Insulin-like growth factors (IGFs) and their binding proteins play an essential role in regulating animal growth and metabolism. The initial portion of the current review focuses on the physiological effects of the IGFs and delineates their role as regulators of animal growth and metabolism. The role of IGFs as mediators of growth hormone effects, as insulin-like metabolic regulators and as foetal growth regulators is discussed. The remainder of the review is devoted to the IGF binding proteins, their modulation of IGF action and their role in foetal and postnatal regulation of growth.

A series of three replicated 3 × 3 Latin-square design experiments was carried out with lactating dairy cows (15 in experiments 1 and 3, and 18 in experiment 2). The objectives of these experiments were to investigate if the feeding of high concentrations of molasses would be detrimental to the performance or health of cows, and if the strategic supplementation of nitrogen or unprotected fat could enhance the efficiency of molasses feeding. In experiment 1, complete diets were based on grass silage with three inclusion rates of a liquid molasses-based supplement (Molaferm 20) to supply molasses dry matter (DM) of 125, 250 and 375 g/kg DM respectively. In experiment 2, the control diet contained (g/kg DM) 460 grass silage, 310 'molaferm 20' and 192 barley and 22 soya-bean meal, and was then supplemented with urea (12 g/kg DM) or soya-bean meal (177 g/kg DM). In experiment 3, the control diet was based on (g/kg DM) grass silage (460), molaferm 20 (310), barley (130), soya-bean meal (65) and oatfeed (20). Two concentrations, low and high, of unprotected tallow were added to the control diet (12·5 and 25·8 g/kg DM, respectively).

In experiment 1, cows suffered from some scouring on the highest molasses treatment, but recovered when changed to either the medium or low molasses treatment. However, there were no clinical symptoms of ill health observed during experiments 2 and 3. In experiment 1, animal intake and performance on the diets containing molasses DM of 125, 250 and 375 g/kg DM respectively were: total DM intake, 12·8, 16·2 and 18·6 kg/day (s.e.d. 1·03, P < 0·001); milk yield, 15·5,17·4 and 17·6 kg/day (s.e.d. 0·53, low v. medium or high, P < 0·01); fat concentration, 39·6, 39·7 and 40·0g/kg (s.e.d. 0·70, P>0·05); protein concentration, 31·6, 32·7 and 33·6g/kg (s.e.d. 0·22, P < 0·05). In experiment 2, supplementation of the control diet both with urea and soya-bean meal significantly increased DM intake (P < 0·01); milk yield (P < 0·01) and protein concentration in milk (P < 0·05), but had no significant effects on fat concentration in milk (P > 0·05). In experiment 3, there were no significant differences in DM intake between the three treatments. However, supplementation with both low and high concentrations of unprotected tallow significantly increased milk yield (P < 0·01) and significantly decreased fat (P < 0·01) and protein (P < 0·001) concentrations in milk.

It is concluded that lactating dairy cows could be given molasses up to 250 g/kg DM in grass silage-based complete diets without adverse effects on milk production or health. When a diet contained a high concentration of molasses (248 g/kg DM), supplementation with urea and soya-bean meal increased intake and milk production, and supplementation with unprotected tallow also increased milk yield, but fat and protein concentrations in milk were decreased.

