Showing papers in "Animal Science in 2001"

Effect of double-muscling in Belgian Blue young bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic acid and polyunsaturated fatty acids

Abstract: The effect of double-muscling (DM) genotype (double-muscling, mh/mh; heterozygous, mh/+; normal, +/+) of Belgian Blue (BB) young bulls on the intramuscular fatty acid composition, in particular conjugated linoleic acid (CLA) and polyunsaturated fatty acids (PUFA) was examined in five different muscles. The relative fatty acid composition showed only minor differences between muscles within genotypes. However, the DM genotype had a large effect on both the intramuscular total fatty acid content and on the relative fatty acid composition. Across muscles, the mh/mh animals had a lower total fatty acid content compared with the +/+animals (907 v: 2656 mg/100 g muscle; P < 0·01) and a higher PUFA proportion in total fatty acids (27·5 v 11·3 g/100 g total fatty acids; P < 0001), resulting in a higher PUFA/saturated fatty acid ratio (0·55 v 0·18; P < 0·01) and a lower n-6/n-3 ratio (5·34 v. 6·17; P < 0·01). The heterozygous genotype was intermediate between the two homozygous genotypes. The relative CLA content was similar in the mh/mh and +/+ genotypes and approximated 0·4 to 0·5 g/100 g total fatty acids. From the data it is further suggested that differences in the metabolism of the n-3 and n-6 fatty acids could exist between DM genotypes.

The influence of sow behaviour on piglet mortality due to crushing in an open farrowing system

Abstract: The objectives of this study were to establish what changes in posture by sows carried a high risk of piglet crushing in a group farrowing system during early lactation and also to determine what factors influenced the risk of crushing during lying down. A total of 24 Large White ✕ Landrace sows were studied during the first 7 days of lactation in a group farrowing system. Cross-fostering was not carried out so as not to influence behaviour. Dead piglets were removed and cause of death ascertained from external observation and post-mortem examination. Sow and piglet behaviour was video-recorded continuously. A total of 268 piglets were born alive, with 67 liveborn piglets subsequently dying during the 7-day experimental period, 50 as a result of crushing. A total of 7425 posture changes were analysed and 11 types of posture change were identified, the most dangerous being lying down from standing and those involving swapping sides, or rolling over, whilst lying. Dangerous events during lying down were more likely to occur (1) in the first 24 h after farrowing, (2) when the sow lay down in the middle of the pen, (3) when the sow lay down without carrying out much piglet-directed pre-lying behaviour and (4) when the piglets were spread out but near to the sow. The amount of pre-lying behaviour decreased over time and crushing mortality also decreased. The results confirm that the piglets are most vulnerable to crushing during the first 24 h of life, when they are spending much of their time near the udder and have relatively poor mobility. Co-ordination of behaviour between the sow and her litter is important to reduce the risk of crushing. It is also important that the design of open farrowing systems incorporates knowledge about how crushing deaths occur in order to improve piglet welfare.

Microbial activities of faeces from unweaned and adult pigs, in relation to selected fermentable carbohydrates

Abstract: A comparison of in vitro microbial activity was made between inocula from faeces of adult and unweaned pigs, using a range of carbohydrate-rich substrates. The substrates tested were classified into groups (fibre-rich, grains, gums, pectin, saccharides, storage carbohydrates, and miscellaneous). Proximate and fibre analyses were determined for all substrates tested. Fermentation kinetics were measured according to the cumulative gas production technique. End-point products such as gas, volatile fatty acids and ammonia were also determined. The faeces from the adult pigs (ATF) were collected from four castrated finisher pigs (Dutch Landrace × Great Yorkshire). These were offered a diet based on highly digestible maize starch and fish meal, so as to be as free as possible of fermentable carbohydrates. The unweaned piglet faeces were collected from 19 unweaned piglets (male and female) which were 27 to 30 days old. The parameters were tested for significance by an analysis of variance using the Tukey's studentized range test of multiple comparisons. There were significant differences in the fermentation patterns both due to source of substrate and inoculum. It would appear that the metabolic activity of the microflora does differ significantly between adult and weanling pigs, though this varied for the different carbohydrates tested. Suggestions are made as to how to select potential carbohydrate ingredients for an in vivo experiment, based on their in vitro fermentation characteristics.

Effectiveness of exogenous microbial phytase in improving the bioavailabilities of phosphorus and other nutrients in maize-soya-bean meal diets for broilers

Abstract: A 3-week feeding trial using 300 1-day-old male broiler chicks was conducted to evaluate the effects of adding three levels of a microbial phytase (Finnfeed phytase; 250, 500 and 1000 U per kg diet) to a maize-soya-bean-meal diet containing 3·0 g/kg non-phytate phosphorus and 8·0 g/kg calcium. A diet containing 4·0 g/kg non-phytate phosphorus and 9·0 g/kg calcium served as the positive control. The responses were evaluated in terms of broiler performance, toe ash contents, ileal phytate degradation, ileal digestibility of nitrogen, amino acids, phosphorus, starch and fat, apparent metabolizable energy, apparent ileal digestible energy, and apparent retention of phosphorus and nitrogen. The addition of 500 U phytase per kg diet to the phosphorus-deficient maize-soya-bean-meal diet improved the performance and toe ash contents of broilers to equal those given the positive control diet. Ileal phytate degradation data provided direct evidence to the efficacy of phytase in hydrolysing the phytic acid. Addition of 500 U phytase per kg to the maize-soya-bean-meal diet which contained 3·0 g phytate-phosphorus per kg resulted in more than doubling of phytate degradation from 0·218 to 0·481. Supplemental phytase improved ileal digestibility of nitrogen, amino acids, starch and lipids, with these improvements being eventually reflected in enhancements in ileal digestible energy and apparent metabolizable energy.

