Alternative index procedures for selection on non-linear profit are quadratic indices, desired gains indices, group or mate selection indices, or direct optimization of responses over multiple generations. In this study a multiple generation time horizon was considered and several linear, quadratic and desired gains indices were compared. Genetic and economic responses over multiple generations were calculated considering a quadratic profit function combining protein yield and days open.

Directly optimizing reponse over multiple generations was found to yield slightly higher economic responses (+ < l.5%) than stepwise (each generation) adjustment of a linear index. A constant linear index using base population averages and a quadratic index were found to be less efficient. The quadratic index was less efficient than the linear index when considering multiple generations. Desired gains indices allowed stabilization of base population average for days open, however, forcing considerable economic losses. Relative efficiencies of methods depended on the degree of non-linearity of the profit function.

A total of 148 dairy cows in their first lactation and with a mean calving date of 6 December were used in a 4–year experiment. The experiment was designed to examine the effect of level and distribution of concentrate given during the winter period in addition to grass silage (ad libitum) and hay (4 kg/day) on total lactation performance. Each year the same five treatments were compared: three levels of concentrate supply during the winter period (H, M and L), and, for levels M and L, two different allocation patterns (standard (S) or flat rate (F)). Concentrate allocation was individually pre-determined according to expected milk production. During summer, all animals grazed together as a single group. During the experimental period (weeks 4 to 18 of lactation), concentrate and roughage intakes were 6·3, 5·0 and 3·6 kg dry matter (DM) per day and 9.;5, 9·6 and 10·0 kg DM per day in group HS, MS and LS respectively. Milk yield and protein concentration of group HS were higher than that of group MS (+1·3 kg I day and +1·0 g/kg) or LS (+3·0 kg/day and +1·7 g/kg). During winter, live-weight changes were +4, -26 and -39 kg for group HS, MS and LS respectively. Over the 40 weeks of lactation, the differences in milk production and concentrate supply were 193 kg and 196 kg DM between groups HS and MS, and 518 kg and 413 kg DM between groups HS and LS. There was no significant difference between groups S and F.

Crossbreeding data involving Ghana Shorthorn, Sokoto Gudali and their Jersey F1s and backcrosses collected over a 16-year period were analysed to estimate additive and heterotic effects for milk production, reproduction and calf growth traits. Sokoto Gudali was significantly better than Ghana Shorthorn in all milk production traits. Calving interval and annualized milk production were better in Gudali than in the Shorthorn. The F1s had higher lactation milk yield, milked longer, produced their first calves earlier and had shorter dry periods and calving intervals than their corresponding purebreds. However, genotype was not significant for number of services per conception. Both F1s had higher average daily gain and weaning weight than their corresponding purebreds. Sokoto Gudali backcross (Jersey × F1) was significantly (P < 0·05) better than the F1 in lactation length. However, in Gudali crosses, there was no advantage in increasing the proportion of Jersey genes beyond 0·5 for milk production traits. Additive effects were significantly (at least P < 0·05) lower in the Shorthorn and the Gudali than in Jersey for milk production traits except proportion of butterfat. Heterosis estimates were significant (P < 0·01) for milk production traits for the Shorthorn but not for the Gudali. Heterotic effects were large and significant (at least P < 0·05) in improving annualized milk production in Shorthorn crosses, whilst none of the heterotic effects for reproductive traits was significant. At both 0 and 0·5 levels of Jersey inheritance, the Gudali was superior (P < 0·01) to the Shorthorn in birth weight, weaning weight and pre-weaning average daily gain. Heterotic effects for calf traits were positive and much larger in Gudali crosses than in Shorthorn crosses. In general, backcrosses were, at best, similar to the F1s implying that upgrading these indigenous breeds beyond 0·5 European inheritance may not be desirable.

