Animals living in temperate climates are continually adapting to seasonal demands of reproduction and survival. Whilst it is well documented that ruminants show seasonal changes in both reproductive and non-reproductive physiological and behavioural characteristics (reduction of metabolic rate and appetite during the winter with respective increases during spring and summer), this information has not been fully established in the non-ruminating ungulate species of Equidae. This may be important information from a practical management perspective since groups of equids are increasingly being kept in natural conditions for the purposes of conservation grazing.

The aim of this study, therefore, was to document the behavioural and physiological adaptive changes made by ponies during a 12-month period and to relate these to changes in forage availability and environment. Five mature pony stallions were kept in west Wales (4°5′W, 52°25′N) and monitored for 12 months. A range of physiological (testis size, body weight, condition score (CS), hoof growth, moult (M), pelage fibre length, depth and density) and behavioural measurements (foraging and non-foraging activities) were recorded along with monthly forage analysis (crude protein (CP), water-soluble carbohydrates (WSC)), dry matter (DM)) and environmental conditions (day length and minimum ambient temperature). All physiological measurements were significantly (P<0·001 to P<0·05, r2=0·16 to 0·69) related to day length and all except testis size, body weight and M were significantly related to minimum temperature, CS (P<0·001; r2=0·583), hoof growth (P<0·001; r2=0·457), pelage fibre length (P<0·001; r2=0·61), pelage fibre depth (P<0·001; r2=0·489) and pelage density (P<0·05; r2=0·192). Fewer significant relationships were observed in relation to forage characteristics; significances only obtained between CP and CS (P<0·001; r2=0·854), fibre length (P<0·01; r2=0·625) and pelage fibre depth (P<0·01; r2=0·624); between DM and CS (P<0·05; r2=0·352) and pelage fibre depth (P<0·05; r2=0·343); between WSC and pelage fibre depth (P<0·01; r2=0·55) and pelage fibre depth (P<0·05; r2=0·34). Behaviour results showed a significant relationship between time spent alert and day-length (P<0·05; r2=0·35) and between minimum ambient temperature and time spent eating (P<0·05; r2=0·37), locomotory behaviour (P<0·01; r2=0·53) and passive interaction (P=0·001; r2=0·63). A significant relationship was also reported between eating and CP (P<0·01; r2=0·53) as well as DM (P=0·01; r2=0·43). The ponies in this study demonstrated a series of adaptive changes during winter concomitant with energy conservation, however, forage availability and intake also decreased indicating lower energy input. Despite energy conserving adaptations it is unlikely that nutrient intake was adequate to account for the limited winter decline in CS and weight. In conclusion, it was considered that: (a) ponies demonstrated physiological and behavioural adaptation in response to environmental demands, (b) during winter ponies demonstrated behaviours indicative of a cost benefit analysis of expending energy in the pursuit of poor quality forage, (c) despite energy conserving adaptations, intake is unlikely to have been adequate to maintain the CS observed, and (d) reduction in metabolic rate and increased food conversion efficiency may be additional adaptations made during times of environmental challenge.

Transport and accompanying mixing of pigs causes fights among pigs and stress resulting in decreased welfare and reduced meat quality. This study investigates the effect of toys available during transport and lairage on behaviour, stress responses, and meat quality of slaughter pigs. Cross-bred (Piétrain×Hypor) pigs (109·1±10·1 kg) were allocated to one of three treatments during transport and lairage: 1) no toys (control) 2) rubber toys and 3) balls. The rubber toy consisted of two fixed rubber sticks; the plastic ball was filled with pieces of maize, which became available for the pigs in small amounts by manipulating the ball. Per group of 11 pigs, two toys were provided. Totally, divided over 4 replicates, 144 pigs were involved, of which 72 were used for blood sampling and meat quality measurements. Five minutes scans during lairage revealed that treatment did not affect the percentage of pigs that lay (P=0·20), stood (P=0·83) or sat (P=0·12) and that in almost all scans at least one pigs was manipulating a ball, compared with half of the scans in which at least one animal was manipulating a rubber toy (P=0·02). However both toys resulted in a lower incidence of shoulder lesions compared with the control group (P=0·06; 31·1% and 28·9% of the pigs for the rubber toys and balls respectively, versus 51·1% for the control group). Blood sampling at sticking showed that pigs with the balls during transport and lairage tended to have lower cortisol concentrations (P=0·07) than pigs with the rubber toys. Also, a decrease in plasma lactate concentration was observed for these pigs in comparison with the control group (P=0·08), and a higher pH of the m. longissimus dorsi 45 min post mortem for the pigs with the balls was found than for the pigs with the rubber toys (P=0·01). These results indicate that enrichment of compartments during transport and lairage with balls reduced glycolysis in muscle resulting in a lower lactate production and a slower pH decline. The pH 45 min post mortem of the m. biceps femoris and the pH, electrical conductivity, colour, and water-holding capacity of the loin 48 h post mortem were not affected by treatment. In conclusion, environmental enrichment with toys during transport and lairage can decrease shoulder lesions and lower the pH decline 45 min post mortem, especially by provision of plastic balls filled with maize.

