects of terminal sire genotype, sex, feeding regimen, and slaughter-house on growth performance, carcass and meat quality characteristics and the eating quality of fresh pig meat suggested that pigs reared under ad libitum feeding grew faster and produced more tender, juicier meat than those rearing under restricted feeding.
Abstract: A total of 897 pigs were used in a study to investigate the relative effects of terminal sire genotype (lines A v. B v. C), sex (castrate v. gilt), slaughter weight (80 v. 100 v. 120 kg), feeding regimen (ad libitum v. restricted, 0·82 ad libitum intake) and slaughter-house (H1 v. H2 v. H3) on growth performance, carcass and meat quality characteristics and the eating quality of fresh pig meat. Sire line A was a pure Duroc population, and B and C were European-type experimental lines where C contained Pietrain and B did not. In total, 26 sires from line A, 42 sires from line B, and 21 sires from line C were mated to females from the same crossbred dam line and progeny were reared under standard conditions to slaughter. Following slaughter and carcass evaluation, samples of longissimus dorsi were investigated for a range of meat quality and organoleptic characteristics. Line A produced fatter carcasses (C fat depths = 15·6 v. 14·0 v. 14·0 mm for lines A, B, and C, respectively, average s.e. 0·39) with higher killing-out proportions (g/kg) (790 v. 779 v. 786 respectively, average s.e. 1·4) and higher visible marbling, less tissue separation, firmer backfat, and juicier (3·81 v. 3·67 v. 3·71 respectively, average s.e. 0·044: on a scale 1 (extremely dry) to 8 (extremely juicy)) and more acceptable meat (4·54 v. 4·37 v. 4·41 respectively average s.e. 0·037: on a scale 1 (dislike extremely) to 8 (like extremely)) with a lower shear force (5·35 v. 5·78 v. 5·67 kg respectively, average s.e. 0·078) than lines B and C which were similar in most respects. Increases in slaughter weight were associated with a reduction in growth rate (785 v. 769 v. 725 g/day for 80, 100 and 120 kg slaughter weight respectively, average s.e. 8·5), increases in backfat (C fat = 13·3 v. 14·1 v. 16·3 mm respectively, average s.e. 0·34) and longissimus muscle area (34·6 v. 40·7 v. 44·6 cm 2 respectively, average s.e. 0·59) and a deterioration in tenderness (4·72 v. 4·40 v. 3·95 respectively, average s.e. 0·062: on a scale 1 (extremely tough) to 8 (extremely tender) and overall acceptability (4·65 v. 4·44 v. 4·25 respectively, average s.e. 0·045) and an increase in shear force (5·37 v. 5·58 v. 5·87 kg respectively, average s.e. 0·085). Slaughter-house had a significant impact on pork odour scores but not on other organoleptic properties. Pigs reared under ad libitum feeding grew faster (840 v. 678 g/day respectively, average s.e. 3·7), were fatter (C fat = 15·8 v. 13·2 mm respectively, s.e. 0·28), had lower carcass yields (780 v. 790 g/kg respectively, average s.e. 1) and produced more tender, juicier meat than those reared under restricted feeding. Differences between castrated males and gilts in growth and carcass trait were in line with other studies and there were no significant differences between the sexes for eating quality. There were relatively few significant interactions (P < 0·05) for eating quality traits and most of these involved slaughter-house and were for pork odour intensity, which are of limited practical significance. This suggests that the effects of sire genotype, slaughter weight and feeding regimen on eating quality identified in this study are likely to be additive.
207 citations
TL;DR: Genetic variation exists for acquired but apparentl~ not for innate resistance to infection in Scottish Blackface lambs, indicating that r~sistance to gastrointestinal parasites may be an important genetic determinant of growth rate in this environment.
Abstract: Faecal egg counts and live weights were measured on approximately 200 predominantly twin-born Scottish Blackface lambs each year for 3 years, from 1 to 6 1'lonths of age. Measurements lvere made at 4-ti'eek mt/:'ltlals following anthelmintic treatment. Heritability estimates (with s.e.s) of log transformed faecal egg count at each age were 0.01,0.00,0.12 (0.10), 0.14 (0.12), 0.15 (0.07) ard 0.22 (0.13), for ages 1 to 6 months respectively. Therefore, genetic variation exists for acquired but apparentl~ not for innate resistance to infection. Maternal common environmental effects (with s.e.s) were 0.36 (0.11), 0.2b (0.05), 0.27 (0.09),0.06 (0.08), 0.15 (0.09) and 0.16 (0.08), for ages 1 to 6 months respectively. Genetic correlatiqns between faecal egg counts in Iambs older than 3 mpnths u'ere not significantly less than 1.0, indicating that faecal egg counts at different ages are expressions of the same trait. Phenotypic correlations between faecal egg colfnts were generally positive but small. Measurement ,error contributed one-third of the observed variation for indrvidual egg counts. The heritability of mean faecal egg count from.3 to 6 months was 0:33 (s.e. 0.15), .indicatin~ ~hat selection decisions can be ma~e mo~e accurately using multIple egg counts per anImal. PhenotypIc correlatIons between faecal egg counts and live weIght were generally negative but close to zero. However, genetic correlati~ns between faecal egg counts and live weight in lambs older than 3 months were close to -1.0, indicating that r~sistance to gastrointestinal parasites may be an important genetic determinant of growth rate in this environment.
192 citations
TL;DR: Estimates of digestive enzyme activity and absorptive capacity of the gut did not corroborate the large differences seen between treatments in villous height and crypt depth and illustrate the interdependence between voluntary food intake and mucosal architecture in determining piglet performance after weaning.
