Concern for the welfare of export lambs during long-distance road transport has prompted much research and a recommended change in procedure. The latter envisages an absolute maximum journey time of 31 h and includes a rest-stop (minimum duration 1 h) for feeding and watering. In the present experiment, the physiological and behavioural responses to this new protocol have been investigated in fleeced and shorn lambs (no. = 10 per group) provided with venous catheters and heart rate monitors. The two groups were loaded on a vehicle into separate adjacent pens and driven for 14 h; then unloaded into a lairage, where their behaviour was recorded. After 1 h they were reloaded and driven for a further 15·5 h, finally arriving at a slaughterhouse where carcass condition was evaluated. Blood samples collected at 30- or 60-min intervals by experimenters travelling with the animals were analysed to determine haematocrit, plasma osmolality, plasma concentrations of glucose, creatinine phosphokinase (CPK), and the stress-responsive hormones, cortisol, prolactin, adrenaline and noradrenaline. The results showed that haematocrit increased after loading although the general trend during transport, as with osmolality, was a decline (P < 0·05). No significant changes in plasma glucose were detected but CPK increased in fleeced lambs after loading (P < 0·05). Cortisol release was stimulated by loading, especially in fleeced sheep (P < 0·001) but returned to home pen values within 6 h; heart rates changed in a similar manner. Transport did not markedly affect prolactin release although concentrations were consistently greater in fleeced sheep (P < 0·001). Noradrenaline, however, tended to be higher in shorn animals (P < 0·05). In lairage, both groups readily consumed hay, and especially concentrates, but the shorn lambs spent more time eating (P < 0·001). None of the shorn sheep, and only a few fleeced animals, drank water. There was no evidence for differences in weight loss between the two groups during the experiment and carcass quality at slaughter was within the normal expected range. The implications of these, and other related studies, for future transport policy are discussed, with particular reference to rest-stop duration and handling procedures.

The influence of breed and sex on relative growth patterns of muscle, bone and fat in beef cattle has been investigated. Comparisons were made of growth coefficients estimated using Huxley's (1932) allometric equation relating muscle, bone or fat to muscle plus bone using data from the dissection of half carcasses of 63 young bulls, 106 steers and 22 heifers representing a number of breed groups. Growth coefficients for muscle and for bone were found to be similar among different breed groups of bulls, steers and heifers. The proportion of muscle increased and that of bone decreased as the size of animal, measured by muscle plus bone, increased. Muscle and bone weights adjusted to common muscle plus bone weights were significantly different among breed groups within sex. Differences in amount of muscle relative to bone were therefore established at earlier stages of growth and maintained over the period represented in the present study.

Growth coefficients for fat were significantly different among breed groups within sexes.

Sex within breed group had no statistically significant influence on growth coefficients for muscle or for bone. Muscle and bone weights adjusted to a common muscle plus bone weight were similar for sex groups within all breed group comparisons. Sex did not have a marked effect on rate of fattening since differences between growth coefficients for fat (between sexes, within breeds) were not statistically significant—although in all comparisons growth coefficients for fat were lowest for bulls, intermediate for steers and highest for heifers. Sexes differed in weight of fat adjusted to common muscle plus bone weight, heifers being fatter than steers and steers fatter than bulls, a difference probably resulting more from early onset of the fattening phase in heifers, followed by steers, rather than relative rate of fattening.

In two experiments over 2 years, 113 North Country Cheviot and 132 South Country Cheviot hill ewes were differentially group-fed over a 10-week period to achieve either good or moderate body con- dition. Ewes were maintained in these levels of condition over the 5 weeks prior to mating. After mating, ewes were killed either on return to service or between days 23 and 85 for counts of corpora lutea and viable embryos.

Ovulation rate in each breed was positively related to body condition at mating. Embryo mortality, as ova loss, was not influenced overall by breed, type of ovulation, year of recording, or body condition. Although comparisons of loss were partly confounded by a differen- tial distribution in the number of ova shed in each breed and body condition group, there was an apparent breed difference in loss of single- and multiple-shed ova. Potential lambing rate therefore showed greater response to improved body condition at mating in the North Country Cheviot breed than it did in the South Country Cheviot.