High digestibility ryegrass was ensiled using either good methods including formic acid application (HDG) or poor methods without formic acid (HDP). Low digestibility ryegrass (LDG) and lucerne (LUC) were ensiled using similar methods to HDG. Digestible organic matter in the dry matter (DM) in vivo (DOMD) for HDG, HDP, LDG and LUC were 0·756, 0·774, 0·645 and 0·562 respectively. Silages were offered ad libitum to 40 HolsteinFriesian cows in two Latin-square design experiments during weeks 8 to 22 of lactation either alone (experiment 1) or with 3, 6, 9 or 12 kg concentrate DM per day (experiment 2). Relative intakes of silage given alone were respectively 1·00, 0·44, 0·98 and 0·79. Low intake of HDP could not be predicted from silage analysis. In experiment 2, DM intake increased by 0·11 kg and milk yield by 0·24 kg for each 0·010 change in grass silage DOMD. Intake of HDG, LDG and LUC declined linearly with increasing concentrate, on HDP the effect was non-linear and intake increased up to the 6 kg level.

In experiment 1, milk and protein yields were greatest on HDG, protein yield was higher on LDG than LUC and fat concentration higher on HDP and LUC. With supplementation milk yield was greatest on HDG up to the 6 kg level, at higher levels differences between silages were not significant. Fat concentration was highest on LDG and protein highest on HDG and lowest on LUC. On all silages giving the highest concentrate level reduced the concentration and yield of fat. Protein concentration increased up to the 9 kg level. Fat plus protein yields reached a maximum on HDG with 6 kg concentrate DM per day and with 9 kg on the remaining silages.

Overall efficiency of energy utilization (i.e. total net energy intake as a fraction of metabolizable energy intake) in cattle given food ad libitum was calculated from information included in the United Kingdom energy evaluation system as published by the Agricultural Research Council. For growing cattle (live weight 250 kg), overall efficiency was estimated for five levels of diet metabolizability (ranging from q = 0·45 to q = 0·65) for each of two diet types: coarse/long roughage and fine/pelleted diets. The overall efficiencies varied from 0·58 to 0·62 and were not systematically affected by diet type or diet metabolizability. For lactating cattle (live weight 600 kg), overall efficiency was also calculated for five diets with metabolizability ranging from 0·45 to 0·65. Calculations were made for cows at equilibrium intake (i.e. zero energy balance) and at milk production levels proportionately 0·30 higher or lower than those attained at equilibrium intake. Overall efficiencies varied from 0·60 to 0·63 and were not systematically affected by diet metabolizability.

It is concluded that, in practical cattle production systems with ad libitum feeding, the net energy content of food may be estimated at 0·6 of the metabolizable energy content (or 0·5 of the digestible energy content), irrespective of diet type, diet metabolizability or productive function.

Two experiments were conducted to determine whether female to female influences could reduce the duration of the post-partum anoestrous period in beef cows. In experiment 1, cows were housed from calving, either in individual stalls, which precluded physical contact with other cows (treatment I; no. = 19) or as a group, with a cow in oestrus introduced to the group twice per week (treatment G; no. = 18). The percentage of cows cycling by day 50 post partum was similar for both treatments, but at 91 days post partum was significantly higher (P <0·05) in the G than in the I cows (89% v. 58%).

In experiment 2, cows were housed in individual stalls from calving and exposed twice per week to either cervical mucus collected from cows in oestrus (treatment M; no. = 21) or distilled water (treatment W; no. = 24). The percentage of cows cycling by 70 days post partum was similar in both treatments but by 130 days there were significantly more (P <0·05) M cows cycling (86% v. 58%). In neither experiment were LH profiles at 22,43 or 64 days influenced by treatment.

The results indicate that cervical mucus of cows in oestrus contains pheromone(s) which can reduce the postpartum anoestrous period in beef cows with extended anoestrous periods.

The aim of this experiment was to determine whether there is any physiological basis for concerns that selection for fleece mass may decrease fitness by increasing the partitioning of nutrients to wool at the expense of other body functions.

Forty-five Merino rams (24 months old) were given food at an ad libitum and a maintenance level of nutrition. Animals were grouped into high, average or low clean fleece growth-rate categories on the basis of measurements made during the ad libitum feeding period. During ad libitum feeding, high producers grew proportionately 0·42 more clean fleece, and deposited proportionately 0·36 more energy and 0·42 more nitrogen (N) as greasy fleece than average producers. This was achieved by partitioning a higher proportion of N consumed to wool (0·08 v. 0·06), and not by increased energy or N retention. High producers adapted to the maintenance diet by decreasing clean wool growth rate proportionately by 0·32. There were no differences between high and average wool producers in clean wool growth rate or the percentage of N or energy intake partitioned to wool at the maintenance level of feeding. Although there were no differences in initial live mass between groups, low producers gained proportionately 0·45 more live mass during the experiment than average producers.