Abstract: The hypothesis tested in this experiment was that the structure and function of the small intestine of piglets given a milk liquid diet after weaning depends on their level of energy intake. At weaning (28 days), 42 piglets were allocated to one of five treatments: (1) control group killed at weaning; (2) piglets offered a dry starter diet ad libitum; (3) piglets given cow's fresh milk at maintenance energy intake (Ma); (4) piglets given cow's fresh milk at 2-5 Ma; and (5) piglets given cow's fresh milk ad libitum. On the 5th day all piglets were killed and samples of gut were taken for histological and biochemical examination. Piglets given milk ad libitum grew faster (P < 0·001) than piglets on all other treatments. Piglets offered the dry starter diet ingested similar quantities of dry matter and energy, and grew at the same rate as piglets given cows' milk at 2·5 Ma. As predicted, piglets given milk at maintenance energy intake grew slower (P < 0·001) and consumed less food (P < 0·001) than piglets in all other treatments. For piglets given both cows' fresh milk and the dry starter diet, there were significant linear relationships (r = 0·72 to 0·82, P < 0·05) between villous height and crypt depth with dry matter (energy) intake after weaning. In turn, mean villous height in both milk-fed and starter-fed piglets was significantly correlated (r = 0·68 to 0·79, P < 0·05) to empty body-weight gain in the first 5 days after weaning. Estimates of digestive enzyme activity and absorptive capacity of the gut did not corroborate the large differences seen between treatments in villous height and crypt depth, and possible reasons are discussed. These data illustrate the interdependence between voluntary food intake and mucosal architecture in determining piglet performance after weaning.
185 citations
TL;DR: An animal model was used to estimate heritabilities of faecal egg count (FEC) and packed cell volume decline (PCVD) in lines of Merinos selected for divergent levels of resistance to Haemonchus contortus, finding that younger animals had higher FEC and PCVD than older animals.
Abstract: An animal model was used to estimate heritabilities of faecal egg count (FEC) and packed cell volume decline (PCVD) in lines of Merinos selected for divergent levels of resistance to Haemonchus contortus. The estimated heritability of FEC was 0·23 (s.e. 0·03) and of PCVD was 0·21 (s.e. 0·03). A cube root transformation was found to be effective in normalizing FEC data and reducing the range of within selection line-birth year variances from 118-fold to 10-fold. Transforming FEC data increased the heritability estimate to 0·29 (s.e. 0·03) and reduced selection bias due to heterogeneity of variance, but the further step of pre-adjusting the transformed data to a common variance had only a trivial effect. Heritability estimates for FEC in years with high means and variances were similar, as were estimates for transformed FEC. The estimated genetic correlations between measurements in years with high and low means and variabilities were 0·77 to 0·91.PCVD and pre-adjusted transformed FEC had a phenotypic correlation of 0·48. Estimates for the genetic correlation ranged from 0·76 in the decreased resistance line to 1·00 in the increased resistance line and 0·87 with pooled data. Other effects on resistance included birth type and dam age, with twins and progeny of maiden dams being more resistant than their cohorts. Sex effects were unimportant for FEC but males had higher PCVD than females in most, but not all, years. Younger animals had higher FEC and PCVD than older animals. Maternal genetic effects were found to be unimportant, as were the effects of low levels of inbreeding.
141 citations
TL;DR: Two experiments investigated the welfare of pigs during transport and found that pigs appeared to stand to reduce travel sickness in the unmixed condition and in the mixed condition this preference for standing seemed to be due to fighting which stressed and exhausted the animals.
Abstract: Two experiments investigated the welfare of pigs during transport. In experiment 1, 12 groups offour 90-kg pigs were transported to slaughter in a commercial livestock lorry for 1·5 h. Half the animals were transported in their social groups (unmixed condition) and half were transported with groups of previously unfamiliar pigs mixed together (mixed condition). Behaviour was recorded, a general activity index scored and saliva samples taken at different stages of the journey for analysis ofcortisol. Pigs spent most of their time standing in both conditions. The journey was very rough (as revealed by characterization with an accelerometer) and in the unmixed condition the pigs appeared to stand to reduce travel sickness. In contrast, in the mixed condition, this preference for standing seemed to be due to fighting which stressed and exhausted the animals (the general activity index was three times the unmixed condition). Levels of salivary cortisol were higher in the mixed condition at the beginning, middle and end of the journey. In experiment 2, six 35-kg pigs, prepared in advance with jugular vein catheters, were loaded onto a commercial livestock lorry (09.30 h) where they were individually penned. The vehicle remained stationary with the engine off and blood samples were taken at 30-min intervals during the next 8 h (control). Two days later this procedure was repeated while the vehicle was driven for 8 h (on main roads and motorways). Plasma concentrations of cortisol and beta-endorphin increased markedly in both conditions immediately after loading. Cortisol levels were greater (relative to control) at the beginning, in the middle and at the end of the journey. Concentrations of beta-endorphin did not differ between control and experimental conditions except during the final 180 min of the journey when the control levels were higher.
132 citations
TL;DR: Forty primiparous Holstein dairy cows were monitored from calving through 100 days in milk to evaluate the effect of energy balance in the early post-partum period on subsequent fertility.
Abstract: Forty primiparous Holstein dairy cows were monitored from calving through 100 days in milk to evaluate the effect of energy balance in the early post-partum period on subsequent fertility. The post-partum interval to first ovulation (R2 = 0·41; P < 0·005) was lengthened by greater negative energy balance, and reduced by greater body weight at parturition or decreased body-weight loss during the experimental period. Luteal activity (R2 = 0·58; P < 0·0001), measured by plasma progesterone area under curve, was increased in the first cycle post partum by a shorter interval to first ovulation, improved energy balance during the 1st week of lactation and by decreased body-weight loss. Pregnancy status following first artificial insemination was related positively to the number of ovulations before insemination, improved energy balance during the 1st month post partum, fewer days to first ovulation and greater body weight at calving. These data suggest that energy balance and body weight are important in determining the post-partum interval to first ovulation and the subsequent fertility of first lactation dairy cotes.
115 citations
TL;DR: Compensatory mating turns out to be proportionately about 0-30 more effective than minimum coancestry matings for situations with low rates of inbreeding, such as phenotypic selection or high population size, although the advantage is less apparent if common environmental effects are important.
Abstract: Stochastic simulation is used to compare different systems of mating to reduce rates of inbreeding in selection programmes with phenotypic or animal model best linear unbiased prediction (BLUP) evaluation. Compensatory mating (the mating between individuals from the largest selected families to individuals from the smallest) turns out to be proportionately about 0-30 more effective than minimum coancestry matings for situations with low rates of inbreeding, such as phenotypic selection or high population size, although the advantage is less apparent if common environmental effects are important. A modification of this system of mating is proposed which can be applied for overlapping generations, and this is shown to reduce rates of inbreeding proportionately by about 0-50 more than for discrete generations. Under high inbreeding, however, such as for BLUP selection and small population size, minimum coancestry matings, or even avoidance of sib matings are more effective. A procedure combining compensatory and minimum coancestry matings is also simulated and gives the largest reductions in the rate of inbreeding. The effects of these and other systems of mating on the rate of inbreeding are shown to occur through a reduction in the cumulative effect of selection and a deviation from Hardy-Weinberg proportions.