A randomized block design experiment involving 64 lactating dairy cattle was carried out to evaluate a bacterial inoculant and two rates of formic acid as silage additives. Herbage from the primary growth of a predominantly perennial ryegrass sward was ensiled unwilted using two precision-chop harvesters. Alternate loads of herbage were either untreated (UT) or treated with formic acid applied at the rate of 2·7 l/t grass (LF) and 5·7 l/t grass (HF) or an inoculant enzyme preparation applied at the rate of 2·2 l/t grass (I). The mean dry matter (DM) and water-soluble carbohydrate (WSC) concentrations and buffering capacity of the UT herbage were 148 g/kg, 151 g/kg DM and 638 mEq/kg DM. Inoculant treatment had no effect on the rate of silage fermentation post ensiling relative to the UT silage whereas HF treatment produced a restricted fermented silage. For silages UT, LF, I and HF, pH values were 4·53, 3·89, 4·32 and 4·05 (s.e.d. = 0·061); ammonia nitrogen (N) concentrations were 179, 89, 150 and 73 g/kg total N (s.e.d. = 10·4); butyrate concentrations were 6·0,1·9, 5·1 and 2·0 g/kg DM (s.e.d. = 1·24); and WSC concentrations were 14·4, 35·2, 18·0 and 100·7 g/kg DM (s.e.d. = 1·24), respectively. The silages were offered ad libitum. The UT silage was supplemented with either 2 (UT2), 4 (UT4) or 6 (UT6) kg concentrates per head daily while the LF, I and HF silages were supplemented with 4 kg (LF4,14, HF4) of concentrates. For treatments UT4, LF4, 14 and HF4, silage DM intakes were 9·69, 10·89, 9·93 and 10·89 (average s.e.d. = 0·465) kg/day; fat plus protein yields 1·39,1·44,1·32 and 1·49 (average s.e.d. = 0·057) kg/day; protein concentrations 29·2, 31·1, 29·9 and 30·2 (average s.e.d. = 1·01) g/kg. Inoculant treatment increased N apparent digestibility (P < 0·05) of the total diets relative to UT. The apparent digestibilities of neutral-detergent fibre (P < 0·05) and hemicellulose (P < 0·01) were decreased due to HF treatment. For the production of a constant milk fat plus protein yield it was estimated that an extra 0·63 kg per head per day and 1·04 and 1·77 kg per head per day less concentrate would be required for the I, LF and HF treatments, respectively. It is concluded that relative to the UT treatment, I treatment had no beneficial effects on silage fermentation, total diet apparent digestibility (other than N apparent digestibility) or animal performance. The LF treatment improve lage fermentation and intake, and tended to increase the yield of fat plus protein (P > 0·05) whereas HF treatment restricted silage preservation and increased silage intake and the yields of protein and fat plus protein.

The effect of active immunization against somatostatin and β-agonist administration alone and in combination on growth, carcass composition and endocrine responses was investigated in young steers given a pelleted diet of dried grass and barley (0·7: 0·3) ad libitum for 16 weeks. Immunization alone increased growth rate by proportionately 0·10 but had no effect on plasma growth hormone (GH) or insulin-like growth factor-1 (IGF-1) concentrations (P > 0·10). Carcass protein content was unchanged but fat content tended to be increased. This was possibly associated with increased (P < 0·10) plasma insulin concentrations observed in these animals. Cimaterol administration significantly increased growth rate (P < 0·05) and carcass weight (P < 0·01). Carcass protein content was significantly (P < 0·01) increased and carcass fat was significantly (P < 0·001) reduced. Administration of cimaterol to immunized animals resulted in an enhancement of the repartitioning effect of the pagonist although growth rates were intermediate between the separate treatments. The mechanism by which this was achieved is unclear. Plasma IGF-1 concentrations tended (P < 0·10) to be lower in these animals compared with controls. Plasma insulin concentrations were also reduced (P < 0·05) in these animals. Both immunized animals and those given cimaterol alone showed an increased GH response to a single intravenous injection of growth hormone releasing factor (GRF) (P < 0·05). Animals given the combined treatment however showed a reduced response suggesting that the effects were not mediated through direct changes in GH secretion. The improved lean:fat ratio in the carcass was observed to be mediated through an enhancement of the lipolytic response to the /J-agonist with only small effects on protein accretion. It is suggested that immunoneutralization of somatostatin may increase the sensitivity of adipose tissue to lipolytic stimuli. This could occur through changes in the secretion of gastrointestinal or pancreatic hormones as a result of neutralization of the inhibitory influences of somatostatin. Further work is required to clarify these effects.

The objective was to determine the daily live-weight gain, behaviour, adrenal and immune responses of finishing beef heifers housed at two different space allowances. Heifers (no. = 32) with a mean live weight of466 (s.e. 3·6) kg were assigned to either 1·5 or 3·0 m2 average individual space allowance in four slatted-floor pens (two per treatment) for a period of 104 days. On days 5, 40, 68 and 96, heifers (no. = eight per treatment, four per pen) were challenged with 1·98 i.u. ACTH per kg M0·75, and serial blood samples were analysed for plasma cortisol concentrations. The other 16 heifers were immunized against keyhole limpet haemocyanin (KLH) on day 28, and blood samples collected on days 28, 42, 56, 70, 84 and 98 were analysed for anti-KLH immunoglobulin (Ig) concentrations. All heifers were blood sampled on days 0, 14, 56 and 98, and red and white blood cell numbers, packed cell volume (PCV) and plasma concentrations of creatine kinase (CK), non-esterified fatty acids (NEFA) and urea were determined. Behavioural observations were conducted on days 8, 43, 71 and 99 by scan sampling for 24 h (10-min intervals), and continuous 4-h observations were conducted on days 100 and 101.