Three groups of 16 cattle each comprising three multiparous Jersey cross Holstein-Friesian cows, seven primiparous and six multiparous Holstein-Friesian cattle were offered, ad libitum, a silage-based complete diet with different concentrate ingredients following an initial 3-week covariate period. The relationship between these three diets and other parameters with lesions of the weight-bearing surface of the hoof was studied by scoring mobility weekly (locomotion score) and examining all the feet of all cows for visual lesions particularly those involving the horn of the foot. In addition hoof angle, hardness and growth and wear were also recorded. The mean locomotion score during the initial 3-week covariate period was a significant covariate for the subsequent locomotion score, milk yield, and live weight (P < 0·001). Furthermore weekly locomotion score also proved a significant covariate for weekly milk yield (P < 0·05). There were no significant differences between dietary treatment groups for locomotion score, overall lesion score (despite significantly fewer ulcers of the sole in one dietary group: P < 0·001) but a significant (P < 0·05) difference between cow ‘type’ and there was also a significant (P < 0·05) diet × breed interaction for locomotion score and milk yield. It was concluded first that initial mobility was an important factor in subsequent mobility of the cow and so experimental design; secondly that while nutrition and genotype interacted to influence mobility, visual lesions of the hoof and lameness, the mechanisms involved were far from clear; and thirdly that the simple lesion score used required some adjustment or correction factor(s) to ensure that more severe lesions were given a greater weight than a simple unitary increase.

The current study was conducted to determine the effect of different α-tocopherol (vitamin E) inclusion levels on trans(t)-18:1 and conjugated linoleic acid (CLA) profiles in subcutaneous and intramuscular fat of steers fed a barley-based diet. Fifty-six feedlot steers were offered a barley-based finisher diet (73% steam rolled barley, 22% barley silage and 5% supplement as-fed basis) with four levels of supplementary dl-α-tocopheryl acetate (340, 690, 1040 or 1740 IU/steer per day) for 120 days. Adding vitamin E to the diet had little effect on the overall fatty acid composition of intramuscular fat. The proportion of individual and total t,t- and cis(c),t-CLA, n-3 fatty acids, total polyunsaturated fatty acids (PUFA), mono-unsaturated fatty acids and saturated fatty acids to PUFA ratio in subcutaneous fat were not influenced (P > 0.05) by dietary vitamin E supplementation. Increasing levels of vitamin E led to linear reductions in t6-/t7-/t8-18:1 and t10-18:1 (P < 0.05), and linear increase in t11-/t10-18:1 ratio (P < 0.05) in subcutaneous fat. The content of 20:3n-6 and total n-6 in subcutaneous fat decreased (P < 0.05) linearly with increasing amounts of vitamin E. The subcutaneous fat n-6:n-3 ratio showed a quadratic (P < 0.05) response to vitamin E. In conclusion, although vitamin E supplementation has some potential to reduce t10-18:1 formation and increase t11-/t10-18:1 ratio in subcutaneous fat of cattle fed barley-based diets, the changes in the present study were limited and may not have been sufficient to impact on human health.

The activities of bulls, their feeding behaviour and their ruminal pH were examined at several stages during the finishing period, according to the forage-to-concentrate ratio of their diet. Twenty-four bulls of the Blond d’Aquitaine breed (initial body weight = 326 ± 21 kg) were assigned to six balanced pens with a space allowance of 9.4 m2 per bull during the finishing period. They were fed three different diets with achieved forage-to-concentrate ratios of (i) 8% straw and 92% concentrate, (ii) 44% hay and 56% concentrate and (iii) 57% maize silage and 43% concentrate. Bulls had ad libitum access to feed dispensed once daily. Offered and refusals were weighed on 5 consecutive days per week. The bulls were slaughtered at the common final live weight of 650 kg and the finishing period lasted 138, 181 and 155 days for straw–concentrate, hay–concentrate and maize silage–concentrate diets, respectively. The time budget was estimated four times by scan sampling with a 10-min interval. Feeding behaviour was appraised using data from electronic feeding gates. Ruminal pH was measured from a ruminal fluid sample collected by rumenocentesis. On average, the bulls spent 78% of the time lying or standing still, and 11% of the time eating. The forage-to-concentrate ratio of the diet influenced only those activities directly linked to feeding, i.e. eating and drinking. Bulls fed a high-concentrate diet spent less time eating than the other bulls (47 min v. >2 h) and took shorter meals (7 min v. 17 min). The bulls fed the straw–concentrate diet spread their meals over the entire day, whereas the others maintained two major peaks of eating activity, the main one in the morning after feed dispensing, the other one at the end of the diurnal period. Intake rate ranged widely between diets, from 58 g/min on average for the diets based on hay or maize silage up to 173 g/min for the high-concentrate diet. The concentrate-diet bulls also had a lower ruminal pH during the first 2 months of the finishing period. The dispersion of meals based on a high-acidosis-risk diet may be a way to limit the decrease in ruminal pH.