Observations on the pre- and post-weaning behaviour of piglets reared in commercial indoor and outdoor environments

Abstract: A number of behavioural problems are associated with weaning piglets including belly nosing, ear and tail biting, and low intake of solid food. These appear to be less pronounced in piglets reared on outdoor systems, which initially consume more solid food and show less belly nosing and aggression than comparable indoor-reared piglets. The objective of this study was to investigate how these differences in post-weaning behaviour relate to the piglets’ pre-weaning behaviour in the two rearing environments. The study was carried out at a commercial pig unit, where piglets of the same genotype are born into conventional indoor or outdoor farrowing systems. In the intensive system, sows were singly housed prior to farrowing in crates and their piglets received a solid ‘creep’ food prior to weaning. On the outdoor system, sows were allowed to build straw nests in arks for farrowing and both sow and piglets had access to pasture. Indoor and outdoor piglets were weaned at 24 (±3) days of age and mixed in straw-yard housing with access to a solid food. Prior to weaning, teat-directed activity was more common in indoor piglets than outdoor piglets. Outdoor piglets performed more rooting, standing and locomotion and were seen chewing the sows’ roll-nuts. Following weaning, outdoor-reared piglets performed more feeding and rooting, and less fighting than indoor-reared piglets. This study supports previous findings that undesirable activities such as fighting are less common in piglets weaned from outdoor systems, even when mixed with indoor piglets. In addition, outdoor-reared piglets were more likely to exploit solid food even though they did not have access to creep food prior to weaning.

The effect of feeding salmon oil to sows throughout pregnancy on pre-weaning mortality of piglets

Abstract: Salmon oil (16·5 kg /t), a source of long-chain polyunsaturated n-3 fatty acids, was included in diets offered to multiparous sows during pregnancy and lactation to measure responses in pre-weaning mortality and performance of piglets in two studies. The first study, carried out under commercial conditions, included 196 sows which were offered salmon oil and control diets from immediately post service until weaning. The same diets were also offered to 10 sows per treatment from day 58 of pregnancy in a controlled nutritional study which measured the effects of salmon oil on piglet tissue fatty acid composition. Offering salmon oil to the sow significantly increased gestation length and decreased individual piglet birth weight but had no effect on litter size at birth. Overall, salmon oil reduced pre-weaning mortality from 11·7% to 10·2% mainly by reducing the incidence of deaths from crushing by the sow. More detailed analysis of mortality using a general linear mixed model and 2294 piglet records, demonstrated that the incidence of pre-weaning mortality was significantly decreased with increasing individual piglet birth weight and by inclusion of salmon oil in the diet; the incidence of mortality increased with average piglet birth weight in a litter. Salmon oil inclusion had no effect on weight of litter weaned, sow lactation food intake or subsequent reproductive performance. In both studies, dietary salmon oil increased the proportions of long-chain n-3 polyunsaturated fatty acids in colostrum to a similar extent. In the nutritional study, inclusion of salmon oil reduced the proportions of 20: 4 n-6 in piglet liver and brain at birth and increased the proportions of long-chain n-3 polyunsaturated fatty acids. Therefore, despite reducing piglet birth weight, offering sows salmon oil reduced pre-weaning mortality of piglets. The nutritional study showed that the amount and type of marine oil used may not have been optimal.

Effect of the level of concentrate supplementation, herbage allowance and milk yield at turn-out on the performance of dairy cows in mid lactation at grazing

Abstract: In order to establish the response of dairy cow performance to concentrate supplementation in contrasting grazing conditions and for cows differing in milk yield at turn-out, three experiments were conducted. Each year, two levels of herbage allowance were studied in interaction with four (experiment 1) or three (experiments 2 and 3) levels of concentrate on two groups of 30 to 40 mid-lactation Holstein cows producing between 20 and 46 kg milk at turnout. Amount of concentrate and herbage allowance ranged from 0 to 6 kg fresh weight and from 12 to 22 kg dry matter (DM) per cow per day respectively. The supplementation led to average responses, per kg DM concentrate, of 104 kg milk, +66 g/day body-weight gain, +0·19 g/kg milk protein and -0·57 g/kg milk fat. These responses remained linear up to 4 or 6 kg according to the years and treatments. The response to the concentrate did not vary with the milk yield or composition at turn-out. The increase in the herbage allowance from 12 to 16 kg DM per cow per day (experiment 1) improved milk yield (+1·2 kg/day) and milk protein (+0·7 g/kg) while the increase from 16 to 22 kg DM (experiments 2 and 3) had less effect (+0·5 kg/day milk yield and +0·4 g/kg milk protein). There was no clear interaction between concentrate supplementation and herbage allowance. Under the usual conditions of spring pasture, with cows in mid lactation, the use of a constant level of concentrate at grazing proves to be a technique of some interest.

Technical review of the energy and protein requirements of growing pigs: food intake

Abstract: A review of work reported in the literature was used to present quantitative descriptions of protein use in the growing pig. These are detailed in the text, which also points to preferred values, and to anomalies and lacunae. The review was prepared with the objective of allowing from its content the inclusive and quantitative modelling of amino acid requirement. Requirement was approached as the sum of the component factors: maintenance and protein retention. Ileal true digestible protein and amino acid requirements are presented in a form consistent with that forwarded for energy. Thus both energy and protein elements can be conceptualized within a single coherent framework. Priority uses for absorbed amino acids were assumed to be (a) to support endogenous protein losses resultant from the passage of food and incomplete re-absorption prior to the terminal ileum, (b) to replace lost hair and skin, and (c) to cover the basic maintenance losses which will occur as a result of minimal protein turn-over even when protein retention is zero. The bulk of the protein requirement was directly linked to the daily rate of protein retention, for which the linear-plateau response was accepted. For determination of the maximum rate of protein retention the Gompertz function was proposed, although the use of a single value throughout the growth period was not dismissed. The balance of amino acids for protein retention is specified as different from that for maintenance. Central to the approach was the proposal that the inefficiency of use of ileal digested ideal protein, even when not supplied in excess, was an expression of protein losses occurring as a result of protein turn-over. The requirement for the satisfaction of the losses from protein turn-over occurring as a consequence of protein retention, and therefore additional to the requirements for maintenance, was identified. Quantification was attempted with sufficient success to warrant its inclusion into requirement estimation. It was concluded that this element addressed previously inadequately explained protein utilization inefficiencies. Algorithms are presented based upon protein turn-over which appear to be consistent with empirical findings.

