The carry-over effect of a pre-starter diet (0 to 3 days of age) deficient in lysine on subsequent growth and body composition (3 to 10 days) was examined in two experiments on male broiler chicks raised in cages. In experiment 1, lysine deficiency was applied from 3 to 10 days after providing a balanced pre-starter control feed (D+, 1.40% lysine) or a lysine deficient feed (D−) during the first 3 days. Three levels of deficiency (A = 0.63%, B = 0.72%, C = 0.82%) were tested. Growth and feed intake were higher in D+ than in D− chicks ( P < 0.001). However, the feed conversion ratio from 3 to 10 days of age was higher in D+ chicks ( P < 0.001); pre-starter and starter feeds interacted ( P < 0.04) with the feed conversion of treatment D+/A = 2.07 being better than treatment D+/A = 2.61 ( P < 0.05). This suggests that chicks deficient from hatching exhibit a relatively lower sensitivity to lysine deficiency than chicks started on a control diet. In experiment 2, performance, slaughter parameters and body composition were analysed at 3 and 10 days of age, in chicks having received a lysine deficient feed (D0, 0.72% lysine), a control feed (D+, 1.40% lysine) or having been pair fed with control feed adjusted to D0 intake (PF) from 0 to 3 days of age, and then fed D0 ad libitum from 3 to 10 days of age. At 3 days, PF chicks had a higher body weight ( P < 0.05) than D0, and thus a better feed conversion. Body composition in relative values was little or not affected by dietary treatments, but the breast muscle weight at 3 days was higher in D+ and PF chicks compared with D0 ( P < 0.05) and this effect was even accentuated at 10 days of age. The present work confirms that early nutrition can have subsequent consequences on the adjustment of fast growing broiler chicks to their nutritional conditions. It also suggests that breast muscle development is a more reactive parameter than whole body composition in this kind of experiments.

Breeding entire males is an alternative to surgical castration to improve their welfare. However, entire males may have a major quality defect called boar taint. Boar taint is partly due to the presence of androstenone in fat. In this study, we estimated the genetic parameters between androstenone and production traits to evaluate the consequences of selection against boar taint for traits of interest. We focused on growth traits, meat quality, lesions, hormone levels and computerised tomography measurements in purebred Piétrain (P) or Piétrain cross Large White (X) entire males. The number of measured animals varied from 670 P and 734 X for hormones concentrations to 553 P and 645 X for computerised tomography measurements. Skin lesions were measured on live pigs shortly after mixing, at the end of the fattening period, and on carcasses. Heritabilities of traits measured by tomography ranged from low to high: femur density (P: 0.34, X: 0.69), loin eye area (P: 0.53, X: 0.88) and loin eye density (P: 0.12, X: 0.18). The mean number of lesions at each stage was lower in purebred pigs than in crossbreds (entering the fattening stage 4.01 in P and 4.68 in X; before slaughter 3.72 in P and 4.22 in X; on carcass 4.50 in P and 4.96 in X). We also observed a decrease in the average number of lesions between the two stages in live pigs. We found high genetic correlations between stages in purebred pigs (0.74 to 0.76) but low correlations (−0.30 to 0.29) in crossbred pigs. Selection aiming to decrease fat androstenone is feasible (h2 = 0.57 in P and h2 = 0.71 in X). It would have overall positive effects on meat production and quality traits. Selection aiming to reduce plasma oestradiol would strongly reduce the level of fat androstenone (rg = 0.89 in P and rg = 0.84 in X). Selection against oestradiol is easier and less invasive since it would only require a blood sample rather than a fat biopsy in live animals.