It was reasoned that, if we used a large sample of pigs, we could demonstrate that total and differential numbers of leukocytes, expression levels of swine leukocyte antigens (SLA) I and II, and serum concentrations of IgG and haptoglobin show additive genetic variation and are, therefore, potentially useful as criteria to improve selection of pigs for resistance to clinical and subclinical disease. We tested this premise by assessing 4204 male pigs from the Duroc, Landrace, and Yorkshire breeds for total and differential numbers of leukocytes and serum concentrations of IgG and haptoglobin; 1217 of the Duroc and Landrace pigs were also assessed for expression levels of SLA I and II. We estimated the amount of additive genetic variation by fitting linear animal models to the total and differential numbers of leukocytes and serum concentrations of IgG and haptoglobin. We fitted linear sire models to the expression levels of SLA I and II. We detected additive genetic variation for each group of traits. Total and differential numbers of leukocytes were moderately heritable (h2=0·22 to 0·30), expression levels of SLA I and II were moderate-to-highly heritable (h2=0·46 to 1·23), while serum concentrations of IgG and haptoglobin were lowly heritable (h2=0·14 to 0·16). The additive genetic variation shown for the immunological traits is encouraging for pig breeders. It indicates that these traits are potentially useful as criteria to improve selection of pigs for resistance to clinical and subclinical disease.

Polymorphisms at codons 136, 154 and 171 of the gene encoding the prion protein (PrP) are associated with susceptibility to classical scrapie in sheep. Genetic selection for scrapie resistance based on PrP genotypes is central to the scrapie eradication programme in Great Britain but there are concerns about how this may affect other economically important traits. The objective of this study was to evaluate associations of PrP genotypes with live weight and slaughter traits in a hill sheep breed in Great Britain. Data used were from an experimental flock of Swaledale sheep in which the alleles ARR, ARQ, AHQ and VRQ were present. About 1450 genotyped lambs with birth, marking and weaning weights, and 620 with slaughter records were used for the study. Mixed models with various fixed effects and random direct genetic and maternal effects were tested to determine the appropriate model to use for each trait. None of the differences in lamb performance between PrP genotypes consistently reached significance. Therefore, this study does not support existence of significant relationships between PrP genotype and lamb performance traits in this breed.

Mixing of commercial pigs frequently leads to intense aggression. Considerable phenotypic variation exists between individuals and selection against aggressiveness may offer a long-term reduction in aggression without incurring additional costs to the primary producer. The genetic contribution to aggressiveness was quantified in this study using the number of skin lesions as an indicator of involvement in aggression. A sample of 1132 pigs were mixed at an average weight of 27·9 (s.d. 4·6) kg into 96 pens on a commercial sire line nucleus unit. Post-mixing aggressiveness of pigs was assessed using the lesion score (LS) approach. Growth rate, between 27·9 and 91·9 kg, and backfat depth at 91·9 kg were recorded for a subsample of 658 pigs. With a pedigree file of 1947 animals, a heritability of 0·22 was estimated for the LS trait. No significant genetic or phenotypic correlations were found between LS and growth rate or backfat depth, but standard errors of estimates were large. The response to selection, when all selection pressure was placed on the LS trait, was a 25% reduction in LS per generation. It is therefore technically possible to select for a reduced LS without substantially inhibiting genetic progress in growth rate or backfat depth through antagonistic genetic relationships.

