The non-linear model y = ae(−hW−c/W) was fitted to weekly calculated daily gain (DG), daily food intake (FI) and food efficiency (FE) of 653 barrows and gilts fed ad libitum or restrictedly during a growing period from 27 to 108 kg live weight. Where y was DG, FI or FE, W was live weight and a, b and c were parameters. The model fitted well to the expected course of the traits, with an accuracy similar to that of quadratic polynomials. Parameters for one trait could simply be derived from the parameters for the other two traits. For each trait, four basic patterns were distinguished, depending on the signs of b and c. Curves with a maximum (b > 0 and c > 0) occurred most frequently. In cases of curves with a maximum, the model could be reparameterized to a model with parameters having a simple biological meaning.

Coefficients of determination in barrows averaged 0·29 for DG, 0·88 for FI and 0·45 for FE, whereas these values were somewhat lower in gilts. With ad libitum feeding, a DG curve with a maximum was fitted in proportionately 0·83 of the barrows and 0·61 of the gilts. The maximum DG was on average at live weights of 64 kg for barrows and 77 kg for gilts. A maximum in the FI curve was predicted in proportionately 0·60 of the barrows and 0·39 of the gilts. Curves for DG and FI in gilts were less curvilinear than in barrows. FE curves, with ad libitum feeding, had a maximum in proportionately 0·59 of the barrows and 0·52 of the gilts. This predicted maximum FE was, on average, before the start of the growing period. Gilts had a higher FE than barrows from 35 kg body weight onwards, and the difference increased with increasing live weight. Differences in FE between ad libitum and restricted feeding were small, with a tendency for animals fed at a restricted feeding level to be more efficient at the end of the growing period.

Average FE curves and individual FI or DG curves were used for indirect prediction of individual DG or FI curves, respectively. The correlation between directly and indirectly predicted values of DG and FI at live weights of 30, 65 or 100 kg was about 0·7 in ad libitum fed barrows and gilts, and greater than 0·8 in pigs fed at a restricted level. This indicates that the model is suitable to predict and control the course of individual daily gain by influencing the course of food intake.

The purpose of the experiment was to investigate the possibility of using concentrations of hormones and metabolites in plasma of potential breeding bulls early in life as indirect selection criteria for butterfat production. Sixteen Red Danish bull calves were included in the experiment, 10 were offspring of parents selected for high butterfat production for two or three generations, and six were from parents selected for low butterfat yield. The average estimated relative breeding values of the calves in the two groups were 111 and 91.

At 3·5 and 7 months of age blood samples were collected every 6 h during 2 days of ad libitum feeding, 5 days of fasting and 2 days of refeeding. The samples were analysed for glucose, urea, free fatty acids, insulin and thyroxine. At 3·5 months plasma concentrations of free fatty acids were significantly correlated with breeding value under all feeding conditions examined. The increase in plasma glucose during refeeding at both ages was positively related to breeding value. Plasma insulin during the 1st day of fasting was positively correlated with genetic merit at 3·5 months of age and negatively correlated at 7 months. Plasma thyroxine was negatively correlated with breeding value at both ages, but the correlation was only significant at 7 months. Multiple regression analyses showed that a large part of the variation in breeding value for butterfat production could be described by plasma levels of hormones and metabolites when more than one variable was included in the model. With six variables in the model 0·67 and 0·73 of the variation could be accounted for at 3·5 and 7 months of age respectively.

The results of the experiment have to be considered with caution because only one sire was used per group, the parents were preselected, and the number of animals was small. The results, however, do indicate that plasma levels of hormones and metabolites in the early life of potential breeding bulls, measured after suitable physiological challenges, may be useful as selection criteria for butterfat production of their offspring.

The genetic progress in live-weight-for-age (LFA), milk production, and in overall economic value expected as a result of performance and progeny testing of young bulls with respect to milk production and LFA was computed. It was shown that performance testing can contribute considerably to overall progress in economic value, while under certain circumstances progeny testing for LFA can also contribute to genetic progress in overall economic value, but to a lesser degree than performance testing. The relative economic value of LFA and milk production was derived and found to be relatively stable under differing economic conditions.

