Following a pilot study, the aim of this study was to test the hypothesis whether occurrence of massaging the anogenital region of a calf by a non-maternal hind is a reliable indicator of adoption. The investigation was conducted between 28 May (1st day of calving) and 2 September (abrupt weaning of all calves) on a red deer farm at Vimperk, Czech Republic. Fifty hinds and their calves were observed but only complete data sets of sucking bouts were considered for evaluation. Massaging occurred mostly during the 1st month of the calf’s life. All filial calves were massaged repeatedly. Other calves received ano-genital massage at least twice (termed adopted), on a single occasion or not at all (termed non-filial). Filial and adopted calves behaved in a similar way but differently from non-filial calves. They sucked in an antiparallel standing position so that the hind could lick their ano-genital region more often than the non-filial calves. This occurred even when two calves were involved in the bout. When two calves were involved in the sucking bout, non-filial calves sucked from behind, between the hind’s hind legs. This position occurred more frequently with non-filial than among the filial and adopted calves. It was therefore concluded, that repeated allonursing accompanied with massaging of the ano-genital region of the sucking calf by the hind can be considered a signal of adoption. Hinds usually adopted calves older than their own progeny. The adopted calves were on average 2·5 days old. This suggests that it is most likely the calf’s activity which leads to bonding. No reciprocity was found in allosucking and/or allonursing. The fact that non-filial calves commonly initiated allosucking from a non-maternal hind during the day when she gave birth appeared crucial for establishing bonding which subsequently led to adoption. Hinds may be bonded with several calves including their own. Therefore, bonding with a non-filial calf did not principally mean failure in looking after their own progeny as shown in other studies.

This study investigated the effect of chromium picolinate supplementation on growth performance, carcass characteristics and lipid metabolism of growing-finishing pigs. Sixty Landrace ✕ Yorkshire ✕ Duroc (LYD) pigs with a mean initial body weight of 46·65 (s.e. 6·72) kg were randomly allocated into three groups with two replicates. They were supplemented with 0 , 200, or 400 μg/kg (ppb) chromium in the organic form of chromium picolinate for 90 days. Supplementation with chromium picolinate in the pigs’ ration improved their growth performance, enhanced average daily gain (P < 0·05), and increased their food consumption, especially in the 200 ppb group ( P > 0·05). Chromium picolinate supplementation also improved carcass characteristics, as the average back fat thickness was reduced and the loin-eye area was enhanced ( P < 0·05). The serum chromium concentration in the chromium picolinate supplemented groups was approximately twice that of the controls ( P < 0·05). Supplementation with chromium also markedly reduced serum total cholesterol, triacylglycerol (TG) and urea concentrations in the pig serum ( P < 0·05). Serum insulin was significantly decreased in the 400 ppb group, while serum glucose was decreased in the 200 ppb group ( P < 0·05). Very low density lipoprotein (VLDL) was reduced and low density lipoprotein (LDL) was increased in the chromium supplementation group. Meanwhile, the high density lipoprotein-cholesterol and VLDL-cholesterol were markedly increased, while LDL-cholesterol was significantly diminished ( P < 0·05) in the 200 ppb group. The adipocyte diameter and volume in the chromium-supplemented groups tended to be larger than in the control ( P = 0·07). In vitro studies indicated that incorporation of [u, 14C]glucose into total lipids (P < 0·05) was increased by chromium supplementation. However, there were no lipolysis differences among the groups (P > 0·05). The carcasses of the pigs that received the chromium supplemented ration contained less oleic acid (C18 : 1) and total unsaturated fatty acids (P < 0·05). On the other hand, the total saturated fatty acid content was higher than that of the controls (P < 0·05). Results in this study demonstrate that chromium picolinate supplementation in pigs has several beneficial effects.