114 citations
TL;DR: In this paper, the authors measured protein (PD) and lipid (LD) deposition rates according to comparative slaughter technique over the whole experimental period (experiments 1 and 2) and according to the nitrogen and energy balance technique at four stages of growth: 48, 64, 79 and 94 kg mean body weight.
Abstract: Between 45 and 100 kg body weight, Large White castrated males (cLW), and crossbred Pietrain × Large White castrated males fcPP×) and boars (bPP×) were either given food ad libitum in experiment 1 or allocated to four energy levels (0·70, 0·80, 0·90, 1·00 ad libitum) in experiment 2. Daily protein and amino acid supplies were calculated to be non-limiting for growth. Protein (PD) and lipid (LD) deposition rates were measured according to the comparative slaughter technique over the whole experimental period (experiments 1 and 2) and according to the nitrogen and energy balance technique at four stages of growth: 48, 64, 79 and 94 kg mean body weight (experiment 2). Average daily gain increased linearly with metabolizable energy (ME) intake, the slope of the relationship being significantly different between types of pig (from −28 to +36 g per additional MJ ME). Daily PD increased with ME intake above maintenance (MEp) according to a linear-plateau relationship in the three types of pig: the slope was significantly affected by type of pig (from +3·4 to 6·0 g per extra MJ MEp) but not by stage of growth. Daily LD increased linearly with MEp intake; neither the type of pig nor the stage of growth affected its slope (+13-5 g per extra MJ MEp). The LD/PD ratio in the extra body-weight gain associated with increased energy intake was affected only by the type of pig.
108 citations
TL;DR: The effects of spineless cactus supply on digestion of wheat straw was studied n rumen cannulated sheep and water consumption, food intake, digestibility, diurnal variations of ruminal fermentation and cellulolytic activity in the umen were measured.
Abstract: The effects of spineless cactus (Opuntia ficus indica var. inermis) supply on digestion of wheat straw was studied n rumen cannulated sheep. In addition to urea (10 g) and mineral and vitamin mixture (30 g), the animals — received wheat straw alone or supplemented with graded levels of spineless cactus (150, 300, 450 or 600 g dry natter (DM) per head per day). The diets were studied in five successive 25-day periods from February to June 992 in Tunisia. "Water consumption, food intake, digestibility, diurnal variations of ruminal fermentation (pH, mmonia nitrogen, volatile fatty acids, protozoal concentrations in rumen fluid) and cellulolytic activity in the umen were measured.Spineless cactus had high contents of ash (260 g/kg DM) and water (926 g/kg fresh weight) and low neutral-detergent fibre content (185 g NDF per kg DM). Crude protein (CP) content of spineless cactus was 2-5 times reater than that of wheat straw (58 v. 23 g/kg DM, respectively). Drinking water consumption was substantially educed (P < 0·001) as the level of spineless cactus increased. When spineless cactus supply exceeded 300 g DM peray, sheep consumed practically no drinking water. The voluntary intake of straw increased significantly with vineless cactus level. Total diet apparent digesibilities of DM, organic matter and CP tended to increase with mneless cactus supply. Such increase was significant only with the 450 and 600 g levels of cactus. NDF and acidetergent-fibre apparent digestibilities were not affected by spineless cactus supply. Addition of spineless cactus up i 300 g DM significantly increased ruminal ammonia nitrogen (P< 0·001) but there was no additional effect with irther supplementation. When sheep were supplemented with spineless cactus, total rumen volatile fatty acid icreased and acetate: propionate ratio decreased significantly. Moreover, spineless cactus supply increased total wtozoa number and reduced significantly rumen cellulolytic activity measured as DM and NDF disappearance of heat straw from incubated nylon bags.
105 citations
TL;DR: The halothane genotype had a significant effect on meat quality and the heterozygote produced much paler, softer and more exudative meat, however, the effect of cross and carcass weight was not significant for meat quality measurements determining pale, soft and exudatives meat.
Abstract: Carcass and meat quality traits were studied in 94 barrows of known HAL-1843 genotype (homozygote - - and heterozygote - +) from three crosses slaughtered at 90 kg and 120 kg live weight. Crosses A and B were produced from sires of which 0·5 of the genes were from a heavy-muscled × Large White line and 0·5 from pure Pietrain (A) or Duroc (B). Sows for both A and B were from a hyperprolific Large White × Landrace line and this latter line produced the pigs for cross C (control). The carcasses from cross A which were sired from boars having 0·75 of their genotype from heavy-muscled genetic lines had higher killing-out proportion, better conformation scores, greater loin depth and loin area, less carcass length and bone content, and greater lean proportion compared with cross C. The carcasses from cross B, with roughly 0·25 of Duroc genes had a significantly higher backfat thickness than either cross A or C. However their composition was not significantly different from C, since the higher backfat was counter-balanced by their better conformation. Carcass and lean weight distribution was more favourable in crosses A and B, which had significantly higher economic yields than cross C. The halothane genotype did not have a significant effect on fatness and carcass composition, although the heterozygote showed a significantly greater muscle depth. In addition, no significant effect of the halothane gene on carcass and lean weight distribution was observed. In relation to the light group of carcasses (72·8 (s.e. 4·4) kg), the heavy group (100·1 (s.e. 2·7) kg) had greater killing-out proportion, better conformation, longer carcasses, higher fatness and greater loin depth and area. These genetic lines showed a 9·6 g/kg increase in fat and a 6·1 g/kg decrease in lean for every 10 kg of increasing slaughter weight. With the slaughter weight increase the longissimus dorsi muscle became less pale due to a higher muscle pigment concentration, and the backfat had a higher proportion of oleic and lower proportion of linoleic and palmitic fatty acids. The halothane genotype had a significant effect on meat quality. The heterozygote produced much paler, softer and more exudative meat. However, the effect of cross and carcass weight was not significant for meat quality measurements determining pale, soft and exudative meat.