The apparent and true amino acid (AA) digestibility from soya-bean meal (SBM), vetch meal (VM), field pea meal (FPM) and bitter vetch meal (BVM) were determined in the lower ileum of growing chickens force-fed on semisynthetic diets (120 g crude protein and 13·1 MJ metabolizable energy per kg dry matter) based on each meal as the sole source of protein. The average apparent and true digestibility values were 0·82, 0·73, 0·76 and 0·60 and 0·90, 0·91, 0·87 and 0·74 for diets SBM, VM, FPM and BVM, respectively. Marked differences in AA digestibility among diets were found. The apparent digestibility of methionine, the most limiting essential AA in poultry diets, was significantly higher in diet SBM than in diets FPM and BVM (P < 0·05). It is concluded that the seeds of vetch and field pea may be suitable for inclusion in poultry diets as partial substitutes for soya bean. The use of bitter vetch is not recommended.

One hundred and sixty-two spring born steers comprising 54 Charolais × Friesian (CH), 54 Hereford × Friesian (HE) and 54 Friesians (FR) were reared together from shortly after birth until the end of their second grazing season at a mean age of 573 days. The animals were then blocked on weight within genotype, housed in a slatted shed and allocated to either a high (12·6 MJ metabolizable energy (ME) per kg) or a medium (10·4 MJ ME per kg) energy diet offered ad libitum until slaughter at one of three target carcass weights · light (260 kg (HE, FR and CH)), normal (300 kg (HE and FR) and 320 kg (CH)) or heavy (340 kg (HE and FR) and 380 kg (CH)) to give a 3 (breed type) · 2 (energy level) · 3 (slaughter weight) factorial arrangement during the finishing winter. The trial was repeated in 3 years consecutively.

CH were significantly heavier than HE at all times up to 18 months of age when they were 43 kg heavier, at which stage they were also 24 kg heavier than FR. CH grew significantly faster at pasture than HE in both seasons and faster than FR in the second season. HE had the best daily gain in the finishing period.

Overall slaughter weights per day of age, carcass weights per day of age and carcass weights of CH, HE and FR were 812, 771 and 761 (s.e. 9·2) g, 448, 418 and 405 (s.e. 4·8) g and 318. 299 and 298 (s.e. 2·2) kg, respectively. CH had significantly better killing-out proportions (lOg/kg) than HE which in turn were 10 g/kg better than FR. CH and FR had similar carcass length, carcass depth, leg length and leg widths and both were significantly larger than HE. CH had significantly larger longissimus dorsi areas than either HE or FR (80·9 v. 67·0 and 66·4 cm-); they also had significantly better conformation scores than HE which in turn were significantly better than FR.

Increasing the energy level during the finishing period increased daily gain by proportionately 0·52 (1089 v. 684 g/day), reduced slaughter age by 51 days (711 v. 762 days) and significantly increased killing-out proportion (551 v. 534 g/kg) and conformation score (4·86 v. 4·64). Offal as a proportion of empty live weight tended to be higher for FR than for HE or CH, the exception being the hide, which was significantly lower for FR.

In a 12-week trial, 12 Alpine and 12 Saanen dairy goats in mid lactation were housed in individual stalls for behavioural, digestive and metabolic studies. Eight of them were fitted with ruminal cannulae. They were offered ad libitum four complete diets CR, CS, FR and FS (450 g dry matter (DM) per kg) in a 4 ✕ 4 Latin-square design. Forage: concentrate ratio was either low (C = 30: 70) or high (F = 55: 45) and starch source either rapidly (R, barley) or slowly (S, maize) degraded in the rumen.

Diet preferences were tested. DM intake, chewing activities and performance were determined. Ruminal pH and ammonia-nitrogen (NH3-N) concentrations were measured. Goats were also challenged intravenously with glucose (0·2 g/kg live weight) to assess glucose homeostasis.