It was concluded that Merino rams of high clean-wool production potential are not more efficient, but partition more of the available nutrients to wool production at the cost of body tissue deposition.

Fleece weight and shedding score, a measure of premature fleece loss, were examined at first shearing and in older female sheep of three hilt breeds and their reciprocal crosses. Starting from a non-inbred base, the sheep were mated, mostly by younger-parent × offspring, for four generations, to produce inbreeding coefficients from 0·25 to 0·59. Crosses of inbred lines were also produced within breed type. The experimental design allowed the effects of inbreeding of the individual to be separated from the effects of maternal inbreeding.

Inbreeding of the individual significantly and linearly reduced fleece weight. This effect was still apparent after adjustment for body weight. Maternal inbreeding significantly reduced only the weight of first fleeces, but the trends were similar at the later ages, especially among the purebreds. There was no significant interaction of purebred/crossbred status with level of inbreeding. Inbreeding did not significantly affect shedding score. The pure breeds and the crosses did not differ, on average, in fleece weights or shedding scores, but within the purebred and within the crossbred classes breed variation was significant. Fleece weight declined and the incidence of shedding increased with increasing age. The larger the number of lambs born in the year of shearing the lower the fleece weight and the greater the extent of fleece shedding.

The effects of inbreeding could not be fully explained, statistically, in terms of dominance alone. Therefore, it seems probable that epistasis also plays a role in producing the observed changes with inbreeding in these traits.

Breeding schemes for ivool sheep based on natural service (N), MOET (multiple ovulation and embryo transfer) in adults (A) and MOET in juveniles (J) are compared using Monte Carlo simulation allowing overlapping generations and selection across age groups. In all schemes parents can be a maximum of 6 years old when their offspring are born, and can be a minimum of 2 years in N or A schemes or 1 year in f schemes. Embryo transfer success rates follow realistic distributions (only 70% of flushes resulting in live lambs) with a mean of 2·13 or 345 6-month-old lambs per donor per flush for current or ‘future’ situations. Under natural mating an average of 1·09 6-month-old lambs per ewe mated is assumed. The trait under selection has a heritability of 0·4 and is measurable on both sexes by 18 months of age, which is before selection in N and A schemes but after the initial opportunity for selection in f schemes where selection is based on a pedigree index. Two culling policies for males are considered in J schemes: all sires culled if not selected (J), or all sires available for selection after their record is collected even if they were not selected on their pedigree index in the previous year (f o ). Comparison of schemes is made on the basis of response depressed by the effect of inbreeding and cumulated and discounted over a medium time horizon. For a given population size (constant expected number of lambs per year and therefore numbers of dams dependent on fertility rates) different numbers of sires were utilized. The optimum number of sires was determined as the number which maximized the response criterion. N, A, J and J° schemes have different optimum numbers of sires (5, 8,30 and 20 respectively) which occur at different rates of inbreeding and which are approximately independent of population size. Advantages in the response criterion of A, J and J° over N schemes are 23%, 33% and 47% respectively for ‘future’ embryo transfer success rates and mass selection. Increasing the number of lambs born per donor ewe from 2·13 to 13·8 (by increasing embryos per flush and number of flushes) increases the response criterion by up to 25% in A and up to 11% in J schemes (assuming donor ewes are mated to a different sire for each flush) with 345 lambs born per year. Use of best linear unbiased prediction (BLUP) estimated breeding values increases response by 8%, 3% and 3% in N, A and J schemes respectively. The advantages off over A and N schemes, of increased lambs per donor and of BLUP over mass selection all increase as population size increases. Insemination of the poorer ewes with semen which gave only female offspring gave 5% increase in the N scheme and no benefit in A or f schemes.

