Advancing maturity of forage maize is associated with increases in the proportion of dry matter (DM) and starch, and decreases in the proportions of structural carbohydrates in the ensiled crop. This experiment investigated the effects of three maize silages of 291 (low), 339 (medium) and 393 (high) g DM per kg fresh weight on the performance of 48 Simmental X Holstein-Friesian cattle. Equal numbers of steers (mean start weight = 503 (s.d. 31.3) kg) and heifers (mean start weight = 378 (s.d. 11.2) kg) were offered individually isonitrogenous diets composed of the three silages plus a protein supplement with minerals once daily until slaughter at the target live weight of 575 and 475 kg for steers and heifers, respectively. Intake was reduced on the low diet (P < 0.01) compared with the other two treatments. Dietary starch intake increased by a total of 1 kg/day between low and medium diets but by only 0.2 kg/day between medium and high diets. Unlike starch intake, total neutral-detergent fibre intake showed no significant difference (P > 0.05) between diets. There were no differences in live-weight gain between treatments but differences (F < 0.05) in food conversion efficiency indicated relative gains of 115,100 and 102 g gain per kg DM intake for diets low, medium and high, respectively. There were no differences between diets in carcass weights, fat score and overall conformation.

Endogenous flows of nitrogen and amino acids at the terminal ileum of broilers (6 weeks old), layers (70 weeks old) and adult roosters (70 weeks old) were determined using the peptide alimentation method. The ileal endogenous output of nitrogen and total amino acids in broilers, layers and roosters, expressed as mg/kg dry matter intake, were similar (F > 0-05). Endogenous flows were similar (F > 0-05) for nine of the 17 amino acids analysed, but the flows of serine, glutamic acid, proline, alanine, isoleucine, tyrosine, arginine and methionine differed (P < 0-05) among the classes of chickens. The amino acid profile of endogenous protein, expressed asg/100 g crude protein, did not differ (F > 0-05) between the three classes of chickens, except for serine, glutamic acid, proline and isoleucine. The concentrations of proline were higher (F < 0-05) in broilers, compared with the other two groups. The concentrations of glutamic acid in layers were lower (F < 0-05) than the other two groups. The concentrations of serine and isoleucine were higher (F < 0-05) in roosters than the other two groups. In all three groups, the most abundant amino acid in the ileal endogenous protein was glutamic acid, followed by aspartic acid, proline, serine, glycine and threonine. The present study provides estimates for endogenous amino acid flow at the terminal ileum in broilers, layers and adult roosters under normal physiological conditions.

The conformation, tissue composition, and chemical composition of three types of pigs, given food ad libitum and slaughtered over a nominal live weight range of 35 to 115 kg, was assessed in relation to data provided on the live animals by a visual image analysis (VIA) system. The pig types were named as ‘3⁄4 Landrace’, ‘1⁄2 Pietrain’, and ‘1⁄4 Meishan’ types, representing ‘attenuated’, ‘blocky’, and ‘flabby’ types. Three analyses of the shape, conformation and composition data were performed. First, the relationship between conformation and age/size was assessed using linear regression of logarithmically transformed VIA and carcass data. In relation to age, ‘1⁄2 Pietrain’ pigs were found by both VIA and carcass measurements to have the widest shoulders. Both analyses also found this type to have the widest ham, trunk, and shoulders in relation to body length across most of the body length range studied, although the greatest rate of increase in ham width in relation to body length was found in the ‘1/4 Meishan’ type pigs. Second, the relationship between composition and VIA shape was examined using linear regression of transformed and standardized data. Significant relationships were found between fat, lipid, muscle, and protein weight and VIA shape, although relationships were weaker for protein and muscle weight. For fat and lipid, the VIA shape measures from the trunk region proved the most informative, whereas the VIA ham measures proved the most informative for muscle and protein. Third, detrended measures of composition/conformation and shape were used to remove the effect of animal size from the data. Removal of the variation due to growth generally led to substantial decreases in the adjusted R2 statistics and in the R2-like statistics for prediction. Although in the models without detrending, relative fat and lipid weight had been found most strongly correlated with VIA shape, relative muscle was found most strongly correlated with shape in the detrended data. This was considered to result from the low between-animal variation in the data set combined with greater across-weight variation in fat and lipid weights than muscle and protein weights in the data without trend removal. Future trials with greater between-animal variation imposed would allow more precise determination of the relationship between conformation and shape.