This in vitro study aimed at understanding how abiotic, that is chemical and electrochemical potentials, and biotic factors combine to impact the outputs of rumen volatile fatty acid (VFA). Using a 48-run design optimized by means of an exchange algorithm, the curvilinear effects of pH, Eh and partial pressure of dihydrogen (H2) on fermentation yields were investigated in 6-h batch cultures of mixed rumen microbes, fed on glucose so as to bypass the enzymatic hydrolysis and conversion steps preceding the glycolytic pathway. The role played by rumen microbiota in the expression of these effects was explored by testing three inocula grown on feeds supplying a microflora adapted to fibre, slowly degradable or readily degradable starch as the dominant dietary polysaccharide. Data were fitted to 2nd-order polynomial models. In fibre-adapted cultures, the yields of major VFA were mainly influenced by pH and H2 partial pressure, in opposite ways. In wheat grain-adapted cultures, the VFA yields underwent the opposite influences of pH, in a curvilinear way for propionate, and Eh since acetate production yield was not significantly modified by any factor. In maize grain-adapted cultures, acetate production yield was not modified by any factor but H2 in a quadratic way when the production yields of higher VFA underwent opposite influences of pH and Eh. In conclusion, the effects of environmental factors were dependent on the nature of the inoculum, a major source of variation, and more particularly on its adaptation to high- or low-fibre diets. These effects were loosely interrelated, the pH being the most active factor before the Eh and H2 partial pressure.

An experiment (complete randomised design) was conducted to investigate the effects of supplementing different molecular weights (MW) of chitooligosaccharide (COS) on pig performance, selected microbial populations and nutrient digestibility post-weaning. A total of 396 weaned piglets (24 days of age, 7.3 kg ± (s.d.) 1.7 kg live weight) were assigned to one of six dietary treatments (22 replicates/treatment) for a 33-day experimental period. The dietary treatments were as follows (1) control diet (0 ppm COS), (2) control diet plus <1 kDa COS, (3) control diet plus 3 to 5 kDa COS, (4) control diet plus 5 to 10 kDa COS, (5) control diet plus 10 to 50 kDa COS and (6) control diet plus 50 to 100 kDa COS. The COS were included at 250 ppm in the diets. There was no significant effect of dietary treatment on piglet performance during the starter period (days 0 to 18; P > 0.05). However, there were quadratic responses in both daily gain (P < 0.05) and gain to feed ratio (P < 0.05) to the increased MW of COS inclusion during the weaner period (days 18 to 33) with all COS-supplemented treatments improving daily gain and gain to feed ratio compared with the control. There was a quadratic response in faecal scoring to the increased MW of COS inclusion from days 0 to 7 (P < 0.001), days 7 to 14 (P < 0.001) and during the overall experimental period (P < 0.01) with all the COS-supplemented treatments having an improved faecal score compared with the control. During the weaner period, there was a cubic response in lactic acid bacteria and Escherichia coli populations as the MW of COS increased (P < 0.05). The 5 to 10 kDa and 10 to 50 kDa COS increased lactic acid bacteria populations compared with the control, whereas lactic acid bacteria populations decreased at 50 to 100 kDa. The 5 to 10 kDa, 10 to 50 kDa and 50 to 100 kDa COS decreased E. coli populations compared with the control. There was a cubic response in the apparent total tract digestibility of dry matter (DM; P < 0.01), organic matter (OM; P < 0.01), ash (P < 0.01), nitrogen (N; P < 0.01) and gross energy (GE; P < 0.01) to the increased MW of COS inclusion during the weaner period. The 5 to 10 kDa COS had a higher apparent total tract digestibility of DM, OM, ash, N and GE in comparison to the control, whereas the apparent total tract nutrient digestibility of these nutrients decreased at 10 to 50 kDa. The current results indicate that the MW ranges of 5 to 10 kDa and 10 to 50 kDa COS decreased E. coli numbers while increasing nutrient digestibility of the diets.