Heifers at 1·5 m2 space allowance had a lower daily live-weight gain compared with those at 3·0 m2 (0·60 v. 0·87 (s.e. 0·04) kg; P < 0·001). Heifers at 1·5 m2 had lower pre-ACTH baseline cortisol concentrations (P < 0·05) and lower post-ACTH peak cortisol concentrations (P < 0·05). There were no effects of treatment on serum anti-KLH IgG1 or IgG2 responses (P > 0·05). Heifers at 1·5 m2 had lower plasma NEFA concentrations (P < 0·05). Red and white blood cell numbers, PCV, CK and urea were not affected by treatment (P > 0·05). The time spent lying down was lower for heifers at 1·5 m2 (10·0 v. 21·1 h/day; P < 0·05). Social interactions were fewer (P < 0·05), and incidence of head-resting behaviour was higher (P < 0·05) among heifers at 1·5 m2 compared with 3·0 m2 space allowance. In conclusion, the restricted space allowance resulted in a substantial decrease in daily live-weight gain, and changes in adrenal response and behaviour.

Five mathematical models were compared to select the most satisfactory model to describe digesta kinetics of solids and fluids in the gastrointestinal tract of buffaloes (Mediterranean bulls), cattle (Friesian bulls) and sheep (Delle Langhe rams) given food at maintenance level, according to a Latin-square arrangement for four consecutive periods of 21 days. Chromium mordanted alfalfa hay and cobalt-ethylenediamine tetraacetic acid were used as nonabsorbable markers and were administered through the rumen cannula in a single dose. Four different isonitrogenous diets (N × 6·25 = 140 g/kg dry matter) with different concentrate:forage ratios (12·5:87·5, 25:75, 37·5:62·5, 50:50) were used.

Faecal chromium and cobalt concentration curves were fitted with five non-linear models: three gamma (G2, G3, G4) age-dependent one-compartment, one gamma age-dependent/age-independent two-compartment (G2G1) and one multicompartment (MC).

Wilcoxon tests on residual sums of squares of the different models for solids showed that MC and G4 gave a better fit than G2G1, G2, G3 for all the data and within the species. The comparison of MC v. G4 did not show any significant difference (P > 0·05) for all the data computed together or within each species. Nevertheless, MC had a higher number of curves with lower residual sums of squares in comparison with G4 and was also able to produce estimates of digesta kinetics in the second compartment.

The cobalt excretion curves for fluids, considering all the data, and only within sheep, showed G4 as the best fitting model. When G4 was compared with other models no significant differences were recorded either for cattle: G4 v. G2 (F = 0·6645), G4 v. G2G1 (P = 0·0620) and for buffalo: G4 v. G2 (P = 0·1575), G4 v.G3(P = 0·0796) and G4 v. G2G1 (P = 0·1641).

It is concluded that the multicompartment model (MC) and G4 model were the best fits for solids and for fluids respectively.

The need to complement in vitro gas production measurements with residue determination is demonstrated by the recalculation and reassessment of published data on in vitro gas production, in sacco degradabilities and voluntary dry matter intake (DMI). The in sacco degradability — gas volume ratio was determined at 24 and 48 h of incubation, termed partitioning factor (PF) and combined with rate and extent parameters of in sacco degradability and in vitro gas production to predict DMI. In vitro gas production and in sacco degradability characteristics (a + b) and c as described by the equation y = a + b(1−ect) explained 0·373 and 0·668 respectively of the variation in DMI of 19 legume and grass hays. The complementation of gas production parameters by the PF24 increased the R2 value to 0·744 with PF24 accounting for 0·407 of the variation in DMI, the rate of gas production (c) for 0·218 and the extent of gas production (a + b) for 0·119 of the variation in DMI. As a single parameter, PF48 showed the highest correlation (R2 = 0·597) with DMI but the combination of PF4S with rate and extent of in sacco or in vitro gas production measurements did not improve the correlation further, probably due to an intercorrelation between rates of fermentation and PF4S. Hays which were degraded at faster rates had higher PF values indicating proportionally higher microbial yield and lower short-chain fatty acid production per unit substrate degraded. Generally, hays with high in sacco degradabilities but proportionally low gas production i.e. hays with high PF values showed higher DMI.