TL;DR: In this paper, the effects of road transport on stress hormone responses in pigs were investigated by loading seven 40-kg pigs onto a livestock lorry and transported over a 2-day period on routes characterized, by means of an accelerometer, as rough or smooth.
Abstract: Two experiments were made to investigate the effects of road transport on stress hormone responses in pigs. In experiment 1, seven 40-kg pigs, prepared with jugular catheters, were loaded onto a livestock lorry and transported over a 2-day period on routes characterized, by means of an accelerometer, as rough or smooth. Two 100-min journeys, one rough and one smooth, separated by a 100-min rest period, were conducted each day. The experimenters travelled with the animals and blood samples were taken for hormone analysis from each pig at 20-min intervals. On the 3rd day, samples were collected from the pigs when housed in their home pen (control). Plasma concentrations of cortisol increased after loading, remained higher for longer on rough compared with smooth journeys and were higher during both journeys on day 1 compared with day 2. Concentrations of beta-endorphin increased after loading on day 1 but neither beta-endorphin nor lysine vasopressin showed clear changes in secretion pattern during rough or smooth journeys. On day 3 (control), mean concentrations of all three hormones were significantly lower than on days 1 and 2, indicating that the responses observed were not due to a diurnal rhythm. In experiment 2, six 35-kg catheterized pigs were loaded on a lorry (09.30 h) that remained stationary while blood samples were taken at 30-min intervals during the next 8 h (control). Two days later, this procedure was repeated with the vehicle in motion for 8 h. Plasma concentrations of lysine vasopressin during driving increased between 2 and 4·5 h which coincided with behavioural observations indicating that the pigs were travel sick.
TL;DR: It is suggested that relatively short-term feeding of amino acid-deficient diets can produce substantial increases in intramuscular fat levels.
Abstract: The objective of the study was to investigate the influence of amino acid-deficient diets and high dietary leucine levels offered for intervals of either 21 or 35 days pre-slaughter on the intramuscular fat content of pig muscle. Twenty-four hybrid gilts were offered individually ad libitum one of four diets that comprised combinations of amino acid levels (supplemented or deficient: 5·6 v. 4·0 g lysine per kg) and low or high leucine levels (10·3 v. 30·3 g leucine per kg). Live weights at the start of the study were 74·5 and 87·0 kg for pigs on the 35- and 21-day feeding regimens, respectively. There were no significant effects of dietary amino acid level, leucine level, or feeding interval on food intake, daily live-weight gain or food efficiency. Pigs given the amino acid-deficient diets had lower killing-out proportions (736 v. 747 (s.e. 3·4) g/kg; P < 0·05) and longissimus dorsi muscle areas (32·6 v. 35·7 (s.e. 0·71) cm2, P < 0·01) than those given amino acid-supplemented diets. Subjective score for longissimus dorsi colour indicated that pigs on the high leucine diet had darker muscle than those on the low leucine diet. Intramuscular fat contents of the longissimus dors i muscle at the Wth/llth rib and the 3rd/4th lumbar vertebra and of the semimembranosu s muscle were increased by 19, 18 and 18 g/kg, respectively (P < 0·05), for pigs given amino acid-deficient compared with those given amino acid-supplemented diets. Dietary leucine level had no significant effect on intramuscular fat level. Pigs given the diets for 35, compared with 21, days had higher fat levels in the semimembranosu s muscle (52 v. 30 (s.e. 5·2) g/kg; P < 0·01) but not in the other two muscle locations studied. This study suggests that relatively short-term feeding of amino acid-deficient diets can produce substantial increases in intramuscular fat levels.
TL;DR: In this article, the authors measured the time taken to lie down and stand up by 32 sows in two dry-sow housing conditions and related to physical and genetic parameters, and found that stall-housed sows had strongest association with body length and the proportion of muscle weight to total body weight.
Abstract: The time taken to lie down and stand up was determined for dry sows from different housing systems and related to physical and genetic parameters. In experiment 1, the times taken to lie down by 32 sows in two dry-sow housing conditions were measured. Sows housed long-term in stalls took longer to lie down than group-housed sows (20·42 v. 9·28 s, P < 0·001). Group-housed sows took longer to lie down in the open than to lie down against a wall (11·07 v. 7·48 s, P = 0·004). The length of time taken for stall-housed sows to lie down had strongest association with body length (P = 0·033, R2 = 0·718). The length of time taken for group-housed sows to lie down in the open had strongest association with the proportional weight of the extensor carpi radialis, (P = 0·001, R2 = 0·915). In experiment 2, the times taken for 30 sows in stalls to lie down and stand up were measured and genotype differences investigated. There were no differences between genotypes in total times taken to stand up or lie down, but total times taken to stand up quickly and lie down had strongest association with body length (P = 0·032, R2 = 0·185, and P < 0·001, R2 = 0·574 respectively). The results indicate that sows housed long-term in gestation stalls experience difficulty of movement when standing up quickly and lying down. Although the chronic effects of lack of exercise and the acute effects offloor type may contribute to this difficulty, the major factor is likely to be space restriction as the times taken to lie down and stand up quickly both increase as body length, and hence dynamic space requirement, increases. Lying down in an unrestricted environment is under muscular control and the degree of control depends on the proportion of muscle weight to total body weight. The factors affecting lying down and standing up should be considered when designing dry-sow and farrowing accommodation.
TL;DR: The results indicate that confinement of sows, with a consequent lack of exercise, results in reduction of muscle weight and considerable reduction of bone strength.
Abstract: Confinement has been shown to affect bone strenth in poultry but this weakness has not been documented in other species housed in confinement. The objectives of this experiment were to compare muscle weight and bone strength in non-pregnant sows, of similar age and parity, housed throughout eight or nine pregnancies in two different dry sow systems: (1) individually in stalls and (2) communally in a large group. Following slaughter, the left thoracic and pelvic limbs were dissected and 14 locomotor muscles removed and c. ???lied. A proportional muscle weight was then calculated by dividing individual muscle weight (g) by total body weight (kg). Where there were significant differences, stall-housed sows had lower absolute and proportional muscle weights than group-housed sows. The left humerus and femur were also removed. The bones were broken by a three-point bend test using an Instron Universal Tester. Both bones from stall-housed sows had breaking strengths that were about two-thirds those of group-housed sows. The results indicate that confinement of sows, with a consequent lack of exercise, results in reduction of muscle weight and considerable reduction of bone strength.
