Twenty-five New Zealand White × Californian lactating doe rabbits were used to study the effect of different dietary fibre concentrations on the amino acid contribution of soft faeces to the total amino acid intake. Five isoenergetic diets containing 312, 334, 360, 384, and 412 g/kg neutral-detergent fibre (DM basis) were formulated. All diets were designed to maintain the same amino acid pattern. Soft faeces production showed a trend to increase (P = 0·07) as dietary fibre increased. The content of isoleucine (P < 0·01), glutamic acid, leucine and alanine (P < 0·05) in soft faeces decreased as the dietary fibre increased. A trend to decrease with the increase of dietary fibre was also observed for aspartic acid (P = 0·06), lysine (P = 0·07), methionine and valine (P = 0·1). As a consequence, the soft faeces contribution to the total intake of individual amino acids did not vary with the type of diet. The average contribution of soft faeces to the total amino acid intake for the most limiting amino acids of lactating doe rabbits under practical conditions, methionine, threonine and lysine, were 0·17 , 0·21 and 0·18 g/g, respectively.

In the livestock husbandry compensatory growth may be explored as a means to improve nutrient utilization, to reduce gut health problems due to excess protein intake, to simplify feeding strategies and thus to improve production efficiencies. This study investigated the effects of early protein restriction (EPR) and early antibiotic intervention (EAI) on growth performance, intestinal morphology, colonic bacteria, metabolites and mucosal gene expressions during the restriction phase and re-alimentation phase. A total of 64 piglets (10.04 ± 0.73 kg) were randomly divided into four treatment groups according to a 2 × 2 factorial arrangement with two levels of proteins (14% v. 20%) and two levels of antibiotics (0 v. 50 mg/kg kitasamycin and 20 mg/kg colistin sulphate). After a 30-day restriction phase with four kinds of diets, all groups were fed the same diets for another 74 days. The results showed that EPR decreased BW, average daily gain (ADG), average daily feed intake in the restriction phase (P < 0.01) and increased ADG on days 66 to 104 of the late re-alimentation phase. Early protein restriction could decrease the villus height in the jejunum (P < 0.05), while shifting to the same diets restored the villus height. Meanwhile, during the re-alimentation phase, pigs in the protein restriction groups had increased concentrations of total short chain fatty acids (P < 0.05), and modified the abundances of Firmicutes and Bacteroidetes in the colon. Furthermore, the lower microbial diversity caused by EPR was improved, and gene expression analysis indicated a better barrier function in the colon. During the whole trial, EAI had no interaction with EPR and played a dispensable role in compensatory growth. Collectively, the retardation of growth caused by EPR can be compensated for in the later stages of pig raising, and accompanied by altered intestinal morphology, microbial composition.

A crossmothering experiment was conducted to measure the direct and the maternal components of the response to divergent selection for yearling growth rate in beef cattle. The animals were from three closed lines of Angus cattle. Two lines had been selected since 1974 for either high (high-line) or low (low-line) average daily gain from birth to yearling, and the third line was maintained as a randomly bred control-line. A total of 221 female calves born between 1984 and 1987 was used in the crossmothering experiment, and an additional 113 cows bearing calves in 1988 were used to obtain more records of milk production.

On average, high-line calves born in 1984-87 were 45 kg heavier at weaning (200 days of age) than low-line calves and 65 kg heavier at yearling age, corresponding to a proportional divergence in daily weight gain of 0·29 and 0·32 respectively. The direct component of the response to selection was 0·82 (s.e. 0-05) of the divergence in body weight at weaning and 0·89 (s.e. 0·05) at yearling age. The maternal component was 0·18 (s.e. 0·06) and 0·11 (s.e. 0·04) for weaning and yearling weight respectively. Over the years 1984-88, high-line dams produced 1·15 times the milk of low-line dams and only 1·03 times that of control-line dams. There were small differences in the composition of milk sampled in 1984 which resulted in the milk of high-line dams having a higher content of metabolizable energy (ME) than that of control-line dams. The ME in the milk consumed by the calves from the three selection lines was sufficient to fuel similar proportions of their pre-weaning growth and indicated that the expression of the maternal component of the selection response may be via small differences in the quantity and quality of the milk produced by the dams. Expression of the direct component appeared to be at least partially via differences in appetite of the calves. These results, together with results for sheep, mice and rats, show that the direct component of the response to selection for growth is much larger than the maternal component.