The objective of this study was to investigate the effect of orally administered spermine at various doses on intestinal maturation in sucking piglets. Thirty-six 11-day-old sucking piglets were assigned randomly to one of six treatments to receive via a stomach tube 0, 0·1, 0·2, 0·3, 0·4, or 0·5 mmol spermine per kg live weight (LW) per day for 3 days. At day 14 of age, duodenum, jejunum and ileum were obtained for biochemical and morphological analysis. Increasing the dose of orally administered spermine increased intestinal weight (linear effect, P<0·01), mucosal weight (linear effect, P<0·05), and mucosal protein, DNA and RNA contents of the duodenum (linear effect, P≤0·01) and jejunum (linear effect, P<0·01). Elevating spermine doses also enhanced (linear effect, P≤0·02) the specific activities of maltase and sucrase but decreased (linear effect, P<0·01) lactase specific activity in the jejunum and duodenum. Furthermore, augmenting oral doses of spermine increased crypt depth and villus width but reduced villus height in the jejunum (linear effect, P<0·05) and duodenum (linear effect, P<0·01). For most measurements, the effects were observed at the oral spermine doses of 0·3 to 0·5 mmol/kg LW per day. Collectively, the results show that oral administration of optimal doses of spermine to 11-day-old sucking piglets induces precocious intestinal maturation and promotes intestinal growth.

Seven mature Welsh-cross pony geldings provided the faecal inocula in a cross-over design experiment, consisting of two 14-day periods. In period 1, four ponies (group 1) were offered a low-starch fibre mix (LS), and three (group 2) were offered a conventional high-starch coarse mix (HS). Both groups were offered these mixes in a 50:50 ratio with mature grass hay, to give a total daily dry-matter intake of 17·5 g/kg live weight per day. Diets were then switched in period 2. At the end of each experimental period freshly voided faeces were collected from each animal and assessed for their ability to ferment grass hay (H), fibre mix (FMix) or starch-based coarse mix (SMix) using the gas production (GP) technique of Theodorou et al. (1994). Donor animal diet and donor animal had no effect on any end-point measurements. Lag times recorded for the SMix were significantly (P<0·001) greater in LS-inoculated bottles compared with the HS inocula (1·74 v. 2·25 h, respectively). Lag times for FMix and SMix varied significantly (P<0·001) between ponies (0·82 to 1·78 h in the FMix and 1·64 to 2·51 h in the SMix). The degradation rate of H also differed significantly (P<0·001) between ponies with the time taken to reach 50% of GP (T50) ranging from 12·70 to 17·30 h. Consequently, it would appear that the effect of feeding LS or HS on the in vitro fermentative capacity of equine faecal inocula is minimal; moreover, the GP technique appears to be valuable tool for evaluating such effects.

Two experiments were conducted to study the effects of phytase derived from Escherichia coli (ECP) and Peniophora lycii (PLP) on performance, nutrient digestibility, and phosphorus (P) equivalency values of young pigs; and the influence of varying ratios of calcium (Ca) to total phosphorus (Ca:tP) with or without ECP on growth performance of pigs. In each experiment, 48 10-kg pigs were housed in individual pens for 28 days. Experiment 1 was designed to study the efficacy of ECP and PLP in improving growth performance and bone mineralization of young pigs given a low inorganic P (iP) diet. In the experiment, pigs were blocked by weight and sex and randomly allocated to eight dietary treatments. Each treatment had six replicates. The treatments were a positive control with adequate iP (PC); a low iP negative control (NC) diet; NC with supplemental iP in the form of monosodium phosphate added to provide 0·75 or 1·50 g iP per kg diet (as-fed basis); NC with ECP or PLP added at 500 or 1000 FTU per kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 μmol of iP per min, at pH 5·5, from an excess of 15 μmol/l sodium phytate at 37°C). In experiment 2, the objective was to study the effect of varying Ca:tP ratio with or without ECP on growth performance of growing pigs. Pigs (eight replicates) were blocked by weight and sex and randomly assigned to six dietary treatments in a 3×2 factorial arrangement of Ca:tP ratios at 1·2, 1·5, or 1·8; and ECP at 0 or 1000 FTU per kg (as-fed basis). In experiment 1, ECP ( P<0·001) and PLP ( P<0·05) linearly increased daily gain. There was a positive linear ( P<0·05) response to the supplementation of the NC diet with ECP or PLP in the mineralization of the third and fourth metacarpal bones. Phosphorus equivalency values for 500 FTU of ECP or PLP based on mineralization of the third metacarpal bone were 0·77 g or 0·572 g, respectively. There were linear ( P<0·001) and quadratic ( P<0·05) responses to ECP, and linear ( P<0·01) response to PLP in P digestibility. Neither iP supplementation nor either of the two phytases had significant effects on digestibility of dry matter, protein or energy. In experiment 2, reducing Ca:tP ratio linearly improved ( P<0·05) daily gain, food intake, and food efficiency in pigs regardless of phytase supplementation. There was an enzyme by Ca:tP interaction on food intake. These studies in young pigs showed that ECP and PLP were efficacious in improving the growth performance and bone mineralization and that reducing the Ca:tP ratio enhanced performance response to phytase supplementation.