Carcass and eating quality characteristics of crossbred wether and female lambs sired by Charollais (C), Suffolk (S) and Texel (T) rams out of Mule ewes (Bluefaced Leicester ♂ × Scottish Blackface ♀ or Swaledale ♀J)were evaluated in a study carried out over a 3-year period in an upland flock. A total of 10 unrelated rams of each breed were used as sires. Lambs (no. = 280) were selected for slaughter at the same estimated subcutaneous fat level on four occasions within each year (i.e. at weaning in July and at approx. monthly intervals thereafter). Following slaughter, the left side of each carcass was physically dissected. A loin joint from lambs slaughtered in the 2nd and 3rd years of the study (no. = 184) was used to evaluate eating quality.

Suffolk-sired lambs were heavier at slaughter (S: 42·2; C: 41·0; T: 40·7 (s.e. 0·35) kg) but had similar killing-out proportions compared with the other two breeds (S: 444; C: 450; T: 452 (s.e. 26) g/kg). Texel-sired lambs had higher lean proportion (S: 543; C: 550; T: 567 (s.e. 4·4) g/kg) and lower total carcass fat proportion (S: 240; C: 242; T: 233 (s.e. 5·3) g/kg) compared with S and C sired lambs. Bone proportion was similar for C and T lambs but was higher for S (S: 199; C: 191; T: 191 (s.e. 2·1) g/kg). Lean: bone (S: 2·75; C: 2·90; T: 2·99 (s.e. 0·037)) and lean:fat (S: 2·38; C: 2·40; T: 2·54 (s.e. 0·034)) ratios were higher for T-sired lambs. Female lambs were lighter (40·4 v. 42·2 (s.e. 0·24) kg), and had proportionately more intermuscular fat than wethers (122 v.118 (s.e. 1·3) g/kg) but the sex differences for other tissue proportions were small. Carcass weights and total carcass fat proportions increased and lean proportions decreased across the four slaughter dates. There were no effects of breed or sex on eating quality. However, samples from lambs slaughtered at weaning were judged to be more tender than those slaughtered later in the season.

One hundred and twenty-six twin-bearing ewes were given either formic acid (FA) treated grass silage or grass/ molassed sugar-beet pulp (MSBP) silage in order to investigate factors affecting colostrum yield and quality and the efficiency of immunoglobulin (IgG) absorption. The experiment commenced on day 91 of pregnancy and the diets consisted ofFA-treated silage (Tl), FA-treated silage + soya-bean meal (SB) (72), MSBP silage (T3), MSBP silage + SB (T4), FA-treated silage + MSBP (T5), FA-treated silage + MSBP + SB (T6) or FA-treated silage + 150 g/kg of a crude protein concentrate (T7). Soya-bean meal was offered only in the last 3 weeks of pregnancy aiming for a total crude protein intake of220 g per ewe per day. Blood samples were taken from lambs in order to measure serum Ig concentrations. Ewes were milked at 1 h,10h and 18 h post lambing. Daily metabolizable energy intakes of 6·8, 11·4, 9·6, 12·8, 10·5, 13·7 and 14·7 (s.e. 0·58) M] per ewe were recorded for Tl to T7 respectively over the last 3 weeks of pregnancy. Respective crude protein intakes of 72, 213, 110, 225, 109, 215 and 175 (s.e. 5·64) g per ewe per day were recorded for Tl to T7 over the last 3 weeks of pregnancy. The addition of protein increased colostrum yield at 1 h (P < 0·01), 10 h (P < 0·01) and 18 h (P < 0·01) post lambing and total yield of colostrum to 18 h (P < 0·001). There was no significant response (P > 0·05) in colostrum production during the first 18 h following protein supplementation when the basic diet was FA-treated silage. There was no difference (P > 0·05) in colostrum production during the first 18 h between ewes offered MSBP treated silage or MSBP supplemented silage. Ewes offered FA-treated silage produced less colostrum during the first 18 h compared with ewes offered either MSBP treated or supplemented silage (P < 0·05). The production of colostral IgG during the first 18 h after parturition was related to the amount of colostrum produced; the greater the colostrum production the greater the Ig production. There was a significant quadratic relationship between the total amount of IgG ingested per kg lamb birth weight during the first 18 h and lamb serum IgG at 24 h (R2 = 0·4005; P < 0·0001). Lamb serum Ig level increased linearly with increasing colostrum IgG consumption up to 15 g/kg lamb birth weight. Proportionately about 0·17 of the IgG ingested was present in the lamb's circulation at 24 h. Ewe protein supplementation pre-lambing increased the lamb's efficiency to absorb colostral IgG (P < 0·05) during the first 24 h. In conclusion, the data show positive relationships between feeding regimes, colostrum production and IgG transfer.

