The partition of the total genetic variance into its additive and non-additive components can differ from trait to trait, and between purebred and crossbred populations. A quantification of these genetic variance components will determine the extent to which it would be of interest to account for dominance in genomic evaluations or to establish mate allocation strategies along different populations and traits. This study aims at assessing the contribution of the additive and dominance genomic variances to the phenotype expression of several purebred Piétrain and crossbred (Piétrain × Large White) pig performances. A total of 636 purebred and 720 crossbred male piglets were phenotyped for 22 traits that can be classified into six groups of traits: growth rate and feed efficiency, carcass composition, meat quality, behaviour, boar taint and puberty. Additive and dominance variances estimated in univariate genotypic models, including additive and dominance genotypic effects, and a genomic inbreeding covariate allowed to retrieve the additive and dominance single nucleotide polymorphism variances for purebred and crossbred performances. These estimated variances were used, together with the allelic frequencies of the parental populations, to obtain additive and dominance variances in terms of genetic breeding values and dominance deviations. Estimates of the Piétrain and Large White allelic contributions to the crossbred variance were of about the same magnitude in all the traits. Estimates of additive genetic variances were similar regardless of the inclusion of dominance. Some traits showed relevant amount of dominance genetic variance with respect to phenotypic variance in both populations (i.e. growth rate 8%, feed conversion ratio 9% to 12%, backfat thickness 14% to 12%, purebreds-crossbreds). Other traits showed higher amount in crossbreds (i.e. ham cut 8% to 13%, loin 7% to 16%, pH semimembranosus 13% to 18%, pH longissimus dorsi 9% to 14%, androstenone 5% to 13% and estradiol 6% to 11%, purebreds-crossbreds). It was not encountered a clear common pattern of dominance expression between groups of analysed traits and between populations. These estimates give initial hints regarding which traits could benefit from accounting for dominance for example to improve genomic estimated breeding value accuracy in genetic evaluations or to boost the total genetic value of progeny by means of assortative mating.

Approximately 110 million birds from nineteen documented indigenous, heavier and lighter bodied chicken breeds and numerous non-descript types are bought and sold at unorganized meat markets in India. Improving the economic production profile for poultry farmers had been a focus since independence. Genetic improvements by selection over seven generations in non-descript chicken breeds has resulted in 19 more eggs and 4 g higher egg weight. Indigenous exotic crossbreds have shown an increase of 24-45 eggs, which has been associated with increased body weight and earlier age of sexual maturity. Heterosis for egg number ranged from 15-23 percent. Hybrids of the Aseel and Delhem Red breeds produced more eggs than either of the parents. Exotic crossbreds, including the Vanraja, Giriraja, Nadanum, Kuroiler (semi-broiler types) and Krishna-J, Grampriya, Krishipriya, Hit-CARI, Up-CARI (lighter weight) were introduced to scavenging in small scale poultry operations by both public and private sector organisations. The production of the Kalyani-DK and Satpura-Desi synthetic hybrid prototypes, which resemble indigenous fowl in body conformation, multi coloured plumage, dull shanks, pink skin and single comb have generated new opportunities for poultry production in rural areas. The Satpura-Desi attained 1.0 kg bodyweight in 8-9 weeks with 2.45 kg feed. In the ‘quick return’ scheme for free range flocks the 200-300 g birds grew to marketable weight in another 50-60 days and were worth 150% in market price compared to the broiler chicken. Whereas, in a gradual income scheme, the egg produced, surplus cockerels and culled hens resulted in a net gain of US$64-70 annually; the quick return scheme for meat chicken produced a net income of US$96 for village women which exceeded the gradual financial returns generated from egg production. Small scale poultry farmers, raising 100-2000 Satpura-Desi chickens, have been able to capitalize on its acceptance as an indigenous breed in the local meat markets, which has been apparent from the sale of 0.67 million chicks in last 12 months.

