Two experiments were carried out with sheep, to characterize fodder beet in terms of its effects on rumen function. In experiment A, a study was made of the effects of supplementing hay with fodder beet (FB) on rumen pH and volatile fatty acid (VFA) concentration compared with two control supplements of either barley/maize (BM) or molassed sugar-beet shreds (SBP). Hay was offered with all three supplements in a 50: 50 ratio on a dry matter (DM) basis. The mean rumen pH for the fodder beet diet was 6·34 and intermediate between two controls (BM 6·20 and SBP 6·38). There was no significant difference in rumen concentration of total VFA for the three different diets (FB, SBP and BM) but there were highly significant effects due to diet for acetic and propionic acid molar proportions (P < 0·001). Molar proportion of propionic acid for diets FB, BM and SBP were 0·2064, 0·2221 and 01880 respectively. The loss of DM from nylon bags incubated in the rumen of sheep given the test diets was 471, 447 and 486 g/kg for FB, BM and SBP respectively. In experiment B, the rate of in sacco organic matter (OM) disappearance of the three supplements were compared in sheep given a constant high forage diet (900 g/day hay DM + 200 g/day compound food DM). There were highly significant differences in rates of OM disappearances for the supplements (P < 0·001). The losses of OM measured after 3 h incubation in the rumen were 767, 608, 378 and 236 g/kg for fodder beet, barley/maize, molassed sugar-beet shreds and hay respectively.

Due to genetic selection for fast growth and high breast meat yield, commercial strains of broiler chickens and broiler breeders are predisposed to high feed intake; however, feeding broiler breeders ad libitum impairs their health and reproductive performance. Broiler breeders are feed-restricted throughout rearing to maintain health and performance, yet feed restriction results in hunger, feeding frustration and lack of satiety. The objective of this study was to examine the effect of alternative feeding strategies, including feed additives (separately or combined) and a fixed non-daily feeding schedule, on the feeding motivation and welfare of broiler breeders during rearing. At 3 weeks of age, 180 Ross 308 breeder pullets were allocated to 90 cages and fed with one of five isocaloric treatments: (1) daily control diet (control), (2) daily calcium propionate diet (CaP), (3) daily soybean hull diet (SBH), (4) daily alternative diet (alternative: CaP + SBH) and (5) 4/3 control diet (four on-feed days and three non-consecutive off-feed days per week). The CaP diet included calcium propionate at 1.4% from 3 to 6 weeks of age, and at 3.2% from 7 to 12 weeks of age, and the SBH diet contained soybean hulls included at 40%. The alternative diet included both soybean hulls and calcium propionate at the same inclusion rate as the SBH and CaP diets, respectively. Pullets were weighed and scored for feather coverage every week. A feed intake test was conducted at 3, 4, 8, 10 and 11 weeks of age for 10 min during on- and off-feed days. At 12 weeks of age, feather samples were analysed for fault bars. Data were analysed using linear mixed regression models, with cage nested in the models and age as a repeated measure. At 4 weeks of age, pullets fed soybean hull-enriched diets (SBH and alternative diets) and those on the 4/3 schedule had lower feed intake than control pullets (P = 0.02). Feathers from pullets fed the SBH diet had fewer fault bars than those fed the CaP diet (P = 0.04). The results indicated that the inclusion of soybean hulls (alone or combined with calcium propionate) and a 4/3 feeding schedule can reduce feeding motivation of broiler breeders during early rearing.