Benefits of collection of annual versus a single fleece record are investigated for breeding programmes of Australian Merino sheep. Breeding scheme alternatives are based on natural mating (N) or multiple ovulation and embryo transfer (MOET). The breeding objective is assumed to be an adult fleece trait which is expressed annually from a minimum of age 2 years, with a unity genetic correlation between annual records. Initial selection of parents can occur prior to the availability of their adult records, based on records collected at 6,12 or 18 months which have a maximum genetic correlation of 0·8 with the adult trait. Monte Carlo simulation is used to compare breeding programme alternatives, which allows overlapping generations and selection across age groups. MOET schemes select parents of minimum age 19 months in adult (A) schemes, 7 months in juvenile (J) schemes or 13 months when there are two breeding seasons per year. Natural mating results in an average of 1·09 lambs per ewe mated, whilst embryo transfer success rates follow realistic distributions (only 70% of donors giving live lambs) with an average of 3·45 lambs per donor flushed. Estimated breeding values, on which selection is based, are calculated by multiple trait selection index of an individual's own records or by multivariate best linear unbiased prediction (BLUP). In J schemes 7-month-old lambs may be selected on the basis of a pedigree index if no individual record has been collected at 6 months of age. Breeding scheme alternatives are compared on the basis of genetic response, rate of inbreeding and economic ‘income’ which is calculated as genetic response reduced for inbreeding depression, cumulated and discounted over a medium time horizon (14 years). The quantitative benefits of the collection of annual records are dependent on the choice of genetic and phenotypic parameters between traits, but these were chosen from the literature to be representative of annual fleece weight records in Merino sheep. Genetic response to selection and ‘income’ associated with the adult trait is increased by at least 15% in N, A and J schemes compared with when only a single record is collected at 18 months. The advantage of MOET over N schemes and the optimum number of sires to use is unchanged, but the average age of sires is increased. Both annual rate of inbreeding and average age of dams are unchanged. In N schemes, 80% of the benefits of collecting annual records on both sexes can be achieved by collecting records on males alone, whilst in MOET schemes measurement of dams contributes up to 50% of the benefit of the measurement of both sexes. Since MOET schemes have fewer dams to be recorded, the cost-effectiveness of collecting records on females is much higher than in natural mating schemes. Breeding programmes operating two mating seasons each year are found to be a viable alternative to J schemes: although genetic response is less, rate of inbreeding is also less, so that ‘income’ response is approximately equal.

The aim of this work was to investigatethe effect of stockingrate (0·6 m2 per pig or ≥1·2 m2 per pig) and faeces plus urine deposition on skatole concentration (boar taint)in subcutaneousfat. The study utilized pens with concrete flooring and different environmental temperatures.

The experimental material consisted of 144 cross bred male and female pigs in each of two experiments. One experiment was carried out in the summer (temperature ≥ 22°C) and one in the winter (temperature approx. 17°C in the pig house). In both experiments, stocking rate and faeces deposition were kept constant up to first delivery to the abattoir. Then stocking rate and faeces deposition were changed to the opposite treatment a week before the last three of the four deliveries to the abattoir.

The experiment confirmed the hypothesis that the pigs which lay in their faeces plusurine in pens with the high stocking rate for at least a week had a higher skatole level in subcutaneous fat than pigs kept clean in pens with the low stocking rate. It was feasible within a week before slaughter to increase or lower the skatole level by changing the treatment of the pigs.

Male and female pigs showed similar differences. Air temperature (season) had a significant influence on skatole level. The level was significantly higher in subcutaneous fat at hight emperatures in the summer experiment compared to the winter experiment despite the fact that the pigs with high stocking rate in the winte rexperiment were as heavily fouled with faeces and urine as those in the summer experiment.

Skatole concentrations in faeces of individual pigs were not influenced by different temperatures or treatments, and there was no significant correlation between the skatole level in faeces and in subcutaneous fat.

High skatole levels in subcutaneous fat seemed to have a genetic component.

It is hypothesized that skatole from faeces plusurine (excreta) especially at temperatures of 30° Cor more may pass through the skin of the pig and/or that skatole in a gaseous form may be absorbed through the lungs.