Random regression models were used to analyse the daily growth data for a total of 25 pigs of two commercial crossbred types between 75 and 140 days of age. A visual imaging system placed above a feeding station provided daily the plan area and length measurements of different body parts. Daily live-weight measurements of the pigs were obtained from a platform balance integrated into an electronic feeding station. Growth curves associated with different measures, pigs and types were compared. Significant differences in the age growth curves between the pig types could only be found in the ham width measurements (P < 0.05). The linear measure of ham width showed the greatest difference between the two types, and the lowest coefficient of variation among individual animals. Size measures were shown to be a more consistent indicator of pig performance during growth than live weight: pigs with a relatively large surface area or ham width at the early growth stage also have relatively large surface area or ham width at later stages and the between-animal variation in these measurements remains constant with age. Gain in live weight relative to increase in size differed significantly between the two pig types (P < 0.05). Pigs of the two types had significantly different shapes, but the change of shape during growth did not differ significantly between them. The allometric relationships between surface area and ham width1.85 and between body length and ham width0.85 indicate that the ham widths of pigs increase faster in proportion to full body measures. Variations between individual animals in size increase and shape change are significant (P < 0.05). The analysis suggests that VIA size and shape measurements provide valid descriptors of pig growth.

The effects of season in a tropical climate and parity on lactation performance of 106 Large White sows over several reproductive cycles (301 lactations in total) were studied in Guadeloupe (French West Indies, 16°N latitude, 61°W longitude) between January 1999 and March 2003. Two seasons were determined a posteriori from climatic parameters recorded continuously in a station close to the experimental unit. During the warm season, ambient temperature and relative humidity averaged 23-5°C and 0-831, respectively. In the hot season, the corresponding values were 26-0°C and 0-834, respectively. Over the 28-day lactation period, average daily food intake (ADFI) was lower (P < 0-001) and live-weight (LW) loss was higher (P < 0-05) during the hot season than during the warm season (3-9 v. 4-7 kg/day and 17 v. 12 kg, respectively). Growth rate and mean LW of piglets at weaning were lower (P < 0-05) during the hot season (203 v. 220 g/day and 7-0 v. 7-5 kg, respectively). However, the weaning-to-oestrus interval was not affected by season (5-4 days on average). The effect of season on ad libitum ADFI was less accentuated for primiparous than for multiparous sows (warm-hot 360 v. 2002 g/day). Irrespective of the season, ADFI was lower (P < 0-01) and piglet growth rate tended to be lower (P < 0-2) in primiparous than in multiparous sows (4-0 v. 4-4 kg/day and 205 v. 215 g/day, respectively). Moreover, the percentage of sows that returned to oestrus later than 5 days after weaning was higher in primiparous than in multiparous sows (25 v. 2%, P < 0-001). This study confirmed the negative effects of the hot season on performance of lactating sows raised in a humid tropical climate; the effects of season are dependent on parity number.

The aim was to determine whether dietary threonine levels affected hepatic insulin-like growth factor-1 (IGF-1) mRNA expression as well as plasma IGF-1 concentration and IGF binding protein (IGFBP) profile in growing pigs. Two male 6-week-old pigs from each of seven litters were used. Each littermate was assigned to one of two diets, control or low threonine (LT), providing per kg 14·3 MJ digestible energy in both diets, 170 g protein in the control diet and 167 g protein in the LT diet. The control diet contained all essential amino acids in the recommended amounts, including 8·2 g threonine per kg. The LT diet was similar but contained only 5·1 g threonine per kg. Pigs were pair-fed these diets for 3 weeks. Growth rate and food efficiency of pigs given the LT diet were significantly lower than those of pigs given the control diet (P 0·001). Plasma IGF-1 concentration of pigs given the LT diet was proportionately 0·44 lower than that of pigs given the control diet (P 0·01). Plasma free threonine concentration of pigs given the LT diet was lower than that of the pigs given the control diet (P 0·001). Plasma IGFBP2 level of pigs given the LT diet was significantly higher than that of pigs given the control diet (P 0·05). Pigs given the LT diet had a significantly lower plasma IGFBP3 level compared with their littermates given the control diet (P 0·05) suggesting that clearance rate of circulating IGF-1 was higher in the LT group. Dietary threonine level did not affect IGF-1 mRNA abundance in the liver. It is concluded that lower plasma IGF-1 level caused by reduced dietary threonine level may have been partly due to increased clearance rate of circulating IGF-1 but not due to IGF-1 gene expression in the liver.