Slaughter is a crucial step in the meat production chain that could induce psychological stress on each animal, resulting in a physiological response that can differ among individuals. The aim of this study was to investigate the relationship between an animal’s emotional state, the subsequent psychological stress at slaughter and the cellular damage as an effect. In all, 36 entire male pigs were reared at an experimental farm and a cognitive bias test was used to classify them into positive bias (PB) or negative bias (NB) groups depending on their decision-making capabilities. Half of the animals, slaughtered in the same batch, were used for a complete study of biomarkers of stress, including brain neurotransmitters and some muscle biomarkers of oxidative stress. After slaughter, specific brain areas were excised and the levels of catecholamines (noradrenaline (NA) and dopamine (DA)) and indoleamines (5-hydroxyindoleacetic acid and serotonin (5HT)) were analyzed. In addition, muscle proteasome activity (20S), antioxidant defence (total antioxidant activity (TAA)), oxidative damage (lipid peroxidation (LPO)) and autophagy biomarkers (Beclin-1, microtubule-associated protein I light chain 3 (LC3-I) and LC3-II) were monitored during early postmortem maturation (0 to 24 h). Compared with PB animals, NB pigs were more susceptible to stress, showing higher 5HT levels (P<0.01) in the hippocampus and lower DA (P<0.001) in the pre-frontal cortex. Furthermore, NB pigs had more intense proteolytic processes and triggered primary muscle cell survival mechanisms immediately after slaughter (0 h postmortem), thus showing higher TAA (P<0.001) and earlier proteasome activity (P<0.001) and autophagy (Beclin-1, P<0.05; LC3-II/LC3-I, P<0.001) than PB pigs, in order to counteract the induced increase in oxidative stress, that was significantly higher in the muscle of NB pigs at 0 h postmortem (LPO, P<0.001). Our study is the first to demonstrate that pig’s cognitive bias influences the animal’s susceptibility to stress and has important effects on the postmortem muscle metabolism, particularly on the cell antioxidant defences and the autophagy onset. These results expand the current knowledge regarding biomarkers of animal welfare and highlight the potential use of biomarkers of the proteasome, the autophagy (Beclin-1, LC3-II/LC3-I ratio) and the muscle antioxidant defence (TAA, LPO) for detection of peri-slaughter stress.

A standardised methodology is required for classification of starchy diets. One important question is what feeding status is optimal to describe glycaemic and insulinaemic responses to the respective starchy diet. Four horses were fed, in a randomised order, four different feeding protocols relative to offering hay before or after cracked corn (CC): (i) ad libitum hay for 12 h before feeding CC and ad libitum hay after CC intake for 9 h (+CC+), (ii) ad libitum hay for 12 h before feeding CC and no hay after CC intake for 9 h (+CC−), (iii) feed restriction for 12 h before feeding CC and ad libitum hay after CC intake for 9 h (−CC+) and (iv) 1.2 kg hay/100 kg body weight (BW) per day, divided into two equal portions and offered at 0900 h and 1900 h, feed restriction for 12 h before feeding CC and no hay after CC intake for 9 h (−CC−). CC intake was adjusted to a starch intake of 2 g/kg BW. The different hay offerings did not affect basal plasma glucose and insulin levels. A significant rise in plasma glucose and insulin was found after CC intake for all diets. The highest peak glucose levels were analysed for −CC+, and the lowest glucose peaks were found for +CC− (diet P < 0.05). The highest insulin peaks were monitored for −CC+ (31.27 ± 18.19 μU/ml) and lower peaks for +CC− (13.36 ± 2.93 μU/ml) (diet P < 0.05). Insulin for −CC− and +CC− returned to resting values about 300 min after CC feeding. For +CC+ and −CC+, insulin levels were still above resting levels 510 min after CC intake (diet P < 0.05). The present data suggest that feed restriction for 12 h before feeding the starchy diet and no further roughage intake during blood sampling period provide the best-defined conditions.