An experiment was made to examine the effects of food intake and an orally active progestagen on plasma steroid concentrations and subsequent reproductive performance of multiparous sows. Thirty-five multiparous Landrace × Large White sows were assigned to one of four treatments immediately after parturition. Treatment H-AT sows were offered a high level of food intake throughout lactation: 3·5 kg of a diet containing 160 g/kg dry matter (DM) of crude protein and 13 MJ digestible energy per kg DM given twice daily. Treatment H+AT sows were offered the same food intake as H-AT sows and in addition they were given 20 mglday of allyl trenbolone (AT) mixed with the morning feed. Treatment L-AT sows were given 1·5 kg of the same diet offered twice daily during lactation and treatment L+AT sows were also offered this lower level of food intake and given AT. The respective levels of food intake were offered to sows from the 1st day of lactation onwards until weaning at 21 days post partum. Litter weights at weaning were influenced significantly by feeding level (P < 0·001) and also by AT administration (P <0·05). Sows on the high level of feeding had the heaviest litters and food-restricted sows had the lightest litters. AT treatment depressed litter weight at weaning. There was no effect of food level or AT on the plasma concentrations of progesterone or oestrogens during lactation. There was a highly significant (P <0·001) difference in mean plasma oestrogen concentration between high (H-AT and H+AT) and low (L-AT and L+AT) fed groups during early pregnancy in the subsequent cycle. Sows given a combination of high energy in lactation and AT (H+AT) exhibited shorter intervals from weaning to oestrus than both groups of food-restricted (L-AT and L+AT) sows fP <0·01) but treatment had no significant effect on either the farrowing rate or on the subsequent litter size. It is concluded that despite significant changes in the live weight and condition of sows and changes in steroid hormone concentrations due to food intake and the administration of allyl trenbolone, there were no significant effects on reproductive performance.

Measurements were carried out on 200 selected carcasses in order to investigate whether single or multiple site measurements could provide an accurate estimation of the lean meat proportion in the carcass and the major cuts i.e. ham, shoulder, loin and belly. Fat measurements were taken with the Hennessy Grading Probe II at 17 sites on the left side of the carcass, and muscle measurements at four of these sites. The day after selection 200 left sides were dissected according to the simplified European Community (EC) reference method.

Fifty of these left sides were further dissected according to the full EC reference method. The use of multiple site measurements, compared with a single site measurement, only slightly reduced the residual s.d. of the estimated lean meat proportion in the carcass and the major cuts, e.g. addition of a second site measurement reduced the residual s.d. values by 0·3 to 1·3 gjkg only. The measurement between the 13th and 14th thoracic vertebrae, 7 cm off the dorsal mid line, appeared to be the best single estimator, of the sites probed, for lean meat proportion in the carcass and in the major cuts. Prediction of lean meat proportion in the belly appeared to be problematic (residual s.d.> 29 g/kg).

During the experiment two problems emerged. Firstly, the algorithm, which calculates fat and muscle thickness from the optically measured tissue profile, was not appropriate for every site. Secondly, the definition of the probing position did not always coincide with the anatomical position of the intended superficial layer of muscle underneath the subcutaneous fat.

Two randomized-block experiments were carried out with growing pigs housed in groups of 10 from about 36 to 92 kg live weight and offered non-pelleted diets from single-space feeders containing separate food and water dispensers both operated by the pigs. The dispensing rate of food could be adjusted and rates of 1·4, 2·7 and 5·3 g per press of the nose plate were compared in experiment 1 and 4·8, 6·9 and 9·3 g per press compared in experiment 2. As dispensing rate increased in experiment 1 there were significant increases in food intake, growth rate and backfat thickness and a significant improvement in food conversion ratio on a carcass gain basis. There was no effect on the variation in growth rate between pigs within pens nor were there treatment effects in experiment 2 on any of the above measurements. The amount of food accumulating in troughs increased with feeder setting in both experiments.

Behaviour at feeders was observed in each pen for 24 h during the 5th week using time-lapse video recording. The number of visits to feeders was not significantly affected in either experiment but time spent feeding was significantly increased at the lowest setting in experiment 1. Both the number of withdrawals from feeders accompanied by aggressive encounters and the number of pigs queuing decreased up to the dispensing rate of 6·9 g per press. There were tendencies for all parameters of behaviour to continue changing up to the highest dispensing rate.

