Voluntary food intake, milk production and blood characteristics were measured in mares between the 3rd month before foaling and the first 5 weeks of lactation. The effect of breed during pregnancy was determined using 15 light mares and eight heavy mares (522 and 763 kg live weight (LW) after foaling respectively). The effect of parity was studied on light mares (seven were primiparous and eight were multiparous). In lactation, only four primiparous and four multiparous light mares were retained. Diet consisted of 900 g hay and 100 g concentrates per kg and was offered ad libitum. Voluntary food intake in pregnancy was higher for heavy mares than for light mares: 15·2 v. 10·3 kg dry matter (DM) daily. This difference was explained by differences in LW, since DM intake was the same when expressed as a fraction of LW or metabolic weight (M). Energy and nitrogen supply exceeded requirements, in the same way for light and heavy mares. No significant variations in blood measurements were observed between light and heavy mares, except for glucose. Primiparous mares ate less DM than multiparous mares in pregnancy: 9·7 v. 10·8 kg DM (P > 0·05), significantly so relative to LW and M. DM intake per kg LW or M depended on the parity. This difference had no effect on blood measurements, except for acetate. During lactation, no other differences in voluntary food intake were observed with regard to parity, whatever the week of lactation. Milk yield was higher for multiparous mares than for primiparous mares (16·6 v. 14·6 kg daily). Gross energy of milk varied according to a similar pattern, principally because of variations in fat concentration (20·2 v. 16·5 g/kg for multiparous and primiparous mares respectively). Energy balance was significantly more positive for multiparous than for primiparous mares.

Genetic and phenotypic parameters were estimated for farmed red deer (Cervus elaphus) in an upland environment in the north-east of Scotland. Genetic parameters were estimated using restricted maximum likelihood analyses. Heritabilities of pre-weaning traits associated with growth were moderate for birth weight (0·27 (s.e. 0·04)), weaning weight, generally in September at 3 months of age (0·21 (s.e. 0·06)) and growth rate from birth to weaning (0·15 (s.e. 0·03)). Heritabilities for post-weaning traits were 0·10 (s.e. 0·05) for turn-out weight in April/May, 0·14 (s.e. 0·06) for September weight, at 15 months of age, 0·08 (s.e. 0·05) for growth rate weaning to turn-out and 0·12 (s.e. 0·06) for growth rate turn-out to September. Correlations between weaning weight and post-weaning traits were high indicating the usefulness of weaning weight as a selection criterion for red deer on upland farms. While Wapiti (Cervus elaphus canadensis) crosses grew faster than pure red deer they also tended to have higher mortality rates pre-weaning. Older dams were more likely to have a successful pregnancy and also tended to calve earlier. Date of calving was found to show no heritable variation in this study.

Worm meal obtained from worms (Eisenia fetida) raised on waste materials was evaluated for Rainbow trout as a replacement for fish meal at dietary concentrations of 250, 500 and 1 000 g replaced per kg. During the study period none of the diets was detrimental to fish health. The dietary concentrations of 250 and 500 g/kg replacement gave higher growth rates than that of the control group (0 g/kg replacement), the former having consumed less food. The biological parameters of food conversion efficiency and protein efficiency ratio, for these replacement levels, also showed values better than the control diet. Liver somatic index and the chemical composition of fish fillets showed no significant differences between diets, except for a significant decrease in lipid content with increasing worm meal inclusion.

Pigs were fed either ad libitum or given 300 g/day of the same food (digestible energy 15·4M)/kg; crude protein 208 g/kg fresh food) from 6 to 12 kg live weight (LW). Four pigs were killed at 6 kg LWand eight (equal numbers from the two sexes) from each treatment at 12 kg LW. Eight pigs (three males and five females; AL) were continued on ad libitum feeding to 24 kg LW when they were killed. Ten (four males and six females; R) of the pigs which had been restricted to 12 kg LW, were fed ad libitum to 24 kg LW, when they were killed. The entire empty bodies of the pigs killed were chemically analysed and the weights of organs determined. The empty body was considered as three fractions: the entire skin, including the subcutaneous fat (SK); the internal organs and the empty gastrointestinal tract (INT) and the remainder (CARC). The distributions of the chemical components between these three fractions were determined.

The R pigs took 19 days longer and 2·6 kg more food to go from 6 to 12 kg LW. At 12 kg LWthey had less gut fill, lighter organs concerned with food processing and less lipid, more protein and heavier CARC weights than the AL pigs. The R pigs took 5·5 days less and 2·4 kg less food to go from 12 to 24 kg than the AL pigs. At 24 kg LW they had more gut fill, similar weights of the organs concerned with food processing, and slightly less lipid and protein. Over the 12 to 24 kg weight interval the R pigs gained lipid and protein at faster rates than the AL pigs. None of the increase in protein growth rate was in the CARC fraction.