Polyphenol oxidase (PPO) in red clover (RC) has been shown to reduce both lipolysis and proteolysis in silo and implicated (in vitro) in the rumen. However, all in vivo comparisons have compared RC with other forages, typically with lower levels of PPO, which brings in other confounding factors as to the cause for the greater protection of dietary nitrogen (N) and C18 polyunsaturated fatty acids (PUFA) on RC silage. This study compared two RC silages which when ensiled had contrasting PPO activities (RC+ and RC−) against a control of perennial ryegrass silage (PRG) to ascertain the effect of PPO activity on dietary N digestibility and PUFA biohydrogenation. Two studies were performed the first to investigate rumen and duodenal flow with six Hereford×Friesian steers, prepared with rumen and duodenal cannulae, and the second investigating whole tract N balance using six Holstein-Friesian non-lactating dairy cows. All diets were offered at a restricted level based on animal live weight with each experiment consisting of two 3×3 Latin squares using big bale silages ensiled in 2010 and 2011, respectively. For the first experiment digesta flow at the duodenum was estimated using a dual-phase marker system with ytterbium acetate and chromium ethylenediaminetetraacetic acid as particulate and liquid phase markers, respectively. Total N intake was higher on the RC silages in both experiments and higher on RC− than RC+. Rumen ammonia-N reflected intake with ammonia-N per unit of N intake lower on RC+ than RC−. Microbial N duodenal flow was comparable across all silage diets with non-microbial N higher on RC than the PRG with no difference between RC+ and RC−, even when reported on a N intake basis. C18 PUFA biohydrogenation was lower on RC silage diets than PRG but with no difference between RC+ and RC−. The N balance trial showed a greater retention of N on RC+ over RC−; however, this response is likely related to the difference in N intake over any PPO driven protection. The lack of difference between RC silages, despite contrasting levels of PPO, may reflect a similar level of protein-bound-phenol complexing determined in each RC silage. Previously this complexing has been associated with PPOs protection mechanism; however, this study has shown that protection is not related to total PPO activity.

Until recently, beef carcass payment grids were predominantly based on weight and fatness categories with some adjustment for age, defined as number of adult teeth, to determine the price received by Australian beef producers for slaughter cattle. With the introduction of the Meat Standards Australia (MSA) grading system, the beef industry has moved towards payments that account for intramuscular fat (IMF) content (marble score (MarbSc)) and MSA grades. The possibility of a payment system based on lean meat yield (LMY, %) has also been raised. The BeefSpecs suite of tools has been developed to assist producers to meet current market specifications, specifically P8-rump fat and hot standard carcass weight (HCW). A series of equations have now been developed to partition empty body fat and fat-free weight into carcass fat-free mass (FFM) and fat mass (FM) and then into flesh FFM (FleshFFM) and flesh FM (FleshFM) to predict carcass components from live cattle assessments. These components then predict denuded lean (kg) and finally LMY (%) that contribute to emerging market specifications. The equations, along with the MarbSc equation, are described and then evaluated using two independent datasets. The decomposition of evaluation datasets demonstrates that error in prediction of HCW (kg), bone weight (BoneWt, kg), FleshFFM (kg), FleshFM (kg), MarbSc and chemical IMF percentage (ChemIMF%) is shown to be largely random error (%) in evaluation dataset 1, though error for ChemIMF% was primarily slope bias (%) in evaluation dataset 1, and BoneWt had substantial mean bias (%) in evaluation dataset 2. High modelling efficiencies of 0.97 and 0.95 for predicting HCW for evaluation datasets 1 and 2, respectively, suggest a high level of accuracy and precision in the prediction of HCW. The new outputs of the model are then described as to their role in estimating MSA index scores. The modelling system to partition chemical components of the empty body into carcass components is not dependent on the base modelling system used to derive empty body FFM and FM. This can be considered a general process that could be used with any appropriate model of body composition.

The effect of transportation on energy metabolism in young calves was assessed at two feeding levels by indirect calorimetry during a 5·5-day experimental period. Twenty-six Holstein-Friesian male calves were assigned in a 2 × 2 factorial arrangement of treatments. Calves were fed below or near the maintenance requirements (270 or 420 k) metabolizable energy per kg M0·75 per day). At 5 days of age, 13 calves were transported. The applied transportation procedure was aimed to mimic common transport of young calves. The other 13 calves were controls. Metabolizability of dietary energy was low (0·808), but similar for control and transported calves. Despite the similar salivary cortisol concentrations after transportation, heat production was higher by 23 kJ/kg M0·75 per day in transported than in control calves. Calves were not in a steady-state regarding their energy metabolism. Heat production decreased with time. Both transportation and feeding level influenced the decline in heat production with time. Only during the first 3 days after transportation was heat production enhanced, suggesting a relatively short-term effect of transportation in young calves. The impact of transportation on heat production and time related alterations in heat production were not related to the calfs activity.