TL;DR: Under the conditions of this study, sheep with a live weight of 35 kg can be transported for 12 h at space allowances of between 0·22 and 0·41 m2 per sheep without showing major physiological changes indicative of injury and dehydration, but the sheep appeared to be hungry after 12 h without food and showed a cortisol and heart rate response to transport, indicating that some aspect of transport was acting as a stressor.
Abstract: There is limited information on the behavioural and physiological responses of sheep to the components of road transport. Behavioural observations and physiological measurements of ‘stress’, injury and dehydration were made on weaned lambs (35 kg) before, during and after either stationary confinement or transport for 22 h at four space allowances (0·22, 0·27, 0·31 and 0·41 m2 per sheep). Two groups were not loaded (a control group with access to food and water, and a group with no food and no water for 12 h). During the confinement and transport period, the proportion of scans spent lying and the proportion of scans spent ruminating was significantly less than that before treatment (P 0·05). Under the conditions of this study, sheep with a live weight of 35 kg can be transported for 12 h at space allowances of between 0·22 and 0·41 m2 per sheep without showing major physiological changes indicative of injury and dehydration. However, the sheep appeared to be hungry after 12 h without food and showed a cortisol and heart rate response to transport, indicating that some aspect of transport was acting as a stressor. A space allowance of 0·22 m2 per sheep cannot be recommended for 35 kg sheep as there is insufficient space for most of the sheep to lie down during transport. Whereas a space allowance of at least 0·27 m2 per sheep does allow most sheep sufficient space to lie down.
TL;DR: In this paper, five published equations were compared on their ability to adjust different patterns of lactation curves, including season (SE) and pregnancy (PE), and the final equation was equal to (i) + SE + PE with SE = a + b cos (2π(wc + w - l)/52) + c sin(2n(w c + w − 1)/52), with wc= week of the year at calving, w = week after calving and a = 0·0065, b = -1·26 and c
Abstract: Five published equations were compared on their ability to adjust different patterns of lactation curves. The equation y(t) = a exp(b1t'2/2 + b2/t – c(l + t'/2)t') with t' = (t – 21·4)/l00 (i) was retained because of the quality of the adjustment and the absence of convergence problems when applied on individual curves. Including an effect of season (SE) and an effect of pregnancy (PE) improved the quality of individual adjustments (no. = 339). The final equation was equal to (i) + SE + PE with SE = a + b cos (2π(wc + w - l)/52) + c sin(2n(wc + w - 1)/52), with wc= week of the year at calving, w = week after calving and a = 0·0065, b = -1·26 and c = 0·374, and PE = a (wp –18) e-bwp, with w p = week of pregnancy and a, b fixed parameters. Individual cow characteristics were used to analyse equation (i) parameters. The predictions obtained with this equation and several predictive functions of the equation (i) parameters, which differed in the way they included or not the potential of production, were compared. With no indication of this potential, the prediction was very poor. With the initial production (mean production of the 4th, 5th and 6th days of lactation) as an estimate of this potential, 75% of the lactations had the median of absolute values of errors less than 2·95 kg/day. The results were highly improved by using the yield during the 5th week of lactation. The threshold of 2·95 was reduced to about 2 kg/day. The quality of the individual prediction was better for primiparous than for multiparous cows, and for French Friesian and Montbeliarde cows than for pure or crossbred Holstein cows. Although individual predictions were not always satisfactory, they provided excellent agreement when averaged per group (20 cows).
TL;DR: The behaviour of two groups of pigs in concentrations of ammonia gas that are frequently recorded in piggeries (0, 10, 20 and 40 p.p.m.), was continuously observed for 14 days each in a choice test as discussed by the authors.
Abstract: The behaviour of two groups offour pigs in concentrations of ammonia gas that are frequently recorded in piggeries (0, 10, 20 and 40 p.p.m.), was continuously observed for 14 days each in a choice test. An octagonally shaped (annular), eight compartment preference chamber was built to house the pigs. Each compartment supplied the pigs with ample food, water and bedding material but differed in the level of atmospheric contamination. Adjacent compartments were separated by plastic curtains, allowing the pigs free access to neighbouring compartments while reducing cross-contamination of the pollutant. The position of the contamination was changed weekly to eliminate positional preferences. The location of the pigs was scan sampled every 15 min and their behaviour at this time was instantaneously recorded. A significantly greater proportion of their time was spent in the unpolluted compartments (53·4%) than in the 10 p.p.m. (26·9%), 20 p.p.m. (7·1%) or 40 p.p.m. (5·1%) compartments (P 0·05). The occupancy pattern was resumed following the rotation of the ammonia concentrations and/or following cleaning (P > 0·05). Higher concentrations of ammonia were visited less often (P = 0·005) and once there, the pigs stayed for a comparatively shorter time (P = 0·003) for approximately 35 min. As the aversion was not immediate, it is suggested that aversion was not due to the odour of ammonia initially experienced on entry. Instead the insidious aversion may be due to a sense of malaise that may develop while a pig is in a polluted atmosphere. The pigs chose to rest (P = 0·002), sit (P = 0·007), feed (P = 0·007) and forage (P = 0·013) more in the unpolluted compartments. Overall more feeding behaviour was observed in the fresh air and more food was consumed in these compartments of the chamber (P = 0·002).
TL;DR: Neither gliricidia nor leucaena supplel1lentation affected the apparent digestibility of the diet or in sacco DM degradation characteristics of the forages, but since the responses were linear, further experiments are required to quantify the responses to higher levels of these legume supplements.
