Showing papers in "Animal Research in 2002"

The relationship of temperature-humidity index with milk production of dairy cows in a Mediterranean climate

Abstract: Two experiments were conducted using lactating Friesian-Holstein cows to measure the effects of heat stress, using temperature-humidity index (THI), on milk production, milk composition and dry matter intake (DMI) under the Mediterranean climate. These trials were carried out in two pe- riods differing in average THI values (68 ± 3.75 vs. 78 ± 3.23 for the spring and summer periods, re- spectively). Daily THI was negatively correlated to milk yield (r = -0.76) and feed intake (r = -0.24). When the THI value increased from 68 to 78, milk production decreased by 21% and DMI by 9.6%. Milk yield decreased by 0.41 kg per cow per day for each point increase in the THI values above 69. Milk fat (3.24 vs. 3.58%) and milk protein (2.88 vs. 2.96%) were lower for the summer group. THI was positively correlated to respiration rate (RR) (r = 0.89), heart rate (HR) (r = 0.88), rectal tempera- ture (RT) (r = 0.85) and cortisol (0.31), and negatively with free thyroxin (-0.43). As the THI values increased from 68 to 78, RT increased by 0.5 o C, HR by 6 beats, and RR by 5 inspirations per min. The average concentration of cortisol increased from 21.75 to 23.5 nmol·L -1 (P > 0.05), while that of free thyroxin decreased from 15.5 to 14.5 pmol·L -1 ,( P > 0.05). Summer heat stress reduced milk yield and DMI, altered milk composition and affected the physiological functions of confined lactating Hol- stein cows managed under Mediterranean climatic conditions. dairy cow / temperature-humidity index / milk production / intake / physiology

Mycotoxins in feeds and their fate in animals: a review

Abstract: Mycotoxins are secondary metabolites secreted by moulds, mostly belonging to the three genera Aspergillus, Penicillium and Fusarium. They are produced in cereal grains as well as for- ages before, during and after harvest, in various environmental conditions. Due to the diversity of their toxic effects and their synergetic properties, mycotoxins are considered as risky to the consum- ers of contaminated foods. Mycotoxin metabolism is complex and involves pathways of bioactivation and detoxification in both humans and animals. Detoxification occurs via biotransformation mediated by enzymes in the host cells and in the digestive microbial flora. Some of the toxins or their metabolites may become fixed in animal or human tissues. However, most are elim- inated in the urine, faeces and milk. In animals, toxicity is generally revealed as chronic minor trou- bles and only rarely causes death. The presence of mycotoxins in feeds may decrease feed intake and affect animal performance. In addition, the possible presence of toxic residues in edible animal prod- ucts (milk, meat, offal), may have some detrimental effects on human health. Maximum acceptable doses in feeds and milk have been set for certain mycotoxins by international authorities. The poten- tial risks of mycotoxins may be controlled by checking plant material for fungal contamination, by improving methods of cultivation, harvest and storage, by eliminating or diluting toxins from the con- taminated food or feeds, and by using adsorbents to reduce the bioavailability of toxins in the diges- tive tracts of animals. These measures will be assessed in the present paper. mycotoxins / feeds / ruminants / detoxification / rumen microbes

Effects of xylanase and beta-glucanase addition on performance, nutrient digestibility and physico chemical conditions in the small intestine contents and caecal microflora of broiler chickens fed a wheat and barley based diet

Abstract: Corn- or wheat and barley-based diets were supplemented or not with xylanase and β-glucanase (Quatrazyme HP, Nutri-Tomen, France) and fed to broiler chickens (n = 12 per group) from 3 to 25 days of age. The unsupplemented wheat and barley-based diet reduced (P ≤ 0.05) weight gain and feed intake, and increased the feed conversion ratio as compared to the corn-based diet. Vis- cosity in the supernatant of the small intestine contents was increased (P ≤ 0.05), whereas pH and osmolality values decreased (P ≤ 0.05). Crude fat and protein digestibility were reduced as well as the apparent metabolizable energy (P ≤ 0.05). Moreover, wheat and barley consumption, when com- pared with the corn-based diet, produced an increase in the microflora of the caeca, with 10.0 vs. 8.9 log CFU·g -1 for facultative anaerobic bacteria, 6.5 vs. 5.6 log CFU·g -1 for E. coli and 9.7 vs. 8.3 log CFU·g -1 for Lactobacillus. The addition of xylanase and β-glucanase to the wheat and bar- ley-based diet significantly reduced the viscosity of the small intestine contents and improved (P ≤ 0.05) weight gain, feed intake and feed conversion ratio. The digestibility of the nutrients, the apparent metabolizable energy and the osmolality of the small intestine contents were also increased without alteration in pH values. At the same time, the number of total facultative anaerobic bacteria and E. coli decreased significantly (P ≤ 0.05). In conclusion, the addition of xylanase and β-glucanase improves the digestibility of a wheat and barley-based diet, probably by reducing the viscosity of the intestine content and by impeding the growth of bacteria (total facultative anaerobic bacteria, E. coli). xylanase / -glucanase / wheat / barley / broiler / microflora

Effect of mastitis and related-germ on milk yield and composition during naturally-occurring udder infections in dairy cows

Abstract: The effect of mastitis and related-germs on milk chemical composition (protein and lac- tose contents) and milk somatic cell count (SCC) was investigated in 501 milk quarter samples during two consecutive years in cows from three experimental herds. Each infected quarter was matched by a healthy one in the same udder, as a control. Milk protein and mineral assays were performed in a sub- sample of 128 milks. Staphylococci were the most frequently isolated germs (Staphylococcus aureus: 27%, coagulase-negative Staphylococci: 26%, Streptococci: 21%). Major milk pathogens (Staphylococcus aureus, Streptococcus uberis or Escherichia coli) associated with clinical signs of mastitis were accompanied by higher SCC (+1.6 log·mL -1 , P < 0.01), lower lactose concentration (-7.6 g·kg -1 , P < 0.01), higher protein concentration (+3.3 g·kg -1 , P < 0.01) and higher soluble protein concentrations (IgG and BSA), hence a sharp decrease in the casein/protein ratio (-10 percentage points, P < 0.01). Changes were more marked when Escherichia coli was present. Corynebacterium bovis did not alter milk chemical composition whereas coagulase-negative Staphylococci slightly re- duced lactose concentration (-1.8 g·kg -1 ) and increased SCC (+0.37 log·mL -1 ). Calcium and phos- phorus milk contents were hardly modified by the presence of microorganisms. The decrease in milk yield during clinical mastitis varied from 1.6 kg·d -1 in the presence of Staphylococcus aureus to 15 kg·d -1 in the presence of Escherichia coli.

