Three experiments were carried out to determine plasma amino acids concentrations in circulating, portal and hepatic blood of growing male Wistar rats given diets containing lactalbumin, faba beans or chickpeas as the only protein source. Diets contained the same amount of digestible energy (15·5 kJ/g) and protein (lactalbumin in controls or legume proteins in the experimental diets; 100 g/kg). Appropriate amounts of essential synthetic amino acids were also added to legume-based diets taking into account their amino acid composition to equalize them to control (lactalbumin) diets. Portal blood flow (8·7±0·3 ml/min) was measured by using a transit-time ultrasound flow probe. Higher (P < 001) plasma concentrations of methionine than of controls were determined in hepatic veins of legume-fed rats. In contrast, lower (P < 001) concentrations of threonine, proline, valine, leucine, phenylalanine and lysine than those of controls were found in faba bean- and chickpea-fed rats. The same result as hepatic was obtained for portal and circulating plasma samples except that alanine and histidine values of legume-fed rats were also lower (P < 001) than controls. Calculated net afferent appearance rates of amino acids to the liver were lower (P < 001) than controls in rats given faba bean and chickpea diets for threonine, alanine, proline, valine, leucine, phenylalanine and lysine. This lower contribution of amino acids to the liver mainly via the portal vein in faba bean or chickpea-fed rats might explain previously reported differences in protein utilization and growth in comparison with animals given other protein sources (lactalbumin).

The effects of terminal sire line, halothane genotype and age on feeding patterns and growth performance were studied in 208 castrated growing-finishing pigs distributed in two batches. In batch 1 (no. = 130), pigs came from crosses of NN Landrace × Large White sows with a Pietrain Nn (Pi-Nn) or a Large White × Pietrain Nn terminal sire line (LwPi-Nn). In batch 2 (no. = 78), the same sows were used but crossed with three different terminal sire lines : a Pietrain nn (Pi-nn), and two Pietrain NN (Pi-NNa and Pi-NNb). Growth performance and feeding patterns of the progeny (Nn or NN for the halothane gene) were measured from 67 to 166 days of age. Pigs were housed in groups of 10 and 13 individuals in Batch 1 and 2, respectively, with a random mixed-breed and halothane genotype sample in each group (space allowance 1·3 m2 per pig and 1·1 m2 per pig, respectively). Feeding patterns were monitored with a computerized food intake recording system (IVOG®-station) and every 3 weeks pigs were weighed and backfat and loin-muscle depth were ultrasonically recorded (PIGLOG®). Carcass quality was assessed with the Fat-o-Meater grading probe. In batch 1, halothane genotype did not have a significant effect on any of the feeding patterns recorded, but Nn individuals had a significantly higher body weight (P <0·05), loin-muscle depth (P <0·05) and lower backfat thickness (P <0·01) in the last measurement taken, 3/4 carcass loin depth (P <0·05) and lower carcass last rib backfat (P <0·05) than NN pigs. Terminal sire line had a significant effect on all feeding patterns recorded except for feeding rate, Pi-Nn sired pigs showing a significantly higher food intake per visit (P <0·05) and feeder occupation time per visit (P <0·05) and lower number of visits (P <0·001) compared with LwPi-Nn sired pigs which, in turn, showed significantly higher food intake per day (P <0·001) and feeder occupation time per day (P <0·01). Terminal sire also affected growth performance and body composition, Pi-Nn sired pigs having a significantly lower body weight (P <0·001) and backfat thickness (P <0·001) but higher killing-out proportion and 3/4 loin depth (P <0·01) than LwPi-Nn sired pigs. In batch 2, Pi-NNb sired pigs showed a significantly lower food intake per day compared with the progeny of the other two terminal sires lines at some of the age measurements taken (P <0·05). The rest of the feeding patterns was not affected by terminal sire line. Body and carcass weights were also significantly lower (P <0·01) for Pi-NNb sired pigs, but their killing-out proportion was higher than Pi-NNa sired pigs. With regard to these variables, Pi-nn sired pigs held an intermediate position between the two NN terminal sire lines. In both batches, age was associated with a significant increase in food intake per visit and per day and feeding rate (P <0·001) and a decrease in feeder occupation time per visit and per day and frequency of visits to the feeder (P <0·001). Overall, the present results suggest differences between terminal sire lines for feeding patterns and confirm their evolution with age from short and frequent meals to long and larger ones in growing-finishing pigs. Under our conditions, the effects of terminal sire line on feeding patterns and growth performance surpassed those of the halothane genotype.