One performance and one ileal apparent digestibility (IAD) trial were conducted to investigate the performance, nutrient digestibility and intestinal disaccharidase activity of weaner/grower pigs given diets containing Chinese stored brown rice (CSBR) extruded and with exogenous enzyme supplements. In experiment 1, 96 crossbred (Duroc X Landrace X Large White) piglets weaned at 24 days of age were randomly divided into four groups according to a 2 X 2 factorial design. The animals were given four diets: (1) CSBR without enzyme supplementation, (2) CSBR supplemented with 625 mg a-amylase (2509 enzyme activity units) and 200 mg glucoamylase per kg (20018 enzyme activity units) per kg diet, (3) a normal temperature extruded CSBR (NTECSBR) without enzyme supplementation, and (4) NTECSBR supplemented with 625 mg a-amylase (2508 enzyme activity units) and 200 mg glucoamylase (20010 enzyme activity units) per kg diet. Growth, food consumption and specific activity of disaccharides in sections of the digestive tract were measured. In experiment 2, six male grower pigs with a mean initial body weight 21 kg, fitted with a simple ‘T’ cannula at the terminal ileum were used in a 6X6 Latin-square design. In addition to CSBR and NTECSBR diets with and without enzymes, a low temperature extruded diet LTECSBR with and without enzymes (as for other diets) was introduced. IAD of nutrients was measured. Extrusion resulted in a poorer (P < 0.05) food/gain for weaned pigs. Extrusion and enzyme supplementation had no influence (P > 0.05) on average daily food intake and average daily gain. Extrusion tended to improve (P = 0.075) IAD of starch but IAD of energy, dry matter, crude protein and amino acids were not influenced (P > 0.05). Enzyme supplementation had no effect on IAD of amino acids (P > 0.05), except for increasing IAD of lysine, threonine and isoleucine (P < 0.05). Extrusion and enzyme supplementation resulted in a higher (P < 0.05) maltase activity in the duodenum at day 14 of the trial. However, extrusion decreased (P < 0.05) the activity of maltase, isomaltase, sucrase and lactase in the jejunum at day 28. Enzyme supplementation increased (P < 0.05) the activities of maltase, isomaltase, trehalase and lactase in the jejunum at day 28. There was a positive extrusion X enzyme interaction (P < 0.05) for the activity of maltase and trehalase in the duodenum at day 14; a negative interaction was observed for the activity of lactase, maltase, isomaltase and trehalase in the jejunum at day 28. The results suggest that neither extrusion nor enzyme supplementation are necessary for CSBR to be used in pig diets.

The effect of including purified jack bean lectin (concanavalin A) in the diet of grower pigs on endogenous ileal nitrogen (N) and amino acid (AA) losses, and apparent and true ileal AA digestibility was investigated in a study with four growing pigs (average initial live weight (LW) 25 kg) fitted with simple T-cannulae at the terminal ileum. Both the homo-arginine (HA) method and peptide-alimentation method were used to estimate endogenous gut AA losses. The animals were offered four diets :(1) an enzymatically hydrolysed casein (EHC) containing diet, (2) an EHC containing diet supplemented with 266 mg/kg jack bean lectin, (3) a normal casein (NC) containing diet, and (4) a NC containing diet supplemented with 266 mg/kg lectin. For the estimation of ileal endogenous AA flows in pigs given NC diets, a subsample ofNC was guanidinated to convert lysine to HA. The experiment was conducted using a 4X4 Latin-square design. In each experimental period, pigs were adjusted to the experimental diets for 5 days. On day 6, ileal digesta was collected continuously for 24 hfor determination of apparent ileal digestibility. At 08:30 h of day 8 the HA NC diets were offered to pigs on NC treatments and ileal digesta were again collected for 24 h from all pigs. There were no interactive effects of casein type and added dietary lectin on apparent and true ileal AA digestibility and endogenous ileal AA flows (P > 0-05). The addition of lectin to the diet did not influence (P > 0-05) the apparent ileal digestibility of dry matter (DM), crude protein (CP) and AA. Casein type did not affect ileal DM digestibility (P > 0-05). Pigs given the NC-based diets had higher (P < 0-05) apparent ileal AA digestibility than pigs given the EHC-based diets. Addition of lectin to the diet did not influence (P > 0-05) endogenous ileal CP and AA flows. Endogenous ileal AA losses were generally higher (P < 0-05) in pigs given EHC diets than in pigs given NC diets. Neither casein type nor diet lectin level influenced (P > 0-05) the true ileal digestibility ofCP and AA; values ranged for most AA between 0-98 and 1-00. These data suggest that including purified jack bean lectin at the level of 266 mg/kg in a casein-based diet did not influence the ileal endogenous CP and AAflow, nor the apparent and the true ileal digestibility ofCP and AA, in growing pigs between 25 and 50 kg LW. Compared with the HA method, the peptide-alimentation method yielded higher estimates of ileal endogenous CP and AA acid losses in pigs given casein-based diets, although these two methods yielded similar estimates of true ileal AA and CP digestibility.