Identification of the main factors that influence caecal fermentation traits in growing rabbits

Abstract: The aim of this work was to determine the main factors that affect caecal pH, the caecal concentrations and molar proportions of volatile fatty acids (VFA) and the weight of caecal contents. The database was constituted of data (n = 92) from three laboratories that included the mentioned traits and the chemical composition and nutritive value of the diets. The laboratory affected caecal pH (P < 0.001) probably because of the differences in sampling time among them. Dietary uronic acids (UA) were measured in 21 diets and were negatively correlated with caecal pH and positively with caecal VFA concentration and the proportion of propionic acid (P = 0.004, 0.06 and 0.03, respec- tively). When UA was removed from the model, no other chemical characteristics significantly af- fected caecal pH, and digestible NDF was the variable which was the best correlated with it (R 2 = 0.58; P < 0.001). Only one laboratory detected a relationship between caecal pH and caecal concentrations of VFA (P = 0.044) and N-NH3 (P = 0.14), which accounted for 12% of the variabil- ity observed in caecal pH. A linear and quadratic effect of dietary NDF and the degree of lignification of NDF on VFA concentration was found (R 2 = 0.56; P < 0.001), indicating a positive effect of high levels of low lignified fibre on caecal VFA. The weight of caecal contents was quadratically influ- enced by dietary NDF (R 2 = 0.39; P < 0.001). It was also linearly affected by the degree of lignifi- cation of NDF (P < 0.001). Dry matter intake was negatively correlated with caecal content weight ( P< 0.001; R 2 = 0.44), once the effects of the laboratory and dietary digestible energy concentration

Effects of the hot season on milk protein fractions in Holstein cows

Abstract: Effects of the hot season on milk protein fractions were studied in 40 mid-lactating Hol- stein cows (141 ± 67 days in milk). The trial was carried out on a commercial dairy herd located in Central Italy (42 o 15' North, 12 o 21' East, 227 m of altitude). Twenty cows were monitored for six weeks from March to April; the other 20 cows were monitored for six weeks from June to August. The two groups were balanced for parity, days in milk (DIM), genetic index for milk production, and fre- quency of κ-casein B and β-lactoglobulin B variants. The diet for the two groups was a base-ration fed as a total mixed ration, plus concentrate given by self-feeders. During the two experimental peri- ods, values of air temperatures and relative humidity were recorded daily and were used to calculate the temperature-humidity index; average feed intake was recorded daily, and rectal temperatures were measured weekly. Milk yield was recorded at both morning (06:00 h) and evening (18:00 h) milkings. Individual milk samples were taken weekly and analysed for concentration of crude protein content, casein number, and protein fractions. During the summer, cows had higher rectal tempera- tures but lower DMI and milk yield. Moreover, milk from cows in the summer had lower contents of crude proteins and caseins, lower casein number, and higher milk serum proteins. Among caseins, the κ-casein fraction did not differ between the two groups. Conversely, milk from summer cows showed lower contents of αs-casein and β-casein. The results from the present study indicate that the reduc- tion of milk protein content observed in the summer was due to the reduction in the casein content, which was in turn caused by a reduction in αs-casein and β-casein contents. These changes might ex- plain the alteration in cheesemaking properties of milk commonly observed during the summer. summer / dairy cows / milk protein fractions / casein

Foraging in patchy grasslands: diet selection by sheep and cattle is affected by the abundance and spatial distribution of preferred species

Abstract: Understanding the distribution of grazing activity and its management is valuable to en- sure the sustainability and productivity of heterogeneous grasslands. Controlled behavioural studies can provide insight into the cognitive abilities of herbivores and suggest new approaches to improve their grazing distribution. We compared the behaviour and diet selection of sheep and cattle in 1-ha fescue (Festuca arundinacea S.) plots, in which the number and size of preferred ryegrass (Lolium perenne L.) patches were varied. Five different patterns were used to investigate the effects of ryegrass abundance and spatial distribution on the searching success of the herbivores. Both heifers and ewes grazed ryegrass more when its abundance increased from 1.5 to 6% , and also when ryegrass was aggregated into a few 8 × 9-m patches, rather than being dispersed into a larger number of 3 × 3-m ones. Neither the interaction between ryegrass abundance and patch size, nor that between herbivore species and patch size was significant. At 6% abundance, aggregating ryegrass into a single 24 × 24-m patch tended to further increase its use by heifers, but not by ewes. Fescue less than 1 meter from the nearest ryegrass patch was usually selected more than the fescue located further away. Fescue be- tween 1 and 5 m from the nearest patch was never selected more than the fescue located further away. Our results, together with those for the diet selected by sheep, cattle and deer, when offered patches of a preferred food in aggregated or dispersed patterns, indicate that over a wide range of abundance, it is advantageous for herbivores to forage on patchy resources when the preferred vegetation is aggre- gated. This corroborates the prediction that foraging costs associated with patch distribution are in- volved in determining diet selection in patchy grasslands, but our results suggest that it is also influenced by some social characteristics of the animals, such as their social attraction and social tol- erance.

Factors associated with stillborn and mummified piglets in high-prolific sows

Abstract: Stillbirth concerns about 2.5 million piglets each year in France and is expected to worsen in the coming years, due to hyperprolific sows. The present study was performed to determine the risk factors of the presence of stillborn piglets or mummies in the litter using data from three ex- perimental herds. From June 1999 until June 2000, sow, stillborn and mummy characteristics were closely recorded around farrowing. Information was recorded on 455 litters, from 308 sows. After se- lection, a total of 447 litters, originating from 302 crossbred (Large White × Landrace) sows were used. Two hundred and fifty-five litters had no stillborn. Neither individual piglet body weight nor variability of piglet body weight within litters were found to influence stillbirth. A reduction in the av- erage litter or sow live weights increased the probability of having a stillbirth. When a full litter was born with a human presence, the proportion of litters without a stillborn was higher than in cases of partial supervision (65.7 vs. 4.5 to 45.6%). At the same time, the number of litters with two or more stillborn piglets was lower (11.2 vs. 23.6 to 30.9%). Only 46% of the litters had no stillborn when no supervision was performed. These results indicate that good supervision (more than 75% of births with a human presence) decreased stillbirth in pigs, while individual piglet weight did not alter it. A reduction in litter live weight decreased the risk of having mummies, whereas an increased litter size had the opposite effect. sow / parturition / stillbirth / mummies / risk factors / supervision

