Meals prepared from low glucosinolate rapeseed screenings (SCREEN) and from seed which had heated during storage (HEAT) were compared against commercial rapeseed meal (COM) for feeding value. Oil, crude protein (CP) and acid-detergent insoluble nitrogen contents in SCREEN, HEAT and COM, respectively, were (g/kg): 118, 246 and 13; 227, 315 and 436; and 17, 64 and 21. in situ dry matter (DM) and protein disappearance rates, soluble protein fraction and effective rumen degradability of protein (EDCP) were lower (P < 0·05) in HEAT than in SCREEN or COM. Comparing oil-extracted meals in situ, EDCP of HEAT was lower (P < 0·05) than EDCP of SCREEN or COM but protein and DM disappearance rates of HEAT were only lower (P < 0·05) than those of SCREEN. Four isonitrogenous barley-based diets (150 g/kg CP, DM basis), containing SCREEN, HEAT, COM or COM supplemented with rapeseed oil (OIL), were given to lambs. For DM, organic matter and neutral-detergent fibre apparent digestibilities, the diets ranked SCREEN > HEAT = OIL > COM (P < 0·05). Digestion and retention of nitrogen were lower (P < 0·05) in lambs given HEAT than in lambs given other diets. Food efficiency of lambs given HEAT was improved (P < 0·05) as compared with lambs given SCREEN or COM. Dressing proportions were higher (P < 0·05) with HEAT, SCREEN and OIL diets than with COM. Other than minor changes in fatty acid composition of subcutaneous fat with HEAT and OIL, carcass traits were not altered by treatment. Feeding SCREEN or HEAT did not adversely affect animal performance or food utilization.

One of Bertrand Russell's contributions to philosophy was to show that there are certain questions, quite simple to state, to which no sensible answer can be given. While writing this paper I began to feel that the question ‘what is the optimum size of the dairy cow ?’ is perhaps among these. Let me first ask what we mean by the question, what assumptions we have to make to answer it, and finally what use is the answer.

Antibiotics have been widely used in piglet diets to promote growth performance and reduce diarrhea incidence. However, the resistance of pathogens to antibiotics and the risk of residues of antibiotics in animal products induced a growing interest in the use of alternatives to in-feed antibiotics. Chito-oligosaccharide (COS), a natural alkaline polymer of glucosamine is currently being tested as a substitute for in-feed antibiotics. In weaned piglets, COS has positive effects on promoting growth, which may be related to its action on intestinal morphology, immune ability and beneficial microbiota. However, previous studies shown variable results with effective doses ranging from 30 mg/kg to 5 g/kg. Therefore, the goal of this study was to test the hypothesis that the use of COS can be an alternative to in-feed antibiotics by improve the intestinal morphology of piglets, using the jejunal explant model. The intestinal explants were exposed for 4 h to following treatments: control – only culture media and culture media with COS in doses of 0.025 mg/ml, 0.05 mg/ml, 0.1 mg/ml and 0.15 mg/ml. After the incubation period the explants were processed for histological and morphometrical analysis. The histological changes were evaluated using an adapted histological score based on the intensity and severity of lesions. Mild histological changes were observed in jejunal explants exposed to different treatments; however, no significant difference in the histological score, villi height, crypt depth or villus : crypt ratio were observed between the COS-groups and the control. In addition, goblet cells density in intestinal explants exposed to COS remained statistically similar to control group. Our results indicate that COS exposure in levels ranging from 0.025 to 0.15 mg/ml induced no effect on intestinal morphology of pig’s explants. The research will provide guidance on the low dosage of COS supplementation on weaning pigs.

There has been growing discussion on the association of dietary factors with human health and disease. One such association which has been highlighted is that between saturated fat and heart disease. It is vital that both food producers and food processors are sensitive to consumer requirements in this context, and that they modify their production processes in response to changing consumer demand. At this stage, however, there is much uncertainty regarding the current and long term demands of consumers and in the degree of variation in such demand, for example, between different locations, age and social groups. Thus, in order to inform farmers and food processors it is necessary to determine consumer beliefs and attitudes regarding aspects of diet in order to get some measure of factors affecting demand now and in the future. This project set out to measure certain aspects of consumer attitude to fat in meat. The ultimate objective was to obtain information for decision takers in the meat industry.