In an experiment lasting from 1.5 years before first calving until third parturition, 24 purebred indigenous Bos indicus (Boran) cows and 24 Boran crosses with Holstein (proportionately 0.50 and 0.75 Holstein blood level) were given a diet composed of Bermuda grass hay and wheat bran (0.65: 0.35) offered at low, medium and high level. This level was adapted in amount to actual body weight every 2nd week corresponding to assumed 1.0, 1.2 and 1.4 times maintenance energy requirements. Cows were subjected to working exercise before and after first parturition. Body weight differences (lower with low and medium feeding level) developed mostly before calving for the first time and showed the typical decline at the start of lactation and increase in the dry period. Additionally, Boran cows given the high level increased their body weight from the first to the second lactation cycle. Body condition scores were higher in the Boran cows and, in both genotypes, with high feeding level. Independent of feeding level and genotype, calving intervals in cycles 1 and 2 were 530 and 421 days, respectively. Lactation length was considerably shorter in the Boran cows than in the crossbred cows. Milk yield, calculated over the first 13 weeks of lactation and over the whole lactation in both cycles, was 2.06 and 3.06 times higher in the crossbreds than in the Boran. Milk of Boran cows had 1.30, 1.15 and 1.20 times higher contents of fat, total solids and protein. In the first 13 weeks of lactation, milk yield of crossbreds with high feeding level (8.7 kg/day) was higher (P < 0.05) than that of the crossbreds with medium (6.5 kg/day) and low feeding level (5.4 kg/day), respectively. Boran cows never showed a significant response in milk yield to feeding level. Accordingly, the amount of organic matter intake required per kg milk increased with feeding level in the Boran cows while it remained unaffected in the crossbreds. Organic matter digestibility, as measured in lactation cycle 1, was higher (P < 0.01) in Boran. Response to high feeding level and estimated maintenance requirements of crossbred cows corresponded with current assumptions, but crossbreds subjected to medium feeding level expressed unexpectedly little difference from those receiving the low level. It seems that current recommendations are not generally applicable to indigenous tropical breeds as these responded differently from crossbreds to feeding level.

A study was conducted to compare the performance of Mukota, Large White (LW) and LW ✕ Mukota F1 pigs given increasing levels of maize cob meal. Sixteen female weaners of each genotype were given, ad libitum, diets containing 0, 100, 200 and 300 g maize cob meal per kg of diet for 14 weeks. The diets were designed to contain similar levels of protein (ca. 160 g crude protein per kg) and energy (ca. 9 MJ metabolizable energy per kg). Average daily food intake per unit metabolic body weight (ADFI per kg M0·75), average daily gain (ADG) and food conversion ratio (FCR) were determined. The pigs were slaughtered and cold dressed mass (CDM) and backfat thickness were determined for each pig. The ADFI per kg M0·75 was similar among the four diets for the three genotypes. The rate of decline in ADG was higher (P < 0·05) in the LW than in the other two genotypes. The FCR in the Mukota was poorer (P < 0·05) than that in the LW and the F1 crosses. The Mukota had the highest (P < 0·05) backfat thickness (K5 and K7·5) values of the three genotypes across the four diets, followed by the F1 crosses. The CDM values for the LW and the F1 crosses were similar and were higher (P < 0·05) than those for the Mukota. The findings indicate that F1 crosses and the Mukota were better able to utilize diets containing high levels of maize cob meal than LW pigs.

Growth and survival of 3673 female and cryptorchid lambs representing the range of types (second cross, first cross and Merino) produced in the Australian lamb industry are reported. The lambs were sired by a selection of Poll Dorset (D; no. = 7), Texel (T; no. = 10), Border Leicester (BL; no. = 12) and Merino (M; no. = 12) rams and born to Border Leicester × Merino (BLM) and Merino (M) dams, which resulted in six lamb genotypes (D×BLM, T×BLM, D×M, T×M, BL×M and M×M). The second cross lambs (D×BLM, T×BLM) were heavier at birth, weaning and post-weaning and had higher growth rates, than first cross lambs (D×M, T×M, BL×M), which were higher than M×M lambs (P< 0·01). For post-weaning weight (cryptorchids at 156 days) second cross lambs were 4·2 (s.e. 0·3) kg heavier than comparable sired first cross lambs, with the BL×M 2·6 (s.e. 0·5) kg lighter than other first cross types and the MxM a further 4·2 (s.e. 0·6) kg lighter. The average advantage of D over T crosses was 1·0 kg for post-weaning weight, with greater variation amongst individual sires.

Lamb survival to weaning was 76% and it was affected by birth weight and birth type (P< 0·01). Sire breed had no significant effect on lamb survival, whereas lambs from BLM ewes had higher survival than those from M ewes (P< 0·01).

Overall the proportion of ewes lambing was 84% with a mean litter size of 1·77. There was no difference infertility between AI (thawed frozen semen and laparoscopic insemination) and natural (single sire) mating, although the M were higher than the BLM ewes (P< 0·01). Gestation length was 2·3 days shorter (P< 0·01) for BLM than M ewes and there was no difference between D and T sire breeds. There was little effect of birth type on gestation length but it increased with birth weight within birth type categories. Between year repeatability of gestation length for ewes was 0·33 (s.e. 0·05).