Influence of dietary fibre level on digestive and metabolic utilisation of energy in growing and finishing pigs

Abstract: The aim of the experiment was to determine the effect of dietary fibre (DF) level on the digestive and metabolic utilisation of energy in pigs. Two diets were prepared: a control low DF diet (the C diet, 100 g Total Dietary Fibre (TDF)·kg -1 DM) and a fibre-rich diet (200 g TDF·kg -1 DM) which corresponded to a combination of the C diet and maize bran (the MB diet). Each diet was fed as pellets during two successive experimental periods to five, individually caged pigs at growing (42 kg BW) and finishing stages (76 kg BW) for the measurement of digestibility, heat production (HP; indi- rect calorimetry) and its components. Energy supply was standardised between the diets (2.4 and 2.3 MJ ME·d -1 ·(kg BW) -0.60 for growing and finishing pigs, respectively). The energy digestibility was not affected by growth stage but was lower for the MB diet (83%) than for the C diet (91%). Simi- larly, the DE value of maize bran (11.5 MJ·kg -1 DM), as calculated by the difference method, was similar at both stages. The fasting HP represented 56% of HP and averaged 0.724 MJ·d -1 ·(kg BW) -0.60 while the physical activity and thermic effect of feed represented on average 14 and 30% of HP, respectively. None of the components of HP was affected by the DF level. The activity HP was greater in finishing (16% of HP) than in growing pigs (12%). Energy cost of standing was constant (kJ·min -1 ) when expressed per kg BW 1.25 . When adjusted for similar ME intake and activity level, total HP and retained energy did not differ between the diets and between the growth stages. In conclusion, the metabolic utilisation of dietary energy was little affected by the DF level in growing and finishing pigs under the conditions of the present study. pig / digestibility / energy value / dietary fibre / heat production

Effect of dietary protein level, amino acid balance and feeding level on growth, gastrointestinal tract, and mucosal structure of the small intestine in broiler chickens

Abstract: In a factorial experiment, two series of feeds containing excess dietary protein, differing in amino acid balance (i.e. balanced (BPS) and unbalanced (UPS) amino acid mixture), and with a range of protein contents (400, 300 and 200 g CP·kg -1 ) at the same energy content of 13 MJ AME·kg -1 were offered at two levels of feeding (ad libitum or 0.75 of ad libitum intake) to 4320 broiler chickens between 10 and 24 days of age. Growth rate was significantly lowered by feed restriction. There was also a significant (P < 0.001) effect of dietary protein on the combined weight of the proventriculus and gizzard but only for the birds on the restricted feeding regime. Relative pancreatic weight in- creased (P < 0.001) with an increase in dietary protein level for the birds fed restricted amounts of BPS. The crypt depth of chicks on the ad libitum feeding regime was higher (P < 0.01) for the chicks on the BPS than for those on the UPS diet. The protein content of the jejunal mucosa was higher (P < 0.001) for birds fed ad libitum on the UPS diet than on the BPS diet. Daily feed allocation had a significant (P < 0.01) effect on jejunal protein content in birds that received the BPS diet, this being reduced in birds on restricted feeding. Maltase (P < 0.001) and sucrase (P < 0.01) activities were sig- nificantly reduced in chicks offered ad libitum access to the UPS diet. At high dietary CP, the specific activity of alkaline phosphatase was lower (P < 0.001) in chicks on the UPS diet than in those fed the BPS diet.

Comparison of carcass composition by parts and tissues between cocks and capons

Abstract: The effect of caponisation on carcass composition by parts and tissues was examined. Twenty-eight castrated and twenty male Penedesenca Negra chicks reared under free-range condi- tions were slaughtered at 28 weeks of age. The birds were castrated at 4 or 8 weeks. The left sides of the carcasses were quartered (wing, breast, thigh and drumstick), and the parts dissected into the tis- sue components (skin, subcutaneous fat, intermuscular fat, muscle, bone and tendons). Capons showed more abdominal, intermuscular and subcutaneous fat than the cocks, both at the same slaugh- ter age and at the same weight. The breast and thigh were heavier in the capons than in the cocks. However, the whole muscle mass in the breast was increased by caponisation. This favourable effect was achieved at the expense of decreasing the carcass yield. The age of castration up to 8 weeks did not affect the carcass composition of the parts and tissues. chicken / capon / carcass / tissue composition

Effects of adding a mixture of malate and yeast culture (Saccharomyces cerevisiae) on milk production of Murciano-Granadina dairy goats

Abstract: Twenty-four Murciano-Granadina dairy goats were used to investigate the effects of supplementation with a mixture of malate and yeast (Saccharomyces cerevisiae) on milk production. The goats were machine milked once a day after parturition and were assigned to two balanced groups on week 4 of lactation. The experimental groups were kept separately in pens and were fed a daily diet based on a dehydrated forage mixture (alfalfa hay: maize whole plant, 1:1) ad libitum, 0.3 kg alfalfa pellets and 0.2 kg barley grain. The basal diet was completed with 0.6 kg concentrate pellets fed indi- vidually. Two different dietary treatments were randomly assigned to each goat group: control (with- out supplementation) and supplemented (with a mixture of malate and yeast included in the concentrate at a level of 10 g·kg -1 ). Feed intake, milk yield, milk composition and body weight were evaluated from week 4 to 16 of lactation. Malate content of the control and supplemented concentrate was 2.4 and 6.0 g·kg -1 DM, respectively. Supplementation with the malate and yeast culture mixture did not affect (P > 0.05) feed intake (2.04 vs. 2.03 kg DM·d -1 ), milk yield (2.09 vs. 2.08 L·d -1 ), milk fat (5.17 vs. 4.85%), milk protein (3.70 vs. 3.63%) or milk casein (2.57 vs. 2.51%) for the control vs. the supplemented goats, respectively. Nevertheless, the supplemented goats gained more body weight than the control goats (39 vs. 19 g·d -1 ; P < 0.05). We conclude that supplementation with the mixture of malate and yeast culture, under the conditions of our experiment, had no beneficial effects on the performance of dairy goats. The relatively high contents of malic acid in the forage mixture (7.3 g·kg -1 DM) and in the alfalfa pellets (14.2 g·kg -1 DM) may have decreased the response to malate