During a 3-year period, from April 1991 to December 1993, in a flock with four lambing periods annually, faecal samples from lambs at weaning at the age of 3 months (no. = 1756), were examined for gastro-intestinal nematode eggs by the McMaster method. Faecal samples were also examined at the age of 9 (no. = 170), 12 (no. = 157), 15 (no. = 253) and 18 (no. = 85) months from the females only. From June to December 1993 packed cell volume (PCV) was also examined from lambs at weaning. Seven genotypes were used in this study.

The faecal egg counts were affected by genotype, birth season, type of birth and rearing, sex and age. First generation cross of Sumatra × Barbados Blackbelly had lowest eggs per g of faeces (EPG) followed by Sumatra, St Croix, Sumatra × St Croix Fl and F2 and Sumatra × Java Fat tail. Lambs born in February-March when rainfall was low had lower EPG (V < 0·05) than those born in May-June or August-September. The EPG of lambs born and reared singly were significantly lower (P < 0·001) than those born twin, triplet or quadruplet. Female lambs had lower EPG than male lambs (P < 0·001). The EPG of lambs at 3 months were higher than at 9, 12, 15 or 18 months (P < 0·001).

PCV was affected by genotype, sex, type of birth and rearing and season of birth. There was a positive correlation between PCV and weaning weight of lambs and a negative correlation between EPG and weaning weight. These results show that the crosses of St Croix and Barbados Blackbelly with local Sumatra sheep are at least as resistant or more resistant to gastro-intestinal nematodes than pure Sumatra breed and therefore these breeds can be used in cross breeding programmes to improve the body size of local Sumatra sheep.

After 14 h of confinement in a stationary trailer, sheep were found to have lost proportionately a mean of 0·057 of their body weight. Two experiments, one with a heterogeneous flock (28·6 to 93·2 kg body weight) and the other with a more homogeneous flock (32·4 to 46·6 kg) showed very little recovery of this loss after 1 h of ad libitum food and water. When offered familiar concentrates, sheep ate on average 1·2 kg per animal in the 1st h, water only being taken in quantity (>5·01 per animal) in the next 6 h. Hay was taken at a much lower rate (0·25 kg per animal) and less water drunk (1·51 per animal). Competitive social interactions were five times more frequent during hay feeding than during concentrate feeding. After 14 h of confinement a break of Ih is evidently insufficient for feeding and watering and could result in poor welfare. If concentrates are offered, the resulting water deficit will not be redressed within 1 h, resulting in a strong motivation to drink when no water is available. If hay is offered, the heightened level of competitive social interaction could also result in poor welfare.

The influence of pre-slaughter nutrition on the potency of foetal serum in cell culture was studied. Ewes carrying late-gestation foetuses (120-day gestation) were either fasted for 66 h (F), fasted for 66 h but drenched with Ketol, a propylene glycol preparation, (5 × 120 ml doses; FK), given food ad libitum (A), or given food ad libitum and drenched with Ketol (5 × 120 ml doses; AK). Following slaughter foetal blood was collected for the determination of potency in cell culture using industry-standard cell culture bioassays: cloning efficiency, plating efficiency and a 96 h cell proliferation assay. Foetal serum insulin-like growth factor (IGF) concentrations were also measured. Pre-slaughter fasting or drenching with Ketol had no effect on the potency of foetal serum in any of the cell culture bioassays. Fasting significantly lowered foetal plasma IGF-1 levels (F < 0·01). Foetal IGF-2 levels were unaffected by fasting or drenching with Ketol.