Pony colts (~12 m) are generally infertile during the breeding season of mature stallions. The mechanism which ‘delays’ puberty beyond the first potential breeding opportunity has not been described. Four pre- and four post-pubertal colts were monitored from November for 13 (group 1, 6 to 19 months of age) and 9 months (group 2, 18 to 27 months of age). Fortnightly, 15 blood samples were collected at hourly intervals from each colt to determine concentrations of prolactin (PRL), LH, FSH and testosterone (T). Testicular biopsies were collected monthly to evaluate spermatogenic activity. Puberty occurred between 17 and 19 months, and at the onset of the 2-year-old breeding season, all colts were fertile. Seasonal changes in the concentrations of all four hormones were observed in both groups. Prolactin concentrations were correlated with changes in day length (r = 0·88) in both groups, but a biphasic profile was noted in group 1. Moulting of the winter coat was coincident with seasonally increased PRL concentrations (P < 0·001). Seasonal changes in FSH, LH and T concentrations were similarly timed between groups and levels were maximal in mid April, mid March and mid May, respectively. However, overall mean concentrations of LH and T in group 1 animals were only 0·33 and 0·22 of group 2 values (P < 0·001). Suppression of gonadal activity during the colts’ first ‘quiescent’ breeding season was associated with low concentrations of circulating LH. Appropriately timed changes in plasma PRL, FSH and T concentrations and pelage indicated that the photoperiodic mechanism was functional in the pre-pubertal colt but pituitary LH release may be blocked by immaturity or active suppression.

It is generally presumed that allosucking brings benefits to the allosucking infants. Nevertheless, the data supporting such a presumption are rare. The aim of the study was to determine whether allosucking has any impact on growth rates of the allosucking calves. Fifty pregnant hinds were observed between 28 May (1st day of calving) and 2 September (abrupt weaning of all calves) on a red deer farm at Vimperk, South Bohemia, the Czech Republic. Of the 50 calves born the growth curve was calculated for 39 calves. During their 1st month of life these calves were observed in 1015 sucking bouts. In 690 cases the calves sucked from maternal hinds and in 325 cases non-maternal hinds. Only 25·64% of calves sucked exclusively from maternal hinds. The prevailing type of sucking behaviour was a combination of sucking from maternal hinds and allosucking (74·36%). Calves sucking from maternal and non-maternal hinds showed 1·6-fold higher sucking frequency than did calves feeding from maternal hinds only. Our results indicate that to some extend allonursing behaviour of the hind may affect their calves’ feeding behaviour. The more non-filial calves the maternal hind nursed, the higher frequency of the sucking by their calves occurred. The groups of calves did not differ in birth weight. With increasing age, the relative body weight increased faster in calves sucking maternal hinds only than in calves sucking maternal and non-maternal hinds. This gain in body weight was not essentially influenced by the fact whether or not the calf’s maternal hind nursed non-filial or exclusively filial calves. However, at weaning (99 days), the lowest body weight occurred in allosucking calves whose maternal hinds were allonursing. The results suggest that allosucking does not mean an extra profit to the allosucker. Instead, in our subjects, allosucking was rather attributed to compensation of nutritional requirements based on a combination of various factors, such as discrete differences in body weight at birth and also later and allonursing of the maternal hind.

There is evidence that, in cattle, rapid compensatory growth after a period of growth restriction may increase the variability of beef quality and that variability is greater in breeds which reach larger body size at maturity. This experiment investigated the effect of compensatory growth following a period of winter growth restriction on carcass quality in steers of small and large mature size grazed on pasture. Angus (no. = 120) and South Devon ✕ Angus (SD✕ A; no. = 110) steers were allocated to non-restricted or restricted growth treatment groups and for 126 days over winter their grazing was managed to achieve mean live-weight gains of approximately 0·7 kg/day or to maintain live weight for each group respectively. Steers were slaughtered at the start (no. = 10 per breed) and end (no. = 20 per nutrition group (10 from each breed)) of the winter period for carcass evaluation. Thereafter, remaining steers were grazed together at a high pasture allowance to maximize growth and were slaughtered for carcass evaluation as they reached target live weights (Angus, 590 kg; SD✕ A, 620 kg). SD✕ A steers grew faster ( P < 0·05) during both the winter and finishing periods and reached target slaughter live weights approximately 20 days earlier than Angus steers. SD✕ A steers also had leaner carcasses than Angus steers at each slaughter although there was no significant difference in meat quality between breeds. However, there was a significant effect of restriction treatment on carcass weight and meat quality. The non-restricted steers grew faster, had heavier carcasses and more tender steaks than restricted steers, although there was no significant difference in carcass fatness (adjusted for hot carcass weight). Muscle calpain activities were positively correlated with live-weight gain during the finishing period suggesting increased potential for post-mortem myofibrillar proteolysis and therefore increased meat tenderness. However, in the present experiment this was confounded by an increase in shear force with age-at-slaughter, especially in the non-restricted steers. Nevertheless, steers which were heaviest at the start of the experiment reached slaughter live weight earliest, were leaner than average and had higher calpain system activities at slaughter regardless of breed or restriction treatment. Furthermore, in the non-restricted group, high initial live weight and early slaughter was associated with lower pH and more tender meat. In conclusion, although restriction affected meat quality attributes, it appears that live weight prior to food restriction also had a considerable effect on carcass characteristics at slaughter. Therefore, the characteristics of the early growth phase prior to the finishing period may have important consequences for meat quality.