Combined effects of once-daily milking and feeding level in the first three weeks of lactation on milk production and enzyme activities, and nutritional status, in Holstein cows

Abstract: Effets de la traite une fois par jour combinee au niveau d'alimentation pendant les trois premieres semaines de la lactation sur la production et les activites enzymatiques du lait, et l'etat nutritionnel, chez des vaches Holstein. Vingt-quatre vaches multipares ont ete reparties des le velage en 4 lots, selon un schema factoriel 2 x 2: 2 frequences de traite (1 traite par jour pendant les 3 premieres semaines de lactation, puis 2 traites par jour vs. 2 traites par jour en permanence) x 2 concentrations energetiques de la ration (normale ou basse). L'essai a dure en moyenne 30 semaines et s'est termine au pâturage, le 28 mai 2000. Pendant la periode hivernale, les vaches etaient logees ensemble dans une stabulation libre a logettes et recevaient a volonte une ration complete. La traite omise etait celle du soir. Les vaches non traites ont emis significativement plus de vocalisations que les temoins autour de la traite omise, et elles ont ete plus nombreuses a perdre du lait. La traite 1 fois par jour a progressivement reduit la quantite de lait secretee par rapport a celle produite par les vaches traites 2 fois par jour, l'ecart atteignant 8,5 kgj -1 (P 0,10) pour l'ensemble de l'essai. La traite 1 fois par jour n'a pas affecte la teneur du lait en matieres grasses, en proteines (vraies), en albumine serique, et en lactose, ni le nombre de cellules somatiques ou l'activite de la plasmine et celle induite par l'activation du plasminogene. Elle a accru la teneur en immunoglobulines G1 (P = 0,02; mesure a la semaine 3) et a diminue l'activite de la lipoproteine lipase, ce qui n'avait pas encore ete rapporte. Elle a ameliore l'etat nutritionnel en debut de lactation (pertes de poids vif et d'etat corporel reduites, bilan energetique calcule accru) et n'a eu aucun effet sur la quantite de ration ingeree. La ration de concentration energetique normale a entraine, par rapport a celle de concentration energetique basse, les effets attendus: accroissement significatif des quantites ingerees (1,2 kg MSj -1 ), de la quantite de lait produite (3,1 kgj -1 ), de son taux proteique (2,0 gkg -1 ) et des index nutritionnels, notamment. La reduction de quantite de lait produite au cours des 3 premieres semaines de la lactation entrainee par la traite 1 fois par jour a ete de 5,5 kgj -1 et 8,5 kgj -1 respectivement pour les lots recevant les rations de concentration energetique faible ou normale (interaction non significative; P > 0,10).

Rumen digestion and intestinal nutrient flows in sheep consuming pea seeds: the effect of extrusion or chestnut tannin addition

Abstract: Degradation ruminale et digestion intestinale de la graine de pois: effets de l'extrusion ou d'un ajout de tannins de châtaignier. L'effet de differents traitements visant a diminuer la degradabilite ruminale des proteines du pois a ete evalue par des mesures in situ et in vivo de la digestion ruminale et intestinale. Quatre moutons fistules ont ete utilises. La graine de pois constituait 50 % de la matiere azotee totale (MAT) de la ration. Le pois a ete distribue cru (RP), avec des tannins de châtaignier (RPT2, 2 % de la MAT du pois; RPT3, 3 % de la MAT du pois) ou extrude. La degradabilite theorique du pois a diminue sous l'effet du traitement d'extrusion (83,3 % vs. 90,8 %), mais n'a pas ete affectee par l'ajout de tannins. In vivo, l'addition de tannin n'a eu aucun effet sur les parametres de la digestion de la matiere organique (MO) et de l'N. L'extrusion a diminue la digestion apparente de la MO dans le rumen, mais celle-ci a augmente dans l'intestin grele. Ainsi la digestibilite de la MO dans l'ensemble du tube digestifn'a pas ete modifiee. Le flux duodenal de NAN a augmente de 27 % entre les regimes RP et EP. Cette augmentation s'explique essentiellement par une augmentation du flux de NAN non-microbien. La digestibilite intestinale apparente n'a pas ete modifiee par l'extrusion et la quantite de NAN apparemment digeree dans l'intestin grele a augmente de 23 % entre les regimes RP et EP. Une legere diminution de la digestibilite totale de l'N a ete observee avec le traitement d'extrusion. L'efficacite de la synthese de proteines microbiennes a ete superieure avec le regime EP. La quantite d'acides amines apparemment digeree dans l'intestin grele a ete plus elevee avec le regime EP qu'avec le regime RP, mais le profil des acides amines apparemment absorbes n'a pas ete modifie. Cette etude montre que des faibles doses de tannins (jusqu'a 3 % de la MAT du pois, ou 1,5 % de la MAT de la ration) sont inefficaces pour diminuer la degradabilite ruminale de la graine de pois, par contre l'extrusion peut largement ameliorer la valeur azotee de ce proteagineux.

Influence of low dietary starch/fibre ratio around weaning on intake behaviour, performance and health status of young and rabbit does

Abstract: The influence of a low starch/fibre ratio (S/F) diet given to rabbits and does around weaning on their performance and health status was studied. In the LS group (n = 29 litters), the rab- bits were fed a low S/F (0.68) diet (LS diet: 11.7 DE MJ·kg -1 DM) from day 18 to day 44; then they were changed to a fattening diet (F diet: 12.5 DE MJ·kg -1 DM). In the HS group (n = 29 litters), the rabbits were fed a high S/F (0.98) diet (HS diet: 12.6 DE MJ·kg -1 DM) from days 18 to 32 (weaning), and after weaning they received the F diet. From day 18 to weaning, the females and litters were fed the same diet. From day 18 to day 21, after the feed change, the LS females' feed intake dropped (-6%). As a consequence, they lost weight (-4%), and produced less milk from days 21 to 24 than the HS females (-17%; P < 0.05). Moreover, a high mortality was registered for the LS females (7/29 vs. 0/29, in LS vs. HS respectively; P = 0.01). From day 25 to weaning, the feed intake of the litters was lower in the LS group than in the HS group (-13%; P < 0.05). Consequently, at weaning, the live weight of the LS rabbits was lower (-6%; P < 0.01). From days 18 to 32, mortality was higher in the LS group (5.2 vs. 0.8%; P < 0.01). After weaning, feed intake tended to be higher in the LS group, and on day 44, live weight did not differ between the groups. From days 32 to 44, morbidity tended (P = 0.06) to be lower for the LS rabbits. In conclusion, young rabbits would not regulate their feed intake according to the dietary DE level. Moreover, a feed change for females, at the lactation peak, reduced their intake level, leading to a lower milk production. This also induced a lower health status both in the females and in the liters. rabbit / feed intake / milk intake / does / starch/fibre ratio / sanitary status