Channel catfish raised in the southern United States require two growing seasons to reach market size. Growing seasons are separated by a cool period of about 3 months when feed intake and growth are greatly reduced. A cool-weather feeding strategy to improve feed intake, growth or health of catfish might improve survival and reduce the time needed to achieve market size. We conducted a feeding trial with channel catfish at a suboptimal temperature (15°C) to determine the effects of supplementing diets with either a dairy/yeast prebiotic or flaxseed oil (high in 18:3n-3) compared with a control with soybean oil (high in 18:2n-6). The trial was conducted in recirculating systems with 1140-l tanks containing 100 fish each (mean initial weight 61.4 g±0.43 s.e.m.). A 28%-protein basal diet was supplemented with 20 g/kg cellulose and 20 g/kg soybean oil (SBO, control), 20 g/kg cellulose and 20 g/kg flaxseed oil (FLAX) or 20 g/kg of a dairy/yeast prebiotic and 20 g/kg soybean oil (PREB). Fish were fed once daily to satiation and weighed every 3 weeks to track growth. Hematology, non-specific immune responses, proximate and fatty acid composition of muscle were determined to assess diet effects. Catfish-fed FLAX or PREB had higher weight gain, feed consumption and lysozyme activity than fish fed SBO. Total n-3 fatty acids in muscle were higher in fish fed SBO or FLAX than those fed PREB. Total n-6 long-chain polyunsaturated acids were higher in muscle of fish fed PREB than those fed SBO. Fatty acids in the PREB and SBO diets were similar, so the PREB appeared to increase elongation and desaturation of n-6 fatty acids in muscle. Flaxseed oil and the dairy/yeast prebiotic both have potential to increase catfish performance at a low temperature.

The effect of feeding different sources of dietary fibre at varying rates of inclusion on the concentrations of skatole and indole in the backfat of finishing pigs and their subsequent carcass quality was studied. Sugar-beet pulp (SBP) and straw (S) were selected because of their assumed widely differing hind-gut fermentability characteristics. They were individually and in combination added to a diet at three rates of inclusion designed to provide concentrations of 40, 80 and 120 g non-starch polysaccharide (NSP) per kg. The digestible energy (DE) contents varied between the three levels of inclusion of NSP but were formulated to a lysine: energy ratio of 0.625 g: MJ DE with other amino acids being in the same individual proportion to lysine. The nine experimental diets were offered to 10 replicate (five entire males and five females) pigs of initial live weight 55 kg. Food intakes were adjusted between treatment to ensure that energy and nutrient intakes were common. Animals were slaughtered on reaching 85 kg live weight. Adipose tissue was analysed for skatole and indole and meat quality characteristics assessed. No significant differences in performance were detected although carcasses from animals given sugar-beet pulp were significantly fatter. There were significant correlations between the level of skatole in the backfat and the following eating quality characteristics: skatole odour intensity of the fat, abnormal odour intensity of fat, abnormal odour intensity of lean and abnormal flavour intensity of lean with correlations coefficients of 0·656 , 0·709 , 0·496 and 0·523 respectively (coefficients >0.276; P < 0·05). The range in skatole levels in the backfat were attributable substantially to very high levels found in three boars. No significant correlations were found between indole concentrations in the backfat and eating quality characteristics. However no effects of dietary NSP type or inclusion level on the eating quality characteristics of pig meat, with pigs given diets on the basis of equal energy and nutrient intakes, were detected.

An evaluation of the effects of the proportion of Texel or Rouge de l’Ouest (Rouge) genes in ewes (0, 0·5 or 1·0; the remainder being Greyface (Border Leicester × Scottish Blackface)) on prolificacy, lamb viability and lamb output was undertaken. A comparison of Texel and Rouge sires was carried out on Greyface, Texel and Rouge ewes. Prolificacy was higher in Greyface compared with Texel ewes (P = 0·06) but was lower in Greyface compared with Rouge ewes (P < 0·001). Prolificacy was similar in Greyface and Texel × Greyface ewes mated to Texel rams and in Greyface and Rouge × Greyface ewes mated to Rouge rams. The level of dystocia was similar in Greyface and Texel × Greyface ewes but significantly higher in Texel ewes (P < 0·001). The proportion of Rouge genes in the ewe had no effect on the level of dystocia. Litter weight of lambs at birth was significantly heavier in Greyface (P < 0·001) and Texel × Greyface (P < 0·01) ewes compared with Texel ewes. The proportion of Rouge genes in the ewe had no significant effect on litter weight. Lamb mortality (no. of lambs born dead and died birth to weaning) was significantly greater with Rouge ewes compared with the other ewe breed types (P < 0·001). The number of lambs which died from birth to weaning was lower with Texel × Greyface compared with Greyface ewes (P < 0·01). Expressed on a unit metabolic weight basis, Greyface ewes produced a significantly greater weight of lamb compared with Texel (P < 0·05) and Rouge ewes (P < 0·001). Texel × Greyface ewes produced a significantly greater weight of Texel-sired lamb compared with Greyface (P < 0·01) and Texel ewes (P < 0·001).