In order to evaluate the effect of exercise training and spontaneous physical activity on growth performance, carcass composition, and locomotory ability 48 female and 48 entire male pigs were subjected to one of three treatments: individual housing in pens of 2-5 m2 (confined; C), individual housing and treadmill training for 15 minlday at a speed of 4 km/h, 5 days/week for a period of 70 days (trained; T) and group-housing equal to 0·9 m2 per animal (free; F). Pigs in treatment C and T did not differ with regard to daily gain, food intake, kg food per kg gain and carcass lean content. Training did, however, induce significant cardiac hypertrophy (by a proportion of 0·06). In treatment F (i.e. large pens), daily gain was 135 g lower than in treatment C. Dissection of the carcasses showed that treatment F increased the weight of m. psoas major (by 30 g) and the total carcass bone mass (by 130 g) when compared with treatment C. Proportions of carcass lean and intramuscular fat were unaffected by treatment F. Likewise, leg weakness and osteochondrosis did not differ between treatments, whereas the locomotory ability was positively affected by rearing in large pens (treatment F) but not by treadmill training (treatment T). Thus, physical activity in large pens induced various adaptations throughout the body.

Subacute ruminal acidosis (SARA) is a prevalent metabolic disorder in dairy cows known to elicit local and systemic immune responses. We recently showed that cows experiencing SARA and challenged intramammarily with lipopolysaccharide (LPS) experienced stronger metabolic disturbances compared with cows without SARA. Therefore, we hypothesized that cows experiencing SARA have a modulated innate immune response and impaired plasma metabolome compared with healthy cows when experiencing an acute mastitis challenge. A total of 18 Simmental cows were subjected either to a Control (CON, n=6) or SARA (n=12) feeding regimen, receiving either 40% or 60% concentrates for 30 days. Thereafter, six SARA (SARA-LPS) and the CON (CON-LPS) cows were intramammarily challenged with 50 µg LPS from Escherichia coli (O26 : B6), while the remaining six SARA cows (SARA-PLA) received a placebo. Blood and milk samples were analyzed for acute phase proteins and a targeted ESI-LC-MS/MS-based metabolomics approach was performed in blood samples 24 h after the LPS challenge. The LPS infusion caused a strong increase in immune response variables, with a higher concentration of milk amyloid A 48 h after the LPS challenge in SARA-LPS compared with CON-LPS cows. Cows receiving the LPS infusion had a lower plasma concentration of several amino acids and lysophosphatidylcholines but without differences in SARA cows and healthy cows. In conclusion, our results revealed that an intramammary LPS infusion increased acute phase proteins and modulated the blood metabolome. While no systemic differences between SARA and healthy cows were observed, cows experiencing SARA showed a higher concentration of an acute phase protein at the local level of the mammary gland. Further research is required to elucidate the underlying mechanisms and to evaluate its clinical significance for udder health.

Herbage intake and grazing times were measured in four experiments in which adult sheep grazed short and long pastures. The digestible organic matter (DOM) intake of adult wooled Merino and Corriedale wethers was higher, both absolutely and per kg live weight, when they were lower in live weight due to prior under-nutrition. The relative differences were similar on both abundant and scant pasture and were proportional to the relative differences in live weight. The higher intakes were achieved by differences in the time spent grazing and in the rate of intake per hour of grazing. DOM intake of shorn sheep was increased by up to 44% per kg live weight within 5 weeks of shearing in two experiments when the mean temperature was 8°C but no increase in DOM intake was observed in four other experiments when the mean temperature was 11°C. Shorn sheep achieved higher intakes on both abundant and scant pastures by increasing intake per hour of grazing.