CR was the most preferred diet. The level of intake differed according to the type of starch (2·2 kg DM per day of CR and FR and 2·0 kg DM per day of CS and FS). FS lowered ruminal pH significantly less than the other diets after the meal. Ruminal NH3-N concentrations were lower in goats given CR and CS than FR and FS. Goats’ resistance to a glucose challenge was not different among diets. Milk yield was 2·00, 1·85, 2·01, 1·85 kg/day on CR, CS, FR and FS respectively. Milk fat content decreased significantly with diets rich in concentrate (24 v. 26 g/kg milk) but milk protein content varied only a little.

In conclusion it appears that (1) higher forage: concentrate ratios were less preferred and decreased ruminal acidity but increased daily chewing, ruminal NH3-N and milk fat content; and (2) rapidly degraded starch increased intake, ruminal acidity and milk yield.

Five groups of 24 Aberdeen Angus steers, initially 8 months old and 185 kg in weight were subjected to varying degrees of restriction of energy intake, by feeding them on diets containing 1·45 to 2·85 Meal metabolizable energy (ME)/kg dry matter (DM) for 16 weeks. During the realimentation period that followed, all animals were fed ad libitum on the diet containing 2·85 Meal ME/kg DM. When realimentation began the feed consumption of all animals, which had been markedly different, rapidly became similar. When compared at equal live weight the restricted animals had higher intakes than the controls; at an equal age, however, feed intakes were practically the same. This led us to discard compensatory feed intake as a possible explanation for compensatory growth. Age explained 65% of the variability in feed intake, live weight explained 43% and both parameters jointly explained 73%. It is concluded that in restricted and realimented animals, age is a better predictor of feed intake than live weight. Compensatory growth is attributed to a lower maintenance requirement in restricted animals because of their lower live weight at the beginning of the realimentation period.

The relationships between the sucking behaviour of newborn piglets during bouts of sucking and their serum immunoglobulin G (IgG) levels at 12 h of age were investigated in 274 Landrace × Yorkshire piglets from 24 second parity Yorkshire sows. Mean IgG level differed between litters but was not related to the number of live-born piglets or the mean birth weight of the litter; in addition, the amount of variation in IgG level within a litter was not related to the number of live-born piglets or the amount of variation in birth weight of the piglets.

Within a litter, lower serum IgG levels were found in piglets of birth orders greater than eight and piglets that had a very low frequency of sucking bouts. The piglets that had the higher IgG levels within a litter were those that started to suck sooner, sucked from many teats and won more of their teat disputes. Piglets that were involved in fewer teat disputes within a litter or took a greater proportion of their sucking bouts on anterior teats did not have higher IgG levels. Piglets that died differed from their surviving litter-mates in having lower IgG levels and having lost weight during the first 12 h after birth. Within a litter, IgG levels were not related to 10-day weight gain. However, litters with a lower mean IgG level also had a lower mean 10-day weight gain. It is suggested that a low mean IgG level in a litter reflects or predicts a low milk production by that sow.

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.

Three experiments employing 40, 39 and 15 Large White × (Landrace × Large White) gilts respectively were carried out to investigate possible primer pheromone activity (i.e. regulating endocrine systems) for those 16-androstene steroids with known signalling pheromone activity (i.e. immediate behavioural effects) in the pig. Experiment 1 consisted of groups of prepubertal gilts exposed to one of the following odour sources (a) 5α-androstenone (5α-androst-16-en-3-one), (b) 3α-androstenol (5α-androst-16-en-3α-ol), (c) a mixture of both steroids, and (d) a diethyl ether extract of boar submaxillary salivary gland. Age at the onset of puberty in these gilts was compared with that in an unstimulated control group. Experiment 2 was similar to Experiment 1 except that the steroids were used at a higher concentration (100 fold), and a fifth group of gilts was exposed to an intact boar. In the third experiment, age at the onset of puberty was noted following exposure of groups of gilts to one of the following (a) a castrated boar which had received long term injections of testosterone, (b) urine from an intact boar, (c) an intact boar.