Feeding behaviour and intake of heifers fed on hays of various quality, offered alone or in a choice situation

Abstract: We studied the feeding behaviour of cattle offered unconstrained choices between two hays of either different or similar nutritive values, and linked these choices to their behaviour when the same forages were offered alone. Over successive 10-day periods, six 15-month-old Aubrac heif- ers received three hays (a leafy one, G, and two late cut ones, C1 and C2, of very similar nutritive value), ad libitum, alternately alone and associated two by two. As expected, the heifers ate more G than C1 or C2 when the hay was offered alone, and preferred G in choice trials. They displayed a simi- lar behaviour towards C1 and C2 when they were given alone, and also when they were independently associated with G (C1 and C2 making up 18% and 17% of the total intake and 21% and 17% of total feeding time, respectively) or when they were offered together (each accounting for nearly 50% of the total intake or feeding time). The choices could be related to the daily intakes of the forages given alone, which could thus be a good predictor of relative daily intakes under choice conditions. Heifers always showed partial choices, which could be seen as the research of the maintenance of optimal ruminal conditions, the result of sampling behaviour and/or the pleasure associated with the diversity of the diet. Their tendency to diversify the diet was also supported by the reaction to the recent diet by temporarily increasing their preference for the hay that had not been offered during the previous no- choice sub-period. Finally, all the choice situations raised the daily dry matter intake, which could be seen as the result of their motivation to eat due to the diversity of the offer. feeding choice / intake / cattle / hay

Bioavailability of two sources of zinc in weanling pigs

Abstract: Thirty-two pigs, weaned at 28 days of age with an average body weight of 9 kg, were used in an experiment devoted to the assessment of the bioavailability of an organic Zn source (ZnOrg) compared to Zn sulfate. Pigs were fed a basal diet containing 28 mg·kg -1 of Zn supplemented with ZnSO4 or ZnOrg to provide 0, 10, 20 and 30 mg·kg -1 of supplemental Zn. In order to reduce the amount and the variability of their Zn stores, pigs were fed the basal diet for a 7-day adjustment period preceding a 19-day experimental period. Growth performance and bone bending moment were not affected by the level nor the source of zinc. On the contrary, plasma zinc concentration and alkaline phosphatase activity (P < 0.001), bone zinc concentration (P < 0.001), liver and empty body zinc concentrations (P < 0.01) as well as the amount of Zn retained estimated both by the balance tech- nique (BT) (P < 0.001) and by the comparative slaughter technique (CST) (P < 0.01) increased lin- early in response to supplemental Zn. However, the two Zn sources exhibited a similar bioavailability. Twenty-seven percent of Zn intake was retained when measured by means of the balance technique, regardless of the dietary level or zinc source. Zn retention was 54% lower when measured by means of the CST as compared to the BT. pig / zinc / bioavailability / source / indicator

Bone development and activity in chickens in response to reduced weight-load on legs

Abstract: In order to find out whether a reduction in load-bearing on chicken legs would modify the activity and leg bone tissue, an original suspension device was developed in order to alleviate half of the weight-load on the legs. Thirty-six 5 d-old male meat-type chicks were assigned to 12 groups, each of 3 birds: a control bird (C), a bird equipped with a harness (H) and one equipped with a harness and suspended from a balance (S). The counterweights of the balance reduced the load on the legs by 50%. Behaviour in the birds was recorded twice for a 22-hour period. The birds were slaughtered at 19 d of age. Their legs were then weighed and the humeri, tibiotarsi and femurs were used for compu- tation of length, biomechanical stiffness and composition. Tibiotarsi were also used for histomorphometry. Body weight at 19 d of age was significantly higher in the C birds (642 g vs. 586 g in the H and S groups, P < 0.05). The distance travelled as measured in the second week of the experi- ment was greater in S birds (338 m per 22 h vs. 246 in the C group and 252 in the H group, P < 0.05). The length of the tibiotarsi and femora was greater in the S birds when corrected for body weight (P < 0.05). Bone stiffness, composition and histological parameters were not significantly different in the 3 groups. We thus concluded that a reduction in load-bearing on the legs of young chicks en- hances locomotor activity and longitudinal growth of leg bones. Bone quality was not affected, prob- ably due to the contradictory effects of increased exercise and reduced weight. chicken / locomotion / exercise / bone / growth

Distribution of trans-vaccenic acid and cis9, trans11-conjugated linoleic acid (rumenic acid) in blood plasma lipid fractions and secretion in milk fat of Jersey cows fed canola or soybean oil

Abstract: To determine fatty acid distribution in lipid fractions of bovine blood plasma, 24 multiparous Jersey cows at peak lactation were fed a control diet (no supplemental oil, NOS) or the control diet supplemented at 35 g·kg -1 dry matter with canola oil (CAN), soybean oil (SOY), or a mix- ture of equal amounts of canola and soybean oil (MIX) for 4 wk. Plasma lipid fractions were isolated with aminopropyl columns. Fatty acid concentration in the phospholipid (PL), cholesterol ester (CE), and triglyceride (TG) fractions of plasma from cows fed supplemental oil was 142 (+47%), 144 (+57%), and 26 (+72%) µg·mL -1 greater than those of the control group. Oleic acid increased from 153 to 195, 100 to 151, 35 to 53, and 103 to 161 mg·g -1 of total fatty acids in the free fatty acid (FFA), PL, CE, and TG fractions, respectively, when CAN-fed cows were compared with NOS. In contrast, SOY intake increased 18:2n-6 in FFA, PL, CE, and TG fractions from 37 to 55, 327 to 366, 684 to 744, and 42 to 72 mg·g -1 , respectively. In the TG fraction, feeding SOY also increased trans11-18:1 from 40 to 105 mg·g -1 and cis9,trans11-18:2 from 1 to 12 mg·g -1 . Concentration and yield of trans11-18:1 in milk fat were 21 mg·g -1 and 13.7 g·d -1 when feeding NOS, and increased to 45 mg·g -1 and 43.1 g·d -1 in response to SOY. Similarly, concentration and yield of cis9,trans11-18:2 were 5 mg·g -1 and 7.3 g·d -1 , and increased to 13 mg·g -1 and 11.2 g·d -1 in response to SOY. Concentrations of trans-iso- mers in blood plasma and milk fat ranked by treatment reflected linoleic acid intakes, and were greater in SOY-fed cows compared with NOS or CAN-fed cows. Plasma lipid fractions can be used to appraise incomplete biohydrogenation of unsaturated fatty acids in the rumen.