Genetic parameters for body weights in Timahdite sheep were estimated using records of 10370 lambs from the ‘Société Nationale de Développement de l’Elevage’ born in 1988-89 to 1998-99. An animal model with derivativefree restricted maximum likelihood procedures was used. Random effects were direct and maternal additive genetic, maternal permanent environmental, and error. Direct and maternal heritability estimates were 0·05 and 0·05 for birth weight, 0·02 and 0·07 for weight at 30 days, 0·07 and 0·08 for weight at 70 days, 0·06 and 0·01 for weight at 90 days. Estimates of fraction of variance due to maternal permanent environmental effects were close to zero, except for weight at 90 days. Genetic correlations between direct and maternal genetic effects were –0·55, –0·51, –0·50 and –0·17 for body weights at birth, 30, 70 and 90 days, respectively. Estimates of direct genetic correlations among body weights were positive and high, ranging from 0·69 to unity. Phenotypic correlations were positive and moderate to high, being lower than their corresponding direct genetic correlations. Estimates of correlations between maternal genetic effects among weights were positive and high, varying from 0·79 to unity. Cross-correlations between direct genetic effects for one weight and maternal genetic effects for another weight were consistently negative, ranging from –0·05 to –0·63. These results indicate that selecting for improved maternal and/or direct effects in Timahdite sheep is expected to generate only slow genetic progress in terms of early growth.

Observations were made on a commercial herd of female pigs (sows) where a managemental system was employed which enabled sows to be served during lactation. The system involved grouping between 2 and 8 sows together with their litters about 3 weeks post partum. The sows were fed ad libitum from grouping, and the piglets had ready access to creep food. After one day a male pig was introduced to the group. No exogenous hormone therapy was used.

Results from 39 batches, comprising 180 sows, suggested that sows kept under these conditions will exhibit oestrus, and conceive during lactation with a high degree of predictability. Lactational oestrus was shown by all sows and conception to first service was 84·9%. The number of days between grouping and oestrus, and parturition and oestrus, were 11·15 ±0·28 and 35·53 ±0·47 respectively. Litter size and performance did not appear to be adversely affected by the concurrent lactation and pregnancy, either at the present or subsequent parturition. The average farrowing interval of 153 days allowed a performance of 2·35 litters/sow per year, and, with 9·47 piglets weaned/litter, a productivity of 22 piglets/sow per year.

The effects of administering bovine growth hormone (bGH) on milk production in cattle were examined in two experiments.

In experiment 1, a Latin-square design, three groups of four Friesian cows were injected daily with one of two doses of bGH (6 ng/kg and 30 ug/kg; 0·82 unit/mg) or with saline (control) throughout three successive 21-day periods in mid-lactation. At 30 ug/kg daily bGH stimulated a significant increase in milk yield (P < 0·001) and this response increased with the duration of treatment. Changes in the yields of milk fat, protein and lactose closely followed the changes in milk production. The concentrations of milk fat (P < 0·05) and protein (P < 0·05) rose and fell respectively during the 1st week of injections.' A daily dose of 6 ug/kg bGH failed to stimulate an increase in milk yield but milk lactose content was reduced (P < 0·05) during the 2nd and 3rd weeks of treatment. The proportion of milk serum samples containing detectable quantities of the hormone was increased by the higher dose of bGH.

In experiment 2 the milk yields of four Friesian cows were measured when bGH (21·0 to 37·9 mg/day) or saline was infused intravenously for 6 days. The infusions produced up to eight-fold increases in plasma bGH. These were within physiological limits, and remained at elevated levels throughout the 24-h period. Three of the cows demonstrated a clear increase in milk production.