The results confirmed that the intact boar accelerates puberty in gilts. Although there was no conclusive evidence indicating that isolated boar odours had an effect on the onset of puberty, it is noteworthy that of those gilts exposed to 3α-androstenol, more reached puberty earlier than control gilts. However there is the possibility that transportation may have enhanced the earlier puberty found in some of the gilts taken to a source of 3α-androstenol. Prolonged treatment of a castrated boar with testosterone did not maintain its ability to accelerate puberty in gilts.

Pyrroloquinoline quinone (PQQ), a putative essential nutrient and redox modulator in microorganisms, cell and animal models, has been recognized as a growth promoter in rodents. Growth performance, carcass yield and antioxidant status were evaluated on broiler chickens fed different levels of PQQ disodium (PQQ.Na2). A total of 784 day-old male Arbor Acres (AA) broilers were randomly allotted into seven dietary groups: negative control group (NC) fed a basal diet without virginiamycin (VIR) or PQQ.Na2; a positive control group (PC) fed a diet with 15 mg of VIR/kg diet; and PQQ.Na2 groups fed with 0.05, 0.10, 0.20, 0.40 or 0.80 mg PQQ.Na2/kg diet. Each treatment contained eight replicates with 14 birds each. The feeding trial lasted for 6 weeks. The results showed that chicks fed 0.2 mg PQQ.Na2/kg diet significantly improved growth performance comparable to those in PC group, and the feed efficiency enhancement effects of dietary PQQ.Na2 was more apparent in grower phase. Dietary addition of PQQ.Na2 had the potential to stimulate immune organs development, and low level dietary addition (<0.1 mg/kg) increased plasma lysozyme level. Broilers fed 0.2 mg PQQ.Na2/kg diet gained more carcasses at day 42, and had lower lipid peroxide malondialdehyde content and higher total antioxidant power in plasma. The results indicated that dietary PQQ.Na2 (0.2 mg/kg diet) had the potential to act as a growth promoter comparable to antibiotic in broiler chicks.

Enhancing healthy fatty acids (FAs) in ewe milk fat and suckling lamb tissues is an important objective in terms of improving the nutritional value of these foods for the consumer. The present study examined the effects of feeding-protected lipid supplements rich in unsaturated FAs on the lipid composition of ewe milk, and subsequently in the muscle and subcutaneous adipose tissues of lambs suckling such milk. Thirty-six pregnant Churra ewes with their new-born lambs were assigned to one of three experimental diets (forage/concentrate ratio 50 : 50), each supplemented with either 3% Ca soap FAs of palm (Control), olive (OLI) or fish (FO) oil. The lambs were nourished exclusively by suckling for the whole experimental period. When the lambs reached 11 kg BW, they were slaughtered and samples were taken from the Longissimus dorsi and subcutaneous fat depots. Although milk production was not affected by lipid supplementation, the FO diet decreased fat content (P<0.001), whereas the OLI milk FA profile resembled that of the Control diet. In contrast, although FO drastically diminished the contents of stearic and oleic acids (P<0.001), all the saturated even-numbered carbon FAs from 6:0 to 14:0 increased (P<0.05). FO also produced the highest levels of c9,t11-18:2 (2.21%) and n-3 FAs, 20:5 n-3 (0.58%), 22:5 n-3 (0.48%) and 22:6 n-3 (0.40%). The high levels of trans-11 18:1 (7.10%) obtained from the FO diet would suggest that Ca soaps only confer partial protection in the rumen. In contrast, the lack of significant differences in trans-10 18:1 levels (P>0.05) and other trans-FAs between Control and FO treatments would indicate that FO treatment does not alter rumen biohydrogenation pathways under the assayed conditions. Changes in dam milk FA composition induced differences in the FA profiles of meat and fat depots of lambs, preferentially incorporated polyunsaturated FAs into the muscle rather than storing them in the adipose tissue. In the intramuscular fat of the FO treatment, all the n-3 FAs reached their highest concentrations: 0.97 (18:3 n-3), 2.72 (20:5 n-3), 2.21 (22:5 n-3) and 1.53% (22:6 n-3). In addition, not only did FO intramuscular fat have the most cis-9, trans-11 18:2 (1.66%) and trans-11 18:1 (3.75%), but also the lowest n-6/n-3 ratio (1.80) and saturated FA content were not affected. Therefore, FO exhibited the best FA profile from a nutritional point of view.