Six production cycles, each of 212 days' duration, were completed with Rambouillet and Suffolk ewes. One group of each breed was maintained under natural light conditions (control) and three groups of each breed were under the influence of various light treatments applied regularly in a rhythmic fashion within each production cycle. Comparison of conception rates between production cycles, breeds, and treatments showed that only in production cycle 2 (mating in June) were the conceptions in control ewes of both breeds significantly lower than those in ewes on altered light treatments. The most meaningful result was the effect of light treatments on prolificacy. Treatment 3 (106 days with 16-h light per day and 106 days with 8-h light per day) gave significantly higher prolificacy than control and treatments 1 (106 days with 8-h light per day starting 65 days before mating) and 2 (42 days with 16-h light per day, then light reduction at 21 min/week for 160 days). Rambouillet and Suffolk control ewes produced annually 179 and 174 lambs per 100 ewes exposed to rams. Corresponding productions were 200 and 197 for treatment 1, 193 and 226 for treatment 2, and 223 and 242 for treatment 3.

Sixty crossbred gilts, comprising 15 groups of four littermates from large litters (> 12 pigs) were used. The experiment was designed as a 2 × 2 factorial, with two initial live weights (light (L) or heavy (H)) and either a low (lp) or high (hp) plane of feeding during the rearing period and post mating within each litter group. The hp gilts were significantly heavier (P < 0·001) and had thicker backfat (P < 0·001) than the lp gilts at first oestrus. The Hhp gilts reached puberty 26·4 days earlier than the Hip gilts (P < 0·05). Level of food intake significantly influenced ovulation rates and total embryo numbers, the hp gilts shedding on average 2·4 more ova and having 1·9 more embryos than the lp gilts 28 to 35 days post mating (P < 0·05). However, due to somewhat higher embryonic mortality in the hp gilts, the mean number of live embryos was not significantly higher than for the lp gilts (P < 0·05).

The grazing behaviour of bulls and steers was examined by observation and the use of vibra-recorders. Twenty-four-h grazing times were similar for both bulls and steers but grazing patterns differed, with bulls being more sensitive to environmental change and grazing more intermittently than steers.

Sixty-four Friesian/Holstein cows culled from dairy herds were selected for uniformity and general health. They were allocated to five groups of 12 on the basis of body condition and live weight excluding the two cows at each extreme. These four cows indicated the range of condition and live weight in the sample and were slaughtered at the beginning of the trial with one group of 12 cows. Of the remaining four groups, two were implanted with 300 mg trenbolone acetate (Finaplix, Hoechst) and two used as unimplanted controls; one implanted group and one control group were slaughtered after 60 days and the remaining cows after 100 days. All cows were individually fed to appetite on a pelleted diet of 500 g dried lucerne and 500 g barley per kg. After slaughter the left side of each carcass was cut into primal joints and then separated into fat, lean and bone.

Implantation resulted in greater live-weight gains to 60 days (1·35 v. 112 kg/day, P > 0·05) and to 100 days (1·31 v. 0·92 kg/day, P < 0·01), greater lean meat production and an increase in the lean proportion of carcasses.

Feeding cows for 100 days rather than for 60 days led to higher slaughter weights but daily live-weight gain decreased and food intake increased progressively between 60 and 100 days. Carcasses from cows slaughtered at 100 days had significantly higher lean, fat and bone weights (P < 0·01) but as a proportion of side weight only the fat proportion of the carcass was significantly increased (P < 0·05).

It was concluded that the supplementary feeding of cull cows produced heavier carcasses but at these high rates of gain increased yield was at the expense of proportionately more fat in the carca?.s. This problem was partially countered by implantation with trenbelone acetate.