1. Rumen-ammonia concentration, pH of rumen liquor and blood-urea concentration have been measured at intervals after feeding in six calves given diets containing ‘soluble’ groundnut meal, ‘soluble’ herring meal or ‘insoluble’ herring meal as the major protein source.

2. There were no significant differences between diets in any of the measurements examined. A difference approaching significance was, however, observed between ‘soluble’ herring meal and the other diets in the direction and extent of the change in rumen-ammonia concentration during the first hour after feeding.

3. On all diets, pH of rumen liquor fell to a value in the region of 5·5 immediately after feeding and increased gradually to around 6·5 during the following 8 hr. Rumen-ammonia concentrations were at all times very low.

4. There was no significant residual correlation between changes in blood-urea concentration and the corresponding changes in rumen-ammonia concentration.

5. Rumen-ammonia concentration increased markedly on the ‘soluble’ herring meal diet when the nitrogen intake of the animals was increased by 50%; under similar conditions, only slight increases in this measurement were observed on the other diets.

6. Thesefindingsare discussed in relation to the efficiency of utilisation of dietary nitrogen.

In vitro gas production studies are routinely used to assess the metabolic capacity of intestinal microbiota to ferment dietary fibre sources. The faecal inocula used during the in vitro gas production procedure are most often obtained from animals adapted to a certain diet. The present study was designed to assess whether 19 days of adaptation to a diet are sufficient for faecal inocula of pigs to reach a stable microbial composition and activity as determined by in vitro gas production. Eighteen multiparous sows were allotted to one of two treatments for three weeks: a diet high in fibre (H) or a diet low in fibre (L). After this 3-week period, the H group was transferred to the low fibre diet (HL-treatment) while the L group was transferred to the diet high in fibre (LH-treatment). Faecal samples were collected from each sow at 1, 4, 7, 10, 13, 16 and 19 days after the diet change and prepared as inoculum used for incubation with three contrasting fermentable substrates: oligofructose, soya pectin and cellulose. In addition, inocula were characterised using a phylogenetic microarray targeting the pig gastrointestinal tract microbiota. Time after diet change had an effect (P<0.05) on total gas production for the medium–fast fermentable substrates; soya pectin and oligofructose. For the more slowly fermentable cellulose, all measured fermentation parameters were consistently higher (P<0.05) for animals in the HL-treatment. Diet changes led to significant changes in relative abundance of specific bacteria, especially for members of the Bacteroidetes and Bacilli, which, respectively, increased or decreased for the LH-treatment, while changes were opposite for the HL-treatment. Changing the diet of sows led to changes in fermentation activity of the faecal microbiota and in composition of the microbiota over time. Adaptation of the microbiota as assessed by gas production occurred faster for LH-animals for fast fermentable substrates compared with HL-animals. Overall, adaptation of the large intestinal microbiota of sows as a result of ingestion of low and high fibre diets seems to take longer than 19 days, especially for the ability to ferment slowly fermentable substrates.

There is a requirement in some beef markets to slaughter bulls at under 16 months of age. This requires high levels of concentrate feeding. Increasing the slaughter age of bulls to 19 months facilitates the inclusion of a grazing period, thereby decreasing the cost of production. Recent data indicate few quality differences in longissimus thoracis (LT) muscle from conventionally reared 16-month bulls and 19-month-old bulls that had a grazing period prior to finishing on concentrates. The aim of the present study was to expand this observation to additional commercially important muscles/cuts. The production systems selected were concentrates offered ad libitum and slaughter at under 16 months of age (16-C) or at 19 months of age (19-CC) to examine the effect of age per se, and the cheaper alternative for 19-month bulls described above (19-GC). The results indicate that muscles from 19-CC were more red, had more intramuscular fat and higher cook loss than those from 16-C. No differences in muscle objective texture or sensory texture and acceptability were found between treatments. The expected differences in composition and quality between the muscles were generally consistent across the production systems examined. Therefore, for the type of animal and range of ages investigated, the effect of the production system on LT quality was generally representative of the effect on the other muscles analysed. In addition, the data do not support the under 16- month age restriction, based on meat acceptability, in commercial suckler bull production.