An experimental administration of dexamethasone was carried out on 15 veal calves in order to assess the rôle of low doses of exogenous glucocorticoids on productive traits and meat quality. Three groups, of five veal calves each, were formed: one group received oral dexamethasone (0·4 mg per calf per day for 25 days), another intramuscular (i. m.) dexamethasone (2 mg at days 14 and 21), and the third was the control. Calves were slaughtered at 165 days of age (day 31). Food conversion ratio (FCR), hot dressing percentage (HDP), chilled dressing percentage (CDP) and shrinkage were determined. From all carcasses, samples of m. longissimus thoracis (between the 8th and 10th rib) were taken in order to evaluate the chemical composition and some organoleptic characteristics: meat colour, waterholding capacity and tenderness. The animals treated with oral dexamethasone showed the lowest daily weight gain (P 0·05) and the poorest FCR (P 0·05). Hot dressing percentage, cold dressing percentage and shrinkage were not affected by the oral treatment. The i. m. injections of dexamethasone did not influence the overall performance. Muscle chemical composition and pH were not affected by the treatments; the meat of calves treated with oral dexamethasone was significantly lighter (P 0·05) and tended to be paler, while i. m. treatment induced intermediate characteristics. The shear force of the meat was rather low. Shear force of cooked meat from animals treated with dexamethasone (both oral and i. m.) was significantly lower than the control (P < 0·05). Treatment with dexamethasone i. m. induced a decrease in water-holding capacity; the oral treatment had no effect on this parameter.

To evaluate the effect of litter size and littermate weight on low-birth-weight (< 1 kg) piglets that have been cross-fostered, piglets' pre-weaning performance in the following groups were compared. Group A (no. = 10), low-birth-weight piglets raised with equal number of heavy-birth-weight piglets in small (eight piglets) litters; group B (no. = 10), low-birth-weight piglets raised with equal number of heavy-birth-weight piglets in large (12 piglets) litters; group C (no. = 10), low-birth-weight piglets raised with equal number of average-birth-weight piglets in small (eight piglets) litters; D (no. = 10), low-birth-weight piglets raised with equal number of average-birth-weight piglets in large (12 piglets) litters; E (no. = 10), small (eight piglets) low-birth-weight litters; F (no. = 10), large (12 piglets) low-birth-weight litters.

Mortality of low-birth-weight piglets in large litters was greater (P < 0.001) with heavy littermates, but in small litters was no different. Weight gain of piglets until day 3 post partum was not significantly (P > 0.05) affected by littermate weight and litter size, or their interaction. Weight at 21 days post partum was significantly affected by littermate weight, litter size, and their interaction. Low-birth-weight piglets in small litters had significantly higher 21-day weights in large litters (P < 0.01, P < 0.05 and P < 0.05 with littermates of low, average and heavy birth weight respectively). In large but not small litters, low-birth-weight piglets missed more nursing episodes and spent more time in teat disputes than their heavier littermates whether in heavy-birth-weight (P < 0.01), or average-birth-weight (P < 0.05) litters.

Littermate weight may affect the performance of low-birth-weight piglets due to direct competition for access to a functional teat.