The present work summarizes research related to the definition of nutrient recommendations for feeds used in the intensive production of rabbit's meat. Fibre is the main chemical constituent of rabbit diets that typically contain 320 to 360 and 50 to 90 g/kg of insoluble and soluble fibre, respectively. Instead, the dietary contents of cereal grains (∼120 to 160 g/kg), fat (15 to 25 g/kg) and protein concentrates (150 to 180 g/kg) are usually low with respect to other intensively reared monogastric animals. Cell wall constituents are not well digested in rabbits, but this effect is compensated by its stimulus of gut motility, which leads to an increasing rate of passage of digesta, and allows achieving an elevated dry matter intake. A high feed consumption and an adequate balance in essential nutrients are required to sustain the elevated needs of high-productive rabbits measured either as reproductive yield, milk production or growth rate in the fattening period. Around weaning, pathologies occur in a context of incomplete development of the digestive physiology of young rabbits. The supply of balanced diets has also been related to the prevention of disorders by means of three mechanisms: (i) promoting a lower retention time of the digesta in the digestive tract through feeding fibre sources with optimal chemical and physical characteristics, (ii) restricting feed intake after weaning or (iii) causing a lower flow of easily available substrates into the fermentative area by modifying feed composition (e.g. by lowering protein and starch contents, increasing its digestibility or partially substituting insoluble with soluble fibre), or by delaying age at weaning. The alteration in the gut microbiota composition has been postulated as the possible primary cause of these pathologies.

In today's production systems, pigs raised for slaughter are mixed many times, resulting in stress and fighting. The negative consequences of mixing are probably more severe with entire males than with castrates, as they fight more. In this project, we studied a system without castration where entire male pigs met unfamiliar pigs only once. Piglets from two litters were allowed to visit each other from circa 2 weeks of age through an opening between the farrowing pens. Entire males from these litters were kept in intact groups from weaning and onwards, and they were slaughtered pen-wise in intact groups. Control pigs were raised and weaned in their litters and mixed with unknown pigs when moved to the growing–finishing unit. They were slaughtered by split marketing based on individual weight. In total, 96 entire males from 24 litters were studied. Activity and social interactions of pigs were studied by direct observations on three observation occasions per pen for pigs kept in intact groups and four occasions for control pigs. All pigs were inspected for skin lesions during raising and at slaughter. Results showed that fewer pigs in intact groups were resting (17.1% v. 28.5%; P = 0.044) and they showed less aggressive behaviour (16.1 v. 27.7 number of interactions per hour; P = 0.001) than control pigs when moved to the growing–finishing unit. They also got fewer skin lesions compared with control pigs (15 v. 35; P < 0.001). Consequently, control pigs tended to grow slower during the 1st week after mixing; however, growth rate during the whole growing–finishing phase did not differ between treatments (P = 0.205). Control pigs directed more aggressive behaviour towards non-litter mates than towards litter mates during the whole growing–finishing phase, whereas pigs from the other treatment made no difference between litter mates and other familiar pigs. At 67 kg, there was more sexual behaviour (mounting) among control pigs (7.6 v. 3.4; P = 0.033), but after slaughter no differences were found in testis weight or boar taint compounds. At slaughter, more entire males that were slaughtered pen-wise and kept in intact groups were without skin lesions compared with the mixed control pigs (74% v. 13%; P < 0.001). This study shows that the welfare of entire male pigs can be improved by socialising piglets and by keeping them in intact groups during raising and at slaughter.