During oestrus, fattening female pigs are more prone to lameness, fractures and wounds due to mounting and agonistic behaviours of penmates. This study assessed the effect of sexual maturity on the behaviour and welfare of heavy female pigs slaughtered at 36 weeks of age (180±10 kg) for dry-cured ham production. An immunocastrated control group was used for comparison. In all, 56 15-week-old female pigs, individually identifiable by back tattoos were equally distributed among four pens. All animals from two pens were subject to a three-dose immunocastration schedule at 16, 20 and 32 weeks of age. Skin lesions and behaviours were assessed at 18, 23, 28, 33 and 36 weeks of age. A blood sample was collected at 20, 24, 28 and 32 weeks of age for assessing health/stress parameters and GnRH antibodies. At slaughter, ovaries were weighed, measured and histologically examined; stomachs, carcasses and lungs were scored for lesions and a further blood sample was taken. Immunocastrated pigs did not significantly differ from controls in growth rate, feed efficiency and slaughter performances (lung score, gastric score, backfat thickness). However, they showed a lower frequency of aggressive interactions at 33 and 36 weeks, lower front lesions at 28 weeks, but higher at 30 weeks; a lower haptoglobin level at 28 weeks, a lower level of cortisol and back lesions at slaughter (36 weeks). These findings suggest a low, yet not negligible, impact of sexual maturity on the welfare of heavy female pigs.

(Co)variance components were estimated for visual scores of conformation (CY), early finishing (PY) and muscling (MY) at 550 days of age (yearling), average daily gain from weaning to yearling (GWY), conformation (CW), early finishing (PW) and muscling (MW) scores at weaning, and average daily gain from birth to weaning (GBW) in animals forming the Brazilian Brangus breed born between 1986 and 2002 from the livestock files of GenSys Consultants Associados S/C Ltda. The data set contained 53 683; 45 136; 52 937; 56 471; 24 531; 21 166; 24 006 and 25 419 records for CW, PW, MW, GBW, CY, PY, MY and GWY, respectively. Data were analyzed by the restricted maximum likelihood method using single- and two-trait animal models. Direct heritability estimates obtained by single-trait analysis were 0.12, 0.14, 0.13 and 0.14 for CY, PY and MY scores and GWY, respectively. A positive association was observed between the same visual scores at weaning and yearling, with correlations ranging from 0.64 to 0.94. Estimated correlations between GBW and weaning and yearling scores ranged from 0.60 to 0.77. The genetic correlation between GBW and GWY was low (0.10), whereas correlations of 0.55, 0.37 and 0.47 were observed between GWY and CY, PY and MY, respectively. Moreover, GWY showed a weak correlation with CW (0.10), PW (−0.08) and MW (−0.03) scores. These results indicate that selection of the traits that was studied would result in a small response. In addition, selection based on average daily gain may have an indirect effect on visual scores as the correlations between GWY and visual scores were generally strong.

Liquid feeding has the potential to provide pigs with sufficient water to remain hydrated and prevent prolonged thirst. However, lack of permanent access to fresh water prevents animals from drinking when they are thirsty. Moreover, individual differences between pigs in a pen may result in uneven distribution of the water provided by the liquid feed, leading to some pigs being unable to meet their water requirements. In this review, we look at the need for and provision of water for liquid-fed pigs in terms of their production performance, behaviour, health and welfare. We highlight factors which may lead to water ingestion above or below requirements. Increases in the need for water may be caused by numerous factors such as morbidity, ambient temperature or competition within the social group, emphasising the necessity of permanent access to water as also prescribed in EU legislation. The drinkers can be the target of redirected behaviour in response to feed restriction or in the absence of rooting materials, thereby generating water losses. The method of water provision and drinker design is critical to ensure easy access to water regardless of the pig’s physiological state, and to limit the amount of water used, which does not benefit the pig.