Genetic evaluation of dairy bulls for energy balance traits using random regression

Abstract: Current selection objectives for dairy cattle breeding may be favouring cows that are genetically predisposed to mobilize body tissue. This may have consequences for fertility since cows may resume reproductive activity only once the nadir of negative energy balance (NEB) has passed. In this study, we repeatedly measured food intake, live weight, milk yield and condition score of Holstein cattle in their first lactation. They were given either a high concentrate or low concentrate diet and were either selected or control animals for genetic merit for kg milk fat plus milk protein. Orthogonal polynomials were used to model each trait over time and random regression techniques allowed curves to vary between animals at both the genetic and the permanent environmental levels. Breeding values for bulls were calculated for each trait for each day of lactation. Estimates of genetic merit for energy balance were calculated from combined breeding values for either (1) food intake and milk yield output, or (2) live weight and condition-score changes. When estimated from daily fluxes of energy calculated from food intake and milk output, the average genetic merit of bulls for energy balance was approximately -15 MJ/day in early lactation. It became positive at about day 40 and rose to +18 MJ/day at approximately day 150. When estimated from body energy state changes the NEB in early lactation was also -15 MJ/day. It became positive at about day 80 and then rose to a peak of +10 MJ/day. The difference between the two methods may arise either because of the contribution of food wastage to intake measures or through inadequate predictions of body lipid from equations using live weight and condition score or a combination of both. Body energy mobilized in early lactation was not fully recovered until day 200 of lactation. The results suggest that energy balance may be estimated from changes in body energy state that can be calculated from body weight and condition score. Since body weight can be predicted from linear type measures, it may be possible to calculate breeding values for energy balance from national evaluations for production and type. Energy balance may be more suitable as a breeding objective than persistency.

Environmental enrichment of intensive pig housing using spent mushroom compost.

Abstract: In a comparative study which examined the effect of having access to mushroom compost in an otherwise barren environment there were three treatments and six replicates. The three treatments were (T1) control barren pen providing 0·7 m2 per pig with fully slatted floor, (T2) empty horizontal rack suspended above the pigs’ heads and (T3) mushroom compost on rack as in treatment 2. Pigs released particles of compost from the rack by nosing the metal grid from below. Almost twice as many pigs with access to mushroom compost (T3) nosed the rack (P < 0·001) and the ground below the rack (P < 0·001) as pigs which had a rack with no mushroom compost (T2). Fewer pigs with mushroom compost were involved in behaviours directed at penmates such as nosing, biting and chewing penmates than pigs in treatments 1 and 2 (P < 0·001). In addition fewer pigs in T3 were involved in feeding behaviour than in T1 and T2 (P < 0·05). Percentages of tail-bitten animals which had to be removed were 11 and 24 for T1 and T2 respectively while T3 had < 1% removed because of tail biting (P < 0·05). Apparent food intake was higher (P < 0·05) and food conversion ratio tended to be poorer in T1 (P = 0·1). It is suggested that pigs will redirect rooting behaviour towards penmates and the feeder in the absence of any rooting substrate. Adding substrate to commercial finishing pens reduces this redirection of behaviour and improves welfare by minimizing injury through tail biting.

Multi-trait selection indexes for sustainable UK hill sheep production

Abstract: Three selection indexes for the UK hill sheep sector are derived to suit the extremes of hill production systems. These are: (i) intensive, where all surplus lambs not required for breeding are finished for slaughter, (ii) extensive, where all surplus ‘store’ lambs are sold to other farmers for finishing, and (iii) semi-intensive, which is intermediate between the two extremes, i.e. farms finish some lambs for slaughter and sell others as store lambs. Parameters for 12 breeding goal and index traits were estimated using a total of 3962 lamb records and 5944 ewe lambing records from Scottish Blackface sheep on two Scottish Agricultural College experimental hill farms. The breeding goal comprised carcass, maternal and survival traits. The evaluation of these indexes showed that improvements in maternal traits are possible, along with more modest improvements in carcass quality traits. Responses to selection are expected to be lower for the extensive farm in general, compared with the intensive farm. Evaluations of alternative indexes show that an index using measurements of fat and muscle on ewes rather than on lambs may be more cost-effective to implement in practice, compared with the original index, although this change results in a higher (i.e. undesirable) gain in mature size. Sensitivity analyses showed that in general, the indexes are robust to changes in economic values and to changes in heritability estimates.

Analysis of censored survival data using random regression models

Abstract: Censoring of records is a problem in the prediction of breeding values for longevity, because breeding values are required before actual lifespan is known. In this study we investigated the use of random regression models to analyse survival data, because this method combines some of the advantages of a multitrait approach and the more sophisticated proportional hazards models. A model was derived for the binary representation of survival data and links with proportional hazards models and generalized linear models are shown. Variance components and breeding values were predicted using a linear approximation, including time-dependent fixed effects and random regression coefficients. Production records in lactations 1 to 5 were available on 24741 cows in the UK, all having had the opportunity to survive five lactations. The random regression model contained a linear regression on milk yield within herd (no. = 1417) by lactation number (no. = 4), Holstein percentage and year-month of calving effect (no. = 72). The additive animal genetic effects were modelled using orthogonal polynomials of order 1 to 4 with random coefficients and the error terms were fitted for each lactation separately, either correlated or not. Variance components from the full (i.e. uncensored) data set, were used to predict breeding values for survival in each lactation from both uncensored and randomly censored data. In the uncensored data, estimates of heritabilities for culling probability in each lactation ranged from 0·02 to 0·04. Breeding values for lifespan (calculated from the survival breeding values) had a range of 2·4 to 3·6 lactations and a standard deviation of 0·25. Correlations between predicted breeding values for 129 bulls, each with more than 30 daughters, from the various data sets ranged from 0·81 to 0·99 and were insensitive to the model used. It is concluded that random regression analysis models used for test-day records analysis of milk yield, might also be of use in the analysis of censored survival data.