Daylengths of 13 or 20 hr were applied to six groups of nine ewes during the 2nd to 8th, 8th to 14th and 14th to 20th week of pregnancy. Two groups of nine non-pregnant ewes received a constant 13- or 20-hr daylength during the above experimental period. A group of 10 non-pregnant ewes which initially received a 20-hr daylength were subjected to a 13-hr daylength in the last 14 to 20 weeks of the experimental period. After parturition (26 March) all the ewes received increasing natural daylength.

The mean number of days from the onset of the experimental light treatments (17 November) to the cessation of oestrous activity did not vary significantly between the three non-pregnant groups of ewes and was on average 89 days.

Only two of the 82 ewes, both non-pregnant, exhibited oestrus prior to the longest day (22 June). The various light treatments did not significantly affect the mean dates of occurrence of the natural breeding season of the groups of ewes.

Enzymic hydrolysis of phytates has been shown to improve the apparent digestibility of phosphorus. Other nutrients bound to phytates may be released during phytate degradation by phytases. Dietary yeast may also improve the availability of phosphorus to pigs by altering gut fermentation patterns.

The objectives of this experiment were (1) to study the effects of phytase on the apparent digestibility of phosphorus and other nutrients associated with phytates, and (2) to determine whether an alteration in fermentation induced by dietary yeast inclusion influenced availability of phosphorus.

There have been few studies realized that evaluate the effects of adopting different nutritional systems in more than one phase of cattle production on carcass and meat characteristics. This study was realized to evaluate carcass and meat characteristics from bulls submitted to different nutritional systems during two production phases. The experiment was conducted at Figueira’s farm during two production phases: I (cow–calf) – 80 calves (99.6±2.72 days of age and 109.7±2.99 kg of BW) with their mothers were randomly assigned into two supplemental diets: cow–calf mineral supplement (n=40) or cow–calf creep-feeding (n=40); II (stocker) – the same 80 calves (201.2±2.11 days of age and 190.2±3.37 kg of BW) were redistributed into two production systems: stocker pasture (n=40) or stocker feedlot (SF; n=40). After, all 80 animals were kept on a pasture system (III) for 290 days, and then finished in a feedlot system (IV) for more 33 days. Then, they were slaughtered at an average 764.2±3.06 days of age and at 499.2±3.33 kg of final BW. After slaughter, the average daily gain was calculated, and the carcass and meat characteristics were measured. The statistical model design used was completely randomized in a 2×2 factorial arrangement (two treatment groups on cow–calf phase and two treatment groups on stocker phase). The single effects between the groups in each phase and the interactions between both phases (cow–calf v. stocker) were analyzed. The results were compared by Fisher’s test, using the R statistical software. A cow–calf by stocker phases interaction occurred for carcass conformation and fiber diameter. For single effects, the greatest influences observed were in the stocker phase. The feedlot group was slaughtered 17 days earlier, with greater final BW (3.8%), hot carcass weight (5.7%), average daily gain (6.9%), dressing percentage (1.8%), carcass length (1.8%), carcass width (1.5%), longissimus muscle area (4.8%) and muscle depth (2.3%) than pasture group. The SF group also had influence on fat color; showing higher L* and lower b* values. These results reveal that bulls reared in feedlot at the stocker phase have higher muscle development and that the stocker phase has the greatest potential to influence carcass characteristics and meat quality.

The objective of this work was to determine the apparent bioavailability of magnesium from four different types of calcined magnesites of Greek origin. These four types (A, B, C, D) were different in particle size fractions and production process. The solubility of the above four magnesium samples and their fractions were determined: (a) in the laboratory using ammonium nitrate solution after 24-h shaking and (b) in vivo using a nylon bag technique after 24-h incubation.

Solubility was correlated with apparent bioavailability as determined in a balance experiment with five wether sheep in a 5×5 Latin-square design.

Sheep were kept in metabolism cages and were given daily a basal diet (500 g hay + 700 g concentrate) plus 2 g magnesium supplements from types A to D. The magnesium bioavailability of the basal diet was used as a base for the determination of the bioavailability of magnesium in A, B, C and D supplements.

