In Experiment 1, 24 early-weaned, male lambs were given ad libitum a diet based on either rolled or whole barley, both pelleted through a 7·4 mm die. Growth rates were 360 and 409 g/day, food conversion ratios 2·80 and 2·56 kg dry matter/kg gain, and organic-matter digestibilities 77·8 and 80·4% for the two diets respectively. In Experiment 2, 12 early-weaned, female lambs were given a diet based on either whole barley pelleted through a 7·4 mm die or unprocessed barley. When the diets were given in restricted quantities those containing unprocessed barley were slightly but significantly higher in digestibility. The feeding of unprocessed barley increased the firmness of subcutaneous fat and the contents of the rumen at slaughter, but decreased liver weight.

In Experiment 3,36 early-weaned, female lambs were given ad libitum diets based on either pelleted rolled barley, pelleted whole barley or unprocessed barley. Growth rates were 260, 270 and 264 g/day; food conversion ratios were 3·20, 3·20 and 3·00 kg dry matter/kg gain organic-matter digestibilities were 80·8, 79·3 and 81·0%, rumen pH values were 5·2, 5·2 and 6·1, and liver weights 728, 788 and 673 g, for the three diets respectively. As in Experiment 2, the subcutaneous fat on the cold carcass was firmer and more acceptable to the butcher when whole barley was given.

Management strategies are needed to optimise the number of piglets weaned from hyper-prolific sows. Nurse sow strategies involve transferring supernumerary new-born piglets onto a sow whose own piglets are either weaned or fostered onto another sow. Such ‘nurse sows’ have extended lactations spent in farrowing crates, which could have negative implications for their welfare. This study used 47 sows, 20 of which farrowed large litters and had their biggest piglets fostered onto nurse sows which were either 1 week (2STEP7, n=9) or 3 weeks into lactation (1STEP21, n=10). Sows from which piglets were removed (R) were either left with the remainder of the litter intact (I) (remain intact (RI) sows, n=10), or had their litters equalised (E) for birth weight using piglets of the same age from non-experimental sows (remain equalised (RE) sows, n=9). Piglets from 2STEP7 were fostered onto another nurse sow which was 3 weeks into lactation (2STEP21, n=9). Back-fat thickness was measured at entry to the farrowing house, at fostering (nurse sows only) and weaning. Sows were scored for ease of locomotion and skin and claw lesions at entry to the farrowing house and weaning. Salivary cortisol samples were collected and tear staining was scored at 0900 h weekly from entry until weaning. Saliva samples were also taken at fostering. Data were analysed using GLMs with appropriate random and repeated factors, or non-parametric tests were applied where appropriate. Back-fat thickness decreased between entry and weaning for all sows (F1,42=26.59, P<0.001) and tended to differ between treatments (F4,16=2.91; P=0.06). At weaning RI sows had lower limb lesion scores than 2STEP7 and RE sows (χ24=10.8, P<0.05). No treatment effects were detected on salivary cortisol concentrations (P>0.05) and all nurse sows had a higher salivary cortisol concentration at fostering, compared with the other days (F10,426=3.47; P<0.05). Acute effects of fostering differed between nurse sow treatments (F2,113=3.45, P<0.05); 2STEP7 sows had a higher salivary cortisol concentration than 1STEP21 and 2STEP21 sows on the day of fostering. 2STEP7 sows had a higher salivary cortisol concentration at fostering, compared with 1STEP21 and 2STEP21 sows. Tear staining scores were not influenced by treatment (P>0.05). In conclusion, no difference was detected between nurse sows and non-nurse sows in body condition or severity of lesions. Although some nurse sows experienced stress at fostering, no long-term effect of the nurse sow strategies was detected on stress levels compared with sows that raised their own litter.

The Iberian pig is one of the pig breeds that has the highest meat quality. Traditionally, producers have bred one of the available varieties, exclusively, and have not used crosses between them, which has contrasted sharply with other populations of commercial pigs for which crossbreeding has been a standard procedure. The objective of this study was to perform an experiment under full diallel design among three contemporary commercial varieties of Iberian pig and estimate the additive genetic variation and the crossbreeding effects (direct, maternal and heterosis) for prolificacy. The data set comprised 18 193 records for total number born and number born alive from 3800 sows of three varieties of the Iberian breed (Retinto, Torbiscal and Entrepelado) and their reciprocal crosses (Retinto × Torbiscal, Torbiscal × Retinto, Retinto × Entrepelado, Entrepelado × Retinto, Torbiscal × Entrepelado and Entrepelado × Torbiscal), and a pedigree of 4609 individuals. The analysis was based on a multiple population repeatability model, and we developed a model comparison test that indicated the presence of direct line, maternal and heterosis effects. The results indicated the superiorities of the direct line effect of the Retinto and the maternal effect of the Entrepelado populations. All of the potential crosses produced significant heterosis, and additive genetic variation was higher in the Entrepelado than it was in the other two populations. The recommended cross for the highest yield in prolificacy is a Retinto father and an Entrepelado mother to generate a hybrid commercial sow.