Effect of weaning age and slaughter weight on carcass and meat quality of Talaverana breed lambs raised at pasture

Abstract: Three weaning treatments (weaning at 45 days of age, at 65 days of age, unweaned) and two slaughter weights (24 and 28 kg) were compared in lambs raised at pasture, and their effect on carcass and meat traits were studied. Unweaned lambs displayed a greater growth rate, lower concentrate consumption, greater dorsal fat thickness, more kidney knob and channel fat and greater total fat levels, measured through dissection of the hind limb. Total collagen concentration was lower in unweaned lambs and the intramuscular fat of these same animals exhibited a greater proportion of saturated fatty acids and a lower n-6/n-3 fatty acid ratio. Slaughter weight influenced scored carcass fatness, which was greater in heavier lambs, meat colour, which displayed greater lightness in lower-weight lambs, and water-holding capacity, which was lower in lambs with the lower slaughter weight. The heavier lambs displayed lower soluble collagen values, and the intramuscular fat of the longissimus dorsi muscle of these same lambs contained higher levels of monounsaturated and lower levels of polyunsaturated fatty acids.

Selection of sheep for response to Trichostrongylus colubriformis larvae: genetic parameters

Abstract: Data were analysed from a long-term selection experiment with Merino sheep, based on immunological responsiveness to the intestinal nematode Trichostrongylus colubriformis. For the first 14 years of selection, the criterion was the mean of five fortnightly faecal worm-egg counts (FECs) of pen-housed lambs that were vaccinated with irradiated larvae then challenged with normal T. colubriformis larvae. For most of the lambs born in the subsequent 6 years, the selection criterion was the mean of three weekly FECs of grazing lambs following a secondary challenge with T. colubriformis larvae. Data from 2233 lambs were included in the analyses. At the end of the experiment, the lines selected for high and low response to challenge differed by 2·3 to 2·9 phenotypic standard deviations. The heritability of average pen-tested FEC was 0·38 (s.e. 0·04), similar to that for average FEC after secondary field challenge (0·37, s.e. 007). Average FECs from the primary field challenge were less heritable (0·21, s.e. 006). Counts recorded on pen-tested animals at 3, 5, 7, 9 and 11 weeks after infection were all highly correlated genetically (estimates 0·93 to 0·99) and of similar heritability (0·33 to 0·39) with a non-significant tendency for later FECs to be more heritable. Phenotypic correlations were lower, ranging from 0·60 for counts 8 weeks apart, to 0·78 to 0·81 for adjacent samples 2 weeks apart. Single-record heritability estimates at 3, 4 and 5 weeks after secondary infection in grazing lambs did not differ statistically from each other but were highest at the 5th week after infection at 0·33 (s.e. 007). FECs determined in pens were imperfectly correlated with FECs determined at pasture (genetic correlation 0·72, s.e. 013). Phenotypic correlations of single-record FECs across primary and secondary field challenges were low (around 0·2), although the genetic correlation between mean primary FEC and mean secondary FEC was not significantly different from unity. Testing under standardized conditions in pens did not result in consistently higher heritabilities than testing immunologically primed lambs at pasture. Repeated measurement in a breeding programme offers little additional benefit, except when lambs have had ample prior experience of parasite infection, with the two measures separated by an anthelmintic treatment. If an objective of a Merino breeding programme is to reduce FEC under field conditions, then using one measure in the field, approximately 3 to 5 weeks after a secondary artificial infection, is likely to lead to long-term progress.

The effect of dietary fish-meal supplementation on parasite burdens of periparturient sheep.

Abstract: Pregnant ewes were offered 0·80, 1·0 or 1·25 of estimated protein requirement, groups P80, P100 and P125, respectively and trickle infected with Teladorsagia circumcincta (average of 10000 larvae per day) and Trichostrongylus colubriformis (average of 7000 larvae per day) for 42 days prior to parturition. Eleven days after lambing half (group TC) received a single challenge infection of 25000 T. circumcincta and 17500 T. colubriformis larvae and the remainder (TO) no further larval challenge. Worm burdens were determined 21 days post partum. Worm burdens were inversely related to dietary protein concentration. Mature worms (L5) of T. circumcincta recovered were (log10 (count + 1)) 4·002, 3·806 and 3·444 in TO sheep and 3·812, 3·633 and 3·113 in TC sheep from P80, P100 and P125 groups, respectively. The corresponding burdens of T. colubriformis were 2·665, 2·893 and 2·029 for TO and 3·985, 2·363 and 1·188 for TC sheep. The numbers of L4 larvae recovered from TC sheep were (log10 (count + 1)) 3·532, 3·288 and 3·127 for T. circumcincta and 3·080, 2·180 and 0·949 for T. colubriformis on P80, P100 and P125 diets, respectively. There was no evidence of inhibition of larval development or egg laying with either worm species suggesting that the major effect of protein supply in enhancing resistance was operating at the larval establishment stage. There was evidence that the post-partum challenge infection affected the fecundity and survival of the established adult worm population of T. circumcincta but not of T. colubriformis.

Carbohydrate utilization and its protein-sparing effect in diets for grouper (Epinephelus malabaricus)

Abstract: To investigate the utilization of different carbohydrate sources and the possible protein-sparing effects of carbohydrates for grouper (Epinephelus malabaricus), six isoeneregtic purified diets were prepared. Three dietary protein levels (500, 460, 420 g/kg) were achieved by substitution with three levels (143, 195, 246 g/kg) and two sources (glucose and starch) of dietary carbohydrate. Each of the six diets was given to triplicate groups of grouper in a recirculating rearing system for 8 weeks. In the glucose group, weight gain of fish decreased with increasing dietary glucose and decreasing protein content. In the starch group, weight gain of fish given the 500 g/kg protein diet was higher (P 0·05). At the 500 g/kg dietary protein level body lipid content of the starch-group fish was higher than that of glucose-group fish. At 500 and 460 g/kg dietary protein levels, fish given starch diets had higher hepatic hexokinase activity than fish given the glucose diets. These results suggest that, at the levels studies, the utilization of starch and glucose by grouper is similar. Decreasing the dietary protein level from 460 g/kg to 420 g/kg by increasing the starch content in the diet from 195 g/kg to 246 g/kg did not reduce (P > 0·05) weight gain and food efficiency, suggesting that starch could spare some protein when the dietary protein level is low.