Oxalic acid (OA) is a secondary compound occurring in a wide range of plants consumed by ruminants, especially in saline lands or in arid and semi-arid regions. However, its impact on the rumen microbial community and its changes over time, as well as the potential consequences on ruminal function, remain unknown. To examine this impact, five ewes fitted with a ruminal cannula and fed low-quality grass hay were dosed daily with 0.6 mmol of OA/kg body weight through the cannula for 14 days. On days 0 (before the start), 4, 7 and 14 of the administration period, samples of ruminal digesta were collected throughout the day (0, 3, 6 and 9 h after the morning feeding) for analysis of the bacterial community and fermentation parameters (pH, ammonia and volatile fatty acid (VFA) concentrations). In addition, two feedstuffs were incubated in situ using the nylon bag technique to estimate ruminal degradation. Terminal restriction fragment length polymorphism was employed to monitor the dynamics of total bacteria, and quantitative real-time PCR was used to investigate the abundance of the oxalate-degrading Oxalobacter formigenes. Neither pH nor total VFA concentrations were affected. Nevertheless, OA dosing altered molar proportions of most individual VFA and ammonia concentrations (P < 0.001). The dry matter disappearance of alfalfa hay was reduced on days 7 and 14 and that of barley straw only on day 7 (P < 0.01). These slight changes were related to others observed in the relative frequency of a number of terminal restriction fragments. Variations in the ruminal microbiota occurred rapidly with OA administration, which did not modify the bacterial diversity significantly but altered the structure of the community. However, many of these changes were reversed by the end of the experiment, with no significant differences between days 0 and 14 of dosing. These results suggest a rapid adaptation of the rumen bacterial community linked to the estimated increase in the abundance of O. formigenes (from 0.002% to 0.007% of oxc gene in relation to the total bacteria 16S rDNA; P < 0.01), which is assumed to be responsible for oxalate breakdown.

An average of 60 Rambouillet and 60 Suffolk ewes was maintained under an intensive management system to lamb about every 7 months. Decreased daylength was used for oestrus induction in normally anoestrous periods. The experiment lasted 3·7 years, during which time six lamb crops were produced, three of them as a result of out-of-season mating. Ewes of each breed were subdivided into three experimental groups and each breed-group was maintained under one of three different light treatments before and during out-of-season mating. Imposed Treatment 1 consisted of a pre-mating period under natural daylight followed by a mating period of short daylength (8 h/day). Ewes under imposed Treatments 2 and 3 were exposed to 16 h of light during the pre-mating period and to 8 h of daylight during the mating period. This did not affect conception significantly in the Rambouillet but it did in the Suffolk. Different intensities and wavelengths of light during the long daylight period (16 h/day) were used in Treatments 2 and 3 but did not cause different responses.

In Rambouillet ewes the first mating (out-of-season) gave 73% conception. It was followed by two in-season matings with 72 and 85% conceptions. The last three matings (out-of-season, in-season, out-of-season) resulted in 57, 42, and 58% conceptions. In the Suffolk ewes, the conceptions were 30, 88, 77, 3, 77, and 10% in the same order as those for Rambouillet. The average production ofRambouil-lets on the three treatments was 166 lambs per 100 ewes per year (165, 177, 157) whereas Suffolks produced 132 lambs (120, 143, 135). Control Rambouillet and Suffolk ewes maintained under natural daylight year-round produced 139 and 117 lambs.

The objective of this study was to evaluate the influences of age and condition score on the live weight of ewes of three Greek dairy breeds. Boutsko (no. = 225), Serres (no. = 292) and Karagouniko (no. = 301) ewes from individually recorded purebred flocks were weighed (±0·5 kg) and condition scored, on a six-point scale, to the nearest 0·5 unit. Within each breed and age group the relationship between live weight and condition score was derived by linear regression. There was a highly significant relationship between condition score and live weight in all of the groups (P < 0·01). Live weight, adjusted to a standard condition score, increased with increasing age up to 3·5 years; beyond this age there was no effect of age on condition score. The live weight and condition score data for ages 3·5 years and upwards were used to derive a single regression between live weight and condition score for each breed. This provides a means to estimate adult live weights standardized to a given condition score. The values of the regression coefficients were directly proportional to the breed mature weight; on average the increase in live weight associated with a unit of condition score was 0·129 kg/kg of mature weight for the three breeds studied. Mature weight was estimated as the weight at a condition score of 5. Using published information, a similar value was found to apply to a wide range of sheep breeds and also to cattle. This robust value permits the live-weight change associated with a unit of condition score to be calculated, for any breed.