Sire had a significant effect on a number of parameters. The number of productive ewes was significantly lower in ewes mated with Texel sires (P < 0·001). Lamb birth weights and pre-weaning growth rates were greater with Rouge sires (P < 0·05). Number of lambs weaned per ewe lambed was significantly greater with Texel sires (P < 0·01). Overall weight of weaned lamb produced per ewe was not significantly affected by sire breed.

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3β-hydroxysteroid dehydrogenase (3β-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3β-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3β-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3β-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3β-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3β-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3β-HSD expression is under the control of sex hormones.

Weaning increased forage intake and depressed live weight; differences in intakes and growth rates of lambs born to South Australian and Fine wool Merinos were small. At 21 days, sucking lambs received less than 2% of their digestible organic matter from pasture and half the lambs weaned at this age died but the survivors consumed twice as much forage as unweaned sheep in the 14 days following weaning. At 49 days, unweaned lambs obtained approximately 41% of their digestible organic matter from pasture, and weaning resulted in less mortality and a proportionally smaller increase in forage consumption.

The production of pork with high amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the pig industry and consumers. Herein, we question the impact of dietary protein reduction (18% v. 13%) on fat deposition in the subcutaneous adipose tissue (SAT) and longissimus lumborum (LL) muscle using genetically diverse pigs for body fatness (lean v. fat). A clear effect of genotype was observed on plasma insulin (P=0.004) and leptin (P<0.001), as well as on backfat thickness (P<0.001), with the fat pigs having higher values. Accordingly, IMF was higher in the fat pigs, when compared with their lean counterparts (P=0.003), which was supported by enlarged adipocytes (P<0.001). The area of lipid droplets within the LL fibres (P=0.039) and extramyocellular lipids number (P=0.017) were increased in pigs fed reduced protein diets, regardless of genotype, which is consistent with higher levels of plasma triacylglycerols (P=0.002). The gene-expression pattern of lipogenic factors in the SAT was distinct from the LL muscle. In the SAT, PPARG expression was similar among genotypes (P>0.05), whereas in the LL muscle it was higher in the lean pigs (P=0.023), especially when fed on low protein diet (P=0.057). The CEBPA and FABP4 mRNA levels were increased in the SAT of fat pigs (P<0.001), without changes in the LL muscle (P>0.05). The influence of diet on FABP4 expression in the SAT was dependent on pig’s genetic background (P=0.005). In conclusion, fat deposition was clearly influenced by genotype and, to a lesser extent, by dietary protein level, the SAT being more sensitive than the LL muscle. One can speculate that the pathways involved in lipid metabolism are downregulated in intramuscular adipocytes when compared with SAT fat cells. This result might be a direct consequence of the relatively low proportion of adipocytes found in the LL muscle.

Thirty-two male pigs were used to investigate the effects of nine levels of dietary lysine ranging from 0·41 to 1·30 g lysine per MJ gross energy (GE) on the performance of pigs weaned at 1 to 2 days of age and growing between 2 and 7 kg live weight. The nine dietary lysine treatments, which contained similar levels of GE and balance of essential amino acids, were offered to the pigs at a common feeding level of 2·0 MJ GE per kg metabolic live weight (M075) per day. Growth performance and protein deposition rates increased linearly with increasing dietary lysine content up to about 0·97 g lysine per MJ GE and remained relatively constant thereafter. The response of protein deposition (PD, g/day) in the whole body of pigs to dietary lysine (L, g lysine per MJ GE) was described by three models. The respective regression equation for the quadratic function was PD = -14·23 + 87·66 L – 36·00 L2 and maximum protein deposition occurred at 1·22 g lysine per MJ GE. The rectilinear model, which had an ascending linear phase (PD = 1·49 + 40·10 L, R2 = 0·98, P < 0·001) and a horizontal component representing a mean protein deposition rate of 39·7g/day revealed that maximum protein deposition occurred at 0·95g lysine per MJ GE. Finally, application of the asymptotic model also revealed a highly significant equation: PD = 43·40 — 79·99 × 0·07111, R2 = 0·94, P < 0·001; which indicates a dietary requirement of 1·07 g lysine per MJ GE assuming that the dietary requirement was estimated at 0·90 of the asymptote maximal value. The results indicate that the dietary lysine requirement for pigs during the first 3 weeks of life appears to have changed little over the past 20 years despite substantial changes in genotype.