Effects of dietary protein source on growth, immune function, blood chemistry and disease resistance of Atlantic salmon ( Salmo salar L.) parr

Abstract: Many studies with fin fish have demonstrated the potential to use alternative dietary protein sources to fish meal based on growth responses, although these trials mostly neglect to determine if such protein sources affect immune function. This study investigated the effect of fish meal replacement with dehulled lupin meal (LPN) or hydrolysed poultry feather meal (FTH). Atlantic salmon ( Salmo salar L.) parr were supplied isonitrogenous and isoenergetic diets with 40% of the dietary protein provided by LPN or FTH, or 400 g/kg of the dietary protein provided equally by LPN and FTH (MIX). A diet mainly containing fish-meal protein acted as a control (CON). Growth, immune function, blood chemistry and disease resistance were assessed after 56 days. Significant differences ( P < 0.05) in weight gain were detected between Atlantic salmon given the CON and FTH diets, whilst those salmon given LPN and MIX did not differ from any other. Productive protein values were significantly lower ( P < 0.01) for salmon on FTH compared with those on CON and MIX. Immune function (as assessed by lysozyme, antiprotease, neutrophil oxygen radical production and plasma total immunoglobulin) and blood chemistry (as assessed by plasma total protein and glucose) were not significantly ( P > 0.05) affected by any diet. Mortality rates of Atlantic salmon challenged with Vibrio anguillarum were not influenced by diet. These data suggest Atlantic salmon could be supplied diets with the fish meal component reduced to supply approximately 600 g/kg of the total protein, with the remaining 400 g/kg supplied by dehulled lupin meal or a combined dehulled lupin and hydrolysed poultry feather meal without any adverse effects on growth, immune function or blood chemistry.

Reproductive performance in holstein-friesian cows in relation to genetic merit and level of feeding when grazing pasture

Abstract: One hundred and eight Holstein-Friesian cows in six herds were run on six separate farmlets over a 5-year period from 1995 to 1999 at Wollongbar Agricultural Institute, on the subtropical north coast of New South Wales, Australia. Three of the herds comprised high genetic merit (HGM) cows — Australian breeding value (ABV) of +49·1 kg for milk fat (F) plus protein (Pr) and three herds comprised low genetic merit (LGM) cows-ABV of 2·3 kg. Within genetic merit groupings, one herd was given 0·34 t (l), one herd was given 0·84 t (m) and one herd 1·71 t (h), of concentrate per cow per lactation. Within each genetic merit group, cows were matched for milk yield and live weight, and over all groups for time of calving and age at the commencement of the study. The 30 paddocks within each farmlet were matched between farmlets for pasture type and pasture growth rate and soil fertility. Half the cows within each herd calved over a 3-month period in spring and the other half in autumn. Strict management criteria ensured that there was no bias towards particular treatment groups. HGM cows were ‘open’ (days from calving to conception) for 8 days longer than the LGM cows (99 v. 91 days). The lHGM cows took 11 days longer to commence luteal phase activity and 21 days longer to first observed oestrus post calving than hLGM cows (P < 0·001), with the other groups being intermediate. After 24 days of mating, 22% of lHGM cows were pregnant, and this was less than half of the rate of the best herd-mLGM. After 9 weeks of mating, the chances of an LGM cow being pregnant was 87% greater than an HGM cow. After 12 weeks of mating, 70% of lHGM cows were pregnant compared with a mean pregnancy rate of 87% for the LGM cows. The number of cows treated for abnormal ovarian activity (anoestrus, cystic) was highest (P < 0·001) in the HGM herds given ‘l’ and ‘m’ levels of concentrate compared with the remaining herds (0·24 v. 0·12 treatments per cow mated, respectively). There was a significant positive relationship between live-weight change from 4 weeks before, to the start of, the mating period and the chances of a cow being pregnant at 24 days (P < 0·05) and at 6 and 9 weeks after the commencement of mating. There was a significant negative relationship (P < 0·001) between the change in daily F plus Pr yield, from the start to 4 weeks after mating began, and pregnancy rate at 9 weeks. The change in F plus Pr yield was +63 g/day for cows pregnant at nine weeks as opposed to +154 g/day for cows not pregnant. The results of the present study indicate that the reproductive performance of HGM cows, with a mean of 61% North American (NA) genes, is lower than LGM cows (22% NA genes) under a predominantly pasture-based system of farming. The influence on reproduction was possibly due to genes favouring partitioning of energy to milk yield rather than body-condition maintenance in the HGM cows and when food intake was inadequate, then being more willing to use body reserves. These reproductive problems may be reduced by more intensive reproductive management. However, such practices are costly and time consuming. Another approach may be to ensure that live-weight loss over the mating period is minimized by strategic supplementary feeding.

The effects of two methods of increasing age at slaughter on carcass and muscle traits and meat sensory quality in pigs