An experiment was started in 1950 designed to find out what proportion of the difference in milk yield between herds is genetic in origin. Sixty-five pairs of twins were split at birth equally between farms having high-yielding herds and farms having low-yielding herds. A previous paper on this experiment reported on the growth of the twins, the present paper on milk yield and on management practices in the herds.

Twenty-four pairs of twins survived to complete one lactation and these provide an estimate of 24%±18% for the genetic part of the difference between the herds.

Aspects of rearing of the twins and of management of the herds were examined. Twins in the high-yielding herds were served and calved earlier than those in the low-yielding group but they had a longer interval between service and calving. Differences between average heifer yields and average cow yields were from one-and-a-half to two times greater in the high- than in the low-yielding herd group. There were no obvious quantitative differences in feeding practice between the two groups although differences in body size suggest that twins in the high group were done better. For the age at first service there was a positive rank correlation of 0·30 between body size differences and subsequent differences in first lactation milk yield. There was no single factor of management or environment which appeared to be the cause of the yield difference between the herds.

The aim of this study was to evaluate the effects of geese’s maternal diet supplemented with flaxseed on the fatty acid profiles of egg yolks and the antioxidant status of their offspring. A total of 288 female Huoyan geese (42 weeks old) were randomly allotted to four experimental groups in this 56-day experiment and fed on diets containing flaxseed at 0% (control), 5%, 10% and 15%, respectively. There were nine replicate pens per treatment, with eight geese per replicate pen. The concentration of α-linolenic acid (linear, P<0.01), EPA (20:5n-3; linear, P<0.01), DHA (22:6n-3; quadratic, P=0.03) and n-3 polyunsaturated fatty acid (PUFA) (linear, P<0.01) levels in the yolk lipids increased with increasing dietary flaxseed levels. Yolk palmitic acid (16:0, linear, P=0.05), saturated fatty acid (linear, P=0.04) level and total n-6/n-3 ratio (P<0.01) decreased in a linear fashion as dietary flaxseed levels increased. Increasing dietary flaxseed levels linearly decreased (P=0.01) the total cholesterol in egg yolks. After hatching, three 1-day-old gosling were selected randomly from each replicate to determine blood characteristics and liver antioxidant status. Aspartate aminotransferase activity (linear, P=0.03), total triglycerides (linear, P=0.02) and total cholesterol (linear, P=0.05) contents in blood linearly decreased as the levels of flaxseed increased. A linear dose response to maternal dietary flaxseed was detected for the activities of the goslings’ liver enzymes catalase (linear, P=0.01), superoxide dismutase (linear, P<0.01) and glutathione peroxidase (linear, P<0.01). The malondialdehyde (quadratic, P=0.03) and alkaline phosphatase content in the livers of goslings decreased as flaxseed supplementation levels increased. In conclusion, the dietary addition of flaxseed up to 15%, in the maternal diet resulted in increased n-3 PUFA levels in egg yolks and improved the antioxidant status of offspring in a dose-dependent manner.

A study was made of the performance of different grades of Friesian × White Fulani crosses using 12 years' records from 1967 to 1978. Milk yield increased progressively with increases in the proportion of Friesian genes. Lactation length also showed a similar trend, with a difference between 1/2 and 7/8 grades of 41 days. Calving intervals averaged approximately 390 days and did not differ among grades. Calf mortality was high, varying from 16 to 29%. The optimal genetic contribution from the Friesian for this environment is considered to be higher than 75 %

Blood metabolite and hormone concentrations are indicative of metabolic status, but blood sampling and analysis is invasive and time-consuming. Monitoring behavior can be done automatically, and behaviors may also be used as indicators of metabolic status. The aim of this study was to analyze the relationships between metabolic status and feeding behavior, lying behavior, motion index and steps of dairy cows in week 4 postpartum. Behavioral data from 81 Holstein-Friesian cows were collected using computerized feeders and accelerometers, and blood samples were collected for analysis of free-fatty acid (FFA), β-hydroxybutyrate (BHB), glucose, insulin, IGF-1 and growth hormone (GH) concentrations. First, cluster analysis was performed to categorize cows as having poor, average, good or very good metabolic status based on their plasma FFA, BHB, glucose, insulin, IGF-1 and GH concentration. Subsequently, the performance and behavior of cows in clusters with poor, average and good metabolic status were compared using GLM. Cows with a poor or average metabolic status tended to have greater fat-and-protein-corrected milk yield than cows with good metabolic status. Furthermore, cows with a poor metabolic status had a lower energy balance and dry matter intake (DMI) than cows with an average or good metabolic status and had a lower number of meals than cows with good metabolic status. Daily number of visits to the feeder and lying time tended to be positively related with metabolic status. Feeding rate (kg/min), daily meal time (min/day), number of lying bouts per day, steps and motion index were not related with metabolic status. In conclusion, better metabolic status in dairy cows in early lactation was associated with a greater DMI, increased feeding activity and a tendency to more time spent lying, compared with poor metabolic status. These results suggest that compromised metabolic status is reflected in altered cow’s behavior in week 4 of lactation.