Relationships among photoperiod and changes in voluntary food intake, feeding behaviour, growth and pelage were determined in seven, 2-year-old pony colts (182·4 (s.e. 5·4) kg). Individually housed colts were provided with ad libitum access to a complete pelleted diet (gross energy = 16·7 MJ/kg dry matter). Voluntary food intake (VFI, kg/ day) was calculated daily and body weights were recorded weekly throughout the 36-week study. Feeding behaviour was evaluated at approximately 4-week intervals by continuous observation (24 h), and the hair weight density (HWD, mg/cm2) of shoulder pelage was determined fortnightly. Day length was artificially manipulated to mimic the prevailing mid-summer photoperiod (16 h light: 8 h dark, 16L: 8D). After 1 week of the study (and the preceding fortnight), day length was abruptly decreased and thereafter animals were exposed to alternating 14-week periods of short (SD, 8L: 16D) and long days (LD, 16L: 8D). The mean daily VFI of individual ponies was calculated weekly and normalized for digestible energy (DE) content and metabolic body weight (DEI, MJ/kg M0·75). The average daily gain (ADG, kg/day) in body weight of each individual was calculated weekly. The apparent digestibility of dietary energy (digestibility) was determined over 72 h (no. = 6) on two occasions (days 92 to 95 and 190 to 193) during the study. Digestibility was similar in both periods (0·48, s.e. 0·01). DEI, ADG and HWD changed in a cyclic manner throughout the study. The period of the appetite cycle (24·4 (s.e. 1·3) weeks) did not differ from that of the 28-week photoperiodic regime. DEI decreased from a maximum of 1·4 (s.e. 0·03) MJ/kg M0.75 per day (day 21), to a nadir of 0·75 (s.e. 0·02) MJ/kg M0.75 per day (day 154, P < 0·001) and had increased (P < 0·001) to attain a second zenith (0·93 (s.e. 0·01) MJ/kg M0.75 per day) before the end of the study. Ponies ate discrete meals of similar duration, but meal frequency was associated with changes in VFI (r = 0·77) as was proportion of time spent feeding (r = 0·79). Changes in ADG reflected those of DEI. Body weight was stable for 4 weeks at the nadir of the appetite cycle. Maximal HWD was coincident with the nadir of the appetite and growth cycles. Regression of individual values for DEI on ADG described a linear relationship (R2 = 0·80) which could be used to predict the energy requirements of growing ponies maintained under similar conditions:

DEI total (MJ/kg M0·75 per day) = 0·654ADG (kg/day) + 0·789 (1).

The duration of the photoperiod, appetite, growth and pelage cycles were similar, suggesting a causal relationship. Physiological responses to photoperiodic change were not immediate and exhibited a delay of 5 to 8 weeks.