Abstract: The aim of this study was to investigate the effects of a 30-day increase in age of pigs slaughtered at 110 kg body weight (BW) on carcass and m. longissimus dorsi (LD) and m. biceps femoris (BF) traits, and meat sensory quality. A total of 60 pigs from two genotypes: synthetic line ✕ (Large White ✕ Landrace) (SL) and Duroc ✕ (Large White ✕ Landrace) (D) were used, each genotype containing five groups of six littermates (three castrated males and three females). At the average BW of 30 kg, littermates of the same sex were allocated to three groups. Pigs of group AL were offered ad libitum a standard growing-finishing diet (13·6 MJ/kg digestible energy, 9·5 g/kg of lysine) from 30 up to 110 kg BW. The R1 pigs received the same diet at 0·75 of the ad libitum intake of their AL littermates. The R2 pigs were submitted to both energy and protein restrictions in order to get the same growth rate as the R1 pigs and the same body composition as the AL pigs. Results were similar in both genotypes. In agreement with the protocol, age at slaughter was increased by 30 days in R1 and R2, and AL and R2 pigs had comparable carcass composition. Compared with AL, average daily gain was decreased in R1 and R2 pigs, and food efficiency was decreased in R2, but remained unaffected in R1 pigs. Intramuscular fat (IMF) concentration was decreased in the R1 pigs, especially in BF (15·5 v. 19·7 mg/g), while it was increased in the LD of the R2 pigs, particularly in the D animals (24·2 v. 17·4 mg/g), compared with AL pigs. Meat quality parameters (rate and extent of pH fall, reflectance and drip loss) were similar in the three feeding regimens. The taste panel did not find any significant difference between feeding regimens for tenderness, juiciness, flavour, flour sensation after mastication and mouth coating of the meat, despite the differences reported in IMF concentration. This suggests that, for the genotypes used in this experiment, an increase of 30 days in the age at slaughter greatly influences the carcass and/or the muscle chemical composition, depending on the feeding strategy applied to reduce the growth rate but does not strongly modify the meat eating quality.

Effects of prenatal restraint stress on hypothalamic-pituitary-adrenocortical and sympatho-adrenomedullary axis in neonatal pigs

Abstract: Studies in rodents and primates strongly indicate that prenatal stress affects the survival, behaviour and physiology of the offspring. Stressful stimuli during gestation may have a direct or hormone mediated effect on the development of stress systems in the foetal organism, resulting in an altered coping during stressful situations. The present study was conducted to elucidate prenatal stress effects in domestic pigs on the responses of the hypothalamicpituitary- adrenocortical (HPA) axis and the sympatho-adrenomedullary (SAM) system as well as on morbidity, mortality and growth of the offspring. Pregnant sows were subjected to a restraint stress for five minutes daily during the last five weeks of gestation. Endocrine reactions of the piglets were tested at 3, 7, 21 and 35 days of age using an immobilization test and an ACTH challenge test. Prenatally stressed piglets showed lower basal plasma cortisol and increased corticosteroid binding globulin (CBG) concentrations at 3 days of age, indicating decreased free cortisol concentrations after birth. Cortisol levels after ACTH stimulation and catecholamine levels after immobilization were not affected by the stress treatment of the sows. Piglets from stressed sows tended to have lower noradrenaline : adrenaline ratios at three days of age compared with the control piglets. In addition, stressed sows tended to have lower litter weights after birth. The morbidity and mortality during the suckling period was higher in the prenatally stressed litters, as shown by a higher frequency of diseased and perished piglets per litter. We suppose that prenatal stress during late gestation in pigs alters the development of the HPA system and impairs the vitality of the offspring.

Genetic variation for resistance to clinical and subclinical diseases exists in growing pigs

Abstract: The objective of this study was to test that genetic variation for resistance to clinical and subclinical diseases exists in growing pigs. A total of 13 551 male growing pigs were assessed for resistance to five categories of clinical and subclinical disease: (i) any clinical or subclinical disease, (ii) lameness, (iii) respiratory diseases, (iv) diarrhoea, and (v) other diseases (i.e. any clinical or subclinical disease with the exception of (ii), (iii), and (iv)). Additive genetic variation for resistance to each disease category was estimated by fitting a Weibull, sire-dam frailty model to time until the pigs were first diagnosed with a disease from that category. Genetic correlations among the resistances to each disease category were approximated as product-moment correlations among predicted breeding values of the sires. Additive genetic variation was detected for resistance to (i) any clinical or subclinical disease (additive genetic variance for log-frailty (± s.e.) = 0·18 ± 0·05, heritability on the logarithmic-time scale = 0·10), (ii) lameness (0·29 ± 0·11, 0·16), (iii) respiratory diseases (0·24 ± 0·16, 0·12), (iv) diarrhoea (0·30 ± 0·27, 0·16), and (v) the other diseases (0·34 ± 0·15, 0·19) and there were generally positive and low-to-moderate correlations among the predicted breeding values (-0·03 to + 0·65). These results demonstrate that additive genetic variation for resistance to clinical and subclinical diseases does exist in growing pigs, and suggests that selective breeding for resistance could be successful.

The relationship between protein nutrition, reproductive effort and breakdown in immunity to Teladorsagia circumcincta in periparturient ewes

Abstract: A nutritional hypothesis for the occurrence of the periparturient relaxation of immunity (PPRI) to gastrointestinal nematodes was tested within the bounds of a nutrient partitioning framework. It was hypothesized that at times of a scarce supply of metabolizable protein (MP), an increase in MP supply or a reduction in MP demand (having singles instead of twins) should lower the extent of PPRI in sheep. Twenty-one single- and 21 twin-bearing and -rearing Finn-Dorset ewes, 2 to 7 years old, and repeatedly infected with Teladorsagia circumcincta, were given one of three pelleted foods (no. = 7). The foods were formulated to supply 0·8 (L), 1·0 (M) and 1·2 (H) times the MP requirements during lactation, and were offered ad libitum from d–21 to d35 (d0 is day of parturition). Faecal egg counts (FEC) were assessed twice weekly as an indicator for host resistance. Dry-matter intake (DMI) during late pregnancy was higher than expected, and MP supply did not limit performance at this stage. In accordance with the hypothesis, there were no indications of a breakdown of immunity to T. circumcincta during late pregnancy. DMI during lactation did not differ between the single- and twin-rearing ewes. Calculated milk production was lower for the L than for the M and H ewes, especially for the twin-rearing ewes. A temporarily elevated FEC was observed during the first few days in lactation, which was probably mainly due to changes in faecal output rather than to PPRI. The FEC returned to low, late pregnancy levels at d12 and remained low for the single- but not for the twin-rearing ewes (P < 0·001). Overall, the L ewes had higher FEC than the M and H ewes from d19 onwards; this effect was more pronounced for the twin- than for the single-rearing ewes. It was postulated that DMI achieved overcame MP scarcity and thus prevented breakdown in immunity in the single-rearing ewes. The data support the view that, at times of MP scarcity, an increase in MP supply and reduction in MP demand can lower the extent of the breakdown in immunity towards T. circumcincta.