This study was conducted to examine the relationship between soya-bean agglutinin and cholecystokinin in stimulating pancreatic enzyme synthesis in rats. In experiment 1, 30 rats were given daily gastric infusions of 0, 3·5, 7·0, 10·5, or 14·0 mg of soya-bean agglutinin (no.=6) for 14 days. Compared with the control group, soya-bean agglutinin reduced weight gains, enhanced absolute and relative dry pancreatic weights, elevated serum cholecystokinin levels, and stimulated cholecystokinin mRNA expression in the intestine (P<0·001). Pancreatic nucleic acid composition and the pancreatic activities of the enzymes amylase, trypsin and chymotrypsin all increased in response to increasing levels of soya-bean agglutinin (P<0·001). In experiment 2, duodenal cells obtained from two rats were incubated at 37°C with either saline, 100 μg/ml soya-bean agglutinin, or a mixture of 100 μg/ml soya-bean agglutinin and 10 mmol/m of the L-type, calcium channel antagonist verapamil. Soya-bean agglutinin stimulated cholecystokinin mRNA expression and cholecystokinin release from small intestinal mucosal cells, and the effect was attenuated by verapamil. In experiment 3, pancreatic acinar cells, obtained from three rats, were incubated at 37 °C with either saline, or cholecystokinin (100 fmol/ml) and soya-bean agglutinin (1000 fmol/ml), either alone or in combination. Amylase, trypsin, and chymotrypsin activities from both culture media and acini cells were stimulated by both the soya-bean agglutinin and the cholecystokinin treatments. Enzyme activities, when the two factors were incubated in combination, were intermediate to those obtained when the factors were incubated alone. This suggesting that soya-bean agglutinin may depress the action of cholecystokinin on pancreatic enzymatic activities. In summary, soya-bean agglutinin appears to stimulate pancreatic enzyme synthesis both directly and also through a cholecystokinin-mediated pathway.

The aim of this study was to evaluate the effects of two dietary supplements (monensin and a live yeast culture) on acid-base balance in steers maintained in a commercial feedlot system, considering effects over the finishing productive cycle. Steers (no. =42) were allotted randomly to one of the three study groups: (1) control group (no supplementation, C), (2) monensin supplementation (MON), and (3) live Saccharomyces cerevisiae strain 47 supplementation (SACC). Venous blood samples were collected for the measurement of acid-base parameters and l-lactate. Production parameters were also used as a complementary tool for understanding the internal changes associated with supplementation. During the finishing period, MON steers tended to gain more efficiently than C and SACC steers. In the C group, the finishing-period diet caused a progressive decline in blood bases, in line with the high-grain diet consumption. In contrast, supplemented animals did not show this trend, although lower HCO3− and base excess values were registered in SACC steers than in MON, indicating that ionophore supplementation is less effective for reducing blood base consumption than yeast supplementation. In our study, the lack of the expected response to yeast supplementation may be attributable to the high crude protein content of the ration, a common feature of commercial feedlot industries.