The intake and the digestibility of herbage, and the effect of level of supplementary concentrate food, were measured in late spring and late summer in two studies, each with eight multiparous, pregnant sows. In the spring study sows were nose rung to prevent rooting but only four nose-rung sows were available for the summer study; the remaining four were unrung. In both cases, sows had access to a plentiful (>2·5 t organic matter (OM) per ha) ryegrass/clover sward in a paddock of 1922 m2. After a week of adaptation to the herbage in the experimental paddock, sows were offered 1·5 or 3·0 kg/day concentrate for consecutive 2-week periods in a change-over experimental design with four sows on each treatment in each period. Samples of herbage were also taken to measure the sward density, chemical composition and n-alkane content. Herbage intake and digestibility estimates were calculated using the n-alkanes technique, with the marker dosed on small food pellets. In the spring study, the herbage intake ranged from 0·9 to 1·8 kg OM per day in the first period (herbage neutral-detergent fibre(NDF) content 439 (s.e.41·6) g/kg OM) and 0·2 to 1·4 kg in the second (475 (s.e.29·3) g NDF per kg OM). The intake was affected by the level of concentrate only in the second period. The results obtained during the summer study with the rung and unrung sows showed an intake between 0·9 and 2·4 kg OM per day in the first period (524 (s.e. 16·0) g NDF per kg OM) and between 1·3 and 4·8 kg in the second (526 (s.e. 21·8) g NDF per kg OM). A high intake estimation for certain unrung individuals appeared to reflect their frenzied feeding behaviour and possible loss of some marker pellets. There were no differences between level of concentrate treatments in either period. Digestibility of the diet was affected by the intake of herbage and the level of fibre consumed (P < 0·01). These herbage intakes equated to proportionately 0·50 (s.e. 0·05) and 0·66 (s.e. 0·1) (or 0·49 (s.e. 0·07) excluding problem sows) of the maintenance energy requirement in each season. Faeces of unrung sows indicated a high ingestion of soil or stones by some individuals: one of the sows produced a bulked faeces sample containing 450 g/kg fresh weight of stones, whilst another sow had a faecal ash content of 937 g/kg DM. The results indicate that the intake of nutrients from herbage by grazing sows is highly variable between seasons and individuals.

The objective of this study was to examine the changes of serum leptin levels in heifers and steers during fattening. Seven steers and seven heifers at 14 months of age were used in the experiment. Live weight and serum leptin levels were determined at 2-month intervals. Initial live weight was greater in steers than heifers and a similar trend of growth was recorded during the experiment. As a result, live weight was higher in the steers than in the heifers during the experiment. Serum leptin concentration in both groups increased during the experiment and reached optimum level at 22 months of age and did not change thereafter. The increase in serum leptin level was more marked in heifers and leptin level was higher (P < 0·05) in heifers than steers between 18 and 26 months of age. The results suggest that serum leptin level increases during fattening in cattle and the trend is possibly affected by gender.

A number of behavioural problems are associated with weaning piglets including belly nosing, ear and tail biting, and low intake of solid food. These appear to be less pronounced in piglets reared on outdoor systems, which initially consume more solid food and show less belly nosing and aggression than comparable indoor-reared piglets. The objective of this study was to investigate how these differences in post-weaning behaviour relate to the piglets’ pre-weaning behaviour in the two rearing environments. The study was carried out at a commercial pig unit, where piglets of the same genotype are born into conventional indoor or outdoor farrowing systems. In the intensive system, sows were singly housed prior to farrowing in crates and their piglets received a solid ‘creep’ food prior to weaning. On the outdoor system, sows were allowed to build straw nests in arks for farrowing and both sow and piglets had access to pasture. Indoor and outdoor piglets were weaned at 24 (±3) days of age and mixed in straw-yard housing with access to a solid food. Prior to weaning, teat-directed activity was more common in indoor piglets than outdoor piglets. Outdoor piglets performed more rooting, standing and locomotion and were seen chewing the sows’ roll-nuts. Following weaning, outdoor-reared piglets performed more feeding and rooting, and less fighting than indoor-reared piglets. This study supports previous findings that undesirable activities such as fighting are less common in piglets weaned from outdoor systems, even when mixed with indoor piglets. In addition, outdoor-reared piglets were more likely to exploit solid food even though they did not have access to creep food prior to weaning.

Ileal apparent digestibility of amino acids (AA) in a cassava root meal and soya-bean meal diet without and with an inclusion (150 g/kg) of sun-dried cassava leaves, ensiled cassava leaves, leucaena leaves and groundnut foliage was studied in a change-over experiment (5 ✕ 5) with post-valve T-caecum cannulated growing pigs.