It is concluded that pigs given a low intake of food adjust their organ weights to be sufficient to process the allowance. On being given ad libitum food they rapidly increase the weights of their organs to process the increased rate of intake, and increase their gut fill. These effects are seen as a short lived, greatly increased rate of LW gain. During rehabilitation lipid stores return to their normal level but carcass protein does not show an increased rate of growth.

Insulin-like growth factor 1 (IGF1) correlates with antler growth and body growth in penned red deer stags. The present study aimed to investigate the relationships among plasma concentration of IGF1, body growth and carcass composition in grazing stags. Twenty-eight 10-month-old stags were kept at pasture from September to February. They were bled, weighed and their antlers measured fortnightly. Plasma was analysed for total IGF1. All stags were slaughtered in February (aged 15 months); organ weights were recorded and the carcasses were analysed chemically for water, fat and ash. The stags began the study weighing 60·7 (s.e. 1·4) kg and were 96·3 (s.e. 2·0) kg at the end. They grew rapidly in spring and early summer but growth rate slowed in mid summer before increasing again in late summer.

Total plasma 1GF1 for each stag throughout the study correlated positively with antler length (P < 0·001), total live-weight gain (P < 0·001), hot carcass weight (P < 0·01), fat-free carcass weight (P < 0·01), carcass fat weight (P > 0·05) and carcass fat percentage (P > 0·05). Thus IGF1 correlated significantly with all measures of body weight except fat. IGF1 correlated positively with antler growth rate (P < 0·001) calculated individually for each stag during each fortnight. IGF1 correlated positively with the spring phase of live-weight gain calculated as above (P < 0·001) but negatively (P < 0·01) with live-weight gain during the late summer growth phase. The relationships between IGF1 and growth in penned stags also pertain in grazing animals, and in addition 1GF1 is closely associated with carcass lean mainly via an overall effect on body size.

The effects of dietary sucrose, glucose and starch were compared to determine whether sucrose as an energy source affected energy or protein metabolism of growing pigs given food either frequently or once daily. Three experiments were conducted using three diets (0·8 g lysine per MJ digestible energy (DE)) containing sucrose, starch or glucose, respectively. In the first experiment, the DE contents of the diets were determined. In the second, the diets were given either once daily (08.00 h) or frequently (3-h intervals) to growing pigs (20 to 45 kg live weight) and growth responses, blood characteristics and energy, protein and fat retention measured. In the third experiment, the three diets were given to seven pigs (50 kg live weight), either once daily or frequently to monitor further the effects on plasma triglycerides, glucose, urea and insulin levels.

Growth rate, on a carcass basis, was slightly lower in pigs given glucose relative to starch (P < 0·05) but there was no effect of carbohydrate source on the retention of energy, protein or fat. Plasma triglyceride levels were lower in pigs given starch (P < 0·05) whilst plasma glucose and insulin concentrations were higher immediately after feeding in pigs given food once daily (7 < 0·05, P < 0·01). All three carbohydrate sources were used less efficiently by the pigs for energy, protein and fat deposition with once daily compared with frequent feeding (V < 0·01). Overall, these results indicate that sucrose as an energy source does not effect energy or protein metabolism by the growing pig. It appears that the metabolism of fructose within sucrose had no effect on metabolism.

Growing pigs were fed either ad libitum to 85 kg live weight, or ad libitum to 95 kg and then half maintenance until their live weight was reduced to 85 kg, when both groups were slaughtered. The middles were divided into eye, wedge and belly dorso-ventral portions and dissected. The carcasses of pigs which lost live weight before slaughter had less fat in the wedge, and less fat and muscle in the belly. They also had a greater proportion of the total middle fat and muscle in the eye portion, less fat in the wedge and less muscle in the belly portion.

Changes in plasma cholecystokinin (CCK) levels after feeding were investigated in dairy cows. Three HolsteinFriesian lactating cows given concentrates at 06.00 and 13.00 h and hay at 16.30 h were used. Blood samples were taken from the jugular vein from 0 (before feeding, 13.00 h) to 6 h at 1-h intervals. The immunoreactivity of CCK was expressed in terms of the CCK-8 equivalent. The plasma concentration of CCK was not changed over the experimental period. This result might be reflected by the continuous flow of digesta from the rumen.

Despite much discussion on the use of simple profit equations to estimate economic weights, no study appears to have tested the accuracy of this method. This paper carries out such a test from the viewpoint of the individual farmer by comparing economic weights calculated in the normal way with results gained from a more empirically acceptable, non-linear equation. Although the study concludes that simple profit equations are likely to be sufficiently accurate in most circumstances, further consideration needs to be given to a series of time periods and the industry and economy at large.