Oxidative stress may be important in early lactation cows due to high metabolic demands. Modifying dietary starch may alter glucose utilization, modify oxidative metabolism and, consequently, increase oxidative stress. To test this hypothesis, early lactation primiparous cows underwent a short-term dietary starch restriction followed by realimentation. At calving, 10 Friesian primiparous cows were randomly assigned to two groups and given a basal starch diet (BSD, 249 g/kg of starch dry matter (DM)) in the form of a total mixed ration until 42 days in milk (DIM). Afterwards, five cows (CTR) continued to receive the same diet and five cows (EXP) were allotted to experimental diets: low starch diet (LSD, 210 g/kg starch DM) from 43 to 65 DIM followed by high starch diet (HSD, 283 g/kg starch DM) from 66 to 85 DIM and BSD from 86 to 94 DIM. Blood samples were collected at 37, 50, 60, 70, 80, and 94 DIM to measure total plasma glutathione (GSH), thiobarbituric acid reactive substances (TBARS), and erythrocyte glutathione peroxidase (GPx) activity as indicators of oxidative stress, N-acetyl-ß-D glucosaminidase (NAGase), lysosyme, and white blood cell counts as indicators of immune response. Metabolic adaptations were evaluated by glucose, non-esterified fatty acids (NEFA), beta-hydroxy-butyrate (BOHB), insulin, and GH concentrations, and the acid/base balance. Milk yield was not significantly different between groups throughout the experiment and was correlated with TBARS (r 0·284; P 0·05) and GSH (r = 0·294; P 0·05). Estimated energy intake was significantly higher in the EXP group at 70 DIM only (P 0·05). Plasma glucose was significantly lower in the EXP group at 50, 60 (P 0·001) and 80 DIM (P 0·05), and was correlated with GSH (r = 0·348; P 0·01) and TBARS (r = 0·367; P 0·01). Plasma NEFA decreased overall in both groups (P 0·01). EXP was lower than CTR in concentrations of plasma BOHB at 70 DIM (P 0·05) and plasma insulin at 60 (P 0·001), 80 and 94 (P 0·05) DIM. Plasma TBARS, GSH and GPx increased throughout (P 0·01) in both groups. This was delayed in the EXP group following introduction of LSD; significant differences between groups at 60 (P 0·01), 80 and 95 (P 0·05) DIM for TBARS, and at 70 (P 0·01) and 80 (P 0·05) DIM for GPx. Indicators of immune response and plasma bicarbonates did not differ between groups. Blood pH was significantly lower in the EXP group at 80 and 94 DIM (P 0·001). Blood pCO2 was significantly lower at 80 and 94 DIM (P 0·05) in the CTR group. While recovering from the negative energy balance, cellular metabolism probably shifted towards oxidative phosphorylation, with a consequent oxidative stress increase. LSD delayed this recovery in the EXP group and thus reduced GSH synthesis. In conclusion, the diet starch content may alter the control of oxidative stress and expose animals to oxidative injuries.

Ninety twin-bearing ewes were given food individually and allocated to five (no. = 18) treatments in order to determine the effects of supplementing their diet in late pregnancy with mineral-block components on colostrum production, lamb serum immunoglobulin G (IgG) concentration and colostral IgG absorption. Ewes were offered grass silage ad libitum, supplemented with 400 to 500 g per ewe per day of concentrates from day 99 of gestation, in addition to receiving one of the following supplements: C, (control) no supplement; B, mineral block; ML, liquid molasses; MN, granular minerals; ML + MN, liquid molasses and granular minerals. The experiment commenced on day 99 of gestation. Ewes were milked at lh, 10 h and 18 h post lambing and all lambs were fed measured quantities of colostrum, proportionate to birth weight, via stomach tube. Treatment had no effect (P > 0-05) on colostrum yield at lh, 10 h or 18 h post partum or on total colostrum yield to 18 h post partum. Ewes offered molasses (ML) or molasses plus minerals (ML + MN) had a lower colostral IgG concentration at lh post lambing than the control ewes (C) (P < 0-05). Ewes offered molasses (ML) also had a lower colostral IgG concentration than the control (C) at 10 h post partum (P < 0-05). Treatment had no effect on total IgG yield to 18 h post partum. When ewes were supplemented with minerals in any combination, with or without molasses (B, MN, ML + MN) it resulted in lambs having an impaired ability to absorb colostral IgG. Lambs from treatments B, MN and ML + MN had significantly poorer efficiency of colostral IgG absorption than lambs born to control ewes (C) or molasses (ML) supplemented ewes (P < 0-001). This in turn resulted in the progeny of mineral supplemented ewes (B, MN or ML + MN) having lower serum IgG concentration at 24 h post partum than either the control (C) or the molasses treatments (ML) (P < 0-001). When ewes were supplemented with molasses only (ML) lamb serum IgG content at 24 h was lower than in lambs born to control (C) ewes (P < 0-05) but this was as a result of a lower intake of colostral IgG (P < 0-05) and not a result of reduced IgG absorption efficiency. In conclusion, the data show that when ewe mineral intake is high in late pregnancy, as was the case in the current experiment, lamb serum IgG concentration and colostral IgG absorption efficiency are reduced. Further work is required to determine which component of the mineral formulation is responsible for this reduced IgG absorption efficiency and the mechanism through which this impaired efficiency operates.