The objective of this work was to evaluate the ultrasound method as a tool for in-vivo breast and abdominal fat prediction on Campero-INTA broilers. Breast length (mm), width (mm), surface (mm2; ultrasound) and depth (mm; ultrasound), and abdominal fat depth (mm; ultrasound) were measured at 65-66 and 72-73 days of age on 96 males. At 79 days of age, the broilers were weighed and slaughtered. Breast and abdominal fat weights (g) were obtained. Multiple regression equations were fitted using live weight (g) and in-vivo measurements to predict breast and abdominal fat weights and proportions (g/g). The best model for each case was selected by the Stepwise procedure. Equations fitted were verified using another set of data. Breast weight prediction using live weight and breast length in the model was as accurate as using live weight and breast depth. The former is recommended for breeding work. Abdominal fat weight prediction using ultrasound measurements of fat was less accurate than breast weight prediction. Repeatabilities for ultrasound breast measurements were higher (0·72 to 0·73) than those for abdominal fat (0·51 to 0·52). Operator effect may be important when training levels are different.

Two hundred and forty pigs of 56 ± 3 days of age were used to investigate the effects of sex (barrows; gilts), boar sire (DD, Danish Duroc; ND × LW, Dutch Duroc × Large White ; P × LW, Pietrain × Large White) and slaughter age (160; 175 days) on performance and carcass and meat quality. Treatments were arranged factorially (2 × 3 × 2) and there were four replicates (five pigs per replicate) per treatment. The female line was Landrace × Large White in all cases. Barrows had greater daily food intake (P <0·001) and average daily gain (P <0·01) and had poorer food conversion ratio (P <0·001) than gilts. Carcasses from castrates were fatter and had a lower yield of trimmed lean cuts than carcasses from females (P <0·001). Longissimus muscle from barrows had more intramuscular fat and higher a* value than muscle from gilts (P <0·05). Pigs from DD sire line grew faster (P <0·05) and had a better food conversion ratio (P <0·001) than pigs from the other two lines. Dressing proportion and backfat thickness were greatest for P × LW sired pigs (P <0·01) and proportion of trimmed lean cuts was greater for DD and P × LW than for ND × LW sired pigs (P <0·01). Longissimus muscle from DD sired pigs had less protein (P <0·01) and more intramuscular fat (P <0·001) than muscle from the remaining lines. Longissimus muscle from P × LW line had more intense colour than muscle from DD and ND × LW lines (P <0·01). Pigs slaughtered at 175 days had poorer food conversion ratio (P <0·01) and less trimmed primal cut proportion (P <0·001) than pigs slaughtered at 160 days. Also, increasing the age at slaughter increased intramuscular fat content (P <0·01), a* value (P <0·001) and colour intensity of the muscle (P <0·01). Danish Duroc boars are a good alternative to ND × LW or P × LW boars for production of heavy pigs whether the crossbreds are sacrificed at 160 or 175 days. Also, an increase in age at slaughter impairs growth efficiency and yield of lean cuts but improves some aspects of meat quality, which might be of interest in the production of heavy pigs destined for the dry-cured product industry.