Ewes of the Segureña breed were allocated to groups and were group-fed different diets composed of concentrates and roughage (lucerne hay in experiment 1 and barley straw in experiment 2), in late pregnancy and lactation. The concentrates were formulated with sunflower cake and barley, either alone (control group) or partly replaced with olive cake (OLC) and olive molasses (OLM) in a 5:1 ratio. The OLC was either untreated or was treated with NaOH or ammonia. Concentrates were given to provide proportionately 0·4 and 0·7 of calculated metabolizable energy (ME) requirements in experiments 1 and 2 respectively. In experiment 2 a further group grazed pasture and was given barley at a reduced rate.

In experiment 1, the mean ME intake during late pregnancy (5+1 weeks pre-lambing) for all treatment groups was about 796 kj/kg M0·75 per day and largely exceeded their average energy requirements, whereas it was close to requirements (601 kj/kg M0·75 per day) in experiment 2. During lactation, ME intake was adjusted to the theoretical needs for ewes suckling a single lamb (835 to 870 kj/kg M0·75 per day) and was slightly deficient (990 to 1020 kj/kg M0·75 per day) for ewes with twins, irrespective of both treatment (except the group at pasture) and experiment.

Minor differences in animal performance, attributed to the type of concentrate offered, were found. In pregnancy, alkali treatment of OLC significantly improved live-weight gains (P < 0·01). Live-weight gains of ewes in experiment 2 were lower than those in experiment 1 in accordance with their lower ME intake, the lowest gains being found in the group at pasture (P < 0·05). Weight losses in lactating ewes in experiment 1 were 17 to 100 and 9 to 165 g per ewe per day for ewes suckling single and twin lambs respectively. In experiment 2 ewes with twins gained weight, while those with single lambs showed little weight change, although differences between experiments were too small to attain statistical significance. No differences in barley straw intake by pregnant ewes were found between treatment groups. However, the intake of barley straw by lactating ewes in the groups offered concentrates containing OLC and OLM was significantly higher than that by controls (P < 0·05).

Birth weight of lambs tended to be higher in experiment 2 when ewes consumed less ME during pregnancy, although variations were not statistically significant. The most important cause of growth rate variation was the number of lambs born to a ewe (P < 0·001). The growth rate of lambs in the outdoor group was significantly lower than that of lambs in the indoor groups (P < 0·05).

To achieve functional but also productive females, we hypothesised that it is possible to modulate acquisition and allocation of animals from different genetic types by varying the main energy source of the diet. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66), a maternal line characterised by hyper-prolificacy; LP (n=67), a maternal line characterised by functional hyper-longevity; R (n=79), a paternal line characterised by growth rate. Females were fed with two isoenergetic and isoprotein diets differing in energy source: animal fat (AF) enhancing milk yield; cereal starch (CS) promoting body reserves recovery. Feed intake, weight, perirenal fat thickness (PFT), milk yield and blood traits were controlled during five consecutive reproductive cycles (RCs). Females fed with CS presented higher PFT (+0.2 mm, P<0.05) and those fed AF had higher milk yield (+11.7%, P<0.05). However, the effect of energy source varied with the genetic type and time. For example, R females presented a decrease in PFT at late lactation (−4.3%; P<0.05) significantly higher than that observed for H and LP lines (on av. −0.1%; P>0.05), particularly for those fed with AF. Moreover, LP females fed with AF progressively increased PFT across the RC, whereas those fed with CS increased PFT during early lactation (+7.3%; P<0.05), but partially mobilised it during late lactation (−2.8%; P<0.05). Independently of the diet offered, LP females reached weaning with similar PFT. H females fed with either of the two diets followed a similar trajectory throughout the RC. For milk yield, the effect of energy source was almost constant during the whole experiment, except for the first RC of females from the maternal lines (H and LP). These females yielded +34.1% (P<0.05) when fed with CS during this period. Results from this work indicate that the resource acquisition capacity and allocation pattern of rabbit females is different for each genetic type. Moreover, it seems that by varying the main energy source of the diet it is possible to modulate acquisition and allocation of resources of the different genetic types. However, the response of each one depends on its priorities over time.