A 3 X 2 factorial experiment was conducted to investigate the interactions between lactofeed 70 (LF70) (860 g/kg whey permeate, 140 g/kg soya-bean meal; Volac International, UK) and soya-bean meal (SBM) or dried skim milk (DSM) in piglet diets. Three hundred and thirty-six piglets were selected after weaning at 21 days with an initial live weight of 6-35 kg. They were blocked on the basis of live weight and within each block assigned to one of six dietary treatments. The pigs were offered the following starter diets : (1) 300 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (2) 200 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (3) 100 g/kg LF70 with 215 g/kg SBM and 100 g/kg DSM; (4) 300 g/kg LF70 with 325 g/kg DSM; (5) 200 g/kg LF70 with 325 g/kg DSM; (6) 100 g/kg LF70 with 325 g/kg DSM. The starter diets were offered for 25 days. Following this, a weaner diet (14 g/kg lysine, 14-5 MJ/kg digestible energy) was given for a period of 12 days. There was a significant interaction between LF70 level and protein source on average daily gain (ADG P < 0.001) and food conversion ratio (FCR P < 0.05) during the starter period. There was a linear increase in ADG and a linear improvement in FCR with increasing LF70 levels in diets with SBM. However, there was a linear decrease in ADG with increasing LF70 levels in diets with DSM. There was a significant interaction (P < 0.001) between LF70 level and protein source on average daily food intake (ADFI) during the starter period. At high LF70 levels, the inclusion of DSM reduced ADFl compared with SBM. However, there was no difference between DSM and SBM at the medium and low LF70 levels. There was a significant interaction between LF70 level and protein source in organic matter digestibility (OMD) (P < 0.01) and gross energy digestibility (GED) (P < 0.01). The pigs offered diets containing DSM had a significantly lower OMD and GED at low LF70 levels compared with pigs offered diets containing SBM. However, the inclusion of DSM had no significant effect on OMD or GED at the medium and high LF70 levels. There was a quadratic response in nitrogen digestibility (ND) with increasing concentrations of LF70 (P < 0.05). There was an increase in ND to 200 g/kg LF70 inclusion, however there was no further increase in ND above 200 g/kg LF70 inclusion. In conclusion, increasing the inclusion of lactofeed from 100 g/kg to 300 g/kg in starter diets where soya-bean meal comprised the principle protein source improved food efficiency and increased daily gain and daily food intake when compared with diets where dried skim milk comprised the principle protein source.