The effects of dietary protein content and level of feeding on carcass characteristics and organs weight were evaluated in 72 male castrated Iberian pigs growing from 15 to 50 kg live weight. Animals were offered six diets providing 223, 192, 175, 156, 129 and 101 g crude ideal protein (CP) (N × 6·25) per kg dry matter (DM) and 14·64, 14·14, 14·37, 14·80, 15·36 and 15·53 MJ metabolizable energy (ME) per kg DM, respectively. Each diet was offered at three levels of feeding : 0·60, 0·80 and 0·95 × ad libitum intake. Mean values of protein, fat, ash and water contents in the carcass determined at 50 kg live weight were 130, 378, 28·2 and 458 g/kg, respectively, with a small but significant effect of CP content of the diet on carcass composition (P <0·001 to P <0·01) favouring both protein and fat content on decreasing dietary protein level. Protein deposition (PD) in the eviscerated carcass reached a maximum value when the diet containing 129 g CP per kg DM was offered (54·6 g/day at the highest feeding level). Nitrogen (N) retention in the carcass represented 70·9% of whole-body N retention and the efficiency of this process (carcass N retention : N intake) increased with declining dietary protein content (P <0·001). Carcass energy retention increased significantly with decreasing dietary CP content (P <0·001) and with feeding level (P <0·001). Raising energy intake resulted in a significant increase on total weight of viscera as proportion of empty body weight (P <0·001). Decreasing the CP content in the diet resulted in a lower proportional shoulder weight (P <0·01) meanwhile the proportion of ham decreased significantly (P <0·05) with increase in feeding level. The proportionate weights of dissectable fat in the shoulder and of intermuscular and subcutaneous fat in the ham increased significantly (P <0·05 and P <0·001) in response to decreasing dietary CP content meanwhile only ham intermuscular fat content increased with feeding level (P <0·001). Thus, decreasing dietary protein concentration from well in excess of requirements and increasing energy intake enhance N and fat retention in the carcass but also increases intermuscular fat content in the ham of the Iberian pig with possible implications for meat quality.

An experiment was undertaken to compare the carcass characteristics and meat quality of lambs from crossbred ewes produced by crossing Texel sires with Rouge de l’Ouest dams and Rouge sires with Texel dams, relative to lambs from purebred Texel and Rouge ewes. The ewes were crossed with Texel or Rouge sires and the relative performance of the sires assessed in terms of lamb carcass quality. Ewe and ram genotype had a significant effect on conformation classification. Lambs from Texel ewes had a greater conformation classification (4·0) than lambs from Rouge ewes (3·4, s.e. 0·09) (P <0·001) and Texel-sired lambs had a greater conformation classification (4·0) than Rouge-sired lambs (3·6, s.e. 0·06) (P <0·001). Fat depth was significantly influenced by ewe genotype with lambs from Texel × Rouge ewes having greater fat depths compared with lambs from Texel ewes (longissimus dorsi 2·3 and 1·9 (s.e.0·12) mm respectively) (P <0·05). Chemical composition of the carcass and meat quality measurements were unaffected by ewe or ram genotype. Significant heterosis effects on lamb live-weight gain (21 g/day; 15%) (P <0·01) from birth to slaughter, age at slaughter (–37 days; –12%) (P <0·01), weight of perinephric and retroperitoneal fat (76 g; 38%) (P <0·01) and fat depth over the longissimus dorsi (0·3 mm; 16%) and gluteus medius (0·5 mm; 17%; P <0·05) were obtained. The results from this study demonstrate that significant heterosis effects, particularly in terms of lamb growth rate, can be achieved by crossing Rouge and Texel breeds. In addition lambs from hybrid ewes have similar conformation characteristics to the Texel breed which has been intensively selected for carcass characteristics.

Sixty crossbred (Large White × Landrace × Duroc) pigs were used to compare the growth performance, carcass and pork quality characteristics of entire, surgically castrated and immunologically castrated male pigs from two Western Australian commercial genotypes (genotype A : ‘lean’ genotype and genotype B : propensity for increased subcutaneous fat deposition). Pigs from genotype B had a higher average daily gain and a superior food conversion ratio compared with pigs from genotype A. Entire males had lower backfat compared with surgically and immunologically castrated male pigs. Pork from entire males was drier, tougher and had lower overall acceptability scores compared with surgically or immunologically castrated male pigs. Pork from genotype A pigs had a lower m. longissimus thoracis (LT) ultimate pH and higher drip loss compared with pork from genotype B pigs. However, consumer taste panel assessment indicated that pork from genotype A pigs was more tender, had higher juiciness and overall acceptability scores compared with pork from genotype B pigs. Within genotype A, the consumer taste panel preferred pork from surgically castrated pigs compared with either entire or immunologically castrated pigs. Within genotype B, the consumer taste panel preferred pork from immunologically castrated pigs compared with either entire or surgically castrated male pigs. These results indicate that interactions between genotype and castration method can significantly influence eating quality of pork.