1. Young adult and adult British Friesian female cattle (heifers and cows) which were lactating were individually fed ad libitum on ryegrass silage of high (HS) or low (LS) digestibility with one of two levels of a supplement of pellets of dried grass (H or L) in a 2 × 2 factorial experiment with three heifer and seven cow replicates.

2. The percentages of digestible organic matters in the dry matter (DM) in vitro were respectively 64·4, 57·5 and 69·0 for forages HS, LS and and the dried grass. The HS crop, however, was significantly lower in DM content, and after ensiling with formic acid additive had a higher lactic and total acid content than the LS crop.

3. The dry-matter intake of the less acid silage LS was greater than that of HS (P<0·05) although the dry-matter digestibility of the LS diets was on average 6 units lower than the HS diets. The intakes of digestible dry matter (DDM) and digestible organic matter were greater (P<0·05) in mid lactation when HS was fed. DM and DDM intakes were significantly increased by the higher level of feeding of the dried grass supplement.

4. The yield, composition and energy content of milk did not differ between silages but the yield and protein content of the milk increased significantly at the higher level of supplement feeding. The milk yields were respectively 19·35, 17·54, 19·49 and 17·97 ± 0·505 kg/head per day for treatments HSH, HSL, LSH and LSL on these all-grass diets over lactation weeks 4 to 20. Live-weight loss was greater (P<0·01) on the LS diets. Blood composition was normal and did not differ markedly between treatments.

When testing facilities are limited and the number of breeds and/or crosses to be tested is potentially large, then multibreed designs which involve a large number of breeds with only a few animals per breed give the optimum allocation of animals within and between breeds for various objectives. Multibreed designs could therefore form a useful adjunct to existing breed testing and selection programmes. How far such designs should be introduced would depend, among other things, on the degree of confidence in existing information, on the success of existing testing schemes, and on the relevance of the selection criteria currently being used. In this, the first of a series of papers on multibreed designs, the general approach is outlined, and designs for measuring between-breed variation are considered.

To estimate the extent of between-breed variation, the best overall design is to have four unrelated animals per breed and as large a number of breeds as possible. Valuable experimental work on breed variation can therefore be done without vast facilities.

A feeding system, draught cows, disease/work interactions and animal power introduction in a farming system, four areas of recent research on draught ruminants which are important to future development of animal power, are reviewed. A new feeding system for draught animals is described which enables food requirements and the effects of work on live weight and milk production to be calculated.

Recent data on the energy cost of walking are appraised. Research on working cows, mainly in Ethiopia, has shown that undernutrition has a greater effect on milk yield than work, which has a transient effect. The length of the post-partum anoestrous period increases with decrease in body condition. Body-weight loss increases with increasing work load. It is suggested that dairy cows delay conception by 1 day for every day of work done. Work has little effect on food intake or digestive parameters. Although it is associated with an overall increase in food intake of cows, even of un-supplemented forage diets, the increase is not sufficient to meet all the extra energy needs for work. Food intake of both working and non-working cows increases during lactation.

Disease limits the working capacity of draught animals and work can exacerbate disease. These effects were investigated using Trypanosoma evansi in Indonesia and T. congolense in The Gambia. In both studies, infected animals were able to do much less work than non-infected ones and the severity of the effect depended greatly on the strain of trypanosome used. In general, increasing the plane of nutrition did not ameliorate the effects of the disease, nor in the Gambian study did it prevent loss of appetite in infected animals.

The technical and agronomic innovations necessary for the introduction of animal power into an inland valley region of central Nigeria are described and some of the sociological implications discussed.

The development of sexual activity, sperm production, semen characteristics, testis growth and body size was studies in 10 male sheep (ram lambs) of the Romanov breed and 11 of the Finnish Landrace breed between the ages of 4 and 15 months.

The sexual responses, observed daily for 40 days from the age of 4 months, developed earlier and more intensively in the Romanov than in the Finnish ram lambs, being fully developed in the former breed after 4 days as compared with 14 days in the latter breed. All lambs of both breeds, however, were considered capable of impregnating females by 5 months of age.

In both breeds there was a considerable delay between the onset of sexual maturity and the time at which it became possible to collect semen by means of an artificial vagina. Successful collection was not achieved until the age of 11 months, there being no difference between breeds in this respect.