Exploiting the ‘ram effect’ is an inexpensive alternative for out-of-season breeding in moderately seasonal breeds. For maximum efficacy in Corriedale sheep, oestrous ewes have to be introduced together with the teaser rams. Successful applications depend upon timely manipulation of the animals to induce oestrus in most ewes and to minimize the likelihood of successfully induced non-pregnant ewes returning to anoestrus during the mating period.

In the first of two experiments, the effects of two alternative ram: ewe ratios (1:6 or 1:12) and five different doses (0, 15, 30, 45 or 60 mg) of medroxy-progesterone acetate (MAP) applied in intravaginal sponges for 9 days were assessed on seasonally anovular adult Corriedale ewes. Control ewes (0 MAP) did not receive sponges, but were injected with 20 mg progesterone at ram introduction. A second experiment tested the efficacy of post-oestrus intravaginally applied MAP (30 mg; 7-day treatment starting on days 3 to 6 after oestrus) for improving reproductive variables of successfully induced ewes exposed to entire rams.

Proportions of ewes ovulating and ovulation rates (assessed through laparoscopy) did not differ significantly (P > 0·05) in ewes treated with various MAP doses (213/220 = 96·8% and 1·26 (s.e. 0·031) respectively) or injected with progesterone (56/58 = 96·6% and 1·21 (s.e. 0·058) respectively). The MAP content of the sponges did not affect (V > 0·05) the proportion of ewes ovulating (269/278), marked by the rams (197/213), returning to oestrus (81/197) or lambing among those not returning to first oestrus (87/119). More ewes were marked in the groups exposed to a higher ram percentage (79·7 to 70·6%; P < 0·001) but no other reproductive variable was affected by the ram: ewe ratio at ram introduction (P > 0·05). In the second experiment, post oestrus progestagen supplementation reduced the proportion of ewes returning to first oestrus from 27% to 16% (P < 0·05) but failed to improve lambing rate or the number of lambs born per ewe lambing. Thus, MAP doses as low as 0·25 of the commercial formulation (60 mg) induced oestrus in seasonally anovulatory Corriedale ewes exposed to rams and oestrous ewes. Increasing the ram: ewe ratio augmented the proportion of marked ewes but did not affect any other reproductive variable. Supplementing MAP after oestrus did not improve reproductive rate in Corriedale ewes induced to ovulate during the seasonal anoestrus.

The influence of types of roughage, barley straw (diet B) versus lucerne hay (diet L), on the patho-physiology of a T. congolense infection was compared in eight pairs of Scottish Blackface male twin lambs. One animal of each twin pair was infected and the other used as a pair-fed control. Voluntary food intake, body weight, digestive function, various blood haematological and biochemical measurements were made.

Voluntary organic matter intake decreased significantly after the T. congolense infection, the decrease being greater in the diet L group than in the diet B group lambs (P < 0·01). The apparent digestibility coefficients of crude protein and organic matter were significantly lower in the infected lambs (P < 0·01). Mean retention time of the roughage through the digestive tract in the animals given barley straw was significantly longer (P < 0·05) due to a lower rumen outflow rate constant (P < 0·01). Infection resulted in longer mean retention times (P < 0·01).

Packed cell volume (PCV) was significantly lower before infection in the animals given diet B (P < 0·01). After infection, diet (P < 0·01) and infection (P < 0·01) had an additive effect on PCV. The anaemia was both macrocytic (P < 0·05) and hypochromic (P < 0·01).

Diet B resulted in higher plasma cholesterol (P < 0·05), but lower plasma urea (P < 0·01) and albumin (P < 0·01) concentrations before infection than diet L. The T. congolense infection significantly lowered plasma cholesterol (P < 0·01) and increased plasma urea (P < 0·01) concentrations compared with the uninfected controls. Plasma albumin concentrations decreased, but were more affected by nutrition (P < 0·01) than by infection (P < 0·05).

It ivas concluded that the patho-physiological effects of the T. congolense infection in the Scottish Blackface lambs were affected by the type of roughage offered, but that these effects were additive rather than interactive to the effects of infection.