A total of 276 crossbred pigs were used in three trials to determine if feeding spray-dried animal plasma (SDAP) in simple phase 1 piglet diets with differing soya-bean meal (SBM) levels can influence performance or immunoglobulin G (IgG) levels specific to the antigenic soya proteins, glycinin and β-conglycinin. Pigs were blocked according to initial body weight and equalized across treatments according to gender and ancestry. Blocks of pigs were then randomly assigned to one of three treatments in a completely randomized block design. The dietary treatments were as follows: (1) 10% +: 100 g/kg SBM with 75 g/kg SDAP; (2) 20% +: 200 g/kg SBM with 75 g/ kg SDAP; (3) 20%-: 200 g/kg SBM without SDAP. Pigs were given treatment diets for 14 days, followed by a common diet for the duration of the trials (35 days). Average daily gain (ADG) and gain to food (G: F) ratios were not affected by dietary treatments. Average daily food intake (ADFI), however, was greater for pigs given 10% + as compared with 20% + and 20%- (P < 0.05) during days 0 to 14 post weaning. Addition of SDAP increased ADFI (P < 0.01) and tended to increase ADFI when added to diets containing 200 g/kg of soya-bean meal (P = 0.06). No differences were detected in soya-specific IgG levels during any collection period. These data suggest that SDAP addition to simple phase 1 piglet diets increased ADFI during the first 2 weeks, but did not alter ADG or food efficiency. There was no indication that SDAP addition altered IgG titres against the soya-bean proteins, glycinin and β-conglycinin.

Avilamycin (AGP) and zinc oxide (ZnO) are both frequently included in the post-weaning piglet diet to enhance growth performance and prevent diarrhoea. This study investigated what effect removing these compounds from the post-weaning diet would have on the growth performance and faecal microbiota of weaned piglets. Fifty-two crossbred piglets (JSR Healthbred) were allocated, at weaning, to one of two dietary treatments on the basis of weight, litter origin and gender. The diets were (i) control (no supplemented ZnO or AGP); (ii) ZnO + AGP (supplemented with 3100 mg ZnO per kg food and 40 mg avilamycin per kg food). These diets were offered ad libitum for 20 days post weaning. Thereafter, the pigs received the same non-supplemented grower and finisher diets ad libitum. All piglets were individually weighed, and faecal samples were obtained from pre-selected piglets, at various time points throughout the trial period. Ten-fold serial dilutions of faecal material were cultured on specific media to enumerate aerobes, anaerobes, Lactobacillus spp. and Escherichia coli. ZnO + AGP supplementation enhanced weaned piglet average daily food intake (ADFI) (P < 0·001), average daily live-weight gain (ADG) (P < 0·001) and food conversion ratio (FCR) (P < 0·01) during the initial 20 days post weaning. Piglets previously supplemented with ZnO + AGP gained more weight per day during the non-supplemented grower phase (days 21 to 60) than their control counterparts (741·5 v. 672·5 g per pig per day) (P < 0·01). The bacteriological data showed that ZnO + AGP piglets had lower counts of anaerobic bacteria in their faeces than control piglets (P < 0·01). These findings indicate that dietary AGP + ZnO may enhance growth by reducing gastro-intestinal bacterial populations, and that their removal from the post-weaning diet will increase days to slaughter.