Thirty-six British Friesian entire male calves were reared from 100 kg live weight (LW) to slaughter at 450 kg LW. They were offered maize silage ad libitum plus supplements of minerals and a protein concentrate or urea in three treatment diets: protein concentrate (P), urea (U) and (P/U) in which protein and urea each provided 50% of the supplementary N up to 200 kg LW followed by urea alone. Levels of N × 6·25 in the diet dry matter (DM) were 16% from 100 to 200 kg LW, 14% from 200 kg to 300 kg, and 12% thereafter. Barley was given to all the cattle over 12 mo of age at 1% of LW daily.

Live-weight gain in the 280-day period prior to the introduction of barley averaged 899, 684 and 580 (±31·0) g/day for P, P/U and U, respectively, and was greater for P than for the other two treatments (P<0·05). After the introduction of barley, gains were similar between treatments, averaging 1275, 1333 and 1270 (±43·2) g/day, resulting in mean ages at slaughter of 15, 16·5 and 17 mo for P, P/U and U, respectively.

Substitution of protein concentrate by urea was reflected in a reduced content of metabolizable energy (ME) in the diet and a reduced intake of DM and ME in period 1. Although the contents of ME in the diets were similar in period 2, when barley was given to the cattle, there was little evidence of compensatory growth in treatment P/U and U compared with treatment P. Live-weight gains predicted from ME intake showed good agreement with actual gains. However, reduced intakes and gains by treatments P/U and U compared with treatment P meant that the target weight and age at slaughter of 450 kg and 15 mo of age was met only by treatment P. For the complete system the cattle consumed an average of 2·3 t DM per head of which maize silage DM comprised 78%. Efficiency of feed use averaged 15·5 kg live-weight gain per 100 kg total DM eaten.

With the increased utilisation of land throughout the West of Scotland by the Forestry Commission, the problems arising from the integration of forestry and sheep-farming demand special attention. The Hill Farming Research Station at Lephinmore in Argyll has provided an opportunity over the past four years for the initiation of long-term experiments. These involve various preparatory studies and this paper describes a preliminary survey of the fragments of herbage in the rumen of sheep (after slaughter) with the object of assessing the seasonal variation in their grazing selectivity for heather. The Lephinmore hill is predominantly of heather. Since there are many divergent views as to the preference of sheep for heather, this survey was designed in a rather novel, indirect way to obtain more precise information. The rôle of heather as a dietary constituent is of added significance because, after the afforestation of the lower slopes of a hill, the sheep are then restricted to higher ground where there is greater snow cover in the winter.

The traditional beef production in the South of Portugal is based on a discontinuous growth (DG) system that requires lower external inputs and could enhance meat quality and financial returns to cattle producers. This system allows farmers to take advantage of the bull’s compensatory growth when the pasture is abundant and finishes the cattle on concentrates for 2 to 3 months before slaughter. The fast gain rate before slaughter could be a valuable strategy to improve tenderness and to reduce its inconsistency in beef production. Therefore, the aim of this study was to evaluate the effects of production system (continuous growth (CG) v. DG) on longissimus thoracis muscle properties from Alentejana bulls. In total, 40 Alentejana male calves were allocated to two distinct feeding regimes: in the CG system, animals were fed concentrate plus hay and slaughtered at 18 months of age, whereas in the DG system, animals were fed on hay until 15 months of age and then fed the same diet provided to the CG group until 24 months of age. The DG system had a positive impact on meat tenderness (P<0.001) and global acceptability (P<0.001). DG bulls had greater fibre cross-sectional area (CSA) of glycolytic fibres (P<0.05) and relative area of the muscle (RA) occupied by type IIX fibres (P<0.01) and greater levels of α-actinin (P<0.05) and myosin light chain 2 (P<0.01) proteins, and pH24h (P<0.01) than CG bulls. The latter had greater CSA of type I (P<0.05) and type IIA (P<0.01) and greater RA of type IIA (P<0.05) and oxidative (P<0.05) than CG bulls. The compensatory growth production system had a positive impact on meat tenderness and global acceptability, overcoming the negative effects of slaughter of the bulls at a later age. The DG beef system could be a worthwhile strategy of beef production in Mediterranean areas due to the low-quality pasture in summer.