The objective of this study was to compare some husbandry procedures on the base of physiological stress parameters and evaluate the welfare status in sheep. Forty ewes were used as the study material. Measurements were taken during several routine husbandry procedures such as milking, shearing, weighing, loading and hoof care. Data regarding time spent for each application, as well as heart and respiratory rates were recorded during the applications. Blood samples were taken 15 min before and after each application and malondialdehyde (MDA), glutathione-peroxidase (GSH-Px), cortisol T3 and T4 parameters were measured. In addition, changes in the same parameters between pre- and post-application periods were evaluated. According to the results, machine milking caused less stress than hand milking. No significant difference was seen between shearing methods for hand shearer or clipper; however, both applications caused stress in animals. The results for weighing methods of animals demonstrated significant differences in cortisol, T3 and T4 values in favor of traditional method. Cortisol, T3 and T4 levels were significantly higher in manual loading compared with loading by ramp. Regarding hoof care, all the examined parameters differed in favor of modern method. On the other hand, significant differences were determined between the stress parameters regarding pre- and post-applications. All values differed for hand milking while no significant difference was observed in MDA and T3 values in machine milking group. Parameters in weighing groups changed significantly. For loading process, GSH, cortisol, T3 and T4 values differed in both treatment groups. With regard to hoof care, parameters except T4 in laying group differed significantly. An increase occurred in minute-based measurements of heart and respiratory rates parallel to physiological data. The number of the respiratory rates during the applications differed except for the shearing process. All the parameters displayed significant differences between groups in terms of heart rates. Time spent for each application also differed between groups. Time saved for milking, shearing, weighing, loading and hoof care was 3.23 min, 4.37 min, 1.71 min, 7.85 s and 1.55 min, respectively. These results appear to provide a tangible advantage of using new husbandry methods to the breeders. It was concluded that using new methods in sheep husbandry procedures provided advantages in terms of saving time and reducing labor, as well as improved conditions for welfare of animals. In addition, it facilitated the routine works and flock husbandry.

Scarce and poor-quality food resources limit smallholder dairy production in the tropics. Food resources for zerograzing may be improved by intercropping Pennisetum purpureum (napier grass) with Leucaena leucocephala leguminous hedgerows. To evaluate dairy cow performance from this alley cropping system, 36 Ayrshire/Brown Swiss × Sahiwal cows in a 2×3 factorial design were individually fed from the 3rd week of lactation for 14 weeks on diets of napier fodder harvested at 1·0 m or 1·5 m and offered ad libitum, supplemented with 0, 4 or 8 kg fresh weight leucaena fodder. Average daily milk yield during the 2nd week of lactation was a covariate in the analyses of milk yield, and post-partum live weight a covariate in the analyses of dry matter (DM) intake and live-weight change.

Napier harvesting height and leucaena level had independent effects on performance. Napier height (1·0 m or 1·5 m) significantly (P < 0·01) affected daily napier DM intake (9·3 and 6·8 kg), total daily DM intake (10·5 and 7·9 kg), daily live-weight losses (165 and 490 g) and daily milk yield (8·6 and 6·9 kg respectively). Leucaena supplementation (0, 4 or 8 kg) significantly (P<0·01) increased total daily DM intake (7·8, 9·3 and 10·4 kg), reduced daily live-weight loss (560,235 and 175 g), and increased daily milk yield (7·3, 7·7 and 8·3 kg respectively). The results show that reasonable dairy performance can be achieved in the tropics by supplementing a napier fodder basal diet with leucaena forage, and highlight the importance of the stage of harvesting of the napier fodder. The results are discussed in relation to the nutrient requirements for milk production given by the Agricultural Research Council (1980 and 1984).

It has been estimated (Mason, 1963) that about 70% of beef stores bred in Britain are out of dairy cows. Some 30–40% of them are by beef bulls, so that about 40–50% of animals slaughtered for beef are of pure dairy breeding.

Sanfratellano is a native Sicilian horse breed, mainly reared in the north east of the Island, developed in the 19th century from local dams and sires with a restricted introgression of Oriental, African and, more recently, Maremmano stallions. In this study, the genetic relationships and admixture among Sanfratellano, the other two Sicilian autochthonous breeds and Maremmano breed were assessed using a set of microsatellites. The main goals were to infer the impact of Maremmano breed in the current Sanfratellano horse and to provide genetic information useful to improve the selection strategies of the Sanfratellano horse. The whole sample included 384 horses (238 Sanfratellano, 50 Sicilian Oriental Purebred, 30 Sicilian Indigenous and 66 Maremmano), chosen avoiding closely related animals. A total of 111 alleles from 11 microsatellite loci were detected, from four at HTG7 to 15 at ASB2 locus. The mean number of alleles was the lowest in Oriental Purebred (6.7), the highest in Sanfratellano (8.3). All the breeds showed a high level of gene diversity (He) ranging from 0.71 ± 0.04 in Sicilian Oriental Purebred to 0.81 ± 0.02 in Sicilian Indigenous. The genetic differentiation index was low; only about 6% of the diversity was found among breeds. Nei’s standards (DS) and Reynolds’ (DR) genetic distances reproduced the same population ranking. Individual genetic distances and admixture analysis revealed that: (a) nowadays Maremmano breed does not significantly influence the current Sanfratellano breed; (b) within Sanfratellano breed, it is possible to distinguish two well-defined groups with different proportions of Indigenous blood.