Two similar style experiments were carried out in a climate-controlled pig house to determine the effects of adverse climatic conditions and relocating and mixing on the health status and productivity of pigs. In both experiments, 120 pigs were used. The climate-controlled pig house consisted of two fully separated but identical rooms (experimental and control) with five pens each (12 pigs per pen). Pigs exposed to draught and low environmental temperature had lower daily gain (experiment 1: 45 g/day; experiment 2: 25 g/day) and higher food conversion (food: gain ratio) than pigs housed under optimal climatic conditions (control). Moreover, clinical disease signs (i.e. diarrhoea, coughing, sneezing and haemorrhagic ear lesions) were more pronounced in the experimental than in the control group. In experiment 1, pigs were relocated and mixed at 10 weeks of age either within or between the experimental and control room. Data showed clear negative effects on daily gain and clinical disease signs especially among pigs that were relocated to suboptimal climatic conditions. In experiment 2, pigs were either relocated and mixed between both rooms or they remained in their own pens. Data on daily gain and clinical disease signs revealed that the health of the pigs was strongly affected by mixing. Therefore, the present work emphasizes the importance of climatic environment and social factors in intensive pig production.

An experiment was carried out in Egypt using Giza White rabbits to investigate their lactational performance and to estimate the repeatabilities of milk yield and other litter traits. Data on 325 litters from 115 does fathered by 40 sires were used. Lactation traits involved milk yields during the first 7 days, 21 days and 35 days. Litter traits included litter size and weight at birth, number born alive, litter weight and gain at 21 days, litter size and weight at weaning and pre-weaning litter gain. Linear mixed models were used for analysing such data.

Phenotypic variation in milk yield was relatively high during the first 7 days, and decreased thereafter with advance of lactation stage. Year-season effects were significant for most litter traits, while month of kindling affected litter weight and gain at 21 days and milk yield during the first 7 days (P < 0·05 or P < 0·001). Litters kindled during winter had the highest milk yield compared with litters kindled in the other seasons. Milk production, litter size and weight and litter gain had curvilinear relationship with parity (P < 0·05 or P < 0·001). Sire of doe had no significant effects on litter traits studied. Repeatabilities of all traits were low and ranged from 0·001 to 0·134. Litter size and weight at birth were residually correlated with milk yield. Litter weight and gain at 21 days were significantly correlated with the lactational performance of the doe (P < 0·001).

Twenty-eight Suffolk-cross male castrated lambs aged 7 to 8 months, initial live weight 36 (s.e. 149) kg were given four diets which contained unground pelleted molassed sugar-beet pulp and rolled barley (940 g/kg, fresh weight basis) in the following proportions either A, 0·8 to 0·2 or B, 0·5 to 0·5, with 60 g soya-bean meal per kg. Diets A and B were offered with or without a yeast culture product Yea-Sacc. Diets zvere offered twice daily to appetite with 100 g hay per head. Yeast culture had no effect on any measurement made (P > 0·05). Lambs given diet B consumed more dry matter (DM), grew faster and had superior food conversion efficiencies (all P < 0·01). Rumen fluid taken 3 h after feeding contained higher concentrations of ammonia (F < 0·01), total volatile fatty acids (F < 0·001) and acetic acid (F < 0·001) in samples from lambs given diet A. Rumen fluid samples collected before the 10·00 h meal, produced more gas from diet A than diet B after 6 and 24 h in vitro incubation (F < 0·001) suggesting the presence of more undigested food. When ground diets were incubated, more gas was produced from diet A after 6h (F < 0·05) but not after 24 h fP > 0·05). It is suggested that diet B supported faster growth of the lambs as a result of faster rate of digestion, higher DM intake and superior food conversion.

A two-treatment experiment was made involving 340 crossbred pigs penned in groups of 20 and offered a cereal-based, non-pelleted diet ad libitum from one single-space hopper per pen supplying both food and water. Half the feeders were fitted with stalls which protected the feeding pig from its pen mates. The average number of visits per day to the feeder was reduced from 20·1 to 11·9 (s.e. 1·58, P<0·01) by fitting the stall and the average duration of each visit was increased from 2·06 min to 4·18 min (s.e. 0·298, P < 0·02). The total time of occupation and its circadian pattern were similar for both treatments There were reductions in the incidence of enforced withdrawals (12·7 v. 3·4 (s.e. 0·75), P < 0·001) and of pigs queuing (28·6 v. 84 (s.e. 2·35), P < 0·001) with the addition of a stall which also reduced the occurrence of tail biting. Although the stall improved pig welfare the anticipated reduction in food spillage was not evident.