The objective of this study was to evaluate the effects of malic acid (MA) supplementation on rumen fermentation, urinary excretion of purine derivatives (PDs) and whole gastro-intestinal tract feed digestibility in steers. Eight ruminally cannulated Simmental steers (465 ± 13 kg) were used in a replicated 4 × 4 Latin square design. The treatments were: control (without MA), LMA (MA-low), MMA (MA-medium) and HMA (MA-high) with 0.0, 7.8, 15.6 and 23.4 g MA per kg dry matter (DM), respectively. Diets consisted of corn stover and concentrate (60/40, DM basis). DM intake was approximately 9 kg per day, which was 90% of ad libitum intake including 5.4 kg corn stover and 3.6 kg concentrate. Ruminal pH (range of 6.91 to 6.56), ratio of acetate to propionate (range of 3.88 to 3.25), ammonia N (range of 9.03 to 6.42 mg/100 ml) and lactate (range of 91.25 to 76.31 mg/100 ml) decreased linearly as MA supplementation increased, whereas total volatile fatty acid (VFA) concentration (range of 55.68 to 61.49 mM) linearly (P < 0.05) increased with increase in MA supplementation. In situ ruminal neutral detergent fiber (aNDF) degradation of corn stover was improved but the crude protein (CP) degradability of concentrate mix was decreased with increasing the dose of MA. Urinary excretion of PDs was quadratically (P < 0.01) changed with altering MA supplementation (67.88, 72.74, 75.81 and 73.78 mmol/day for control, LMA, MMA and HMA, respectively). Similarly, digestibilities of DM, organic matter (OM), NDF and acid detergent fiber (ADF) in the total tract were also quadratically increased with increasing MA, and no differences in terms of CP and ether extract digestibility were observed. The results indicate that MA supplementation has the potential to improve rumen fermentation and feed digestion in beef cattle. The MA stimulates the digestive microorganisms or enzymes in a quadratic response. In the experimental conditions of this trial, the optimum MA dose was 15.6 g MA per kg DM.

Nutritional strategies to mitigate the negative effects of heat stress on animal welfare and productivity often involve changes in ration formulation. However, cattle commonly sort their ration in favour of certain components, and it is not clear how feed sorting responds to heat stress. This study investigated the association between heat stress and feed sorting behaviour. Lactating Holstein dairy cows (n = 32; parity = 2.8±1.2; mean±SD) were housed in a free stall barn and milked 3×/day. Cows were fed individually using the Calan Broadbent Feeding System and offered ad libitum access to a total mixed ration (containing on a dry matter basis: 3.3% ryegrass hay, 16.5% ryegrass baleage, 24.7% corn silage, 11.1% brewers grains, 19.7% ground corn, 19.8% concentrate and 4.9% protein/mineral supplement), provided 1×/day. Beginning at 186±60 days in milk, cows were exposed to either: heat stress conditions (HT; n = 15) (average temperature–humidity index: 77.6), or evaporative cooling (CL; n = 17), consisting of misters and fans over the freestall and feed bunks. Data were collected during a 4-day baseline period, and two 4-day experimental periods: starting at 10 days after implementing treatments (defined as acute heat stress for HT cows), and at 62 days after implementing treatments (defined as chronic heat stress for HT cows). Daily feed intake and physiological responses to heat stress (body temperature, respiration rate) were recorded. Samples of fresh and refused feed were collected daily from individual cows for particle size analysis. The particle size separator had three screens (19, 8 and 1.18 mm) and a bottom pan, resulting in 4 fractions (long, medium, short and fine particles). Feed sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. During both heat stress periods, HT cows sorted for long particles more than CL cows (105.0% v. 100.6%; SE = 1.1). During acute heat stress, HT cows sorted to a greater extent than CL cows against medium and short particles, whereas sorting of these fractions did not differ during chronic heat stress. Body temperature and respiration rate were associated across treatments with the extent of sorting for long particles and against short particles during acute heat stress. These results suggest that feed sorting is particularly influenced during acute heat stress, and that sorting for longer particles may increase in heat stress.