Genetic resistance to gastro-intestinal nematode parasites in Galla and Small East African goats in the sub-humid tropics

Abstract: A study was carried out from 1992 to 1996 to compare the resistance to naturally acquired gastro-intestinal (GI) nematode parasite infections (predominantly Haemonchus contortus) of Galla and Small East African goats in the sub-humid coastal region of Kenya. A total of 204 Galla and 349 Small East African (SEA) kids were born from five kiddings. These were the progeny of 18 Galla and 17 SEA bucks. Live weights (LWT), blood packed-cell volume (PCV) and faecal egg count (FEC) were recorded at 1- to 2-month intervals from birth to about 14 months of age. The SEA kids were more resistant to GI nematode parasites than Galla kids as shown by their significantly lower FEC (P 0·05) breed effect on PCV, but Galla kids were significantly heavier (P < 0·001) at all measurement times between birth and 14 months of age. Heritability estimates for LWT, PCV and FEC at the different sampling times were characterized by high standard errors. Heritability estimates for records taken at 4·5 and 8 months of age from a repeated measures analysis were 0·18 (s.e.0·08) for PCV and 0·13 (s.e.0·07) for logarithm-transformed FEC. The phenotypic and genetic correlation estimates between PCV and LFEC were moderately to highly negative and averaged –0·36 and –0·53, respectively. The results are discussed in relation to the limited evidence for resistance to GI nematode infections in goats and compared with the much stronger evidence for resistance in sheep.

Effect of supplemental levels of chromium picolinate on the growth performance, serum traits, carcass characteristics and lipid metabolism of growing-finishing pigs

Abstract: This study investigated the effect of chromium picolinate supplementation on growth performance, carcass characteristics and lipid metabolism of growing-finishing pigs. Sixty Landrace ✕ Yorkshire ✕ Duroc (LYD) pigs with a mean initial body weight of 46·65 (s.e. 6·72) kg were randomly allocated into three groups with two replicates. They were supplemented with 0 , 200, or 400 μg/kg (ppb) chromium in the organic form of chromium picolinate for 90 days. Supplementation with chromium picolinate in the pigs’ ration improved their growth performance, enhanced average daily gain (P 0·05). Chromium picolinate supplementation also improved carcass characteristics, as the average back fat thickness was reduced and the loin-eye area was enhanced ( P 0·05). The carcasses of the pigs that received the chromium supplemented ration contained less oleic acid (C18 : 1) and total unsaturated fatty acids (P < 0·05). On the other hand, the total saturated fatty acid content was higher than that of the controls (P < 0·05). Results in this study demonstrate that chromium picolinate supplementation in pigs has several beneficial effects.

The effects of selection for lean tissue content on maternal and neonatal lamb behaviours in Scottish Blackface sheep

Abstract: British hill sheep are required to give birth to and rear their lambs under harsh extensive conditions. The aim of this study was to investigate whether genetic selection for increased (LEAN) or decreased (FAT) carcass lean content in the Scottish Blackface breed over 7 years had affected the ability of ewes to rear lambs by altering the expression of maternal and neonatal lamb behaviours. The behaviour of 61 ewes (32 LEAN and 29 FAT) and their 119 lambs were recorded at parturition and over the first 8 weeks of life. Overall there were very few effects of selection on the behaviour of the ewes. LEAN ewes were significantly faster than FAT ewes to start grooming their lambs after birth and FAT ewes tended to withdraw more frequently from their lambs than LEAN ewes. There was, however, a highly significant effect of selection line on lamb behaviour. LEAN lambs were significantly quicker than FAT lambs to perform all righting movements (median latency to stand (mins): LEAN = 11·7, FAT = 23·4, P < 0·01), were more likely both to suck (percentage that sucked: LEAN = 81·0%, FAT = 57·1%, P < 0·05), and to play within the first 2 h of birth. The higher rate of sucking in LEAN lambs persisted over the first 3 days after birth (percent observations where lambs were sucking: LEAN = 7·8 (s.e. 0·8), FAT = 5·1 (s.e. 0·6), P < 0·05), when LEAN lambs were also significantly closer to their mothers than FAT lambs. Thereafter, there were no significant effects of ewe or lamb line on behaviours recorded up to 8 weeks after birth. Overall lamb mortality to 8 weeks was 19·3% and was not significantly affected by lamb line. However, lambs that were slow to perform early behaviours had a reduced survival to 8 weeks of age. These data suggest that, although ewe maternal behaviour has not been significantly affected by selection for lean growth, the activity of the neonatal lamb has been affected. Lamb activity was related to lamb survival, even in our indoor lambing conditions. It is likely that the speed with which newborn lambs stand and suck will be even more important for survival under extensive conditions.

Evaluation of a simple method for assessment of rising behaviour in tethered dairy cows

Abstract: Problems with getting up can affect welfare, therefore a simple method for use in assessing rising behaviour was evaluated. Sixty-one Danish Friesian cows housed in two identical tie-stall barns were used. The cows were in their first (no. = 30), second (no. = 16) or third lactation (no. = 15). There were 19 cows in early lactation ( 200 days in milk) and 24 dry cows, divided between the age groups. Rising was scored at three times of day for five consecutive days. Two observers scored the cows at 11:30 h and one of these observers scored them at 15:00 and 17:30 h. Cows were encouraged to rise using increasing levels of encouragement but the minimum possible force and were scored for rising (between 1 - normal rising sequence, smooth movement and 5 - rising front first) and the level of encouragement required. The behaviour of each cow was recorded on video for 21·5 h. Total lying time; lying frequency; maximum lying bout length; time to lie down; time for preparatory phase of lying; time to rise, and time for final phase of rising were recorded from the videos and video records of rising were scored. The rising score was repeatable and was unaffected by the different scoring conditions tested (presence of observer, day of scoring, time of day, level of encouragement). Stage of lactation affected total lying time, number of lying bouts, maximum bout length and rising behaviour, while lactation number only had a minor effect on lying behaviour. The proposed score for rising reliably reflected whether the cows in tie-stalls had difficulty rising when at least three observations were included. The proportion of cows in different stages of lactation and of different parities should be included in any assessment of rising behaviour, since stage of lactation and parity significantly affected rising behaviour.