Two factorial experiments were designed to determine the effects of stage of lactation, and season of the year, on cow responses to supplementary feeding. These experiments were conducted over consecutive years with 128 high genetic merit multiparous Holstein-Friesian cows in early, mid and late lactation in spring, summer, autumn and winter. At each stage of lactation, and in each season of the year, cows were offered a restricted pasture allowance (25 to 35 kg dry matter (DM) per cow per day), either unsupplemented (control) or supplemented with 50 MJ metabolizable energy (ME) per cow per day in experiment 1 and 80 MJ ME per cow per day in experiment 2. Two different supplements were offered, namely, rolled maize grain (MG) and a mixture of foods (BR) formulated to nutritionally balance the diet. In experiment 2, a fourth treatment consisting solely of a generous pasture allowance (60 to 75 kg DM per cow per day, AP) was introduced. Offering MG and BR increased DM intake (DMI). At the restricted pasture allowance, increasing total ME allowance (MEA) by offering supplementary foods increased ME intake (MEI) by 0·68 (s.e. 0·047) MJ per extra MJ ME offered. This highly significant (P<0·001) linear relationship was consistent across seasons, and did not diminish at higher MEA. In experiment 2, cows in early lactation had lower substitution rates than mid and late lactation cows irrespective of season. Substitution rate was higher when higher pasture allowance or quality of pasture on offer enabled the unsupplemented cows to achieve higher DMI from pasture than at other times of the year. These results suggest that one of the key factors determining the intake response to supplementary foods is pasture allowance. Within spring calving dairying systems, the largest increases in total DMI per kg of supplement offered is likely when offering supplements to early lactation cows grazing restricted allowances of high quality pasture.

Two factorial experiments were designed to determine the effects of stage of lactation, and season of the year, on cow responses to supplementary feeding. These experiments were conducted over consecutive years with 128 high genetic merit multiparous Holstein-Friesian cows in early, mid and late lactation in spring, summer, autumn and winter. At each stage of lactation, and in each season of the year, cows were offered a restricted pasture allowance (25 to 35 kg dry matter (DM) per cow per day), either unsupplemented (control) or with supplement at 50 MJ metabolizable energy (ME) per cow per day in experiment 1 and 80 MJ ME per cow per day in experiment 2. The two supplements given in both years were rolled maize grain (MG) and a mixture of foods formulated to nutritionally balance the diet (BR). In experiment 2, another treatment, of a generous pasture allowance (60 to 75 kg DM per cow per day) (AP), was imposed on an additional group of early lactation cows during each season. Direct milk solids (MS) (milk fat plus milk protein) responses in experiment 1 to MG were 169, 279, 195 and 251 g MS per cow per day in spring, summer, autumn and winter, respectively, while those to BR were 107, 250, 192, 289 g MS per cow per day. In experiment 2, however, milk solids responses to both supplements during spring were slightly below the control treatment, with values similar to those in experiment 1 in summer and autumn for cows on the BR but not the MG supplement. Milk solids responses to supplementary foods were largest during seasons of the year when the quantity and quality of pasture on offer resulted in the lowest milk solids yield from unsupplemented cows. When carry-over effects of feeding MG and BR on milk solids production were detected, they were only about half the magnitude of the direct effects. Serum urea concentrations were higher in control cows than those offered MG with a similar effect for BR in all but summer in experiment 1, while serum glucose concentrations were highest in winter and lowest in summer. The most important factor influencing milk solids responses was the relative food deficit (RFD) represented by the decline in milk solids yield of the respective control groups after changing from a generous pasture allowance to restricted allowance when the feeding treatments were imposed. Total milk solids responses (direct and carry-over) to supplements were greatest when severe food restrictions, relative to the cows' current food demand, resulted in large reductions in milk solids yield of the control groups. The RFD was the best predictor of milk solids response to supplementary foods. Therefore, it is likely that cows are most responsive to supplementary foods during or immediately after the imposition of a severe food restriction.

This exploratory holo-analysis of the efficacy of Bio-Mos®, (BM), an outer cell wall derivative of a strain of Saccharomyces cerevisiae, is part of an empirical modelling research programme comparing the efficacies of potential replacements for veterinary prescription-free pronutrient antibiotics in pig production. The data resource was mined from 128 saccharide publications of which 31/97 on BM (1997 to 2003) provided 69 negatively controlled start-to-finish tests from 10 countries (USA 71%) using 3778 pigs(30·5 per treatment). Respective food intake, live-weight gain and food conversion responses of 0·0075 kg/day (0·99%), 0·0145 kg/day (3·58%) and −0·0526 (3·07%) have coefficients of variation of 511, 163 and 229% and beneficial gain and conversion frequencies of 73 and 68%, 54% jointly. Holo-analytical multiple regression models of BM food intake, live-weight gain and food conversion effects using conventional and less stringent probabilities contain significant independent variables for negative control performances, dosage, discontinuous dosage, test duration, year of test, non-USA test, male, grower-finisher, slatted floor, processed food, antibacterial foods, animal protein food, main vegetable protein not soya bean, added oil/fat food and factorial data, which account for 11 to 68% of variations in response. The models quantify differences in research and praxis and indicate areas for future modelling research on BM dose-response relations, effects of ration ingredient and nutrient contents, other saccharide efficacy comparisons, including lactose, and BM comparisons and interactions with other proposed antibiotic replacements.