In order to accurately estimate body composition at slaughter and to meet specific market targets, the influence of age at time of castration (surgical or immunological) on body composition and boar taint indicators must be determined for male pigs. In all, 48 males were randomly assigned to one of four management regimens: (1) entire male pigs (EM), (2) EM surgically castrated at ~40 kg BW and 10 weeks of age (late castrates; LC), (3) conventional, early surgical castrates (within 4 days of birth; EC) and (4) EM immunized with a gonadotropin-releasing hormone (GnRH) analog (primary dose at 30 kg BW and 8 weeks of age; booster dose at 70 kg and 14 weeks of age; IM). Pigs were fed corn and soybean meal-based diets that were not limiting in essential nutrients. Back fat was sampled on days −3, 8, 18 and 42, relative to administering the booster dose of GnRH analog at day 0, to determine androstenone concentrations (n=8 or 9/group). Fat androstenone concentrations in IM were lower than EM between days 8 and 42 after administering the booster dose (173 v. 863 ng/g, respectively; P<0.01), and were not different from surgically castrated males (EC and LC) after day 18. Slaughter occurred at ~115 kg BW, 42 days (6 weeks) after administering the booster dose for IM, and 10 and 20 weeks after surgical castration for LC and EC, respectively (n=8 or 9/group). At slaughter, live BW, liver weight as a percent of live BW, dissectible bone as a percent of cold carcass side, body protein and water contents and whole-body protein deposition decreased with time after surgical castration (linear; P<0.05), whereas dressing percentage, dissectible fat, probe fat depth and body fat content increased with time after surgical castration (linear; P<0.05). The IM had intermediate dressing percentage and dissected fat to EM and EC, whereas liver weight as a percent of live BW and body protein and lipid contents were not different from EM. Whole-body lipid deposition tended to be greater in IM than in EM between 14 and 20 weeks of age (373 v. 286 g/d; P=0.051). In conclusion, castration of male pigs after 6 weeks of age has a lasting effect on physical and chemical body composition. The relationship between time after castration and body composition may be developed to predict carcass composition and can be used to determine the ideal immunization schedule aimed at specific markets in the future.

The objective was to estimate (co)variance functions using random regression models (RRM) with Legendre polynomials, B-spline function and multi-trait models aimed at evaluating genetic parameters of growth traits in meat-type quail. A database containing the complete pedigree information of 7000 meat-type quail was utilized. The models included the fixed effects of contemporary group and generation. Direct additive genetic and permanent environmental effects, considered as random, were modeled using B-spline functions considering quadratic and cubic polynomials for each individual segment, and Legendre polynomials for age. Residual variances were grouped in four age classes. Direct additive genetic and permanent environmental effects were modeled using 2 to 4 segments and were modeled by Legendre polynomial with orders of fit ranging from 2 to 4. The model with quadratic B-spline adjustment, using four segments for direct additive genetic and permanent environmental effects, was the most appropriate and parsimonious to describe the covariance structure of the data. The RRM using Legendre polynomials presented an underestimation of the residual variance. Lesser heritability estimates were observed for multi-trait models in comparison with RRM for the evaluated ages. In general, the genetic correlations between measures of BW from hatching to 35 days of age decreased as the range between the evaluated ages increased. Genetic trend for BW was positive and significant along the selection generations. The genetic response to selection for BW in the evaluated ages presented greater values for RRM compared with multi-trait models. In summary, RRM using B-spline functions with four residual variance classes and segments were the best fit for genetic evaluation of growth traits in meat-type quail. In conclusion, RRM should be considered in genetic evaluation of breeding programs.