Magnesium apparent bioavailability of the basal diet was found to be 0·203 and, for the supplements A, B, C and D, 0·381, 0·339, 0·315 and 0·292 respectively. The solubility of supplements A, B, C and D in ammonium nitrate solution and in vivo (using the nylon-bag technique) was found to be 0·812, 0·805, 0·784 and 0·773 or 0·294, 0·152, 0·102 and 0·200 respectively.

The solubilities of the magnesium supplements in ammonium nitrate solution and in vivo both reflected dietary bioavailability differences up to a point, but neither was well enough correlated with the apparent bioavailability as determined by the balance experiment, this being judged to be the most precise method for bioavailability determination.

Previously, sugar beet feed (SBF) was thought to be of limited value for feeding to growing pigs due to its high fibre content. Maximum inclusion rates recommended were 5 and 10 per cent for pigs from 20 to 45 and 45 to 90 kg live weight respectively (MAFF, 1986). However, the fibre is highly digestible and more recently Longland et al (1988) showed that replacement of cereals with SBF may be possible up to levels of 15 and 30 per cent for pigs of 20 and 75 kg live weight respectively. It was also shown that the performance of older pigs fed SBF was enhanced if SBF was introduced into their diets at an early stage. The work was undertaken on individually housed pigs over a wide range of inclusion rates. The experiment reported here investigated the effect of providing SBF to group-housed pigs from 15 to 35 kg live weight and its effect on subsequent performance during the finishing stage. A further objective was to determine the optimum inclusion rate of SBF when fed to finishing pigs.

Fertility of rams was studied following their exposure to heat for 1 or 3 days in a hot room. Eight to 16 days later exposed rams showed significantly lower fertility as judged by lambing rate of ewes compared with unheated control rams. From 25 to 36 days after exposure treated rams were not significantly less fertile than controls. There were no significant differences in fertility between rams exposed 1 day or 3 days to heat.

This experiment evaluated different strategies for allocating first-cut grass silages to dry dairy cows that had low body-condition score (BCS) at drying off. A total of 48 moderately yielding Holstein-Friesian cows were used, receiving one of three dietary treatments in the dry period and a single lactation diet based on a flat-rate of concentrates and grass silage ad libitum. Throughout the dry period, one group received a low-digestibility silage (harvested 15 June 1998; LL; metabolisable energy (ME) = 10.3 MJ/kg dry matter (DM)) and a second group received a high-digestibility silage (harvested 9 May 1998, HH; ME = 11.7 MJ/kg DM). A third strategy (LH) offered the low-digestibility silage in the early dry period and the high-digestibility silage in the final 3 weeks before calving. The silages had very different crude protein concentrations (144 and 201 g/kg DM) and intakes were widely divergent (10.1 v. 13.5 kg DM/day) across the dry period. No concentrates were fed during the dry period. Silage quality had a very large effect on liveweight change, with treatment means of 0.32 and 1.75 kg/day for LL and HH, respectively. BCS changes followed a similar pattern, though no cows became over-conditioned and blood metabolites were within normal ranges. Increased silage digestibility in the late dry period led to a substantial increase in milk fat concentration and a smaller increase in milk protein concentration, the latter confined to the first full week of lactation. Depression of milk fat appears related to low blood glucose when dry cows in low body condition are fed at a low level. The LH strategy avoided the tendency for lower milk yields and fat concentration that resulted from feeding the low-digestibility silage until calving. This strategy also avoided the higher calf weights that resulted from feeding the high-digestibility silage in the early dry period.

The silage intake and growth rate of naturally suckled calves after weaning was less than that of similar groups of artificially reared animals that had received lower quantities of milk over the period to 8 months of age. Although the silage intake of all groups was linearly related to the level of herbage intake prior to weaning, those calves consuming least herbage had the higher rate of increase in silage intake. It was concluded that silage intake can be influenced for a considerable time after weaning by the level of herbage consumption achieved during the suckling period.