Abstract: Two experiments were carried out to evaluate the effect of incrementa/levels of Gliricidia sepium (gliricidia) and Leucaena leucocephala (leucaena) on forage intake, diet apparent digestibility, microbial nitrogen supply and live-weight changes in cattle. In each experiment, 20 intact and five fistulated crossbred steers (Bos taurus X 80S indicus) were used. Napier grass basal diet was offered ad libitum alone or supplemented with 7.5, 15, 22.5, or 30 g dry matter (DM) per kg metabolic body weight (MO75) gliricidia (experiment 1) or leucaena (experiment 2). In experiment 1, total DM intake increased but not significantly with gliricidia supplementation (5.2,5.1,5.2,5.4, 5.7 (s.e.d. 0.21) kg/day) while intake of napier grass was depressed linearly (5.2, 4.7, 4.5, 4.3, 4.2 (s.e.d. 0.21) kg/ day; P < 0.05). In experiment 2, supplementation with leucaena increased the total DM intake linearly without depressing the intake of napier grass (5.2, 5.8, 6.2, 6.6, 6.7 (s.e.d. 0.31) kg/day; P < 0.001 and 5.2, 5.3, 5.3, 5.3, 5.0 (s.e.d. 0.21) kg/day respectively). Neither gliricidia nor leucaena supplel1lentation affected the apparent digestibility of the diet or in sacco DM degradation characteristics of the forages. Rumen ammonia and live-weight gain were increased linearly (P < 0.05) by supplementation from 130 to 215 mg/l (experiment 1) and 75 to 113 mg/l (experiment 2), from 306 to 478 g/day (experiment 1) and from 538 to 850 g/day (experiment 2), respectively. However, since the responses were linear, further experiments are required to quantify the responses to higher levels of these legume supplements.
TL;DR: In this article, 16 varied grass silages were offered to early-lactation dairy cows (12 per experiment) along with a fixed allocation of 7 kg/day of a standard concentrate.
Abstract: Sixteen varied grass silages metabolizable energy (ME): 9·76 to 11·99 MJ/kg ethanol-corrected toluene dry matter (TDM); crude protein (CP: 149 to 211 g/kg TDM; lactic acid: 3·5 to 134·7 g/kg TDM; butyric acid 0·4 to 46·7 g/kg TDM) were offered ad libitum to early-lactation dairy cows (12 per experiment) along with a fixed allocation of 7 kg/day of a standard concentrate. Four silages were offered in each of four incomplete change-over design experiments with three 21-day periods. This design meant that each cow was allocated to receive three of the four silages evaluated in that experiment. ME intake ranged from 108 to 262 MJ/day (mean 177 (s.d. 30·2)). Similar variation was obtained with milk yields (mean 26·5 (s.d. 4·36) kg/day), fat content (mean 37·7 (s.d. 5·60) g/kg) and protein content (mean 29·0 (s.d. 2·36) g/kg). Urinary purine derivative/creatinine ratio (PD/C), an index of microbial protein measured in spot samples (two per day) averaged 2·92 (s.d. 0·757) mol/mol. Allantoin made up an almost constant molar proportion of PD excretion (mean 0·876 (s.d. 0·0377)), with a small but significant (P < 0·001) decline of 0·0132 (s.d. 0·003) per unit increase in PD/C.
Maximal utilization of silage nitrogen occurred with silages having higher ME and lower CP concentrations. Urinary PD/C suggested that microbial protein yield varied in a way which would not be predicted in current schemes and that it was a major source of variation in milk protein yield under the conditions of the present experiment. Principal components regression confirmed independent effects of ME supply and MP supply (indexed by urinary PD/C) on milk protein yield. Further work should pursue the possibility of using the urinary PD/C technique to refine protein feeding at the farm level.
TL;DR: It is concluded that oral stereotypies in dairy cows are highly affected by feeding strategy, where restrictive feeding of a mixed food induces significant increases of stereotypies.
Abstract: The aim of the present study was to investigate the effect of feeding strategy on the performance of oral stereotypies, such as tongue-rolling and bar-biting, and other behaviours in lactating dairy cows. Thirty–seven cows of the Swedish Red and Wliite breed were randomly assigned into three treatments with different feeding strategies. Cows in treatment (AL) were given food ad libitum during the whole experimental period, which lasted from weeks 3 to 26 post partum. The second group (AL–R) was given food ad libitum during weeks 3 to 14 post partum, thereafter they were given food at a restricted level. The third group (R) was given food at a restricted level during the whole experiment period. All cows were offered a total mixed ration consisting of 650 g concentrate and 350 g forage per kg twice a day and their individual daily food intakes were registered. Behavioural recordings were made for 4 h on a fixed day every 2nd week, where each individual cow was observed every 2nd minute.During the complete experimental period, 27 out of the 37 cows showed stereotypies; 13 cows in group R, 10 in group AL–R and four in the AL group. The proportions of cows showing stereotypies were not independent of feeding treatment within the respective periods (P < 0·01). The stereotypy levels, counted as the mean frequency of recordings per treatment period, increased significantly between period 1 (lactation weeks 3 to 14) and period 2 (weeks 17 to 26) in group AL–R (P < 0·01) and in group R(P < 0·01), but not in the AL group. In period 2 the R cows had significantly higher stereotypy levels than the cows in the AL–R group (P < 0·01). Group R decreased the time spent eating between the periods (P < 0·001), with the same tendency in group AL–R. The AL group had longer eating time in period 2 than the AL–R (P < 0–001) and the R (P < 0·001) cows. The AL cows had a higher frequency of rumination than the other treatments in period 2 (P < 0·01). Both the AL–R and the R cows increased their activity levels between the periods (P < 0·001 for both). There were also differences between treatments in period 2, where the AL cows were less active than the AL–R (P < 0·05) and the R cows (P < 0·01).It is concluded that oral stereotypies in dairy cows are highly affected by feeding strategy, where restrictive feeding of a mixed food induces significant increases of stereotypies. The results of this investigation clearly indicate that restricted feeding of a diet with high levels of concentrate has a negative effect on the well being of lactating cows.
TL;DR: Production and hatchability of over 1200 ostrich eggs on a farm in the United Kingdom were recorded during the 1995 season, and Hatchability is lower, and microbial contamination is higher than published information although this is the most comprehensive study of ostrich production yet published.