Ewe live iveights were recorded 4 weeks prior to mating, at the beginning of mating and 22 to 23 days later over a period of 3 years in a flock of some 300 breeding ewes comprising approximately equal numbers of Australian Merino, Ideal (Polwarth), Merilin and Corriedale breeds in a pastorally based grazing system in Uruguay. Multiple-bearing ewes were generally heavier than single-bearing ewes which in turn were heavier than ewes which did not conceive, these differences being greatest in 3- and 4-year-old ewes (i.e. in their second and third breeding seasons). Body condition scores of non-pregnant ewes were lower than those of pregnant ewes, particularly in the 3-and 4-year-old age groups. Ewe live weights achieved prior to, during and at the end of the mating period and the body condition score achieved 4 weeks prior to mating all had significant influences on the number of lambs born (P < 0·01) but there were no significant effects of changes in either live weight or body condition over the 4 weeks prior to mating or during the mating period. The effect of body condition score over the range from 2·0 to 4·0 was to increase the proportions of single- and multiple-bearing ewes and to decrease the proportion of non-pregnant ewes such that the number of lambs born per ewe mated increased from 0·94 to 1·38. Fleece weights differed significantly between breeds, Corriedales having the heaviest fleeces and Merilins the lightest (4·26 and 3·22 kg respectively). Wool production was also significantly and positively affected by age (P < 0·01) and by ewe weight at mating (P < 0·01). The results demonstrate the importance of giving preferential nutritional treatment to younger ewes to ensure a satisfactory subsequent lambing performance and improved wool production.

The objective of this study was to evaluate the influences of age and condition score on the live weight of ewes of three Greek dairy breeds. Boutsko (no. = 225), Serres (no. = 292) and Karagouniko (no. = 301) ewes from individually recorded purebred flocks were weighed (±0·5 kg) and condition scored, on a six-point scale, to the nearest 0·5 unit. Within each breed and age group the relationship between live weight and condition score was derived by linear regression. There was a highly significant relationship between condition score and live weight in all of the groups (P < 0·01). Live weight, adjusted to a standard condition score, increased with increasing age up to 3·5 years; beyond this age there was no effect of age on condition score. The live weight and condition score data for ages 3·5 years and upwards were used to derive a single regression between live weight and condition score for each breed. This provides a means to estimate adult live weights standardized to a given condition score. The values of the regression coefficients were directly proportional to the breed mature weight; on average the increase in live weight associated with a unit of condition score was 0·129 kg/kg of mature weight for the three breeds studied. Mature weight was estimated as the weight at a condition score of 5. Using published information, a similar value was found to apply to a wide range of sheep breeds and also to cattle. This robust value permits the live-weight change associated with a unit of condition score to be calculated, for any breed.

A study was conducted to evaluate increasing dietary levels of threonine on performance and carcass quality of growing gilt pigs (live-weight period of 50 to 95 kg; no. = 384) by using two different types of basal diets. One basal diet (basal A) was composed of highly digestible food ingredients and the other diet (basal B) of less well digested food ingredients. Before starting the growth trial, Heal apparent digestibility ofamino acids of both basal diets was determined in an in vivo digestibility trial with pigs. Both basal diets were composed in such a way as to obtain equal contents for net energy and Heal digestible threonine, lysine, methionine + cystine and tryptophan. The content of Heal digestible threonine in both basal diets was approximately 3·3 g/kg, corresponding with a total threonine content of 4·8 g/kg in basal diet A and 5·4 g/kg in basal diet B. To both diets three graded dose levels (0·4, 0·8 and 1·2 g/kg) of L-threonine were added, providing at the highest supplemented level 4·5 g/kg Heal digestible threonine. The requirement for Heal digestible threonine was estimated to be 4·1 g/kg regardless of diet composition. This estimated requirement was mainly based on the results for food conversion efficiency. For obtaining maximum weight gain, the requirement for Heal digestible threonine was found to be somewhat higher than for maximum efficiency of food utilization. The estimated requirement figure of 4·1 g Heal digestible threonine corresponded with approximately 5·6 g total threonine per kg in basal diet A and 6·2 g/kg in basal diet B. Carcass quality was not affected by the content of threonine in the diets.