The aim of this study was to estimate genetic and phenotypic (co)variances between objective measures and carcass visual scores, as a test of the potential value of visual scores in selection programmes to improve carcass composition in crossbred lambs. In each of 1986, 1987 and 1988, 22 Suffolk rams were chosen with either high or low scores on an index designed to increase lean growth rate. These rams were joined with 18 to 20 crossbred ewes each and their lambs were grown on grass to one of three target live weights (35·5, 41·5 and 47·0 kg) for slaughter. The carcasses of 1881 lambs were visually scored for overall conformation and fatness using the standard Meat and Livestock Commission methods. Additionally, a more detailed 15-point scale assessment of conformation and a direct visual score of subcutaneous fat on the carcass were taken on 1252 lambs during the latter 2 years of the study. Carcass composition was estimated by dissection of a shoulder joint into lean, fat and bone. The possibility of combining data collected on lambs slaughtered at each of the three target live weights, for the estimation of genetic parameters was investigated. Results indicated that heritability estimates for a trait using data collected within each of the slaughter groups were homogeneous. Genetic correlations between records collected for a trait within each of the slaughter groups were not significantly different from one. These results indicated that data collected at each of the target slaughter weights could justifiably be combined. Heritability estimates were generally higher for shoulder tissue proportions (0·3) than for visual scores (0-2). Genetic correlations between all conformation scores and tissue proportions were not significantly different from 0 and therefore of little or no value in predicting carcass composition. Genetic correlations between visual scores of fat and both tissue proportions and ratios were generally high (around 0·65). These results suggest that fat scores collected on crossbred animals could be valuable in purebred selection programmes where improving carcass composition of the crossbred generation is the underlying objective.

Carcass and eating quality characteristics of crossbred wether and female lambs sired by Charollais (C), Suffolk (S) and Texel (T) rams out of Mule ewes (Bluefaced Leicester ♂ × Scottish Blackface ♀ or Swaledale ♀J)were evaluated in a study carried out over a 3-year period in an upland flock. A total of 10 unrelated rams of each breed were used as sires. Lambs (no. = 280) were selected for slaughter at the same estimated subcutaneous fat level on four occasions within each year (i.e. at weaning in July and at approx. monthly intervals thereafter). Following slaughter, the left side of each carcass was physically dissected. A loin joint from lambs slaughtered in the 2nd and 3rd years of the study (no. = 184) was used to evaluate eating quality.

Suffolk-sired lambs were heavier at slaughter (S: 42·2; C: 41·0; T: 40·7 (s.e. 0·35) kg) but had similar killing-out proportions compared with the other two breeds (S: 444; C: 450; T: 452 (s.e. 26) g/kg). Texel-sired lambs had higher lean proportion (S: 543; C: 550; T: 567 (s.e. 4·4) g/kg) and lower total carcass fat proportion (S: 240; C: 242; T: 233 (s.e. 5·3) g/kg) compared with S and C sired lambs. Bone proportion was similar for C and T lambs but was higher for S (S: 199; C: 191; T: 191 (s.e. 2·1) g/kg). Lean: bone (S: 2·75; C: 2·90; T: 2·99 (s.e. 0·037)) and lean:fat (S: 2·38; C: 2·40; T: 2·54 (s.e. 0·034)) ratios were higher for T-sired lambs. Female lambs were lighter (40·4 v. 42·2 (s.e. 0·24) kg), and had proportionately more intermuscular fat than wethers (122 v.118 (s.e. 1·3) g/kg) but the sex differences for other tissue proportions were small. Carcass weights and total carcass fat proportions increased and lean proportions decreased across the four slaughter dates. There were no effects of breed or sex on eating quality. However, samples from lambs slaughtered at weaning were judged to be more tender than those slaughtered later in the season.

In the winter feeding phase of a lifetime study of spring-born cattle managed in a 20-month beef system, a total of four feeding treatments were imposed by increasing the level of concentrate supplement offered with ad libitum grass silage. The objective was to achieve a difference in live weight at the end of the winter of about 25 kg between food treatments. A multifactorial design was used with three animal factors — maturity (early maturing Hereford crosses v. late maturing Charolais crosses), sex (heifer v. steer) and method of rearing (suckled calves v. bucket-reared calves).

There were no significant differences between breeds but highly significant (P < 0·001) differences for method of rearing and sex. As a consequence live-weight differences at the end of the winter between breed types (18 kg) were less than the difference between the sexes (23 kg) and for method of rearing (25 kg) although all were highly significant. Although suckled animals had significantly lower growth rates they were still significantly fatter at the end of the winter as were heifers and Hereford crosses. Differences in dry-matter intake were reflected in growth rate.