Evidence for heterosis and maternal effects on rabbit semen characteristics

Abstract: The analysis concerned 546 ejaculates from 65 bucks from two strains ('1601', a dupli- cate of the 'Verde' strain from INIA-Valencia, Spain- and '2066' from INRA, France) and their two reciprocal crosses, recorded during a 210 day period spanning from August 1996 to February 1997. Two ejaculates were collected from each buck every three weeks and semen traits were recorded ev- ery six weeks when the semen was used for insemination. All semen traits were recorded for both ejaculates except concentration, which was recorded only for the ejaculate selected for insemination (the better of the two ejaculates for mass motility). On average, mass motility (scale of Petitjean, 1965 (24)) was 6.75 (standard deviation 1.01), pH 7.28 (0.33), volume 0.62 mL (0.19 mL), percent of motile spermatozoa (PMS) 70.1% (7.5%), concentration 492 × 10 6 spz·mL -1 (142 × 10 6 ), the total number of spermatozoa per ejaculate (TSE) 321 × 10 6 (110 × 10 6 ) and the number of motile sperms per ejaculate (MSE) 231 × 10 6 (83 × 10 6 ). Both strains had similar performances except for the vol- ume of the ejaculate (1601: 0.67 ± 0.04 mL; 2066: 0.52 ± 0.04 mL) and PMS (1601: 69.8 ± 1.4%; 2066: 66.4 ± 1.4%). There was a significant heterosis effect for concentration (37.5% of the parental average), mass motility (6.8%) and PMS (4.1%). Heterosis for the synthetic criteria TSE and MSE amounted to 37.6% and 42.3%, respectively. Strain differences in maternal effects were evidenced: strain 1601 exhibited favourable maternal effects on volume, PMS and mass motility. rabbit / semen / heterosis / maternal effects

Effect of nitrogen fertiliser rate and protein supplementation on the herbage intake and the nitrogen balance of grazing dairy cows

Abstract: The objective of this study was to examine the effect of the level of reducing nitrogen (N) fertiliser rate on herbage intake and N balance of dairy cows grazing a pure perennial ryegrass pas- ture. The addition of a protein supplement to cows grazing the low N fertilised sward was also evalu- ated. Three treatments were compared over three periods of 2 weeks using 9 fistulated cows in a 3 × 3 Latin square design: HN (80 kg N·ha -1 ·regrowth -1 ), LN (0-20 kg N·ha -1 ·regrowth -1 ), LN+S (LN + 2 kg of soybean meal (SBM)). Daily herbage organic matter (OM) intake was estimated by chromic oxide dilution in the faeces. Nitrogen and ADF contents in faecal OM were used to estimate the herb- age digestibility. Herbage mass, grazing behaviour and rumen fermentation pattern were measured. Nitrogen intake was estimated by the chemical composition of the defoliated herbage and urinary N was calculated by subtracting milk N and faecal N output from N intake. Digestibility (0.79), daily in- take (16.4 kg OM), grazing time (512 min) and the proportion of volatile fatty acid were not affected by reducing the N fertiliser rate. These results may be explained by the moderate effect of N fertilisa- tion on herbage mass which remained high in the LN swards (3.9 vs. 4.7 t OM·ha -1 for HN) and the rather large herbage allowance which allowed the cows to graze a herbage with a crude protein con- tent that still remained higher than 160 g·kg -1 DM. On the LN sward, N intake was significantly lower (- 80 g·d -1 )( P < 0.01), faecal N and milk N output remained unchanged, whereas urine N output de- creased (- 77 g·d -1 )( P < 0.01). Protein supplementation did not depress HOMI or grazing time, sup- plemented cows consumed 2.4 kg OM more (P < 0.01) and this increased milk yield by 1.3 kg·kg -1 SBM (P < 0.01). SBM supplementation largely increased N intake, and finally N excreted in the urine. It was concluded that N fertilisation, and N supplementation are efficient means to manipulate animal performances and N balance in grazing dairy cows.

Dairy cows grazing an alpine pasture: effect of pattern of supplement allocation on herbage intake, body condition, milk yield and coagulation properties

Abstract: The effect of two patterns of concentrate allocation were studied on twenty-eight Italian Brown cows (initial milk yield, 19.4 kg·d -1 ) grazing an alpine pasture. One group was supplemented at a flat rate, based on the initial milk production (Flat Supplement, FS), while the second was supple- mented at a declining rate, according to the decline of lactation (Declining Supplement, DS). During an 8-week period in July and August, the cows were moved onto 8 successive sectors, ensuring a daily herbage allowance of 20 kg of dry matter per cow. The crude protein content of the herbage decreased from 19.5% at the beginning to 12.4% at the end, while the fibre fractions showed an opposite trend. The DS group showed a slightly higher, not significant, herbage intake (10.9 vs. 10.6 kg OM·d -1 ). BCS changes were in no case different from 0. The milk yield was positively affected by the FS (17.0 kg·d -1 vs. 15.2 kg·d -1 ); no difference was observed in milk composition. Coagulation properties were satisfactory without any appreciable effect of the two treatments. dairy cow / pasture / supplementation / herbage intake / milk production

Effects of high ambient temperature and dietary protein level on feeding behavior of multiparous lactating sows