To investigate the effect of red clover formononetin concentration on lamb growth rate and carcass characteristics, 20 lambs (10 ewe lambs and 10 wethers) were grazed on each of three forages : red clover with a high formononetin concentration (HF), red clover with a low formononetin concentration (LF) and a control perennial ryegrass. Animals were finished at condition score 3L, at which point half of all animals were slaughtered immediately, while the other half of the animals were moved to a common ryegrass plot for 3 weeks as a 'withdrawal' period. Mean formononetin concentrations were 0-0, 4-7 and 3-3 g/kg dry matter (DM) for grass, HF and LF swards respectively. The clover swards had higher crude protein concentrations and lower fibre and water-soluble carbohydrate concentrations than the control ryegrass sward. Lambs grazing the HF clover gained 40 g/day live weight more (P < 0-1) than lambs on the other two forages without an increase in forage DM intake as estimated using the nalkane technique. There was no difference in the empty body weight, killing-out proportion, carcass fat class or condition score between animals finished on any of the three forages. Following the 3-week withdrawal period on ryegrass, there were significant residual effects of previous grazed forage on carcass weight, with HF lambs producing heavier carcasses than other lambs. Plasma concentrations of growth hormone and insulin-like growth factor-1 were highest in lambs grazing the HF clover, and suggest a physiological mechanism for the increased growth rates of these animals. There were no differences in the equol contents of the meat of lambs finished on the clover, compared with animals finished on grass, suggesting that there would be no implications for human health following consumption of meat produced from lambs grazing red clover, even with a relatively high concentration of formo'nonetin.

A 2 ✕ 2 factorial arrangement of treatments used 280 growing pigs and 240 finishing pigs to examine the main effects and interactions between two levels of stocking density (0·75 m2 v. 0·45 m2 per growing pig and 0·88 m2 v. 0·53 m2 per finishing pig) and grouping (static groups v. regrouped) on pig growth performance, carcass characteristics, nutrient digestibility and measurements of physiological indicators of stress responses. Regrouping was achieved by moving four unfamiliar pigs between replicate groups every 14 days. Average daily gain (ADG) and average daily food intake (ADFI) were reduced by an additive interaction between high density and regrouping in growing pigs (P < 0·01). In finishing pigs, regrouping reduced ADG (P 0·05) and carcass weight (P 0·05). Regrouping reduced apparent dry matter and gross energy digestibility in finishing pigs (P 0·05). Rectal temperature increased 3 h after mixing finishing pigs (P 0·05), but not growing pigs. In growing pigs, the neutrophil: lymphocyte ratio tended to increase (P 0·1) after regrouping, although plasma cortisol concentration was unaffected. In finishing pigs, the response to a Newcastle disease virus antigen challenge tended to decrease at high stocking density (P 0·1), although total IgG concentration was unaffected. In conclusion, the growth performance of growing and finishing pigs was affected by social stressors. However, effects on the physiological measurements did not concur with effects on growth performance.

Three strains of Holstein-Friesian (HF) cows: high production North American (HP), high durability North American (HD) and New Zealand (NZ) were assigned, within strain, to one of three pasture-based feeding systems: Moorepark (MP), high concentrate (HC), and high stocking rate (HS). The effects of strain of HF, feeding system and parity on milk production, body condition score (BCS), live weight, energy balance and reproductive performance were studied using a repeated measures model with a factorial arrangement of strain ofHF and feeding systems. Associations between these variables and conception to first service (CONCEPT1), conception to first and second service (CONCEPTl_2), pregnancy rate at 6 weeks (PREG6) and overall pregnancy rate (PREG) were assessed using logistic regressions. When treatment means were compared, the NZ strain had a shorter gestation length and a higher CONCEPT1J2 than both the HP and HD strains. Similarly, the NZ strain had a higher PREG6 and PREG than the HP strain. Feeding system had no significant effect on reproductive performance. The HP strain had the highest milk yield at first AI and peak milk yield, the NZ strain had the lowest milk yield while the HD strain was intermediate. The energy balance of the NZ strain was higher than that of the HP and HD strains. The NZ strain had the lowest live weight and highest BCS; the HD strain had the highest live weight and the HP strain had the lowest BCS. The results show that dairy cows with superior genetic merit for fertility traits have better reproductive performance.

A 4-year experiment has been conducted on finishing Belgian Blue cull cows of double-muscled type in order to study the effects of diets containing adequate levels of metabolizable protein, but either normal (NENP), low (LENP) or medium (MENP) levels of metabolizable energy, on animal performance, carcass and meat characteristics, and plasma metabolites and hormones. The LENP diet was offered during the whole (LENP group) or second half of the finishing (NENP-LENP groups), and the MENP diet during the whole finishing (MENP group). The degree of fatness required for the slaughter of animals from NENP groups was close to 4-5 (scale from 0 (very lean) to 5 (very fat)). In each underfed group, the slaughter of the animals was synchronized to that of NENP cows, by degressive degree of fatness. The same duration of finishing was thus obtained for all groups.