The ileal apparent digestibility of dietary crude protein (CP) and AA were unaffected by the inclusion of groundnut foliage (P > 0·05). In contrast, when sun-dried and ensiled cassava leaves, and leucaena leaves were included in the diet the ileal apparent digestibility of dietary CP and AA were significantly reduced (P < 0·05).

The estimated ileal apparent digestibilities of essential and non-essential AA in groundnut foliage were higher (P < 0·05) than those of the other leaf products and there were no differences among cassava leaves and leucaena leaves (P > 0·05). On average ileal apparent digestibility of essential AA was 0·71 in groundnut meal and 0·56 in cassava and leucaena leaves.

It was concluded that, under tropical conditions, groundnut foliage has the potential to improve the dietary protein and AA supply and to replace partially soya-bean meal, in low fibre diets for growing pigs. Further, when conventional protein-rich foods are not available, cassava and leucaena leaves may also have the potential to improve the protein and AA supply for pigs.

Two experiments were conducted. The first, studied the chronic effect of tryptophan (trp) on glucose disposal and the second, the acute effect of trp on glucose disposal. In experiment 1, 12 piglets were allocated either to a trp deficient diet (T0) or a trp adequate diet (T1). After 14 days a 240-min intraduodenal infusion of glucose (130 µmol/kg per min) associated with D-(U-14C) glucose (1·18 kBq/kg per min) and an intrajugular infusion of D-(6-3H) glucose (1·85 kBq/kg per min) were started. In experiment 2, 18 piglets were given a trp adequate diet (T1) for 14 days. The piglets were then divided into two groups and received an intraduodenal infusion of either glucose (130 µmol/kg per min) or glucose plus trp (0·53 µmol/kg per min) for 240 min. At the same time an intrajugular infusion of D-(U-14C)glucose (1·48 kBq/kg per min) and D-(6-3H)glucose (2·59 kBq/kg per min) was given to all piglets. Blood samples were taken at regular intervals during the infusions for the measurement of plasma concentrations of insulin, glucose, lactate and blood specific activities of 14C-glucose, 14C-lactate, 3H-glucose and 3H-lactate. At the end of the infusion, samples were taken for the measurement of the accumulation of 14C and 3H in glycogen. In experiment 1, plasma insulin concentrations were higher in the T0 compared with the T1 group (at 30 min respectively, 837·7 (s.e.56·6) v. 404·9 (s.e.56·6) pmol/l, P < 0·001). Glucose concentrations were also higher in T0 compared with T1 (at 30 min respectively, 10·9 (s.e. 0·54) v. 9·3 (s.e. 0·54) mmol/l, P < 0·05). Glucose flux was unaffected by trp in both experiments. The accumulation of labelled glucose into liver and carcass glycogen was not affected by trp. The route of administration of glucose label had a significant effect on the percentage of label accumulated in liver glycogen. When both 14C and 3H were infused into the jugular vein there was no difference in the accumulation of the two tracers in liver glycogen (22·7 v. 21·8% of that infused, P > 0·05, respectively). However, when 14C was infused into the duodenum and 3H into the jugular vein, accumulation into liver glycogen was higher for 14C compared with 3H (19·9 v. 15·6%, P < 0·001, respectively). In conclusion, trp does not appear to influence glucose disposal measured at the end of a 240 min intraduodenal glucose infusion. Contrary to results published from experiments with rats the indirect pathway for glycogen synthesis (glucose→lactate→glycogen) does not appear to occur in underfed piglets.