To measure the effect of partially replacing grass silage with urea-treated whole-crop wheat (WCW) four multiparous Holstein/Friesian lactating cows fitted with cannulas in the rumen and proximal duodenum were offered four diets in a Latin-square experiment. Grass silage (GS) was produced from the primary growth of a perennial ryegrass sward. Spring wheat (cv. Axona) was harvested at 603 g dry matter (DM) per kg and preserved with 20 (WCW-20) or 40 (WCW-40) kg urea per t DM. The diets were 6 kg DM of a dairy concentrate daily with one of four forages offered ad libitum The forage treatments were GS alone, a 2: 1 DM ratio of GS with WCW-40 (2: 1 40), or a 1: 2 DM ratio of GS with WCW-20 (1: 2 20) or WCW-40 (1: 2 40). Each period lasted 4 weeks with rumen and duodenal samples being taken on 2 days in the last week. Concentrations of milk fat and protein were increased by WCW inclusion. The digestibility in the rumen of DM, organic matter (OM) neutral-detergent fibre (NDF), acid-detergent fibre and starch fell with increasing WCW-40 inclusion in the diet. Flow of starch and non-ammonia nitrogen to the duodenum increased with WCW inclusion. It was estimated that the amounts of OM, starch, NDF and nitrogen digested post ruminally increased with WCW. With WCW there were increases in the rumen in the ratio of acetic acid plus n-butyric acid to propionic acid and in ammonia concentrations. The level of urea inclusion had no significant effects on rumen digestion. It is concluded that the large reduction in the contribution of the rumen to total OM digestion when WCW partially replaces grass silage may have implications for calculations of metabolizable protein supplies to animals given such diets. Possible means to improve food utilization include processing of the wheat grains and inclusion of readily fermentable carbohydrates in the diet to facilitate the utilization of the rumen ammonia.

‘Sustainability” has been defined in so many different ways that it no longer has an accepted (or acceptable) meaning. Nevertheless, it is being used as a label to confer respectability on corporate plans and research proposals, practical projects, attitudes and intellectual positions. The weaknesses of current definitions are examined with a view to clarifying the physical, biological and socio-economic objectives, covered by the term ‘sustainable’.

Since it is no longer feasible to abandon the term or to restrict its scope, it is worth considering what useful meaning can be attached to the concept. An attempt is made to spell out the tvays in which it could sensibly be used in relation to animal production systems. It is suggested that this would have to take the form of a package of expressions covering the essential attributes offuture animal production systems.

The influence of high fat diets on several production traits of primiparous and multiparous rabbit does was studied in 246 lactations from a total of 61 crossbreed rabbit does (Californian × New Zealand). Starting with a control diet (diet C) with 26 g ether extract (EE) per kg dry matter (DM), two isoenergetic diets were formulated adding fat from vegetable sources up to 99 g EE per kg DM (diet V) or animal sources up to 117 g EE per kg DM (diet A). Digestible energy/digestible protein ratio (DE/DP) was maintained between 82 and 87 kj/g. Food intake decreased with high fat diets compared with the control diet during gestation (P ‘lt; 0·001), which implied a decrease in the DE intake (P < 0·01 and P < 0·05 for primiparous and multiparous does, respectively). Fat addition did not affect food intake of primiparous does during lactation (101·8,106·9 and 103·7 g DM per day per kg live weight (M)0·75 for C, V and A diets, respectively) but increased the DE intake (1121 kj/day per kg M°0·75 for C diet cf. 1325 for V and 1264 for A diets; P < 0·01) and reduced does' weight losses at the end of lactation (F > 0·05). However, multiparous does on C diet showed a greater food intake during the last 2 weeks of lactation (110·6 for C diet v. 101·5 and 98·9 g DM per day per kg M0·75 for V and A diets, respectively; P < 0·001). High fat diets improved significantly the productive parameters at the 21st day of lactation: increasing litter size (P < 0·01 for multiparous does) and weight (P < 0·01 and P < 0·001 for primiparous and multiparous does, respectively) and decreasing the food conversion ratio (P < 0·001). An increase of dietary fat content decreased solid food intake of litters during the last 2 weeks of lactation (P < 0·01 and P < 0·001 for primiparous and multiparous does, respectively) but only affected their solid DE intake slightly. In conclusion, high fat diets seem to improve the productivity of lactating does and their corporal condition during the first lactation.