Plane of winter nutrition had a highly significant effect (P < 0·001) on live weight and condition score at the end of the winter resulting in increments of about 23 kg and 0·12 units of condition for each level of feeding.

Interactions between the main production variables were not significant with the exception of feeding level and method of rearing. Suckled animals showed a significant (Y < 0·001) reduction in winter gain (proportionately 0·85 for that of bucket-reared animals) when offered the same diet. This reduction ranged proportionately between 0·25 and 0·08 for the lowest and highest daily levels of concentrate supplementation respectively. An extra 1 kg concentrates per day was required for suckled animals to achieve similar live-weight gains to bucket-reared animals.

An experiment was carried out to evaluate the effects of forage type and level of concentrate supplementation on forage intake, diet digestibility and milk production. Twenty-four crossbred cows (Bos taurus × Bos indicus), in early lactation, were allocated to the following six dietary treatments: native grass hay (H) or oat-vetch hay (OV), offered ad libitum, and supplemented with either 0, 2·5 or 5·0 kg per cow per day of a wheat-middling-based concentrate. A four-period, partially balanced, change-over design was used and the treatments were arranged as a 2 × 3 factorial.

The daily dry-matter (DM) intake was 640 g (P < 0·001) higher with cows on (H) diets compared with those on OV diets. However, OV diets were more digestible (0·675 v. 0·566, P < 0·001) resulting in 800 g higher (P < 0·05) daily intake of digestible DM. The daily milk yield was 1·24 kg higher (P < 0·001) for cows on OV diets compared with H diets. Milk fat concentration was higher (P < 0·05), but milk protein concentration was lower (P < 0·001) with H diets. The rates of rumen degradation of DM and nitrogen of OV were higher than of H for all incubation periods; similarly the values of the rate constant of DM and nitrogen were greater for OV than for H.

The daily DM intake increased by 3·72 kg/day (P < 0·001), when the amount of concentrate increased from 0 to 5·0 kg/day, indicating a minor substitution of basal forage by concentrate. The apparent DM digestibilities of the diets were higher when the diets were supplemented with concentrates. The milk yield increased linearly (P < 0·001), when the level of concentrate supplement increased from 0 to 5 kg, resulting in 0·52 kg more milk per day per kg additional concentrate given.

Forty-five Friesian × zebu crossbred calves (4 days old) were used to evaluate the effect of feeding different levels of whole milk and weaning at different ages. A total of 252 I whole milk offered over 12 weeks was compared with a feeding level of 134 I milk offered over 8 weeks. Water given ad libitum was also compared with allowing access to water once daily. The calves were penned and fed individually. The average daily gain of the calves weaned at 12 weeks was 464 g compared with 378 g for the calves weaned at 8 weeks of age and allowed access to water once daily and 422 g for the calves weaned at 8 weeks and given water a d libitum. Feeding extra milk and weaning at 12 weeks decreased the intake of concentrates and significantly (P < 0·05) increased live-weight gain. Allowing ad libitum access to water was associated with an increase in concentrate intake but this was not reflected in a significant increase in animal performance.

Resting heat production (H), respiratory rate (RR) and rectal temperature (Tr) were measured at different controlled temperatures (Tt) in Hariana (Bos indicus) and its F, crosses with Jersey (JH), Brown Swiss (BH) and Holstein Friesian (FH) (Bos taurus) breeds and the values obtained were used to assess their relative thermosensitivity.

The lowest Tt at which H significantly decreased from that at 17°c was 32°c for Hariana, JH and BH and 27°c for FH after exposure for 8 days. The corresponding values after exposure for 18 days were 37°c for Hariana and 32°c for all the three crossbred groups. Differences between the genetic groups were also significant. The lowest Tt at which metabolizable energy (ME) decreased significantly in comparison with those at 17CC was 32°c in all the genetic groups. The differences in ME intake between genetic groups were significant only at 32°c Tt. The lowest Tt at which RR significantly increased from those at 17°c were 32°c in Hariana, 27°c in JH, BH and FH for both 5 to 7 and 15 to 17 days of exposure. The corresponding Tt for increase in Tr was 37°c in Hariana, 32°c in JH and 27°c in BH and FH at both 5 to 7 and 15 to 17 days of exposure.

The ambient temperature at which H would have significantly decreased and RR and Tr increased from the respective values at 17CC Tt were calculated curvilinearly for different genetic groups. There were differences in these values of calculated ambient temperatures between genetic groups and between exposure durations in respect of H, RR, and Tr, indicating differences in thermosensitivity.