Little is known about the relationship between feed intake behaviour and cholesterol levels in humans. This can be attributed to the fact that feed intake behaviour in humans is difficult to assess. The relationships between feed intake, feed efficiency and feed intake behaviour, and cholesterol and triglyceride levels were investigated at an average age of 187 days, in a pig model consisting of 202 Duroc barrows. Feed intake and feed intake behaviour were recorded individually and daily by means of an electronic identification system. Animals with high levels of total cholesterol also had high levels of high-density lipoprotein (HDL), low-density lipoprotein (LDL) cholesterol and triglycerides. Animals with high levels of HDL also had high levels of LDL and triglycerides, and animals with high levels of LDL also had high levels of triglycerides. Animals with higher BW, higher backfat thickness, higher BW gain, higher gain of backfat deposition, higher feed intake, higher residual feed intake (RFI) and higher feed intake rate had higher levels of total, HDL and LDL plasma cholesterol. Results indicate that the relationship between feed intake and cholesterol levels is a long-term relationship, while the relationship between RFI and cholesterol levels is more of a short-term nature. The relationship between intake rate and cholesterol plasma levels disappeared after correction for the amount of feed consumed. Results indicate that feed intake independent of metabolic BW, growth and fatness, i.e. ‘RFI’, was positively correlated with cholesterol plasma levels. This suggests that eating food over and above the maintenance and growth requirements constitutes a health risk independent of the level of fatness.

Cubicle characteristics such as cubicle dimensions or management factors such as cow-to-cubicle ratio could affect health and behaviour of dairy cows. The objective of this study was to estimate effects of cubicle characteristics on animal welfare indicators in dairy cattle. A total of 64 loose housing farms in Germany were assessed once during the winter housing period by one experienced assessor. Nearly 15% of the dairy cows had access to pasture during summer months for <6 h/day, whereas 85% were zero-grazing farms. Selected animal welfare indicators (duration of the lying down process, collisions of cows with cubicles, cows lying outside cubicles, cow cleanliness, integument alterations, lameness and subclinical mastitis incidence) of the Welfare Quality® protocol and cubicle characteristics such as cow-to-cubicle ratio and cubicle dimensions were recorded. Data were statistically analysed using a multiple linear regression approach. Pasture access and cubicle type were considered as potential influencing factors. Wider cubicles positively affected the proportion of dairy cows with dirty flanks (−18.5% per 10 cm increase) but increased the number of cows with severe integument alterations (+8.9% per 10 cm increase). Larger lying areas reduced the percentage of cows with dirty udders (−2.9% per 10 cm2 increase). Longer distances from neck rail to curb were associated with higher prevalence of cows with dirty flanks (+3.1% per 10 cm increase) and subclinical mastitis incidence (+1.2% per 10 cm increase). With increasing neck rail height, the duration of the lying down process (−0.1 s per 10% increase), the percentages of cows with dirty legs (−8.4% per 10 cm increase), dirty udders (−7.0% per 10 cm increase) and severe lameness (−3.0% per 10 cm increase) decreased. Compared with rubber mat-equipped cubicles, deep-bedded cubicles showed a reduction in the lying down duration (−0.8 s), percentages of cows with dirty legs (−34.2%), dirty udders (−30.5%) and lesions and swellings (−13.1%). Compared with farms that did not provide any summer grazing, pasture access was associated with an increase of cows with severe lameness (+5.6%). Contrastingly, the number of cows with subclinical mastitis incidence was lower when cows had access to pasture in summer (−5.4%). Findings of the present study indicate several associations between cubicle characteristics and animal welfare in dairy cattle. Bedding type was found as the most influencing factor in terms of health and behaviour. Results of this study are valuable for farmers to identify the optimal cubicle design and improve the animal welfare level.