Two respiratory chamber experiments were conducted with dairy cows to compare metabolizable energy and protein utilization when feeding white or red clover with ryegrass. In experiment 1, fresh ryegrass was mixed with fresh white (WF) or red clover (RF) (60/40, on dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form (WS and RS, respectively), and two ryegrass silage diets, without (GS) or with supplementary maize gluten (GS+). Barley was supplemented according to requirements for milk production. Voluntary forage DM intake remained unaffected in experiment 1 and was higher (P<0·01) in experiment 2 for WS than for GS and GS+(128 v. 98 and 106 g/kg M0·75). Within experiments, no treatment effects occurred for apparent nutrient digestibilities, milk yield, and composition. Protein utilization (milk-N/N-intake) was numerically lower on all clover-based diets (0·24 to 0·25) versus GS (0·29). With added maize gluten (GS+), protein utilization decreased to 0·23, indicating that ryegrass silage (plus barley) alone provided sufficient metabolizable protein. Consequently, higher (P<0·01) urinary energy losses occurred in GS+ compared with GS, despite similar metabolizable energy intakes, and a trend for the highest plasma urea levels was found for GS+ cows (7·59 mmol/l; P<0·1). Overall, this study illustrates that the white and red clovers investigated were equivalent in energy and protein supply, also in comparison to the ryegrass. It remains open whether these forage legumes, when supplemented to a moderate-protein ryegrass, would have contributed to metabolizable protein supply or would have merely increased metabolic nitrogen load.

Investigations utilizing a total number of 3998 farrowings from 1558 sows on two farms have shown a frequency of puerperal diseases (periparturient hypogalactia syndrome=PHS) of 32·7% and 27·0% respectively with significant differences between gilts and sows. Sows without PHS after farrowing (farm A) had a lower frequency of animals without oestrus after weaning of the piglets (0·3 V. 1·1%), a lower rate of late onset of oestrus (3·4% V. 5·9%, P<0·05), fewer sows had abortions (0·9 V. 2·3%, P<0·05) and a lower mortality rate (1·2 V. 4·1%, P<0·05) compared with sows which contracted puerperal diseases. The return rate was significantly lower in sows without PHS (12·4%, 16·1% in herds A and B) when compared with sows with puerperal diseases (15·8%, 21·7%, P<0·05). Also, the litter size of live born piglets was lower in sows with PHS when compared with healthy sows (farm A: 10·42 V. 10·66, P>0·05; farm B: 10·44 V. 10·80, P<0·05)