Subsequent semen production increased to the 14th month of age, with little difference between breeds. Respectively for Romanov and Finnish rams at this age (±s.e.), the mean ejaculate volume was 0·85 + 0·062 and 0·77±0·052ml; motility 64·6 ± 1·62 and 59·7±l·66%; sperm concentration 4·75±0·198 and 4·7 ± 0·197 ×1012perl; number of sperm per ejaculate 4 09±0·338 and 3·63 ±0·259 × 109; and fructose concentration 6·84 × 0·2606 and 4·87 ± 0·2707g/1. In the 15th month there was a tendency for these values to decline except in the case of sperm concentration and, hence, total sperm number.

Mean live weight and size increased until the 14th month and there was no difference between breeds, but testis length and diameter were greater in the Romanov rams at this age.

The influence of body weight (BW) at slaughter and genotype on adipocyte size and number in the omental (OM), perirenal (PR), subcutaneous (SC) and intermuscular (IM) adipose tissues was studied in 168 bulls of Spain's local Asturiana, Avileña, Morucha, Parda Alpina, Pirenaica, Retinta, and Rubia Gallega cattle breeds. The young bulls were slaughtered at two BWs, 320 and 540 kg. The results obtained showed the higher amounts of lipids that accumulated between 320 and 540 kg BW (P < 0.001) to be ascribable primarily to adipose cell hypertrophy, i.e. larger adipocyte size, in the OM and PR depots (P < 0.001). In addition to hypertrophy, there was also an increase (P < 0.001) in the number of adipose cells, i.e. hyperplasia, in the SC and IM adipose depots. Significant differences were observed when comparing the different genotypes, with the Morucha, Retinta and Avileña breeds having the highest amount of adipose tissue and the largest adipocytes. The Asturiana and Rubia Gallega breeds had the lowest amount of adipose tissue and the smallest adipocytes. The Pirenaica and Parda Alpina breeds had intermediate values in between the two groups identified above. In short, the results were indicative of different lipid deposition patterns in the different breeds depending on the individual growth and maturation rates in each. Similar findings were made when comparing the different adipose tissue depots, with adipocyte hypertrophy being the main factor responsible for lipid accumulation in the OM and PR depots, as opposed to adipocyte hyperplasia in the SC and IM depots.

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.

One hundred and eight New Zealand × Californian growing rabbits (nine per diet) were used to determine the nutritive value (digestible energy (DE), digestible protein (DCP) and digestible acid-detergent fibre (DADF)) of five protein concentrates. In assay 1, the effect of the type of basal diet (BD) (7·6 or 10·0 MJ DE per kg dry matter (DM) for BD1 and BD2 respectively) and the substitution level (150, 300 and 450 g/kg) on nutritive value of soya-bean meal was studied. According to the results of assay 1, one basal diet (BD2) and one substitution level (300 g/kg for sunflower 380, gluten meal and extruded soya-bean meal or 500 g/kg for sunflower 320) were selected in assay 2 to determine their nutritive value.

The effect of the basal diet and the substitution level on the nutritive value of soya-bean meal was evident only for the values calculated from BD1 and the lowest level of inclusion. The data obtained by difference at the highest level of inclusion and by extrapolating the linear equations were very similar (16·32 v. 16·35 MJ DE and 387·62 v. 388.58 g DCP per kg DM for BD2), but the standard errors were lower (0·52 v. 0·72 for DE and 6.76 v. 8.95 for DCP) in the former. The DE values obtained for sunflower meal 320 and 380, extruded soya-bean and gluten meal were 10·29, 14·37, 18·58 and 20·57 MJ/kg DM respectively; protein digestibilities were high (with coefficients from 0·80 to 0·90) except in the case of sunflower-320 (0·73). A stepwise regression analysis was made to predict the nutritive value from chemical composition including values from literature. For prediction of DE, the variables selected were: crude fibre, ether extract and ash, obtaining a determination coefficient of 0·935. The protein digestibility was independent of variables employed.