Heritability estimates and genetic correlations were obtained for body weight and scrotal circumference, adjusted, respectively, to 12 (BW12 and SC12) and 18 (BW18 and SC18) months of age, for 10 742 male Nellore cattle. The adjustments to SC12 and SC18 were made using a nonlinear logistic function, while BW12 and BW18 were obtained by linear adjustment. The contemporary groups (CGs) were defined from animals born on the same farm, in the same year and birth season. The mean heritability estimates obtained using the restricted maximum likelihood method in bi-trait analysis were 0.25, 0.25, 0.29 and 0.42 for BW12, BW18, SC12 and SC18, respectively. The genetic correlations were 0.30 ± 0.11, 0.21 ± 0.13, 0.21 ± 0.11, −0.08 ± 0.15, 0.16 ± 0.12 and 0.89 ± 0.04 between the traits BW12 and BW18; BW12 and SC12; BW12 and SC18; BW18 and SC12; BW18 and SC18; and SC12 and SC18. The heritability for SC18 was considerably greater than for SC12, suggesting that this should be included as a selection criterion. The genetic correlation between BW18 and SC12 was close to zero, indicating that these traits did not influence each other. The contrary occurred between SC12 and SC18, indicating that selection using one of these could alter the other. Because of the mean magnitudes of heritabilities in the various measurements of weight and scrotal perimeter, it is suggested that the practice of individual selection for these traits is possible.

Sow litter sizes have increased, subjecting more small piglets to intra-uterine growth restriction (IUGR). Research on the development and growth of IUGR pigs is limited. The objective of this study was to compare the body composition and organ development of IUGR pigs at weaning, and to estimate their growth performance from birth to 30 kg. A total of 142 IUGR and 142 normal piglets were classified at birth based on their head morphology. At weaning, 20 IUGR and 20 normal piglets were collected, a whole-body dual-energy x-ray absorption scan was performed, and the piglets were euthanized for organ measurements. Body weight (BW) was measured weekly from birth to 30 kg, rectal temperature and whole-blood glucose levels were measured weekly from birth to weaning, and blood samples were collected at days 7, 14 and 21 for IGF-1 analysis. Results showed that IUGR pigs have a similar percentage of adipose tissue (P > 0.05) compared to normal pigs at 24 days of age. Organs were smaller (P < 0.001) in IUGR pigs than in normal pigs, whereas brain, liver, lungs and adrenal glands were relatively larger (P < 0.05) in relation to the BW of IUGR pigs. Average birth weight (BiW) of normal pigs was greater (P < 0.001) compared with IUGR pigs (1.38 v. 0.75 kg), and the average daily gain (ADG) of IUGR pigs was reduced from day 0 to 14, day 0 to 28 (weaning) and from weaning to 30 kg compared to normal pigs. From birth to weaning at day 28, IUGR piglets had a 72.9 g/day greater fractional ADG (FADG) in relation to their BiW (P < 0.05), but FADG did not differ (P > 0.05) from weaning to 30 kg. Rectal temperature of IUGR piglets was greater (P < 0.05) on day 7 compared with normal piglets, and, even though blood glucose levels were decreased (P < 0.001) in IUGR piglets at day 0, neither glucose nor IGF-1 concentrations differed (P > 0.05) between IUGR and normal piglets. In conclusion, IUGR piglets exhibited some relatively larger organs at weaning compared to normal pigs, but body composition was similar between IUGR and normal pigs. In addition, IUGR pigs had a reduced ADG from birth to 30 kg, and, although they exhibited a greater FADG during nursing, IUGR pigs still require six additional days to reach a BW of 30 kg in comparison to normal pigs.