Inheritance of faecal egg counts during early lactation in Scottish Blackface ewes facing mixed, natural nematode infections

Abstract: This paper presents an analysis of nematode faecal egg counts from Scottish Blackface ewes facing mixed, natural nematode infections (predominantly Teladorsagia circumcincta). The data set comprised 1445 measurements on 421 ewes taken at 4 and 6 weeks post-lambing, over a 4-year period. The ewes, themselves, were the progeny of 73 sires and 285 dams. Only Strongyle eggs were consistently present, and faecal egg counts from this genera ranged from zero (0·4 of all measurements) to 3388 eggs per g. Faecal egg counts were significantly affected by the number of lambs reared and suckled (increasing reproductive burden led to higher counts) by ewe age (older ewes had lower counts) and by previous selection history (ewes from a line previously selected for increased carcass fatness had lower faecal egg counts than ewes from a conversely selected lean line). The heritability of log-transformed faecal egg counts was 0·23 (s.e. 005) and the repeatability, including both within- and between-year permanent environmental effects, was 0·25 (s.e. 004). The apparent presence or absence of infection had a heritability of 015 (s.e. 007) on the observed scale and 0·39 (s.e. 016) when analysed as a binomial threshold trait. The genetic correlation between average 4-week weight of lamb suckled by the ewe and faecal egg counts was 0·24 (s.e. 010). The results suggest that faecal egg counts during early lactation are heritable and influenced by the reproductive performance of the ewe. Selection to reduce nematode faecal egg output from ewes during this period should be successful in reducing pasture larval contamination.

A genetic analysis of maternal behaviour score in Scottish Blackface sheep

Abstract: Under field conditions, ewe behaviour was quantified by maternal behaviour score (MBS)-a six-point scale which assesses ewe flight distance when lambs are handled for the first time, within 24 h of birth (adapted from O’Connor et al., 1985). MBS was measured on 847 Scottish Blackface ewes on two experimental hill farms, over a maximum of four parities. Live weights of lambs born to these ewes were measured at birth, marking (average age of 42 days) and weaning (average age of 120 days). MBS was significantly higher ( P < 0·05) for ewes with more lambing experience (multiparous ewes), for older ewes and for twin-bearing ewes compared with ewes with single lambs. MBS was under genetic control ( h 2 = 0·13, permanent environmental effect = 0·19, when analysed as the same trait across parities) and the repeatability was 0·32. MBS had no significant effects on weight gain of lambs. However, a moderate, positive genetic correlation was estimated between MBS and the average weight gained by lambs from birth to marking ( rg = 0·4, s.e. 0·22), although the genetic correlation estimated between MBS and weight gained to weaning was close to zero ( rg = 0·02, s.e. 0·16). Ewes with a MBS of 1 (ewe flees and does not return to her lambs) had significantly more lambs dying before marking and weaning than ewes with a higher maternal behaviour score. Selection to reduce the proportion of ewes in this category may therefore be beneficial.

The effect of the quality of dietary lignocellulose on digestion, zootechnical performance and health of the growing rabbit

Abstract: The aim of this study was to evaluate the performance and digestive response of the growing rabbit according to a change in the nature of the lignocellulose (ADF), without a change in the ADF level. Three diets with a linearly decreasing lignin/cellulose ratio (ADL/cellulose = 0·8; 0·4; 0·2; respectively LC8, LC4, LC2) were given to a total of 162 rabbits per diet, from weaning till slaughter weight. A reduction of the ADL/cellulose ratio led to a lower food intake (LC8 v LC2: -11%), associated with a lower daily weight gain (-6% for LC2). Mortality and morbidity rate was significantly greater (+50%) for LC2 and LC4 diets compared with the LC8. Thus, the health risk index (morbidity + mortality) increased by 20 units for LC4 and LC2 compared with LC8 diet. In parallel, rate of passage was slower (mean retention time 4·5 h greater, P = 0045) with LC4 and LC2 diets. Dry-matter digestibility was slightly affected, whereas protein digestion was favoured with low ADL/cellulose ratio. It is recommended that a minimum lignin supply (about 6 g/day) is adopted as well as a minimum dietary lignocellulose to ensure growth performance and health of the growing rabbit.

The farmers' influence on calves' behaviour, health and production of a veal unit.

Abstract: Although veal production is a highly standardized system, there still remains considerable variability in productivity between units. This variability might be due to the farmers working on these units, through differences in stockmanship, work attitudes or behaviour, which in turn may affect animals’ fear responses, productivity and health. A survey was conducted on 50 commercial farms affiliated to the same veal company. All units had calves housed in individual crates, a similar number of crates, and the same diets and management advice. Data were collected on: building and general farm characteristics, farmers’ backgrounds and their attitudes towards their work and calves, farmers’ behaviour with the calves, calves’ reactivity to people, and disease level of the calves. Productivity results (growth rates, food efficiency and mortality) were used to classify veal units as ‘high producing’ (no. = 24) v. ‘moderate producing’ (no. = 26). Calves were less reactive to people in units where the farmer behaved sympathetically and where there were several stockpersons working. The disease level was lower in units where the farmer had a positive attitude towards the sensitivity of the calves to contact and towards the importance of cleaning. Productivity of the veal unit was associated with the health of the calves but not with their reactivity to people. It is suggested that the farmer can have an influence on the success of the veal unit mainly through his/her ability to control the health of the calves and that a positive attitude towards animals and towards work (specifically cleaning actions) can improve the accuracy of surveillance and care of the animals. Moreover, through his/her behaviour with the calves and his/her ability to control their health, the farmer can play an important role in assuring calves’ welfare.