The accumulative effects of different levels of annual energy intake over the first two parities on four breeds of beef cow (small size and low milk potential, Aberdeen Angus; small size and high milk potential, Welsh Black; large size and low milk potential, Charolais; and large size and high milk potential, Simmental) were assessed for various production traits and calf performance. Heifers were allocated to each of two levels of annual energy intake relative to metabolic body weight (M0·75) (mean daily intakes equivalent to 705 and 820 kj M0·75) and for the next 2 years these animals (10 per breed) were continuously housed and given diets designed to represent energy intakes while grazing during the summer and conserved forage feeding during the winter. Changes in live weight and body composition were measured throughout both years and milk yield, milk composition and calf performance during both lactations.

Animals from each of the four breeds gained weight but lost body condition during their first two parities in a manner that was dependent on their annual level of dietary energy intake. Welsh Black cows grew more than Aberdeen Angus cows and Charolais cows more than Simmental cows so that, by weaning during the second parity, the rank order of live weights between breeds was Charolais > Simmental > Welsh Black > Aberdeen Angus. Welsh Black and Simmental cows produced higher yields of milk (7·9 and 8·7 kg respectively) than Aberdeen Angus and Charolais cows (6·5 and 5·7 kg respectively; P < 0·001). Calves from the two large breeds grew more quickly than those from the two small breeds (1·13 v. 0·99 kg/day; P < 0·01) and calf performance was influenced by milk consumption. Biological efficiency, defined as weight of calf at weaning per GJ metabolizable energy (ME) on an annual basis, increased as annual energy intake decreased and tended to be higher for large breeds on 33 GJ ME per year than for small breeds on the same level of annual energy intake (7·19 v. 6·75). The complex means by which the different breed types interacted with their nutritional environment is discussed.

In an experiment on the occurrence of lactational oestrus, 92 multiparous Camborough sows and their litters were grouped in multi-accommodation pens at either 10, 15, 20 or 25 days post partum. The sows were fed ad libitum on a proprietary diet containing 160g crude protein per kg. A boar was introduced to the group the day following grouping. Weaning took place at 42 days post partum.

All sows except one showed oestrus in the period from grouping to weaning. Lactational oestrus occurred on average 10·9, 9·2, 12·2 and 7·3 (s.e. of difference 1·3) days after grouping (P < 0·05), and 21·0, 24·6, 32·2 and 32·8 (s.e. of difference 1·4) days following farrowing (P < 0·001) for the grouping treatments at 10, 15, 20 and 25 days. Subsequent farrowing rates were 48, 61, 78 and 45% and the number of pigs born 9·2, 9·5, 12·2 and 10·6 (s.e. of difference 1·3), respectively.

Piglet mortality in the suckling litters was higher on the day 10 treatment than either the day 20 or day 25 treatment. This led to a significantly lower litter weight for the day 10 treatment compared with any of the other treatments.

Cattle breeds of African, European and Indian origins are being evaluated at Rockhampton for their suitability for beef production in northern Australia. In the current study, Belmont Adaptaur (HS), Belmont Red (AX) and Belmont BX (BX) dams were mated to produce straightbreds and crossbred progeny by Brahman (B), Boran (Bo) and Tuli (Tu) sires. B dams were mated to produce straightbreds and crossbred progeny by AX, BX, Bo, Charolais (Ch), HS and Tu sires. This paper reports values for heterosis for some crosses and live weights on pasture for some straightbred and crossbred genotypes at birth, at weaning and at 18 months.

Heterosis for birth weights was greatest for taurine dam breed × indicine sire breed, generally negative for the reciprocal cross and markedly less for Tu-sired than for B- or Bo-sired progeny. Heterosis was not estimated for Bo and Tu crosses at weaning or at 18 months. At these ages, heterosis for growth includes a component related to resistance to environmental stresses. Thus, heterosis was then greater for B crossbreds derived from the less resistant HS than from the more resistant AX.

There were significant differences between genotypes in live weights at each age. Progeny by B sires from taurine dams had higher live weights than progeny by Bo or Tu sires. Evidence is presented that strongly indicates that the difference in growth rates between the B- and Bo-sired progeny arose entirely from differences in mature live weights of the B and Bo, not from differences in efficiency of growth of their crossbred progeny. Similarly, live weights of progeny by taurine sires from B dams ranked according to the mature live weights of the sire breeds. Thus, the Ch- and Tu-sired progeny had the highest and lowest live weights at all ages respectively. Comparative growth potentials of the indicine sire breeds were estimated by comparing 18-month live weights of progeny from HS dams. Relative to Bo = 100, growth potential of B = 205. Similarly, growth potentials of the taurine sire breeds were estimated from progeny from B dams. Relative to Tu = 100, the estimates were HS = 104, AX = 111 and Ch = 117. Crossbred progeny by B and Bo sires were generally significantly heavier at all ages than the corresponding straightbreds. However, Tu-sired progeny had similar birth weights too, but generally higher weaning and 18-month live weights than, the corresponding straightbreds. Relatively low birth weight and low heterosis for birth weight identify the Tu as a potentially useful sire breed when an increase in birth weight of crossbreds is undesirable.