A total of 104 weanling piglets was used to study the interrelationships between faeces consistency and mucosal integrity, as assessed by specific aminopeptidase and isomaltase-sucrase activity, villus height and crypt depth. Piglets were weaned at 26 (s.d. 1·4) days of age, weighing 8·4 (s.d. 0·70) kg. On the day of weaning (day 0), dissection was performed on one group of eight piglets. The remaining piglets were given restricted amounts of diets containing different protein sources. However, during the first 7 days post weaning 72% of the piglets ate on average less than 0·9 of the amount offered and thus actually had ad libitum access to food. On days 3 or 7 post weaning pigs were weighed and euthanased. Diet composition did not effect small intestine integrity and the data were pooled for further analysis. The weight of the stomach, large intestine and pancreas increased with time post weaning (P < 0·001). Small intestine weight decreased from day 0 to 3 and was increased again on day 7, exceeding the pre-weaning value (P < 0·001). Isomaltase-sucrase and aminopeptidase activities were decreased on days 3 and 7 when compared with day 0. Villus height was decreased after weaning, followed by an increase on day 7 post weaning at the proximal small intestine, but by a further decrease at the mid small intestine (P < 0·001). Crypt depth was increased after weaning (P < 0·001). Faeces consistency was scored twice a day on a scale from 0 to 3 with increasing liquid nature. The average percentage of days during which piglets had more-liquid faeces was 26%. During the 1st week post weaning, 73% of the piglets showed a faeces score of 2 during at least 1 day. Villus height was positively correlated with food intake level, brush-border enzyme activity and dry matter content of the chyme. Villus height was negatively correlated with more-liquid faeces. Crypt depth was positively associated with the weight of various parts of the gastro-intestinal tract. It is concluded that this study supports the concept that food intake by weaned piglets determines villus height in the small intestine and brush-border enzyme production which in turn determine the risk of diarrhoea development.

The management of pastures used by horses poses various problems: swards are often grazed down rapidly, patches of bare ground and refused areas develop. In order to gain a better understanding of the plant-animal interaction behind this problem the influence of sward height on bite dimensions (bite depth, weight, volume, area) of horses was investigated. Perennial ryegrass (Lolium perenne) microswards were grown on artificial substrate to four different heights (3, 8, 15, 19 cm) but the same plant density. Biomass and bulk density for each sward height was determined. Eight horses (predominantly Thoroughbred ×) were allowed to take six bites of each grass height. Bite depth, weight, volume and bite area were calculated.

Bite depth, weight, volume and area were not fixed, but increased with sward height (P < 005). For all sward heights, the horses removed between 51% and 68% of the initial grass length. The horses adjusted their bite dimensions to sward height but did not maximize food intake per bite. The response to sward height might be explained by a preference for easily digested food or the trade-off between energy intake and the cost for food processing.

This experiment suggests that grass height has a major influence on bite dimensions of horses. However there may be more complex factors influencing ingestive behaviour of horses (e.g. age, dietary experience and social behaviour) that have to be considered when horses are grazing pasture.

Two weaning diets (C and S) and three weaning ages (21, 25, and 28 days) were compared in a two factorial arrangement to evaluate their effect on growth performance, body composition and caecal fermentation activity of young rabbits. One hundred litters born the same day from multiparous does were used. Sixty litters were early weaned at 21, 25 and 28 days of age (20 litters per weaning age), put in collective cages (nine kits per cage) (W21, W25, and W28 litters) and offered the control diet C (crude protein (CP) : 175 g/kg dry matter (DM); ether extract : 20 g/kg DM; starch : 157 g/kg DM; acid-detergent lignin (ADL) : 60 g/kg DM; digestible energy (DE) : 11·08 MJ/kg DM) or the starter diet S (CP : 173 g/kg DM; ether extract : 41 g/kg DM; starch : 112 g/kg DM; ADL : 51 g/kg DM; DE : 11·31 MJ/kg DM). At 32 days of age, 180 early weaned rabbits (three rabbits from each of the 60 litters above) were selected : 60 animals were slaughtered; 120 animals were placed into individual cages and offered a fattening diet (CP : 166 g/kg DM; ether extract : 23 g/kg DM; starch : 177 g/kg DM; ADL : 49 g/kg DM; DE : 11·26 MJ/kg DM) from 32 to 56 days of age. At 56 days of age, another 60 representative rabbits were slaughtered. The administration of diet S to the early weaned rabbits increased litter weight at 32 days (6160 v. 6027 g; P <005) and gain to food ratio from weaning to 32 days (752 v 666 g/kg; P <0001) compared with diet C. Moreover, empty bodies (EB) of S rabbits were fatter (fat : 45 v. 41 g/kg; P = 001) and had greater energy content (5·92 v 5·71 MJ/kg; P <001). At 56 days of age, no residual effect of the diet was recorded. Weaning age affected growth performance, body composition and caecal fermentation at 32 days of age : EB weight (P <005) and EB protein concentration increased (from 164 to 168 g/kg, P <0·01) while caecal volatile fatty acid concentration decreased (from 71·7 to 53·8 mmol/l; P <0·01) when weaning age was increased from 21 to 28 days. At 56 days of age, no effect (P > 0·05) of weaning age was recorded on growth performance or caecal fermentation traits, but EB protein remained lower in the earliest weaned rabbits (P <0·05). In conclusion, feeding a high-fat low-starch diet to early weaned rabbits stimulated growth and body fat and energy retention of kits at 32 days of age with no effect on caecal fermentation. The early weaning successfully performed at 21 days of age strongly stimulated caecal fermentation but reduced body protein reserves.