Two experiments were performed to study the effect of ambient temperature and feeding level on energy and protein metabolism of individually housed pregnant sows. In experiment 1, 12 pregnant animals were used. The stage of pregnancy at the start of the experiment ranged from 34 to 41 days. In experiment 2, 10 pregnant animals were used. The stage of pregnancy at the start of the experiment ranged from 38 to 47 days. In each experiment two groups of animals were used. Each group of five or six animals was individually tethered in one of two identical calorimeters and given one of two feeding levels. At the high feeding level the animals received about 1·35 × maintenance. At the low feeding level the animals received about 1·1 × maintenance. The temperature in experiment 1 changed stepwise in both calorimeters by 3°C every 5 to 7 days from 21 to 12°C and then in reverse order. Temperature in experiment 2 changed stepwise in both calorimeters by 2°C every 3·5 days from 25°C to 11°C and then in reverse order.

Energy gain was negative in animals at the low feeding level at the temperatures below 15 to 18°C. At the high feeding level sows lost energy at 12°C or lower in experiment 2. Protein gain was depressed by both low feeding level and low temperatures. Energy balance was depressed by about 90 kJ/kg M0·75 per day at the lower feeding level and by 19 kJ/kg M0·75 per day per °C below thermoneutrality. Protein gain was depressed by about 26 g/day at the low feeding level and by about 6 g/day per °C below thermoneutrality. Fat gain at low feeding level was depressed by about 92 g/day and by about 154 g/day at the lowest temperature. At low feeding level below the critical temperature, gain of fat was negative. Feeding levels used in these experiments did not supply sufficient energy for energy equilibrium or fat gain for the pregnant sow kept for longer periods below the thermoneutral zone.

1. In three experiments, 112 7-day-old British Friesian male calves were used in performance and digestibility trials to evaluate dried cooked potato in liquid and creep diets.

2. A 15% depression in growth rate for each 10% inclusion of cooked potato flour in liquid diets was recorded from 4 to 21 days and the faeces of potato-fed calves also tended to be less solid. Over the whole feeding period, liquid diets containing up to 20% potato did not significantly depress performance to weaning at 35 days.

3. Only when a liquid diet containing potato starch was introduced prior to 4 weeks of age was daily live-weight gain markedly depressed.

4. Incorporating potato starch in milk diets did not influence creep intake.

5. Calves offered a creep diet containing 40% cooked potato flake ate less, but grew faster than calves given a diet containing 40% flakedmaize. At constant intakes of creep, daily gains were 14 to 18% greater on the diet containing potato flake.

6. The apparent digestibility of gross energy and nitrogen was 0·67 and 0·66 for the flaked maize creep and 0·71 and 0·69 for the potato creep. Digestible energy and digestible nitrogen values were 12·7 MJ and 18·2 g/kg dry matter for the maize diet and 13·0 MJ and 19·0 g/kg dry matter for the flaked potato diet.

7. The incidence of bloat was higher for calves fed on potato than for those fed on maize.

The objective of the experiment was to determine the effects of different, sustained levels of undernutrition on the reproductive performance of Brahman heifers, and on their subsequent growth to adulthood, when reared exclusively on a low-quality tropical pasture.

Irrespective of the live-weight gains realized between weaning and the target weight of 270 kg, heifers on all treatments conceived at a similar mean weight of 290 kg. Nevertheless, heifers on the low weight-gain treatment had a significantly different relationship of cumulative conceptions to weight, which was confirmed when Cox's proportional hazard model was fitted to the data, using a dummy variable to represent treatment effect.

A Gompertz growth model was fitted to the live weight of each individual animal. A significantly larger mean asymptotic weight was observed for the low weight-gain treatment, which was unrelated to the number of calvings or weanings, or to the total weight of calves weaned per animal. Asymptotic weights were positively correlated with first conception weight and age, both within and across treatments.

The implications of drastic post-weaning undernutrition and continued suboptimal feeding are discussed briefly.