A 2 × 2 factorial design experiment was conducted for 2 years using 72 British Friesian cows to assess the effects of two levels of concentrate input (822 and 610 ± 13·7 kg/cow) and two stocking rates (6·4 and 4·9 cows/ha) on animal performance. The animals, which had a mean calving date of 22 January, were blocked according to calving date and allocated at random to treatments within each block.

All concentrates were given during the post-partum, indoor-feeding period in addition to ad libitum grass silage. All animals received equal concentrate inputs/kg milk produced for the first 4 weeks after calving following which the input to the low concentrate animals was reduced. The animals went to pasture during mid-April and were rotationally grazed for a 24-week period. The pasture received 450 kg N/ha. No interaction between concentrate input and stocking rate was found. The mean milk outputs during the winter period were 2064 and 1971 ±23·9 kg, during the grazing period 2679 and 2739 ± 53·2 kg, and during the total lactation 4991 and 4984 ± 78·8 kg for the high and low concentrate groups respectively. The mean live weights for the two groups were 515 and 496 + 3·1 kg at the end of the winter period and 549 and 537 ± 4·1 kg at the end of the grazing season. The mean values for the high and low stocking rates respectively were: output/cow at pasture, 2571 and 2847 ± 53·2 kg; total lactation yield, 4804 and 5170 + 78·8 kg; live weight at end of grazing season, 529 and 558 + 4·1 kg. Milk composition data are also presented.

Spreadsheet models were constructed to assess the economic impact of some 30 non-notifiable diseases of farm animals in Great Britain. A standardized methodology and common valuation base were used to derive estimates of the direct costs to livestock production of each disease, separately identifying the costs associated with disease output losses and those relating to disease treatment and prevention. Disease data limitations and uncertainties are incorporated into the estimation procedure. The spreadsheet models are highly transparent with calculations and the origin of parameter values clearly documented. The assessments of six bovine diseases, are presented: BVD, fasciolosis, lameness, leptospirosis, mastitis, and summer mastitis, and full details of the analyses of all the diseases can he accessed on the internet. The models do not consider the wider economic impacts of disease, such as effects on markets, human health and animal welfare. However, the approach is a simple and transparent one which enables exploration of the direct costs associated with a range of livestock diseases and which is easily communicated to policy makers and others.

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to – 20° C. The exposures were separated by a period of two weeks in either a thermoneutral environment ( + 30° C.) or a subcritical environment ( + 8° C.). Thirty-seven out of 40 sheep showed a greater resistance to body cooling at the second exposure. The mean rates of fall of rectal temperature (in° C. per 100 min. exposure) were 0·42 at the first exposure and 0·22 at the second exposure. One group of sheep showed virtually complete resistance to cooling at second exposure under the specific test conditions used. The highly significant increase in cooling resistance was taken as a measure of acclimatisation.

The main conclusions were as follows:

1. Blackface sheep could acclimatise to cold as a result of one acute exposure to cold lasting about 8 hours.

2. Acclimatisation was slightly greater amongst sheep kept at a subcritical temperature (+8° C.) between acute exposures.

3. Additional data suggested that some acclimatisation resulted from 2 weeks prior exposure to +8° C. alone; but none was induced by 2 weeks prior habituation to the climate chamber environment at + 30° C.

4. Sheep on high plane nutrition showed greater initial cold resistance and slightly greater ability to acclimatise than those on low plane nutrition.

5. Cold resistance was more closely related to recent weight gain than to absolute body weight.

6. There was great individual variation in initial cold resistance and in ability to acclimatise.

7. Sheep kept at + 8° C. between acute cold exposures maintained significantly lower rectal temperatures than those kept at +30° C.