Muscle to bone weight relationships within anatomical regions (proximal-distal division into pelvic, thigh and lower leg groups) and subregions (division within regions into gluteal, intrinsic pelvic, cranial, caudal and medial thigh, and cranial and caudal lower leg groups) of the hind limb and also of its most important muscles (no. = 11) were compared between goats and sheep using the method of multivariate analysis of the centred data. In this comparison, a total of 39 animals was considered: 13 male kids of the Alpine breed (K) and a sample of 26 male lambs derived from different breeds or crossbreeds representing, in equal numbers, lambs having good conformation (LGC) and poor conformation (LPC). Lambs were chosen on the basis of the hindlimb length the means of which were 22·9 (s.e. 1·5), 29·3 (s.e. 1·8) and 29·1 (s.e. 2·5) cm for LGC, LPC, and K, respectively. Corresponding cold carcass weights were 19·71 (s.e. 347), 17·28 (s.e. 1·77) and 10·84 (s.e. 0·56) kg.

In both comparisons (K-LGC and K-LPC) the two species were systematically distinguished by the size of the following ratios: (pelvic muscles/os coxae + leg muscles /tibia) relative to thigh muscles/femur (for regions), which was lower in lambs than in kids; intrinsic pelvic muscles/os coxae relative to caudal thigh muscles/femur (for subregions), which was higher in kids than in lambs. For individual muscles, they were distinguished by the size of the following ratios: rectus (emoris/femur relative to semimembranosus/femur (or gluteus medius/os coxae) in the comparison K-LGC, which was higher in lambs than in kids, and vastus lateralis/femur relative to sum of pectineus + gracilis/femur (or gastrocemius/tibia) in the comparison K-LPC, which was lower in kids than in lambs. The results show that the muscle-bone ratios of the anatomical regions, subregions and the most commercially important muscles in the hindlimb can be used as discriminant characteristics of species.

Ad libitum feeding provides the opportunity for animal scientists to explore the genetic and environmental factors which determine voluntary feed intake, a greater knowledge of which could help increase potential appetite thereby raising the level at which the latter may limit productivity. A Braude Travel Scholarship was used to finance a visit to a number of research establishments based in the Netherlands, Denmark and France to observe the extent to which diet and related factors are examined through experimentation, the results of which may contribute to our understanding of the mechanisms of feed intake control. Major differences in the production systems encountered in these countries when compared with the UK include the greater emphasis given to current environmental issues, expression of dietary energy as NE, production of castrated males, heavier slaughter weights and associated export demands. Such factors substantially influence the direction taken by nutrition research programmes. Although the primary purpose of the study tour was the appraisal of dietary factors in relation to food consumption, such effects could not be considered in isolation from associated genetic, physiological and environmental aspects, hence their inclusion in this report.

There are differences in grass-clover proportions and chemical composition between herbage from primary growth (PG) and regrowth (RG) in grass-clover leys. Mixing silages made from PG and RG may provide a more optimal diet to dairy cows than when fed separately. We tested the hypotheses that increasing dietary proportions of grass-clover silage made from RG compared with PG would increase digestion rate of potentially degradable NDF (pdNDF), and increase ruminal accumulation of indigestible NDF (iNDF). Eight rumen cannulated Norwegian Red cows were used in two replicated 4×4 Latin squares with 21-day periods. Silages were prepared from PG and RG of an organically cultivated ley, where PG and RG silages were fed ad libitum in treatments with RG replacing PG in ratios of 0, 0.33, 0.67 and 1 on dry matter basis in addition to 8 kg concentrate. We evaluated the effect of the four diets with emphasis on rumen- and total tract fiber digestibility. Increasing RG proportions decreased silage intake by 7%. Omasal flow of pdNDF decreased, whereas iNDF flow increased with increasing RG proportions. Increasing RG proportions decreased rumen pool sizes of NDF and pdNDF, whereas pool sizes of iNDF and CP increased. Increasing RG proportions increased digestion rate of NDF, which resulted in greater total tract digestion of NDF. Pure PG diet had the highest calculated energy intake, but the improved rumen digestion of NDF by cows offered 0.33 and 0.67 of RG leveled out milk fat and protein yields among the three PG containing diets.