Within each dam breed, no straightbred could match the growth rate of the best crossbred. At 18 months this advantage was proportionately 0·21, 0·09, 0·05 and 0·16 over that of the straightbred HS, AX, BX and B respectively. Live weight of every crossbred based on B dams exceeded that of the straightbred B, the most populous breed in northern Australia. Thus, increases in growth rates could be achieved by crossbreeding irrespective of the base breed. Live weights at 18 month for progeny of Bo, Tu and AX sires from B dams, all of which exceeded those of the straightbred B, suggest that the African breeds can be used to complement the B in crossbreeding programmes in northern Australia.

A statistical analysis strategy for the detection of quantitative trait loci (QTLs) in half-sib populations is outlined. The initial exploratory analysis is a multiple regression of the trait score on a subset of markers to allow a rapid identification of possible chromosomal regions of interest. This is followed by multiple marker interval mapping with regression methods within and across families fitting one or two QTLs. Empirical thresholds are determined by experiment-wise permutation tests for different significance levels and empirical confidence intervals for the QTLs' positions are obtained by bootstrapping methods. For traits with evidence for a significant single-QTL effect, an approximate maximum likelihood analysis is performed to obtain estimates of QTL effect and the probability of the QTL genotype for each parent of a group of half-sibs. The strategy is demonstrated in an analysis of previously published data on chromosome 6 and five production traits from a granddaughter design in dairy cattle. The results confirm and extend evidence for QTLs affecting protein percentage. Informativeness of markers limited the possibility of mapping more than one QTL on the same linkage group.

1. The rates of eating silages and hay throughout a meal were recorded in eight cows consecutively using a special manger and an automatic recording apparatus. At each meal the rate of eating was highest in the first five or ten minutes and then fell gradually. These characteristics were observed both on silages and on hay and for all the experimental cows. The mean rates of eating hay, but not of silages, agreed with previous reports.

2. The highest rate of eating was slightly faster at the evening meal than at the morning meal, when cows received equal amounts of feeds twice each day. The rate of eating declined at much the same rate throughout each meal when the cows received from 2 to 5 meals daily.

3. When the cows were fed twice daily, the rate of eating throughout a meal was not affected by changing the interval between meals from 12 hr to 6 hr.

4. When cows were given large amounts of feed at any one time, three stages of rate of eating, fast, decreasing and slow, were recognized.

5. The quality of feed, individuality of cow and pregnancy evidently affected the rate of eating throughout a meal.

Experimental comparisons of the nutritional value of different wheat cultivars commonly use feeds in meal form even though the large-scale broiler producers use steam pelleted feeds. The aim of this experiment was to examine the effect of steam pelleting on the performance, dietary N-corrected apparent metabolisable energy (AMEn), total tract dry matter retention (DMR), nitrogen retention (NR) and fat digestibility (FD) coefficients, and digestive tract development of broilers fed four different wheat samples in complete diets. Four European wheat samples, with different chemical composition and endosperm characteristics, were used in a broiler experiment. The wheat samples were milled through a 5 mm screen and four basal feeds containing 670 g/kg of each selected wheat sample were mixed. The basal feeds were then split into two batches and one of them was steam pelleted resulting in eight experimental diets. Each diet was fed ad libitum to eight pens of two male Ross 308 broilers from 10 to 24 days of age. Feeding pelleted diets improved (P<0.001) feed intake and weight gain, and daily water intake of the birds. Pelleting also improved dietary AMEn and FD (P<0.001) and DMR (P<0.05). An interaction (P<0.05) was observed between wheat samples and steam pelleting for NR. Steam pelleting improved (P<0.05) NR in the wheat sample with high starch and protein and hard endosperm but not in the rest of the wheat samples. Similar interactions (P<0.05) were also observed between wheat sample and steam pelleting for gain to feed (G : F) and water to feed (W : F) ratios. Pelleting improved G : F ratio the greatest in the wheat sample with high starch and protein and hard endosperm. Feeding the same wheat sample also decreased (P<0.05) W : F but only in the mash diets. Regardless of the wheat sample the values of dietary AMEn did not differ (P>0.05). Feeding different wheat types and pelleting did not (P>0.05) change the development of the gastrointestinal tract of the birds. The study showed that there were differences between four wheat samples when they were fed in pelleted complete feed, but no differences were observed when fed in mash form complete diets. Research on the interaction between pelleting and wheat chemical and quality characteristics is warranted.