Abstract: The farming of ostriches is well established in South Africa and is gaining in popularity in agriculture around the world but few scientific data are available for rates of egg production and the factors affecting incubation and hatching. Production and hatchability of over 1200 ostrich eggs on a farm in the United Kingdom were recorded during the 1995 season. Females of breeding ages (no. = 43) were kept in 13 enclosures in sex ratios of 1: 1 or 1: 2 (M: F). Productivity of all ostriches over the laying season was 25·2% although when results from individual enclosures, and from individual birds, were examined higher rates of production were achieved although only one bird achieved her full laying potential. As group size increased productivity decreased. Overall fertility was 78·7% although fertility greater than 90% was achieved by females kept in pairs or trios. Larger group sizes had lower fertility. Mean weekly hatchability was only 24·1% with hatch of fertile eggs being 31·9%. Maximum hatchability of eggs produced from an individual female was 73% of fertile eggs. Microbial contamination of eggs was 32·6% and this was the biggest cause of failure to hatch, although rates of contamination varied between females. These results for productivity are similar to those published for ostriches in Israel and South Africa. Hatchability is lower, and microbial contamination is higher than published information although this is the most comprehensive study of ostrich production yet published. Future development of ostrich breeding programmes needs to concentrate on small breeding groups, preferably pairs, and on improvements in nest site hygiene and post-laying egg management.
TL;DR: The study offarm animal cognition tells us little about the issue of animal consciousness but, none the less, plays an important role in the animal welfare debate.
Abstract: Although there may be task-specific differences in performance between wild and domestic animals, there is no evidence for any generally reduced cognitive capacity in domestic animals. It is not possible to compare intelligence between species or breeds without recognizing the contribution of differences in attention and motivation, and domestic animals often perform better on learning tasks than wild animals because they are less fearful. Considerable flexibility and complexity in behaviour can arise from context-specific decisions that may not require learning. Examples include alarm calling and maternal behaviour in chickens. However, the majority of intelligent behaviour shown by farm animals is dominated by learned associations, sometimes in response to remarkably subtle cues. Seemingly straightforward learning abilities may result in surprising emergent properties. An understanding of these properties may enable us to investigate how farm animals interact socially, and whether they form concepts. Other abilities, such as imitation and the re-organization of spatial information, do not appear to depend on associative learning. The study offarm animal cognition tells us little about the issue of animal consciousness but, none the less, plays an important role in the animal welfare debate. The types of cognitive abilities animals have provide clues as to the types of situations in which (given the benefit of the doubt) they might suffer.
TL;DR: In this paper, the authors used polynomial models with random regression coefficients to describe food intake and gain as a function of number of days on test for gilts and castrated male pigs which were on test from 30 to 115 kg live weight.
Abstract: Polynomial models with random regression coefficients were used to describe cumulated food intake and gain as a function of number of days on test for gilts and castrated male pigs which were on test from 30 to 115 kg live weight. Growth rate and daily food intake were expressed as the derivative of the curves. The applied models allowed a separation of between and within animal variation. Confidence limits for average curves and prediction limits for individual curves were also obtained. A similar model was used to describe gain as a function of cumulated food intake. From this function food efficiency was obtained. The application of the results in stochastic simulation models is discussed.Growth rate and daily food intake had a more curvilinear progress for castrated males than for gilts. It was estimated that 98% of the castrated males and 96% of the gilts had a lower growth rate at day 80 than at day 50; 74% of the castrated males and 48% of the gilts had a lower daily food intake at day 100 than at day 80. On average food efficiency of gilts was higher than food efficiency of castrated males and the difference increased through the test period.
TL;DR: A threshold of milk acetone at which cows tend to be adversely affected is assessed, which is about 190 kg of 40 g/kg fat-corrected milk (FCM) less in cows with acetone concentrations >l·4 vis-a-vis l·4 mmol/l.
Abstract: Acetone concentration in milk is correlated with subclinical and clinical ketosis and also with milk yield and reproductive efficiency. The purpose of this study was to assess a threshold of milk acetone at which cows tend to be adversely affected. The critical values were estimated on data from 11690 lactations where the change in daily milk yield from weeks 1 to 2 to weeks 5 to 6 of lactation was evaluated in relation to different milk acetone concentrations. Daily milk yield tended to be reduced in cows with acetone concentrations between 0·7 and 1·4 mmol/l, but responses were not entirely consistent. At concentrations >l·4 mmol/l, daily milk yield was clearly reduced. Long-term milk yield (day 0 to 100 and day 0 to 200) was about 190 kg of 40 g/kg fat-corrected milk (FCM) less in cows with acetone concentrations >l·4 vis-a-vis l·4 mmol/l; 4·9 days longer interval from calving to first service (first parity and parity 2+ cows) and 5·7 times a greater risk of cystic ovaries (parity 1), compared with cows with milk acetone <0·7 mmol/l. However, no significant effects on long-term milk yield or on reproductive efficiency were found in cows with acetone concentrations 0·7 to 1·4 vis-a-vis <0·7 mmol/l. The results suggest that 1·4 mmol/l acetone in milk may be used as the most important critical value, as higher concentrations are detrimental to productivity. The interval 0·7 to 1·4 mmol acetone per I milk may be used as a warning class, since early lactation yield may be reduced.
TL;DR: It was concluded that the SA feeding regime was superior in terms of sow performance, despite an increased incidence of agalactia symptoms.
Abstract: Effects of a two-diet system combined with ad libitum lactation feeding of sows on food consumption, sow live weight (LW), backfat depth, condition scoring, rebreeding interval, symptoms of agalactia and culling were studied on 60 sows followed for four parities. Feeding regimes were: CR, conventional i.e. restricted during gestation and lactation; SA, a simplified diet offered at a restricted level during gestation and a conventional diet ad libitum during lactation; CA, conventional during gestation and the same diet ad libitum during lactation. During lactation CR sows consumed 5·9 kg food daily (71 MJ metabolizable energy (ME)), whereas SA and CA sows consumed on average 7·0 kg (85 MJ ME), the difference being larger in multiparous than in primiparous sows and larger in the first than in later weeks of lactation. From the second farrowing onward sows on CR treatment were lighter and had thinner backfat and lower condition scores than sows on CA treatment, with sows on SA treatment in between, i.e. approaching the CR sows in the gestation periods and the CA sows in the lactation periods. At first service LW was 130 kg and backfat thickness 14 mm. During the fourth lactation LW averaged 190 kg in CR sows and around 220 kg for SA and CA sows, and backfat thickness was 11 mm in CR sows and around 16 mm in SA and CA sows. SA sows tended to rebreed earlier after weaning than did CR or CA sows. CA sows and in particular SA sows had higher incidences of agalactia symptoms and higher rectal temperatures post partum than CR sows. The culling rates did not differ between feeding regimes, although the predominant causes for culling did, being shoulder lesions and abscesses in thin CR sows and leg disorders in SA and CA sows. At the end of the experiment, however, more SA sows than others were retained in the experimental herd. It was concluded that the SA feeding regime was superior in terms of sow performance, despite an increased incidence of agalactia symptoms.