The 2002 World Summit on Sustainable Development focussed attention on agricultural sustainability and biodiversity in developing countries. These goals are relevant for livestock production in Kenya, where development agencies encourage resource-poor smallholders to acquire large, exotic, high-yielding dairy cows, despite their poor performance, revealed in recent surveys in the highlands and at the coast. The performance of the cows is not in question. The debate relates to the diagnosis of the causes, their treatment and the prognosis for the production system. To improve our understanding of the dynamics of the system, models of nutrition and energy, modified for the tropics, were used to measure the thermal responses over 24 h of six pure or crossbred Friesians at a mean lactation of 54 (s.d. 21·6) days, in separate zero-grazing units. Four smallholdings were on the hot, humid coast and two in the cooler highlands. The output of the model runs was related to the subsequent lactation, calving interval and profitability of the cows. The model showed that the thermal load caused moderate stress for all cows during the day, which became severe in the sun in the highlands, but the drop in air temperature, from 27 °C to 13 °C, at night dissipated the gain in body heat. At the coast, where the night temperature remained above 24 °C and relative humidity above 0·85, there was no remission of heat stress for cows with a milk yield greater than 11 l/day. The lactation curve, in all cows, declined from an initial peak to a low profile of 5 l/day. Cows in both regions with initial yields above 20 l/day had the steepest decline and longest calving intervals (457 to 662 days). They had the largest lactation yields and lowest direct cost per litre, but their poor breeding record reduced cull sales and increased replacement cost, raising the total cost per litre. By contrast, the cow with the lowest daily and lactation yield had the highest direct cost, but lowest total cost per litre, because she produced 2 heifer calves at an interval of only 317 days. These case studies serve as a reminder that, where heat load depresses appetite or poor food cannot support lactation, the energy deficit and stress reduces cow fertility, fitness, and longevity, so that she fails to breed a heifer replacement during her shortened productive life. The model predicted that food intake, depressed by heat stress, would not support a milk yield above 14 l/day and 3000 l per annum at the coast, and 22 l/day and 5000 l per annum in the highlands. Therefore, although appearing profitable in the short term, the current policy of promoting cows with higher yields than the climate and production system can support, is unsustainable. This outcome has implications for smallholder dairy development policy in Kenya, and probably elsewhere in the tropics. Instead, one should reconsider smaller exotic breeds and crossbreds with improved indigenous dairy cows whose overall productivity from milk yield, fecundity, longevity, and disease tolerance 50 years ago was better than that of the modern Holstein-Friesian in a Kenya smallholding.

The aim of this study was to evaluate the effects of the hot season and nutrition on the oxidative status and metabolic profile of lactating goats during mid lactation. Twenty-four Red Syrian goats were allocated into three groups that were offered the following diets: natural pasture (P), pasture+500 g/h per day of concentrate (PC) and hay plus 500 g/h per day of concentrate (HC). Blood samples were taken in spring (85±7 days in milk (DIM)) and summer (120±7 DIM) and assayed for reactive oxygen metabolites (ROMs), α-tocopherol, glucose, triglycerides, cholesterol, non-esterified fatty acids, total protein, albumin and globulin concentrations and glutathione peroxidase (GHS-Px) and superoxide dismutase (SOD) activities. Milk yield and milk composition were also measured. SOD, GSH-Px and ROMs levels increased during summer when temperature humidity index values were high. The increase in ROMs in the PC and HC groups could be ascribed to the improved nutritional regime and to their higher production level. The markers of the oxidative status and of the metabolic profile measured in this study indicate that goats may have experienced moderate oxidative stress. It seems that, seasonal rather than nutritional factors have a more pronounced effect on oxidative status markers. Concentrate supplementation sustained milk yield and may represent a useful means to extend the lactation period in dairy goats during late spring and summer.

The effects of nutrition on patterns of live-weight change, hair follicle activity, moult, hormone profiles and associated activities of monodeiodinase enzyme types II and III (MDII and MDIII) in cashmere goats were investigated. From 1 week before the winter solstice (mid December), one group of 15 animals was given a ration designed to provide 2·0 × live weight maintenance requirements (high; H) while a second, similar, group was given 0·8 × live weight maintenance requirements (low; L). After approximately 3 months, L animals had significantly lower mean live weights (P<0·01) than H animals. This was associated with lower (P<0·05) overall mean hair follicle activity in L than H animals during the March to May period and a lower overall mean moult score during March and April in L animals (P<0·01) but a similar mean date of moult onset. Mean concentrations of all of the hormones measured exhibited significant changes (P<0·01) with date of sampling. Overall mean concentrations of insulin, tri-iodothyronine and thyroxine did not differ with treatment but, compared with L animals, H animals exhibited higher mean concentrations of prolactin in April and May (P<0·05) and of insulin-like growth factor-1 in December and January (P<0·001). Rates of activity of MDII and MDIII in skin differed with date (P<0·001) but were not significantly affected by nutritional treatment. The MDIII/MDII ratio differed (P=0·05) with month but was significantly higher (P<0·05) in L than H animals in January, only. It is concluded that the reduction in hair follicle activity and the slower onset of moult associated with reduced nutrition were unlikely to be controlled, directly, by differences in activities of MDII or MDIII in skin tissue.