While feed efficiency (FE) is a trait of great economic importance to the pig industry, the influence of the intestinal microbiome in determining FE is not well understood. The objective of this experiment was to determine the relative influence of FE and farm of birth on the pig colonic microbiome. Animals divergent in residual feed intake (RFI) were sourced from two geographically distinct locations (farms A + B) in Ireland. The 8 most efficient (low RFI (LRFI)) and 8 least efficient (high RFI, (HRFI)) pigs from farm A and 12 LRFI and 12 HRFI pigs from farm B were sacrificed. Colonic digesta was collected for microbial analysis using 16S ribosomal RNA gene sequencing and also for volatile fatty acid analysis. The α-diversity differed between the farms in this study, with pigs from farm A having greater diversity based on Shannon and InvSimpson measures compared to pigs from farm B (P < 0.05), with no difference identified in either Chao1 or observed measures of diversity (P > 0.05). In the analysis of β-diversity, pigs clustered based on farm of birth rather than RFI. Variation in the management of piglets, weight of the piglets, season of the year, sanitary status and dam dietary influence could potentially be causative factors in this large variation between farms. However, despite significant variation in the microbial profile between farms, consistent taxonomic differences were identified between RFI groups. Within the phylum Bacteroidetes, the LRFI pigs had increased abundance of BS11 (P < 0.05) and a tendency toward increased Bacteroidaceae (P < 0.10) relative to the HRFI group. At genus level, the LRFI pigs had increased abundance of Colinsella (P < 0.05), a tendency toward increased Bacteroides and CF231 (P < 0.10). At species level, Ruminococcus flavefaciens had increased abundance in the LRFI compared to the HRFI animals. In conclusion, while farm of birth has a substantial influence on microbial diversity in the pig colon, a microbial signature indicative of FE status was apparent.

Four groups each of eight Limousin × Friesian bulls, average weight 344 kg, were offered individually ad libitum diets comprising: 920 g rolled barley, 50 g cane molasses, 15 g urea and 15 g minerals/vitamins mix per kg or 867·5 g rolled barley, 50 g cane molasses, 7·5 g urea, 60 g soya-bean meal and 15 g minerals/vitamins mix per kg, plus or minus yeast culture (YC, 1·5 kg/t) (all weights fresh weights), until slaughter (460 kg). Rumen samples were obtained by stomach tube. YC decreased rumen ammonia concentrations (116·7, 56·0, 74·3, 45·7 (s.e.d. 19·40) mg/l for barley/urea, barky/urea/YC, barley/soya-bean meal and barley/soya-bean meal/YC, respectively). This was associated with increases (P < 0·05) in both the total number of bacteria (2·3, 4·2, 3·5, 6·8 (s.e.d. 1·06) × 109 per ml, respectively) and the protein content of rumen fluid (7·7, 9·6, 8·7, 9·0 (s.e.d. 0·59) g/l, respectively). However, the flow of microbial protein from the rumen as estimated from the appearance ofpurine derivatives in the urine was unaffected (131, 130, 129, 147 (s.e.d. 12·6) g N per day, respectively). Thus although the animals responded to the undegradable rumen protein supplied by the soya-bean meal there was no significant response in live-weight gain with YC (1·28, 1·31, 1·42, 1·48 (s.e.d. 0·081) kg/day, respectively).

The effects of melatonin, administered during anoestrus, on the time of onset of oestrus and on conception rate were investigated in two trials carried out on mature ewes of three indigenous and one imported breed. The ewes lambed between December and February, their lambs were weaned in March and they were hand milked twice daily until September.