In the present study, a commercially available anabolic implant containing trenbolone acetate and oestradiol-17p was investigated in intact and castrated bulls. Measurements of growth rate, serum hormones and metabolites in both phenotypes, and testicular development and function in bulls, were obtained. The experimental objectives were realized in a 2 × 2 factorially designed experiment utilizing eight Angus-sired crossbred bulls and eight similar steers castrated at 7 months of age. Half of each group were implanted with 140 mg trenbolone acetate plus 28 mg oestradiol-17β. Body weights were monitored every 7 days and plasma samples were obtained at 28-day intervals from 9 to 15 months of age. In the implanted groups, mean concentrations of plasma trenbolone and oestradiol-17p were 380 ng/1 and 31 ng/1, respectively. Trenbolone concentrations were undetectable in both non-implanted groups, and plasma oestradiol-17β was less than half that in implanted animals. While plasma GH concentrations were stratified according to implant treatment, they did not differ among the groups. Cortisol levels showed phenotype × implant interaction; implanted steers and non-implanted bulls had lower concentrations than non-implanted steers and implanted bulls. The implant resulted in no significant changes in gross testicular measures in the bulls but did affect the testosterone response to a GnRH challenge and basal plasma concentrations of testosterone were reduced. Plasma urea concentrations were reduced by the implant, but sex phenotype had no effect. Over the 175-day trial, implantation did not significantly improve the growth rate of bulls, except during the first third of the experiment. In contrast, implantation improved the growth rate of steers over the entire experiment, although implanted steers still grew more slowly than either implanted or non-implanted bulls. It can be concluded that the endocrine status of the young bull is set for a fast growth rate, making improvements via an anabolic implant marginal, except in the immature animal.

Two randomized-block experiments were carried out with growing pigs housed in groups of 10 from about 36 to 92 kg live weight and offered non-pelleted diets from single-space feeders containing separate food and water dispensers both operated by the pigs. The dispensing rate of food could be adjusted and rates of 1·4, 2·7 and 5·3 g per press of the nose plate were compared in experiment 1 and 4·8, 6·9 and 9·3 g per press compared in experiment 2. As dispensing rate increased in experiment 1 there were significant increases in food intake, growth rate and backfat thickness and a significant improvement in food conversion ratio on a carcass gain basis. There was no effect on the variation in growth rate between pigs within pens nor were there treatment effects in experiment 2 on any of the above measurements. The amount of food accumulating in troughs increased with feeder setting in both experiments.

Behaviour at feeders was observed in each pen for 24 h during the 5th week using time-lapse video recording. The number of visits to feeders was not significantly affected in either experiment but time spent feeding was significantly increased at the lowest setting in experiment 1. Both the number of withdrawals from feeders accompanied by aggressive encounters and the number of pigs queuing decreased up to the dispensing rate of 6·9 g per press. There were tendencies for all parameters of behaviour to continue changing up to the highest dispensing rate.

An attenuated strain of Salmonella typhimurium has been used as a carrier for oral and intranasal genetic immunization. Here, we evaluate the efficacy of a vaccine strain of S. typhimurium. CSO22 (pGM-CSF/SS, plasmid granulocyte-macrophage colony-stimulating factor/somatostatin) expressing two copies of SS genes. A total of 115 piglets, aged 2 months old, were either orally or intranasally immunized against the vaccine strain CSO22 (pGM-CSF/SS) with three dosages (5 × 1010 colony forming units (CFU), 5 × 109 CFU and 5 × 108 CFU). For oral immunization, the specific anti-SS antibodies were detected in the immunized piglets. The levels of SS antibodies in the high-dose immunized group (5 × 1010 CFU) were significantly higher than that in the phosphate buffered saline immunized group (P < 0.01) and 40% of animals were positive in SS antibodies in the high-dose immunized group. Moreover, the weight gain of the high-dose group was increased by 20.86%, 10.26% and 15.30% during 4, 8 and 12 weeks, respectively, after immunization in comparison to the control. For intranasal immunization, the growth of the low-dose group was increased by 10.23% in the whole test period (12 weeks). In conclusion, our results suggest that the recombinant strain could elicit anti-SS antibodies and improve the growth performance of immunized piglets, and that the oral immunization program is better than the intranasal program.