Three hundred young rabbits were divided into three groups at weaning and given ad libitum a control diet (C), or an experimental diet in which 0·20 of control diet was substituted by maize ear (E) or by whole maize plant (P) in order to examine their effects on fattening rabbits performance, carcass characteristics and meat quality. No significant differences were found in live-weight gain (45 g/day) or in food intake between diets but food conversion ratio was higher in the P group (2·4 g dry matter (DM) per g gain) than in E group (2·2 g DM per g gain). The rate of mortality was similar in the three groups. No differences between groups on live weight (2152 g) or in the digestive tract weight (437 g) were found and the dressing yield was similar in the three groups. At constant carcass weight, the carcasses of rabbits of the P group had lesser lumbar circumference and higher length to circumference ratio (P<0·0001) than of the C or E groups. No differences were found in the weights of liver or thoracic viscera, but kidneys of rabbits of P group were lighter than of the C or E groups. No differences between groups were found in the weights of scapular fat, perirenal fat, forelegs or thoracic cage, but the loin of rabbits of P group was heavier (291 v. 286 g) than in the other groups. Meat of rabbits P had higher L* and b* parameters of colour and higher water-holding capacity (P=0·003) but the meat of rabbits of the control group had less lipids (31 v. 36 g/kg meat) and more moisture (739 v. 735 g/kg meat) than of the experimental groups. The proportion of protein was higher in E group than in P group. Intra and intermuscular fat of hind leg meat from rabbits ‘maize’ substituted was more monounsaturated than control rabbits (34·2 v. 32·5 g·100 g lipids) and had lesser saturated: monounsaturated ratio (1·2 v. 1·3) indicating a more desirable meat from a nutritional point of view, but had less n-3 fatty acid content. Loin meat of the rabbits given E and P diets seems more tender than one fed conventionally (10·4 v. 11·4 kg) and meat of the rabbits ‘whole maize plant’ had more grass flavour (P=0·009) which is a positive factor for acceptability of consumers.

A total of 166 crossbred does were used to study the possible long term effect of two types of crossbred does (H1 v. H2, old and current generations, respectively) from the cross of different generations of lines selected for litter size, the use of a feeding programme based on a low-energy diet during the rearing and the administration of a high-energy diet during reproductive life, on the performance and body condition of multiparous pregnant does. Selection did not affect the live weight (LW) of does at the effective artificial insemination (AI; 4257 g), the LW change (+12·3 g/day) and food intake (172 g dry matter (DM) per day) until the 28th day of pregnancy. However, H2 does showed greater LW losses during the pre-partum period than H1 does (120+g; P<0·05), perhaps related to their higher prolificacy (+1·1 total pups born; P<0·05). H2 does showed a higher perirenal fat thickness (PFT) at first AI (+0·12 mm; P<0·05) than H1 does, these differences disappearing at effective AI. Females given a high-energy reproduction diet showed a lower LW at effective AI than those receiving a medium-energy diet (4210, 4305 g, respectively; P<0·05). However, type of reproduction diet did not affect the LW and PFT changes of pregnancy does, reaching partum with a similar PFT (8·83 v. 8·93 mm) and maintaining the differences in LW. Pregnant does given high-energy diet consumed 20 g DM and 1·4 g digestible protein per day less than does receiving medium-energy diet until the 28th day of pregnancy, but their digestible energy (DE) intake was significantly higher (+78 kJ DE per day; P<0·05). Does given high-energy diet showed a significantly lower litter size at birth (−0·7 pups; P<0·05), although there were no significant differences in the number of pups born alive (9·54 and 9·76 pups for high and medium-energy diets, respectively). Pups from does given high-energy diet were slightly weightier than those from medium-energy diet (+5·4 g; P<0·05). Multiparous pregnant does that received a low-energy diet ad libitum during the rearing period and first pregnancy showed a higher LW at effective AI (+137 g LW; P<0·05) but a lower PFT (−0·26 mm; P<0·05) than those females that received a medium-energy diet restricted during this same period. These differences were maintained at parturition (+142 g LW and −0·20 mm; P<0·05). Feeding programme during rearing affected neither the food intake of multiparous pregnant does until the 28th day of pregnancy, nor the litter size and weight at birth. The interval between parturitions was not affected by the selection for litter size or the reproduction diet received, but was longer for does that received the low-energy diet ad libitum during the rearing period (+2·9 days; P<0·05). In conclusion, rabbit selection programmes by litter size seem to be working well, but high energy reproduction diets, frequently used to cover their higher energy requirements, must be used carefully out of lactation in the long term to avoid a reduction in litter size.