The aim of this study was to investigate the effects of a 30-day increase in age of pigs slaughtered at 110 kg body weight (BW) on carcass and m. longissimus dorsi (LD) and m. biceps femoris (BF) traits, and meat sensory quality. A total of 60 pigs from two genotypes: synthetic line ✕ (Large White ✕ Landrace) (SL) and Duroc ✕ (Large White ✕ Landrace) (D) were used, each genotype containing five groups of six littermates (three castrated males and three females). At the average BW of 30 kg, littermates of the same sex were allocated to three groups. Pigs of group AL were offered ad libitum a standard growing-finishing diet (13·6 MJ/kg digestible energy, 9·5 g/kg of lysine) from 30 up to 110 kg BW. The R1 pigs received the same diet at 0·75 of the ad libitum intake of their AL littermates. The R2 pigs were submitted to both energy and protein restrictions in order to get the same growth rate as the R1 pigs and the same body composition as the AL pigs. Results were similar in both genotypes. In agreement with the protocol, age at slaughter was increased by 30 days in R1 and R2, and AL and R2 pigs had comparable carcass composition. Compared with AL, average daily gain was decreased in R1 and R2 pigs, and food efficiency was decreased in R2, but remained unaffected in R1 pigs. Intramuscular fat (IMF) concentration was decreased in the R1 pigs, especially in BF (15·5 v. 19·7 mg/g), while it was increased in the LD of the R2 pigs, particularly in the D animals (24·2 v. 17·4 mg/g), compared with AL pigs. Meat quality parameters (rate and extent of pH fall, reflectance and drip loss) were similar in the three feeding regimens. The taste panel did not find any significant difference between feeding regimens for tenderness, juiciness, flavour, flour sensation after mastication and mouth coating of the meat, despite the differences reported in IMF concentration. This suggests that, for the genotypes used in this experiment, an increase of 30 days in the age at slaughter greatly influences the carcass and/or the muscle chemical composition, depending on the feeding strategy applied to reduce the growth rate but does not strongly modify the meat eating quality.

Performance in pigs is greatly reduced during periods of heat stress through a reduction in voluntary food intake (VFI). However, little information is available as to what extent growth in piglets is affected by high temperature. The objective of this study was therefore to quantify the change in VFI as affected by environmental temperature. Piglets, initially 15·5 (s.e. 1·9) kg body weight (BW), were individually housed and exposed over a period of 17 days to either 19, 21, 23, 25, 27, 29, 31, 33, or 35ºC. Animals had ad libitum access to a starter diet and water. VFI was measured daily whereas BW was determined twice weekly. Over the 17 days, daily VFI and BW gain were proportionately 0·48 and 0·51 lower at 35ºC than at 19ºC. Due to the reduced VFI at high temperatures, the average BW during the experiment was greater at low temperatures than at high temperatures. Consequently, part of the difference in VFI is directly due to temperature and part may be explained by cascading, indirect effects (i.e. the increased BW). To account for this, VFI was expressed as a power function of BW (VFI = aBWb). It was assumed that environmental temperature affected the scalar (a) through a quadratic or a ‘plateau-linear decline’ function of temperature. The VFI appeared relatively constant between 19 and 25ºC (0·096 (kg/day)/(kg BW0·83)) and decreased thereafter. Between 25 and 35ºC, VFI decreased on average by proportionately 0·28 in a 20-kg pig.

Individual energy balances (EB) and total net energy intake (NEI) were modelled to quantify the energy content of the explanatory variables body-weight change corrected for gut fill (BWC) and body condition-score change (BCSC). A total of 6147 records from 213 lactating dairy cows, 71 Holstein-Friesians, 71 Jerseys and 71 HolsteinJersey F1-crosses was analysed (1st, 2nd and >2nd lactation). Data were collected during 210 days of lactation, from calving to week 30. Individual EB were calculated as total energy for lactation (MJ NEL) minus estimated energy necessary for maintenance and production. Body-weight changes were calculated as differences between weekly means of body weight corrected for gut fill (BWCw) as well as from polynomial regression (BWCp). BCSC were differences between assessed body condition scores. The study included analyses of 1- and of 4-week periods for BWCw and BWCp, of differences between measuring periods for BCSC as well as separate analyses of data from cows in either negative or positive energy balance.

Analysis of repeated measurements were performed applying mixed model theory. Models for EB contained type of dairy cow, lactation and type of roughage as fixed effects, week of lactation and either BWCw, BWCp or BCSC. Models for NEI contained type of dairy cow, lactation and quality of roughage as fixed effects, week of lactation as well as energy corrected milk, metabolic body weight and either BWCw, BWCp or BCSC as covariates.