The experimental feeding strategies reduced the amounts of fat deposited in the carcass and the meat while muscle deposition was remarkably preserved. The proportions of saturated and monounsaturated fatty acids in intramuscular fat were also decreased while their proportions increased in plasma free fatty acids. Plasma insulin levels were also reduced and those ofIGF-1 were, surprisingly, maintained. The low energy diet promoted thus the settlement of a discrete lipolytic state while high levels ofIGF-1 preserved muscle deposition. This feeding strategy should be evaluated in other breeds of cattle.

A theoretical model was developed to predict the heat balance and body temperature of growing and finishing pigs subjected to different environments. The heat transfer modes considered in the model were convection to the surrounding air, conduction to the floor, long-wave radiation between the animal and the surrounding walls, shortwave radiation from the sun, evaporation on the skin surface, evaporation and heating of air in the respiratory tract and heating of ingested food and water. The heat balance is the net heat gain or loss from the environment due to all these processes, added to the animal's heat production. Body temperature is calculated over time using the heat balance, the animal's mass and the specific heat of the animal's body. Behavioural responses to heat and cold environments, such as vasoconstriction, vasodilatation, posture changes and huddling were expressed as changes in heat transfer coefficients and exposed surface area. The increase in evaporation under hot conditions was also considered. It was assumed that the animal's reaction to the environment may be expressed as a function of mean body temperature. The animal's heat production was considered an input to the model, which should reflect the increased metabolic rate in cold environments. Although further research is still needed to determine precisely some of the parameters, the model may be integrated with other models in order to compose a complete pig model.

This paper addresses the problem of assigning economic weights to heritable genetic traits of dairy cows while taking all implicit natural resource values into consideration. To do so, a deterministic bio-economic model of a dairy farm enterprise driven by input probabilities of oestrous detection and conception rates that act through the calving interval is constructed. The model further accounts for biologically limiting factors of both livestock and land within a neo-classical economics framework of profit maximization. Departing from the more customary approach of obtaining gross margins to calculate levels of return in the agricultural sector, we employ a natural resource economics methodology where returns are set against an economic point of reference specified as the value of natural assets' productivity and terminal assets' resale value. Introducing the impact of farming intensity on soil fertility enables us to obtain long-run variations in natural asset values as affected by tillage intensity. Results show that economic weights are not constant over the range of changes in genetic improvements due to the non-linearity of the system induced by diminishing marginal product of inputs and finite carrying capacity of resources employed. These values, while invariant to area farmed, are however subject to variations in resource quality and therefore will reflect the sensitivity of long-term sustainability of the system to managerial decisions on intensity of operation. Results further demonstrated that achieving optimum levels of output while precluding the impact of intensity on land productivity can seriously reduce the time horizon over which sustainability can be maintained. Inclusion of the implicit costs of land use on the other hand tended to suggest optimum levels of output below those identified when only considering accounting data.

This study was designed to obtain information on predicting intake and digestibility from near infrared reflectance spectroscopy (NIRS) scans of faeces in dairy cows given different diets and levels of intake. Comparisons were made between using NIRS to predict alkanes in faeces and direct calibration of NIRS for intake and digestibility. Faecal samples were obtained from 91 cows in five experiments where dry-matter intake (DMI) had been measured for individual cows. All samples were scanned by NIRS and concentrations of alkanes C32, C33 and C36 were determined in 32 samples. DMI (mean 19-4, s.d. 5-06 kg/day) was estimated with standard errors of 0-36 and 0-44 kg/day from C32 and C36 alkanes determined by gas chromatography, and with standard errors of 1-17 and 1-42 kg/day when DMI was estimated from C32 and C36 alkanes predicted by NIRS. When DMI was predicted directly by NIRS, the standard error of prediction was 0-48 kg/day (R2 = 0-97). Prediction of dry matter digestibility by NIRS was not accurate (standard error of cross validation = 0-032; R2= 0-68), probably because of the limited variation in digestibility values within the data set. It is concluded that using NIRS to predict alkane concentrations of faeces does not give accurate estimates of DMI but direct prediction of DMI by NIRS gives estimates with similar accuracy to estimates derived from the traditional alkane technique.