The effect of time after feeding on the distribution of nitrogen (N) in digesta from various segments of the gastrointestinal tract was studied in sheep given a diet of chopped hay once daily. Four groups of four animals were slaughtered at 2, 8,16 and 24 h after feeding and digesta were separated into large (>1180μm), medium (300 to 1180 μm) small (45 to 300 μm) and fine particles and liquid (<45 μm) fractions. The N pool in the reticulorumen decreased with time after feeding but post-ruminal N pools changed very little. Changes in N distribution within the reticulorumen reflected reductions in large particles and increases in fine particles and liquid fractions, the intermediate fractions remaining fairly constant.

Castrated male sheep were offered a roughage without (control sheep, no. = 8) or with calcium, phosphorus and sodium (CaPNa sheep, no. = 8; Ca, P and Na intake 34, 10 and 17 g/day per sheep respectively, given twice daily as drench). Food intake and live-weight change were unaffected. Water intake and urine excretion were higher whereas dry-matter apparent digestibility, nitrogen retention and wool growth were lower in the CaPNa sheep. The excretion of allantoin in urine indicated no differences in microbial protein absorption from the gut. There were small differences in the proportions of volatile fatty acids, numbers of protozoa and mineral concentrations in rumen fluid between the sheep in the two groups. Retentions of Ca, P and Na were higher in the CaPNa sheep, whereas retention of potassium was lower.

A method was suggested that attempts to distinguish between the underlying lactation curve, the effect of season of production, and the effect of time after conception. The composite function was shown to give a better fit than an incomplete gamma function. The estimated parameters of the underlying lactation curve were unaffected by season of calving whereas the parameters of the gamma function were not. Pregnancy started to affect yield 160 days after conception by -0·1 kg/day. The difference between the best season of production (May) and the worst (November) was around 5 kg.

Simulation results of closed MOET schemes have evidenced several problems issuing from selection in small populations using family information and diverse modifications of the original schemes have been proposed. Mate selection, based on linear programming techniques, includes most of the desirable properties of other methods and offers additional advantages. Some applications of this technique to improve the results of dairy cattle MOET schemes with hierarchical and factorial mating systems have been analysed in this note by computer simulation. Other applications of the method are also discussed.

A comparison was made between the rate of passage of digesta through the digestive tract of pigs with an ileo-rectal anastomosis (IRA) or an Heal T-cannula according to the single marker dose method by using polyethylene glycol (PEG) as liquid marker, Cr2O3 as solid phase marker and Yb2O3-mordantedcell walls as fibre marker. The rate of passage was slightly faster with IRA than with cannulated pigs.

The effects on herbage intake of changes of herbage mass associated with different stocking rates were studied in Greyface (Border Leicester × Scottish Blackface) ewes in the autumn. Intake was measured in 5-day periods in late September (PI), late October (P2) and late November (P3) on two established, perennial ryegrass/white clover swards (SI and S2). Both swards had previously been variably stocked to produce areas with a range in herbage masses, some of which were grazed continuously (G) at stocking rates declining from 18 to 6 ewes per ha.

Intake was also measured in P2 and P3 on other areas of the swards which were ungrazed for 6 weeks in September and October (C) and then stocked at 18 ewes per ha. Intakes of dry matter, organic matter and digestible organic matter were 16 g, 10 g and 7·5 g/kg live weight, respectively. Organic matter digestibility was 075 in PI and P2 but declined in P3.

Differences in herbage intake and digestibility arose largely because of differences between the swards in herbage mass, sward height and sward density. Ewes in condition scores > 3·00 in early September had lower intakes at all times than did thinner ewes. Changes in sward management associated with different strategies of use had little long-term effect on herbage intake. Keywords: digestibility, herbage, sheep, stocking rate.

The attainment of puberty in September-born early-maturing ewe lambs was studied at Zaragoza (latitude 41° 40' N). Thirty twin Salz females were allocated to two groups receiving two nutrition levels after 3 months of age: high (500 g/day lucerne hay and 500 g/day concentrate) (H) and low (500 g/ day lucerne hay) (L). Oestrus was detected daily by aproned rams. Corpora lutea were counted after oestrus and plasma progesterone levels monitored each week.

In the first breeding season (January to February) the percentage of females showing sexual activity (silent emulation or oestrus and ovulation) was higher in the H compared with the L group (67 and 20%; P < 0/05). Nonpubertal oestrus before the main breeding season was detected in 67% of animals. In the main breeding season and for H and L groups respectively, percentage of females showing silent ovulation before puberty was 67 and 33% and mean age at puberty extended to 319 (s.e. 4-8) and 314 (s.e. 3·7) days. Ovulation rate at puberty was 1·73 (s.e. 0·13) and 1·33 (s.e. 0·15) respectively (P < 0·05).