Most plausible energy contents per unit body tissue change were estimated for BWCp from weekly data with either EB (with energy partitioned into milk production and maintenance fixed) or NEI (no restrictions concerning partitioning) as the response variable. The estimated energy contents for BWCp were 15·40 and 10·47 MJ NEL, respectively.

A 10-week feeding trial was conducted to re-evaluate the level of dietary vitamin E (DL- α-tocopheryl acetate) that was adequate for juvenile tilapia Oreochromis niloticus ✕ O. aureus given diets containing two dietary lipid concentrations. Purified diets with eight levels of vitamin E (0, 25, 50, 75, 100, 150, 200, 400 mg/kg diet) at either 50 or 120 g lipid per kg were each given to three replicate groups of tilapia (mean weight: 0·69 (s.e.0·02) g) reared in a closed, recirculating system. Food efficiency and protein deposition were significantly (P < 0·05) higher in fish given 50 mg vitamin E per kg diet and 75 mg/kg diet in the 50 and 120 g lipid per kg groups respectively, compared with fish given the unsupplemented control diet. Mortality of fish was not affected by dietary treatment. Weight gain and liver microsomal ascorbic acid-stimulated lipid peroxidation data analysed by broken-line regression indicated that the optimum dietary vitamin E requirements in juvenile tilapia are 42 to 44 mg vitamin E per kg and 60 to 66 mg vitamin E per kg in 50 and 120 g lipid per kg diets, respectively.

The effects of xylanase and antibiotic addition to the diet, and the use of HCl-insoluble ash as a marker, on ileal and faecal apparent digestibilities of nutrients were studied with 12 growing pigs fitted with post-valvular T-caecum cannulae (PVTC). The results showed that the apparent ileal digestibility of non-starch polysaccharide (NSP) was high, (over 0·30). Xylanase, or antibiotics (Avoparcin) or xylanase plus antibiotics supplementation of the wheat middling-based diets did not significantly (P > 0·05) increase the ileal and faecal apparent digestibilities of NSP, neutral-detergent fibre (NDF), dry matter, crude protein, energy or amino acids. There were no significant (P > 0·05) differences between the HCl-insoluble ash and Cr2O3 recoveries at the ileal or at the faecal levels: proportionately, 0·864 and 0·911 for the ileal and faecal recoveries of HCl-insoluble ash, and 0·857 and 0. 915 for the ileal and faecal recoveries of Cr2O3, respectively.

Although veal production is a highly standardized system, there still remains considerable variability in productivity between units. This variability might be due to the farmers working on these units, through differences in stockmanship, work attitudes or behaviour, which in turn may affect animals’ fear responses, productivity and health. A survey was conducted on 50 commercial farms affiliated to the same veal company. All units had calves housed in individual crates, a similar number of crates, and the same diets and management advice. Data were collected on: building and general farm characteristics, farmers’ backgrounds and their attitudes towards their work and calves, farmers’ behaviour with the calves, calves’ reactivity to people, and disease level of the calves. Productivity results (growth rates, food efficiency and mortality) were used to classify veal units as ‘high producing’ (no. = 24) v. ‘moderate producing’ (no. = 26). Calves were less reactive to people in units where the farmer behaved sympathetically and where there were several stockpersons working. The disease level was lower in units where the farmer had a positive attitude towards the sensitivity of the calves to contact and towards the importance of cleaning. Productivity of the veal unit was associated with the health of the calves but not with their reactivity to people.

It is suggested that the farmer can have an influence on the success of the veal unit mainly through his/her ability to control the health of the calves and that a positive attitude towards animals and towards work (specifically cleaning actions) can improve the accuracy of surveillance and care of the animals. Moreover, through his/her behaviour with the calves and his/her ability to control their health, the farmer can play an important rôle in assuring calves’ welfare.