The model incorporates, amongst its novel components, variable efficiency coefficients in the simulation of the responses of growing pigs to nutrient inputs, and thereby increases the accuracy and efficacy of control of feeding and nitrate excretion. The model determines (rather than is presented with) net energy and required amino acid level and balance. The estimation of protein turn-over as a function of rate of protein retention, protein mass and the maturity of the pig was found to be central to both the energy (ATP) and protein economy. Protein turn-over varied from around 0·14 to 0·08 of the protein mass depending upon the size of the pig. Efficiencies of energy yield from lipid, starch (and sugar), protein and (fibre-derived) volatile fatty acids were calculated to be 0·98, 0·86, 0·56 and 0·58 for ATP production and 0·90, 0·70, 0·50, and 0·44 for lipid retention, respectively. The maximum efficiency of use of ileal digestible amino acids was determined as around 0·85. The energy cost of protein synthesis was equivalent to 4·2 MJ metabolizable energy (ME) per kg, and the efficiency of use of ME for protein retention varied from 0·55 to 0·40 depending on the protein mass of the pig. The components of the model and the biochemical drivers are described in detail, and proof of principle of the main elements is presented. The model is different in its architecture to other published simulation models, and is considered to add to the present knowledge base in this discipline.

Crossbred gilts were offered rapeseed press cake (RSP) as follows: control (no RSP in diet during growth/ pregnancy/lactation), M-RSP (medium RSP levels: 100/50/100 g/kg RSP) and H-RSP (high RSP levels: 150/80/ 150 g/kg RSP). Plasma concentrations of free thyroxine (FT4), tri-iodothyronine (T3), luteinizing hormone (LH), prolactin (PRL), progesterone (P4) and androstenedione (A4), weights of thyroid gland, ovaries and uterus, length of uterine horns, and number of corpora lutea (CL) were measured in gilts during the mid-luteal phase of their first oestrous cycle. Serum concentrations of FT4, T3, LH and PRL, weights of thyroids, ovaries, uteri, adrenals, kidneys, liver and spleen were measured in female piglets on 2nd and 28th day of lactation. RSP diets, affected thyroid weights, number of CL, uterine horn length, mean concentrations of plasma FT4, T3, PRL, and P4 in gilts. Changes of weights of ovaries in 2-day-old piglets and weights of uterus, adrenal gland and kidneys in 28-day-old piglets from RSP groups were observed.