Abstract: Trente-trois truies multipares Large White × Landrace ont ete utilisees pour determiner l'effet d'une elevation de la temperature ambiante et du niveau d'extra chaleur alimentaire sur leur comportement alimentaire au cours de la lactation. La temperature ambiante est maintenue constante a 20 ou 29 °C au cours des 28 jours de lactation. Trois regimes experimentaux ont ete utilises au cours de la lactation: un regime temoin (NP; 17,6 % de matieres azotees totales, MAT) et deux regimes a faible teneur en proteines (LP; 14,6 % MAT) ou avec une reduction de la teneur en proteines et un ajout de matieres grasses (LPF, 15,2 % MAT). L'aliment est distribue a volonte du 7 e au 27 e jour de lactation. Les parametres du comportement alimentaire ne sont pas influences par la composition des regimes. Entre le 7 e et le 27 e jour de lactation, la diminution de la consommation d'aliment a 29 °C (P < 0,001; 4149 vs. 7444 g.j -1 a 20 °C) est la consequence d'une reduction de la reduction du nombre de repas (P < 0,001; 6,5 vs. 9,4 repas par jour) et de la taille des repas (P < 0,10; 687 vs. 834 g par repas). La vitesse d'ingestion n'est pas influencee par la temperature (126 g.min -1 en moyenne), et par consequent, la reduction de la consommation d'aliment a 29 °C provoque une diminution du temps d'ingestion et de consommation (respectivement, -25 et -28 min.j -1 ). A 29 °C, la proportion des repas de petite taille (i.e., < 250 g) est superieure alors que celle des repas de taille moyenne (i.e., 250-500 g) est inferieure. La consommation d'aliment et d'eau en periode diurne 'represente respectivement 84 et 79 % de la consommation totale. Deux pics de consommation sont observes, le premier entre 07.00 et 13.00 pour les deux temperatures et le second (17.00 a 23.00 a 29 °C vs. 14.00 a 23.00 a 20 °C) d'une duree plus courte a 29 °C. Le temps passe en position debout n'est pas affecte par la temperature et s'eleve en moyenne a 127 min.j -1 . Environ 70 % du temps passe debout est dedie a la consommation d'aliment et d'eau. D'apres les coefficients de correlation calcules entre la taille du repas et l'intervalle de temps le separant du repas precedent ou du repas suivant, il semble que pour la majorite des truies (67 %), la taille du repas soit partiellement regulee par des mecanismes de satiete.

The effect of remating interval and weaning age on the reproductive performance of rabbit does

Abstract: In this study we investigated the influence of the reproductive system on doe reproduc- tive performance. Two experimental treatments were compared using 36 cages per treatment over an 8-month production period. In the intensive system (IS) rabbit does were mate d4da fter parturition and the litters were weaned at 25 d of age, whereas in the control system (CS) the rabbit does were mated 11 d after parturition and the litters were weaned at 35 d of age. In both systems, the does that failed to mate, conceive or lost their pups were immediately given the opportunity to remate. Initially seventy-two New Zealand × Californian does were assigned to the treatments and used to determine the reproductive traits. Early mating of rabbit does associated with 25-d litter weaning (IS) allowed a shorter parturition interval (39.9 vs. 44.4 d, P = 0.0001) and a higher prolificacy (9.07 vs. 8.11 young rabbits born alive per litter, P = 0.06), litter size at 21 d (8.24 vs. 7.51, P = 0.06) and at weaning (8.21 vs. 7.42, P = 0.05) and tended to reduce the number of young rabbits born dead (0.52 vs. 0.94, P = 0.10) as compared to the animals in the CS treatment. Consequently, numerical productivity in- creased from 61.6 to 73.4 young rabbits per cage and year (P = 0.003). The intensively bred does had a lower receptivity to the male at the first mating (54 vs. 86.9%, respectively), but 88% of these does ac- cepted mating within 7da fter parturition. Fertility was high, above 80%, in all the matings. The treat- ments did not affect either the body weight (4301 g as average) or the mortality of the rabbit does (14.6%) and the mortality of the young rabbits during lactation (11.8%). Feed efficiency increased from 0.241 to 0.309 g of young rabbits weaned per g of feed when the remating interval was longer but these results cannot be compared because of the parallel increase in the age and weight of the young rabbits at weaning. This study indicates that, in the conditions of reproductive management used, the numerical productivity can be increased through earlier mating and weaning. However, more infor- mation is needed about the effect of this system on young rabbit performance after weaning, and about the possibility of increasing the receptivity of rabbit does at 4 d by using bio-stimulation methods.

In situ evaluation of the protein value of soybean meal and processed full fat soybeans for ruminants

Abstract: The rumen degradation and the intestinal digestion of dry matter (DM) and crude protein (CP) of different samples of soybean meal (SBM) and full-fat soybean (FFS) were determined using in situ techniques. Rumen effective degradability (ED) was determined in three rumen fistulated wethers on nine SBM samples, obtained by solvent extraction (SBM1 to 8) and by expelling (SBM9), and on five FFS samples, treated by extrusion (FFS1 to 4) and by toasting (FFS5). Intestinal digest- ibility (ID) in the original feed and in the feed residues after rumen incubation for 8 and 24 h was de- termined in three duodenal fistulated wethers for three samples of SBM (6, 8 and 9) and two samples of FFS (2 and 3). No differences (P > 0.05) were observed between the mean values of SBM and FFS for the degradation kinetic parameters and the ED of both DM and CP. On the contrary, differences were found within each feed category. The ED of CP of SBM9 (46.1%) was lower than that of all sol- vent extracted meals, which ranged from 55.8 to 67.0%. The ED of CP for FFS5 (toasted) was equal to the minimum value of the range of the extruded samples (57.3 to 71.3%). The ED of CP was more closely correlated with the variation of the degradation rate (kd )( r = 0.92; P < 0.001) than with the sol- uble (a) or the potentially degradable (b) fractions (r = 0.67 and -0.68, respectively; P < 0.01). On the other hand, the degradation parameters of DM and CP were closely correlated (r = 0.92, 0.92, 0.81 and 0.79 for ED,kd, b and a, respectively; P < 0.001). The effects of rumen pre-incubation time on the ID of CP, only recorded for three samples, were variable and relatively small in magnitude. The mean values of the ID of CP were similar among samples (from 95.9 to 97.6%). The protein value of soy- bean products is mainly determined by the ED of CP, since the increases of by-pass digestible protein, associated with its reduction, largely exceed the reductions in the microbial protein synthesis caused by the decreased feed degradability. soybean meal / full fat soybean / rumen degradability / intestinal digestibility / protein value

In vitro determination of ruminal dry matter and cell wall degradation, and production of fermentation end-products of various by-products