In the first trial, 12 Chios and 12 Serres ewes were dosed, orally, for 60 days from 19 April with 3 mg melatonin (M) in 10 ml ethanol and water (1: 4 v/v). A similar number of Chios and Serres type ewes in the same flock were nominated as untreated controls (C). Vasectomized rams were used to detect oestrus from 1 May and detected ewes were immediately mated to entire rams of their own breed. The mean dates of first oestrus in Chios ewes were 4 July (s.e. 1·7 days) and 23 July (s.e. 5·4 days) (P < 0·01) for treated and control ewes respectively. Spread of first oestrus was 19 and 61 days, respectively (P < 0·01). Conception rate and ovulation rate were both higher in M (0·90 and 2·3, respectively) than in C (0·55 and 1·8, respectively) but the differences were not statistically significant. The corresponding results in the Serres ewes were 8 July (s.e. 1·6 days) and 31 July (s.e. 6·8 days) (P < 0·01) for date of first oestrus, 19 and 69 days (P < 0·01) for spread of first oestrus, 0·75 and 0·50 (P > 0·05) for conception rate and 1·8 and 1·2 ( P > 0·05) for ovulation rate.

In the second trial, 12 Karagouniko and 12 East Friesland ewes received a single subcutaneous implant of melatonin (Regulin®) on 5 June and a further 12 ewes of each breed were untreated controls. The procedure was as given for trial 1. The mean date of first oestrus was advanced by melatonin in both Karagouniko ewes (25 July (s.e. 3·91 days) v. 11 August (s.e. 6·7 days); P < 0·05) and Friesland ewes (28 July (s.e. 3·2 days) v. 24 August (s.e. 7·3 days); P < 0·01). Spread of oestrus was reduced (43 v. 68 days in Karagouniko, P < 0·05 and 22 v. 87 days in Friesland ewes, P < 0·01). Conception rate of melatonin-treated ewes was higher (0·60 v. 0·45; P > 0·05) in both breeds. Ovulation rate was higher in melatonin-treated Karagouniko ewes (1·8 v. 1·3; P > 0·05 but, in the Friesland breed melatonin-treated ewes had a lower ovulation rate (2·8 v. 3·7; P > 0·05).

In both trials, melatonin treatment significantly advanced and condensed the dates of first oestrus. Conception rate was consistently increased over all groups (P < 0·05) and there was a tendency towards a higher ovulation rate.

The eating quality of lambs slaughtered at weaning or 8 to 9 weeks later off pastures of diploid grass (D), tetraploid grass (T) and tetraploid grass/white clover (TC) was studied. Samples of lean from grilled chops and roasted leg joints were assessed by members of a group of 36 sensory panellists for texture by rating juiciness and tenderness on an eight-point scale. Lamb and abnormal flavour were assessed in lean and fat samples. Lean from lambs slaughtered off the mother at weaning was significantly more tender than from lambs slaughtered 8 to 9 weeks later (5·8v. 5·0, s.e.d. 0·18; P < 0·001). There was a tendency for lambs slaughtered off TC to be more juicy and tender. Lean from chops was significantly more juicy and tender and of superior flavour to lean from leg and overall acceptability was higher for chops. Acceptability of lamb slaughtered at weaning was higher than of lamb slaughtered 8 to 9 weeks later (5·3v. 4·9, s.e.d. 0·14; P < 0·001).

In further studies a trained sensory panel of 12 judges formed a consensus flavour profile for 10 attributes of lean and five attributes of fat. Univariate analysis revealed only small differences between treatments. Multivariate statistical procedures however identified significant treatment effects that appeared favourable to the flavour of lamb slaughtered off the mother although only around a third of the variation was explained.

Analysis of weight loss on cooking showed less wastage when lambs were slaughtered off the mother (0·209 v. 0·225, s.e.d. 0·0043; P < 0·001) and when grazed on grass/clover (TC)v.grass (D, T) (0·206v. 0·222, 0·223; s.e.d. 0·0053;P < 0·01). Weight loss on cooking was negatively correlated with texture and overall acceptability.

The results obtained provide evidence for enhanced eating quality from production systems involving the sale of lambs off the mother. Incorporation of grazing of clover pastures into production systems showed some small benefits.