Cumulus-oocyte complexes with surrounding granulosa cells (COCGs) in early antral follicles (0·5 to 0·7 mm in diameter) were surgically collected from sections of bovine ovarian cortex under a dissection microscope and subsequently cultured in vitro using follicle stimulating hormone (FSH), epidermal growth factor (EGF), insulin-transferrin-selenium (ITS) and hypoxanthine, singly or in combination, to obtain fully grown matured oocytes. Oocytes cultured in the presence of FSH + hypoxanthine increased (P < 0·05) in diameter from 93 µm on the day of commencement of culture to 106·37±0·34 µm on day 5. Oocytes cultured in the presence of FSH, hypoxanthine or hypoxanthine + ITS + FSH increased (P < 0·05) to mean diameters of 105·40 (s.e. 0·47) µm, 105·50 (s.e. 0·39) µm and 105·35 (s.e. 0·55) µm, respectively. By day 11 of culture, oocyte diameters 110·50 (s.e. 0·35) µm, 110·13 (s.e. 0·39) µm, 109·49 (s.e. 0·46) µm, 109·53 (s.e. 0·58) µm and 109·16 (s.e. 0·43) µm were recorded for treatments FSH + hypoxanthine, hypoxanthine + ITS + FSH, FSH, hypoxanthine and FSH + EGF + hypoxanthine + ITS, respectively. The proportions with COCGs which formed an antrum while cultured in vitro; were categorized as morphologically normal following recovery from the gel; matured in vitro; showed germinal vesicle break down and reached metaphase II were highest (P < 0·05) for the FSH + hypoxanthine treatment (49/60 (81·7%), 48/60 (80·0%), 47/60 (78·3%), 45/60 (75·0%) and 15/60 (25·0%), respectively, followed by hypoxanthine + ITS + FSH (47/60 (78·3%), 44/60 (73·3%), 41/60 (68·3%), 41/60 (68·3%) and 12/60 (20%), respectively), FSH (43/60 (71·7%), 42/60 (70%), 40/60 (66·7%), 39/60 (65·0%) and 9/60 (15%), respectively) and hypoxanthine (41/60 (68·3%), 38/60 (63·3%), 36/60 (60%), 35/60 (58·3%) and 8/60 (13·3%), respectively). In experiment II, the in vitro fertilization and cleavage rates of COCGs were highest (P < 0·05) for FSH + hypoxanthine treatment (17/60; 28·3%) followed by hypoxanthine + ITS + FSH (13/60; 21·6%), FSH (12/60; 20%) and hypoxanthine (11/60; 18·3%) treatments. The results of this study show that COCGs from early antral follicles can be isolated, cultured and grown in vitro. Furthermore, supplements like FSH and hypoxanthine can be used singly or in combination(s) in culture medium to enhance the growth of COCGs.

Peripheral concentrations of melatonin in the neonatal mammal are low and the diurnal rhythm is not apparent during the first days or weeks of life. Maternal milk provides a rhythmic although low source of melatonin to the newborn. Diurnal rhythm of serum melatonin was monitored in Friesian calves from birth to 4 weeks of age. Some of the calves under 1 week of age had no clear nocturnal elevation of serum concentrations of melatonin. Thereafter the nocturnal melatonin elevation was apparent in all calves and of the same amplitude as in adult cattle. The effect of oral intake of night-time milk or milk supplemented with low doses of synthetic melatonin was studied during day-time in a group of Ayrshire calves aged 1 to 5 weeks. Two and a half or 3 litres of night-time milk with a mean melatonin concentration of 40 pg/ml, providing 01 to 012 μg melatonin, did not cause any change in the day-time serum concentrations of melatonin, neither did addition of melatonin in doses up to 10 μg per animal. Only the highest dose of melatonin 200 μg in 2 l of milk (01 μg/ml) caused an elevation of day-time serum concentrations of melatonin. These studies show that the pineal gland of a very youg calf is functional and that the concentration of melatonin in blood does not reflect the concentration in milk at the time of feeding. The presence of melatonin in milk suggests, however, its potential significance for the neonate.

An experiment involving a feeding trial and a comparative slaughter was conducted to assess the body chemical composition and patterns of nutrient utilization in pre-ruminant Saanen goat kids. Thirty male kids weighing about 6 kg were divided into five equal groups, one of which was slaughtered as the reference group (G0). The remainder were randomly assigned to four feeding levels of 250, 290, 330 and 370 g goats’ milk per kg M0·75 per day and named as groups GI, GII, GIII and GIV, respectively up to about 15 kg live weight, after which they were slaughtered. Mean milk consumption per unit live-weight gain (LWG) (kg/kg), and daily LWG (g/day), for GI, GII, GIII, GIV respectively were: 13·5 and 110; 10·5 and 160; 10·2 and 180; and 10·3 and 200. Empty body weight (EBW) as a proportion of final live weight was 0·95 in the reference animals, and ranged from 0·80 to 0·88 in the treatment groups. The dry matter (DM) concentration in the empty body of kids increased as their age advanced, from 277 g/kg EBW (G0) to between 308 and 326 g/kg EBW (GI to GIV). The protein and fat concentration of LWGs increased with the level of feeding from GI (142 g crude protein (CP) and 75·5 g fat per kg LWG) to GIV (155 g CP and 109 g fat per kg LWG). Regression of energy retention (ER) on metabolizable energy (ME) intake resulted in an efficiency of ME utilization for body retention (k) of 0·72(± 006). ME requirement for maintenance was estimated as 458 kJ/kg M0·75 per day. Efficiency of nitrogen (N) utilization for growth and N requirement for maintenance were estimated as 0·66(±011) and 0·47 g/kg M0·75 per day, respectively.