In each of 2 years, 20 Friesian cows were given either a low-energy or a high-energy complete diet to appetite during weeks 3 to 20 of lactation. The diets for trial 1 contained concentrates, lucerne silage and chopped grass hay in the proportions 33:47:20 or 58:29:13. In trial 2, concentrates and lucerne silage were mixed in the proportions 38:62 or 75:25. These mixtures had energy concentrations of 10·2 or 11·2 and 10·3 or 11·9 MJ metabolizable energy per kg dry matter (DM) and crude protein concentrations of 144 or 160 and 140 or 157 g/kg DM in the low- and high-energy diets of trials 1 and 2 respectively.

Cows offered the low-energy diet consumed less DM daily (14·5 v. 17·4 (P < 0·001) and 15·2 v. 18·2 (P < 0·001) kg DM per day in trials 1 and 2). Daily milk yields were lower with low-energy diets (19·2 v. 22·3 (P < 0·001) and 18·7 v. 24·2 (P < 0·001) kg/day in trials 1 and 2), and there were significant differences between treatments in milk composition and live-weight changes.

The correlation between food intake and milk yield during weeks 3 to 20 was moderately strong (r2 = 0·58). Variation in food utilization efficiency between diets and parity groups was small in comparison to variation within parity groups.

During weeks 21 to 44 of lactation the cows were at grass. In trial 2, but not in trial 1, cows previously given the low-energy diet gave less milk (1999 v. 2644 (P < 0·001) kg) but gained more live weight. There were also differences in the composition of milk produced in this period.

It has been shown (Robinson, 1951) that in the ewe the number of ova shed can be increased by the injection of a single dose of mare serum gonadotrophin (P.M.S.) if this is given during the follicular phase of the oestrous cycle. The investigations described here were made to examine the usefulness of this treatment for increasing the lamb crop in commercial flocks.

Observations were made on 594 ewes of 3 breeds in 11 flocks (Romneys, 9; Cheviot, 1; Southdown, 1). Most ewes were purebred from old-established flocks. The Romneys were running on the marshlands and mixed farms of Kent and East Sussex, the South-downs were near Glynde, in Sussex, and the Cheviots were on a farm near Brampton in Cumberland. Management within the flocks followed the practice normal for the different breeds. Most ewes were 2½ to 4½ years old at the start of treatment; a few younger ewes (1½ years) and some aged ewes were also involved.

Piglets were weaned at 21 days of age, and given diets containing 13·5 or 17·0g crude protein per MJ digestible energy and either 14·7 or 16·8 MJ digestible energy per kg in a 2 × 2 factorial experiment until 56 days of age. There was no effect on performance or food intake when the diets were offered ad libitum, but energy intake was increased with the higher concentration of dietary energy. The higher levels of both protein and energy improved performance in a metabolism experiment with food intake restricted to 0·80 of ad libitum intake, and the higher protein level increased nitrogen retention (g/day per kg live weight) and plasma urea nitrogen. These results suggest that the level of food intake can affect the response to changes in dietary energy and protein concentrations, and indicate that conclusions from metabolism experiments using restricted feeding may be inappropriate under other conditions.

Two trials were conducted at the BOCM Silcock Development Unit at Stoke Mandeville. The first trial evaluated the response on doe and progeny, from mating to 8 weeks after parturition, of rabbit compound diets containing 0, 100, 200 and 300 g sodium hydroxide-treated straw per kg. Performance data showed no detrimental effect of inclusion levels up to 300 g sodium hydroxide-treated straw per kg despite its high sodium concentration.

A second trial was made to ascertain whether these findings were due to the treated straw itself or to increasing sodium concentrations. A standard rabbit compound diet containing 2·5 g sodium per kg was compared with diets containing either 5·0 or 10·0 g sodium per kg, and with experimental compound diets containing either 80 g sodium hydroxide-treated straw or 80 g untreated straw per kg and both containing 2·5 g sodium per kg. Peak food conversion was estimated to occur at a dietary sodium concentration of 4·6g/kg, although the slope of the dose response curve was not statistically significant at the P ≤ level.

The results indicate that compound diets containing up to 80 to lOOg sodium hydroxide-treated straw per kg may be fed to rabbits and that inclusion of levels of up to 300 g sodium hydroxide-treated straw per kg are not detrimental to performance. On the other hand, an inclusion of 80 g untreated ground straw per kg in compound diets for rabbits had a growth-depressing effect.