Abstract: The samples used in the experiment were nine types of by-products: giant pumpkin, red pepper, melon, broccoli, brewer's grains, fresh and boiled artichoke, lemon peel and orange peel. The dry matter degradability of each by-product was determined by in vitro fermentation with ruminal fluid of the goat. The materials were incubated at 39 oC for 12, 24, 48 and 72 h. At each time, pH, dry matter disappearance, neutral-detergent fibre disappearance, volatile fatty acids, lactic acid and am- monia productions were measured. Approximately 50% of the total dry matter loss of broccoli, melon and peels occurred at 12 h incubation. In addition, the total dry matter loss of the giant pump- kin, fresh and boiled artichoke, and brewer's grains was low ( 70% for all by-products, except for brewer's grains (63.8%), and the propionate proportion was < 20% for all by-products, except for the brewer's grains (21.3%). In conclusion, the ruminal dry matter and cell wall degradations, and production of fermentation end-products by in vi- tro determination offers a convenient method to compare the microbial digestion of the different by- products.

Reducing the impact of condensed tannins in a diet based on carob pulp using two levels of polyethylene glycol: lamb growth, digestion and meat quality

Abstract: Fourteen male Comisana lambs were divided into two groups of seven at age 45 days and were fed a diet containing 56% of dried carob pulp (as fed basis). One group (P10) received a supple- ment of 10 g of polyethylene glycol (PEG) for each kg of diet, while the second group (P40) received a supplement of 40 g of PEG for each kg of diet. Both diets were ground and supplied ad libitum. The experimental diet contained 2.1% of condensed tannins (CT) on a dry matter basis. The lambs fed the P40 diet had higher average daily gain than the P10 lambs (P < 0.05) and obtained higher live weights at slaughter (P = 0.08) although the dry matter intake was not different between the treatments. The increased level of PEG (P40 vs. P10 lambs) increased dry matter digestibility (P = 0.07) and nitrogen (N) and neutral detergent fibre (NDF) digestibility (P < 0.01). The carcasses from the P40 lambs were heavier and fattier than those from the P10 lambs (P < 0.05). Meat (l. dorsi muscle) from the P10 lambs showed higher (P < 0.05) values of lightness (L*) compared to the P40 lambs. No differences in eating quality were registered among the groups. These results indicate that in a diet based on carob pulp (56%), 10 g of PEG per kg of diet are not sufficient to eliminate the effects of CT. carob pulp / meat quality / polyethylene glycol / sheep / tannins

Effect of time of starch supply to the rumen on the dynamics of urea and ammonia net flux across the rumen wall of sheep

Abstract: The effects of rumen starch fermentation on urea and ammonia net fluxes across the ruminal wall were studied in four Texel wethers (67 ± 1.5 kg BW) fitted with catheters in both ruminal veins and in a mesenteric artery, blood flow probes on ruminal arteries, and a ruminal cannula. They were fed 500 g of orchardgrass hay every 12 h. A dose of 120 g of starch was added directly to the ru- men either during the meal or 3 h later. On a daily basis, the time of starch supply did not modify the urea and ammonia net flux across the rumen wall. Within the feeding cycle, whatever the time of starch injection, the decrease in ruminal ammonia and pH and the increase in ruminal volatile fatty ac- ids and CO2 associated with starch fermentation were accompanied by a decrease in ammonia ab- sorption and an increase in urea net transfer across the ruminal wall. This study confirms the existence of a synchronisation between urea net transfer across the rumen wall and rumen carbohydrate fer- mentation within a feeding cycle. Factors acting in the regulation of urea and ammonia net flux in the ruminal veins are discussed. ammonia / urea / flux / rumen / sheep

Cattle feeding behaviour at pasture: a methodology related to on farm measurements

Abstract: In order to study the effects of herbage allowance on cattle behaviour activities on the farm, some methodological aspects had to be defined. Two sets of observations have been conducted on farm using a beef suckler herd containing 24 cows and managed in a rotational grazing system in- cluding a total of 6 paddocks. Behaviour activities were recorded on two successive paddocks. In set 1, the herd activities were recorded every 5 min in daylight and 15 min at night for the first two days on the two paddocks. In set 2, ten cows were individually identified among the same herd. On the first and the last day on the two paddocks, daylight activities were recorded with 5-min frequencies. From these individual observations, total grazing and ruminating duration were calculated, simulating re- cords every 5, 10, 15 and 20 min. In set 1,76% of the total grazing and 28 % of the total ruminating ac- tivities occurred in daylight. Grazing started at dawn and finished at dusk. In set 2, grazing activity followed the same pattern as in set 1 in daylight. Whatever the frequency of the records, grazing and ruminating time were not significantly (P > 0.05) different. However the 10 min frequency gave fewer and lower individual differences than the 15 and 20 min frequencies, compared to the original record (5 min). It is concluded that visual observations of cattle managed in a rotational grazing sys- tem can be readily undertaken at the farm level with 5 to 20 min frequencies. cattle / pasture / feeding behaviour / methodology

Blood serum and skin fatty acid levels in horses and the use of dietary polyunsaturated fatty acids

Abstract: The effect of the addition of a daily 20 g dose of an unsaturated fatty acid rich oil from Purple Viper's Bugloss seeds (Crossential SA 14, Croda) has been studied on saddle horses fed a near to maintenance level of a first cut meadow hay - barley diet. The percentages of the following fatty ac- ids: C16:0, C18:0, C18:1, C18:2 ω6, C18:3 ω3, C18:4 ω3, C20:3 ω6, C20:4 ω3, C20:4 ω6, C22:5 ω3, C22:6 ω3, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, ω3 fatty acids, ω6 fatty acids, were determined in blood serum and skin. The ω3/ω6 ratio was also considered. No statistical differences were found for the treatment. In the skin, compared with blood serum, a higher percentage of C16:0, C18:1, C18:4 ω3, monounsaturated fatty acids, ω3 fatty acids and satu- rated fatty acids were found; the ω3/ω6 ratio was also higher in the skin. Lower percentages of C18:0, C18:2 ω6, polyunsaturated fatty acids and ω6 fatty acids were also recorded for the skin, compared with blood serum. The blood levels of fatty acids were not always similar to the values found in the lit- erature, but some differences can be explained by the differences in the diets used. The low level of oil addition can explain the lack of significance of the effect of the oil used. Further studies are needed to confirm the trend in the differences found between blood serum and skin percentages of fatty acids.