Mechanisms underlying milk fat conjugated linoleic acid (CLA) responses to supplements of fish oil were investigated using five lactating cows each fitted with a rumen cannula in a simple experiment consisting of two consecutive 14-day experimental periods. During the first period cows were offered 18 kg dry matter (DM) per day of a basal (B) diet formulated from grass silage and a cereal based-concentrate (0·6 : 0·4; forage : concentrate ratio, on a DM basis) followed by the same diet supplemented with 250 g fish oil per day (FO) in the second period. The flow of non-esterified fatty acids leaving the rumen was measured using the omasal sampling technique in combination with a triple indigestible marker method based on Li-Co-EDTA, Yb-acetate and Cr-mordanted straw. Fish oil decreased DM intake and milk yield, but had no effect on milk constituent content. Milk fat trans-11 C18:1, total trans-C18 : 1, cis-9 trans-11 CLA, total CLA, C18 : 2 (n-6) and total C18 : 2 content were increased in response to fish oil from 1·80, 4·51, 0·39, 0·56, 0·90 and 1·41 to 9·39, 14·39, 1·66, 1·85, 1·25 and 4·00 g/100 g total fatty acids, respectively. Increases in the cis-9, trans-11 isomer accounted for proportionately 0·89 of the CLA response to fish oil. Furthermore, fish oil decreased the flow of C18 : 0 (283 and 47 g/day for B and FO, respectively) and increased that of trans-C18 : 1 fatty acids entering the omasal canal (38 and 182 g/day). Omasal flows of trans-C18 : 1 acids with double bonds in positions from delta-4 to -15 inclusive were enhanced, but the effects were isomer dependent and primarily associated with an increase in trans-11 C18 : 1 leaving the rumen (17·1 and 121·1 g/day for B and FO, respectively). Fish oil had no effect on total (4·36 and 3·50 g/day) or cis-9, trans-11 CLA (2·86 and 2·08 g/day) entering the omasal canal. Flows of cis-9, trans-11 CLA were lower than the secretion of this isomer in milk. Comparison with the transfer of the trans-9, trans-11 isomer synthesized in the rumen suggested that proportionately 0·66 and 0·97 of cis-9, trans-11 CLA was derived from endogenous conversion of trans-11 C18 : 1 in the mammary gland for B and FO, respectively. It is concluded that fish oil enhances milk fat cis-9, trans-11 CLA content in response to increased supply of trans-11 C18:1 that arises from an inhibition of trans-C18 : 1 reduction in the rumen.

An increased sodium appetite has been demonstrated in cattle following supplementation with sodium in the neonatal period, but it is unclear whether the sodium appetite of calves can be influenced in utero by the dam’s sodium intake during pregnancy. Twenty-two non-lactating, pregnant dairy cows received either a diet of silage and concentrates or the same diet with 70 g NaCl per day added to it for the last 2 months of pregnancy. The sodium supplement increased the birth weight of their calves but after 6 weeks there was no difference between treatments in calf weight. In addition to milk, calves in both treatments were offered a choice of concentrates with normal or high sodium concentrations (5·8 and 10·8 g/kg dry matter, respectively). Calves from the cows that had received supplementary sodium during pregnancy ate more of the high sodium concentrate than calves from cows without the sodium supplement, demonstrating that sodium appetite could be entrained by the sodium intake of the dam during late pregnancy.