Thirty various pelleted diets were given to broilers (8/diet) for in vivo measurements of dietary metabolisable energy (ME) value and digestibilities of proteins, lipids, starch and sugars from day 27 to day 31, with ad libitum feeding and total collection of excreta. Water excretion was also measured. Amino acid formulation of diets was done on the basis of ratios to crude proteins. Mean in vivo apparent ME values corrected to zero nitrogen retention (AMEn) were always lower than the AMEn values calculated for adult cockerels using predicting equations from literature based on the chemical analyses of diets. The difference between mean in vivo AMEn values and these calculated AMEn values increased linearly with increasing amount of wheat in diets (P = 0.0001). Mean digestibilities of proteins, lipids and starch were negatively related to wheat introduction (P = 0.0001). The correlations between mean in vivo AMEn values and diet analytical parameters were the highest with fibre-related parameters, such as water-insoluble cell-walls (WICW) (r = −0.91) or Real Applied Viscosity (RAV) (r = −0.77). Thirteen multiple regression equations relating mean in vivo AMEn values to dietary analytical data were calculated, with R2 values ranging from 0.859 to 0.966 (P = 0.0001). The highest R2 values were obtained when the RAV parameter was included in independent variables. The direct regression equations obtained with available components (proteins, lipids, starch, sucrose and oligosaccharides) and the indirect regression equations obtained with WICW and ash parameters showed similar R2 values. Direct or indirect theoretical equations predicting AMEn values were established using the overall mean in vivo digestibility values. The principle of indirect equations was based on the assumption that WICW and ashes act as diluters. Addition of RAV or wheat content in variables improved the accuracy of theoretical equations. Efficiencies of theoretical equations for predicting AMEn values were almost the same as those of multiple regression equations. Water excretion was expressed either as the water content of excreta (EWC), the ratio of water excretion to feed intake (WIR) or the residual value from the regression equation relating water excretion to feed intake (RWE). The best regression predicting EWC was based on sucrose, fermentable sugars (lactose + oligosaccharides) and chloride variables, with positive coefficients. The best equations predicting WIR or RWE contained the sugar and chloride variables, with positive coefficients. Other variables appearing in these equations were AMEn or starch with negative coefficients, WICW, ‘cell-wall-retained water’, RAV or potassium with positive coefficients.

1. In each of two 2 × 3 factorially designed experiments 72 pigs were individually- and scale-fed diets containing 86·5% of maize, wheat or barley in ground or micronized, flaked and ground (micronized) forms.

2. In both experiments, the first between 17 and 20 kg and the second between 22 and 90 kg live weight, pigs offered the micronized maize and barley diets grew significantly faster and converted the dry matter of their diets significantly more efficiently than did pigs offered the ground maize and barley diets. There were no significant differences between the micronized and ground wheat diets in the first experiment but in the second experiment the micronized diet gave significantly inferior results.

3. In pigs slaughtered at 90 kg live weight those fed all the micronizedbased diets had significantly higher killing-out percentages than those fed the diets based on the ground cereals. Other within-cereal significant differences were those of increased carcass length in pigs given micronized maize and increased fat deposition in pigs given micronized wheat.

This study investigated the response of different dietary protein and limiting amino acid concentrations coupled with a supplement of chromium in growing-finishing pigs. Sixty Landrace × Yorkshire × Duroc bacon type pigs with an initial live weight of 33·08 (s.d. 4·80) kg were randomly assigned into six groups with an equal number of males and females. They were given diets containing proportionately 1·0, 1·1 or 1·2 of the National Research Council recommendation of crude protein and limiting amino acid (lysine and methionine) levels and coupled with supplementing chromium at 0 or 200 ng/kg in the form of chromium picolinate (Crpic). The experiment was completed when the pigs' live weight reached 120 kg. Experiment results indicated that different nutrient levels or Crpic supplement did not significantly affect pig growth (P > 0·05). However, both nutrient levels and Crpic supplementation increased y-globulin concentration (P < 0·05). In addition, Crpic supplement not only significantly reduced the backfat thickness, serum insulin level and VLDL-C + LDL-C concentration (P < 0·05) but also increased the loin-eye area and HDL-C concentration of pigs (P < 0·05). On the other hand, the particle sizes of HDL and VLDL were decreased and increased (P < 0·05), respectively. In addition, Crpic supplement increased the activities of adipose tissue lipogenesis related enzymes such as fatty acid synthetase, ATP-citrate cleavage enzyme and NADP-malic dehydrogenase (P < 0·05 to 0·001). In a similar manner, Crpic supplement increased the activities of adipose tissue lipoprotein lipase and serum lecithin-cholesterol acyltransferase (P < 0·05). However, the interactions of nutrient levels × Crpic supplementation were insignificant (P > 0·05). Results in this study demonstrated that chromium picolinate supplement created a beneficial effect but supplements of chromium coupled with high dietary protein and limiting amino acid levels were unnecessary for bacon-type pigs.