TL;DR: Increased energy intake was associated with increased fatness of body-weight gain, which was higher in cLW and cPP× than in bPP×, and the type of pig significantly affected the slope of the relationship between lean gain and ME intake.
Abstract: The effect of energy supply on physical composition of body weight gain between 45 and 100 kg was studied in Large White castrated males (cLW), crossbred Pietrain × Large White castrated males (cPPX) and boars (bPPX). The pigs were either given food ad libitum and kept in individual pens in experiment 1, or allocated to four energy levels (0·70, 0·80, 0·90, and 1·00 ad libitum ) and kept in metabolism cages in experiment 2. Daily protein supplies were calculated to be the same at the four energy levels within each type of pig and non-limiting for growth. Five additional animals for each type of pig were slaughtered at 45 kg. Daily tissue gain was measured according to the comparative slaughter technique. The daily lean gain increased with metabolizable energy (ME) intake according to a linear-plateau relationship whereas the daily fat gain increased linearly. The type of pig significantly affected the slope of the relationship between lean gain and ME intake (from 15 to 22 g per extra MJ ME) but not the slope of the relationship between fat gain and ME intake (10 g per extra MJ ME on average). Increased energy intake was associated with increased fatness of body-weight gain, which was higher in cLW and cPP× than in bPP×.
TL;DR: In this article, the effect of a progressive substitution of grape pomace (GP) for alfalfa hay (AH) at the rates 0, 100, 200 and 300 g/kg total weight was studied.
Abstract: Four diets were formulated to study the effect of a progressive substitution of grape pomace (GP) for alfalfa hay (AH) at the rates 0, 100, 200 and 300 g/kg total weight. The control diet contained 500 g AH and 192 g acid-detergent fibre per kg dry matter (DM). In experiment 1, 32 Californian × New Zealand White rabbits were used to determine dietary nutrient apparent digestibility. The inclusion of GP decreased the apparent digestibility of crude protein (P 0·10) by the diet, but the ratio gain: food linearly decreased (P < 0·001) with the GP inclusion. Dietary inclusion of GP linearly increased (P < 0·10) the fat content of the empty body of the rabbits. The efficiency of utilization of dietary DE and protein for growth were calculated by the comparative slaughter method, using the chemical body composition data of 22 suckling rabbits slaughtered at 30 days of age for the initial body composition. The efficiency of utilization of DE was not influenced by dietary GP inclusion, but GP linearly increased (P < 0·01) digestible crude protein utilization. The decrease in crude protein apparent digestibility may be the main reason that gain: food ratio was impaired in diets containing GP substituted for AH.
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Abstract: Effects of feeding a protein supplement to dairy cows during the dry period on performance during the following lactation were investigated in two experiments. Holstein-Friesian cows were paired towards the end of lactation, and, after drying off, one of each pair received a typical dry cow management regime of ad libitum grass silage (experiment 1), or a mix of grass silage and distillers' grains or pressed beet pulp (experiment 2). The other cows were offered restricted access to the same basal diet, together with ad libitum access to barley straw and 0·5 kg/day high protein maize gluten meal. During the following lactation, animals from both groups were treated without reference to dry period treatment, and were offered equal access to the same lactation diet. Data were analysed by analysis of variance of experiment means and by parallel curve analysis using sample means. In experiment 1, milk yields were similar (27·2 v. 27·9 (s.e.d. 2·12) kg/day for control and supplemented animals respectively) but milk protein yields, and hence concentrations, were significantly higher (P < 0·001) from supplemented animals (28·9 v. 31·8 (s.e.d. 0·58) g/kg). In experiment 2, milk yields were significantly higher (P < 0·001) from supplemented animals (mean 33·3 v. 35·4 (s.e.d. 1·66) kg/day; however, milk protein yields were also significantly increased (P < 0·001) and the change in milk protein concentration was small. No difference in dry-matter intake was recorded in a subset of animals during early lactation in experiment 2. It is hypothesized that the maternal labile body protein pool was maintained or replenished during the dry period by the provision of the protein supplement, and that this had a significant effect on subsequent lactation performance.
TL;DR: In this article, the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) on growth performance and body composition of boars, gilts and castrated males from 25 to 90 kg live weight were examined.
Abstract: An experiment was conducted to examine the effects of dietary lysine/digestible energy (DE) ratio (g/MJ) on growth performance and body composition of boars, gilts and castrated males from 25 to 90 kg live weight. Twelve pigs (four of each sex) were assigned to each dietary treatment consisting of lysine/DE ratios from 0·4 to 1·4, in 0·2 g/MJ increments. Food was provided at proportionately 0·90 ad libitum and at 90 kg all pigs were slaughtered and the body composition of two pigs per sex per treatment was determined. Responses to lysine/DE ratios were similar for all sexes up to the optimum level after which daily live-weight gain (DLWG) and nitrogen deposition rate (NDR) deteriorated in gilts and castrated males. This deterioration may have been due to energy used for deamination of excess protein not being availablefor growth processes. Lipid deposition rate (LDR) remained constant from the 0·4 to 0·8 g/MJ lysine/DE ratios and then decreased sharply to a lower plateau from the 1·0 to 1·4 g/MJ lysine/DE ratios suggesting that DE levels were adequate to meet NDR requirements up to the 1·0 g/MJ lysine/DE ratio when it became limiting. The optimum lysine/DE ratio for the genotype tested from 25 to 90 kg live weight was of the order of 0·95 to 1·0 g/MJ. The maximum NDR of the genotype tested appears to be of the order of 28 to 30 g/day (175 to 187 g/day protein deposition rate).