Net energy efficiencies were calculated from data of an experimental herd with respect to type of cow, lactation number, stage of lactation and diet. The trial consisted of 71 Holstein-Friesians, 71 Jerseys and 71 Holstein-Jersey F1-crosses in 1st, 2nd and > 2nd lactation. Data were collected during 210 days of lactation, from calving to week 30 and included total dry matter intake, energy content of foods, milk yield, milk solids, body weight, body condition scores and several body measurements. The cows were divided into four feeding groups : high and low energy content of roughage as well as high and low proportion of concentrates. Net energy efficiency was calculated as the ratio of milk energy to total net energy intake after subtracting energy utilized for maintenance and body tissue change. Body tissue change was calculated either via body-weight changes or body condition-score changes. Due to the distribution of the efficiencies being skewed, efficiencies were transformed applying a Box-Cox transformation. Transformed net energy efficiencies were analysed using a repeated measurements design considering the sequential nature of the observations. Mixed models with a compound symmetry structure for the variance components were applied. Final models contained the fixed effects of type, lactation number, feeding group and the covariates week of lactation and its square. Holstein-Jersey crosses were more efficient than purebreds, second lactation cows were least efficient, cows given low energy roughage and a lower proportion of concentrates were more efficient than cows on the other diets. Least efficient were the cows belonging to the high energy roughage and higher proportion of concentrates group. The coefficients of determination of the final models were between 0·357 and 0·492.

During a 2-year study from January 1997 to December 1999, the visual characteristics of the cervical mucous discharge of cows and heifers in oestrus and their relations to conception rate were studied in a large dairy herd of Holstein-Friesian cows. Cows were divided into two groups based on mucous discharge being of normal or abnormal appearance and the group with abnormal discharge was further divided into the following classes: cervical mucus with urine (CMU), cervical mucus with microbes (CMM), cervical mucus with blood (CMB) and a group with no cervical mucus (NCM). From 6169 cases of cows in oestrus, 82·2% had normal discharge, and the remaining 17·8% had abnormal discharge classifications (6·1% CMU, 5·1% CMM, 0·5% CMB and 6·1% NCM). Conception rate after artificial insemination (AI) in the normal group (38·3%) was significantly higher than that of the abnormal group (27·9%), (P < 0·05). When the conception rate of the normal group was compared with each one of the abnormal classifications, it was significantly different from that of CMU (26·5%), CMM (22·6%) and CMB (21·8%), (P < 0·05), but not from that of NCM (34·4%), (P > 0·05). From 1734 cases of heifers in oestrus, only 6% had abnormal discharges, and the conception rates of the normal and abnormal groups were not significantly different (P > 0·05).

We conclude that AI of cows in oestrus discharging cervical mucus that is contaminated with urine, microbes or blood produces conception rates significantly lower than those of cows discharging a normal and clear mucus. Absence of a cervical mucous discharge at the time of AI of cows does not imply a low conception rate. In the case of heifers, appearance of cervical mucus had no effect on the conception rate after AI.

Sixty-four Azawak male weaned calves were allotted to eight treatments (T) in two trials to study the effect of timing (day or day-and-night) and duration of grazing on diet selection, faecal output, eating time, forage intake and weight changes. Grazing time during the day was 6 h for T 1, 2 and 3; 9 h for T 4, 5 and 6; and 12 h for T 7 and 8. Night grazing time was 0 h for T 1, 4 and 7; 3 h for T 2, 5 and 8; and 6 h for T 3 and 6. The trials were conducted from July 1995 to May 1996 covering the wet (WS), early dry (EDS) and late dry (LDS) seasons. Eight oesophageally fistulated steers were used in a cross-over design to sample the diet selected by day-grazers (D1) and by day-and-night-grazers during the day (D2) and at night (N2). Forage intake was determined from individual data on faecal output from all the calves and means of in vitro organic matter digestibility of extrusa of the fistulated steers. Water intake and eating time were measured in LDS. In WS there were no differences (P > 0·05) in the quality of the diet (extrusa) selected for D1, D2 and N2. In LDS, crude protein content for D1 was lower than for D2 (73 v . 79 (s.e. 2) g/kg dry matter, P < 0·05). In all seasons, faecal output and forage intake increased with total duration of grazing. Total time spent eating increased linearly with increasing total time allowed for grazing. These results suggest that allowing additional grazing time during the night leads to increased forage intake and consequently provides an opportunity for better animal production, especially in the dry season.