Three ewes, three female goats and three male fallow deer, aged between 7 and 12 months and weighing 24·0 to 32·2 kg, were used in this experiment to outline the main differences in digestion among the three species. Dietary treatments were three diets with three forage: concentrate ratios of 10: 90, 50: 50, and 90:10 and two different feeding levels (45 and 90 g/kg M0·75 per day). The three diets were given to the three animals of each species in a Latin-square design; the two levels of feeding were compared ivithin diet in each period of the Latin square. The diet selected, apparent digestibility, and rumen retention time of Cr-mordanted neutral-detergent fibre were significantly different among species and dietary treatments. Interactions between species and dietary treatments were also significant for all the above variables. Sheep showed the highest intakes and apparent digestibilities of the forage-rich diets, and the longest rumen mean retention times. Goats tended to select diet components, despite allowance of diets being limited, and had lower food intakes than sheep. Apparent digestibility of forage-rich diet was also lower. Rumen mean retention times were shorter and less influenced by dietary treatments. Fallow deer had an apparent digestibility of forage-rich diets which was even lower than that of goats. Food intake was similar to that of sheep, with no evidence of selection. Rumen mean retention time was shorter than that of goats.

Low winter growth is a characteristic of male red deer and is caused, in part by a combination of reduced appetite and higher energy expenditure due to cold weather. This study aimed to determine whether housing during winter would reduce energy expenditure and increase the growth rate of male red deer calves. An additional aim was to investigate whether food restriction in winter would be compensated for by increased spring growth. In each of two consecutive years, 80 calves were randomly allocated to eight groups (no. = 10) comprising two replicates of four treatments during winter. Groups were housed inside (I) or outside (O) and given food either ad libitum (AL) or restricted (R) to maintain live weight. Winter treatments (southern hemisphere) ran from 22 May to 25 August (year 1) and from 5 June to 5 September (year 2). During these periods, animals were weighed weekly and group food intake recorded daily. At the end of winter animals were moved outside onto pasture and weighed monthly until the end of spring (27 November, year 1 and 7 December, year 2). In year 2 weighing continued during summer, until 4 April. The animals were slaughtered on 28 November and 18 January (year 1) and 5 April (year 2). The effect of housing on live-weight gain (LWG) and dry-matter intake (DM1) in AL groups was not significant in either year. However in R groups, O had a higher DMI than I in both years (P < 0·05) and a higher LWG than I in year 1 (P < 0·05). LWG was loiver in R than in AL groups in winter in year 1 (P < 0·05) and year 2 (P < 0·001) and live weight was lower in R than in AL groups at the end of winter in both years. Live weight was still lower in R than in AL groups at the end of spring in both years (P < 0·01). In year 2, this live-weight difference was not significant by the end of summer. Hot carcass weight (HCW) was greater in AL animals than R animals (P < 0·05) and dressing proportion was higher in R than in AL (P < 0·05) in year 1. GR (an index of body fatness) was greater (P < 0·05) in O than I in year 1 and was greater (P < 0·05) in AL than in R animals in year 2. Differences in GR between treatments were not significant in either year, with HCW as a covariate.

In conclusion, housing calves given food ad libitum during winter did not reduce DMI or increase growth rate. When normal growth rates were prevented by restricting food intake, housing lowered DMI requirement, although such a situation is unlikely to be a useful farm management practice as recovery from the growth check was slow. Annual variations in climate may determine both the food savings made by housing and the extent of compensatory growth of food-restricted animals in spring.

The effects of olive (MONO) or sunflower (POLY) oil-enriched (30 g/kg) diets with either a basal (10 mg/kg food) or supplemented (200 mg/kg) level of a-tocopheryl acetate on some measures of production, fatty acid composition of animal tissues and susceptibility to oxidation of rabbit meat and membrane extracts have been studied. MONO diet produced higher levels of C18:1 in animal tissues. Animals that received POLY diet had a higher level of C18:2 in perirenal and neutral fraction of intramuscular fat and higher levels of C18:2, C20:4, C22:4 and C22:5 in phospholipid, reaching a higher overall unsaturation (P = 0·001). Muscle samples from rabbits given the POLY diet were more susceptible to lipid oxidation (P = 0·0001). Differences in membrane lipid oxidation, between groups followed a similar pattern to that of meat. Diets rich in C18:2 resulted in increases in concentration of pentanal (P < 0·001), hexanal (P = 0·0001) and total volatile aldehydes (P = 0·0001) in meat as monitored by headspace gas liquid chromatography. Dietary supplementation with α-tocopheryl acetate reduced the overall concentration of volatile aldehydes (P < 0·05), particularly hexanal (P < 0·05). Dietary administration of monounsaturated fatty acids not only reduces membrane and meat lipid oxidation but also modifies the relative proportion of volatile aldehydes generated upon heating, with a specific decrease in those generally related to rancidity and off-flavour of meats.