The objectives were to demonstrate the potential of heat production measurements to characterize the gross and net efficiencies of dairy cows under commercial conditions and to compare the efficiencies of purebred Holstein and Montbeliarde × Holstein F1 dairy cows. The heat productions of seven Holstein (H) and seven Montbeliarde × Holstein (MH) cows were measured over two 10-day periods separated by a 75-day interval, during the summer of 2004, in a commercial high-yielding dairy herd in Israel. Energy expenditure was measured by monitoring heart rates and oxygen consumption per heart beat. Milk yield and composition were recorded for these cows and their investment of energy in the milk was calculated from the milk yield and composition. Live weight and body condition score were also recorded in parallel with these measurements. Metabolizable energy (ME) intake was estimated as the sum of heat production, energy in milk and body energy balance. The MH cows were heavier by 90 kg, had higher body condition scores by 0·9 units and secreted proportionately 0·19 and 0·38 less energy in their milk than H cows in the first and second periods, respectively. The gross energy efficiencies, expressed as the percentage of milk production plus body retention in ME intake were 48·3 and 43·4% in the first period and 45·6 and 32·8% in the second period, for H and MH cows, respectively. The milk production of MH cows in this study was lower than the potential of this cross, however, MH cows that expressed this potential would still be expected to require proportionately 0·10 greater intake of ME than H cows, per unit of energy in milk.

Short-term feed preferences were studied in individually caged chickens fed sequentially in order to understand a previously described imbalance in the intake of diets offered. Sequential feeding (SF) was carried out for four 48 h cycles in male broiler chickens. The diets varied in energy (2800 (E−) and 3200 kcal/kg (E+)) and protein (230 (P+) and 150 g/kg (P−)) contents. SF was compared to standard feeding (C) (3000 kcal/kg ME and CP = 190 g/kg). In experiment 1, three treatments were used: C, SE (E− followed by E+) and SE′ (E+ followed by E−). Four treatments were used in experiment 2: C, SP (P+ followed by P−), SE and SEP (P+E− followed by P−E+). Total feed intake was measured during the SF period. After this, short-term preferences were evaluated with a choice test on chickens previously fed with the same feeds during the SF period (experienced birds) and in C chickens (naïve birds). In both experiments, total feed intake was similar among treatments and the percentage of each feed consumed was not significantly different from controls (50%). In experiment 1, SE and SE′ chickens over-consumed E+ and under-consumed E− diets only during the first 15 min of the fourth cycle. The choice test indicated that experienced chickens preferred E+, while naïve chickens preferred E−. Similarly, in experiment 2, chickens over-consumed E+ and E+P− during the first 15 min of the fourth cycle, but the intake of diets varying in protein content was not different from controls. During the choice test, as in experiment 1, experienced chickens preferred E+, while naïve chickens preferred E−. There was a slight preference for the protein-poor diet in naïve birds and there was no preference in the diet varying in both protein and energy contents. Experience modified choice between feeds varying in energy content but not in protein. When feeds were known, preference for energy affected the feed intake immediately after switching from one diet to the other, although lower with the diet also varying in protein, it did not influence the total intake of each diet. Interactions between the nutritional properties and sensorial cues of feed could explain these results.

Two groups of 4 Suffolk rams were each subjected to mating pressures of 90 ejaculates (High) and 45 ejaculates (Low) over a 3-day period during summer and autumn. Every sixth (High) or every third (Low) ejaculate was collected into an artificial vagina and assessed for volume, sperm density, total sperm per ejaculate, motility and percentage of live and abnormal sperm.

There was a general lowering of semen quantity and quality with successive ejaculations. Rate of change of the various measures was greater on the High than on the Low mating pressure. Volume and percentage of live sperm showed a greater decline, and percentage of abnormal sperm a greater increase, during the autumn than during the summer. Density showed a greater decline in summer than in autumn.

The significance of the changes in semen characteristics observed is considered in relation to requirements for high fertility after pro-gestagen treatment.

Increasing rates of obesity and heart disease are compromising quality of life for a growing number of people. There is much research linking adult disease with the growth and development both in utero and during the first year of life. The pig is an ideal model for studying the origins of developmental programming. The objective of this paper was to construct percentile growth curves for the pig for use in biomedical studies. The body weight (BW) of pigs was recorded from birth to 150 days of age and their crown-to-rump length was measured over the neonatal period to enable the ponderal index (PI; kg/m3) to be calculated. Data were normalised and percentile curves were constructed using Cole’s lambda-mu-sigma (LMS) method for BW and PI. The construction of these percentile charts for use in biomedical research will allow a more detailed and precise tracking of growth and development of individual pigs under experimental conditions.