Wafers of dried grass which differed in particle size (modulus of fineness) were prepared and fed ad libitum to cattle and sheep. The response of the two classes of stock to the feeds was similar. The digestibility of organic matter and of cellulose decreased with decrease in modulus of fineness (more fine particles) and this was associated with more rapid passage of the finely-milled material through the alimentary tract. Organic matter intake generally increased with decrease in modulus of fineness, but the pattern of response differed between experiments. In one experiment the difference in voluntary intake between feeds with modulus of fineness of 2·5 and 1·0 was less than 5% and not significant, but in a second experiment the intake of feed with modulus of fineness of 2·1 was 18% lower than that of feed with modulus of fineness of 1·0. In the first experiment the wafers broke down during handling and feeding with the result that the feed of low modulus of fineness was extremely dusty, but in the second experiment a binding agent was included and little breakdown of wafers occurred. It is suggested that dustiness may have restricted the intake of some of the feeds in the first experiment. Intakes of digestible organic matter did not differ significantly between treatments in either experiment.

Ten Landrace × (Landrace × Large White) young female pigs (gilts) were allocated to each of three growth rate treatments so that they attained 73 kg live weight at 135, 160 or 190 days of age. At 73 kg live weight the gilts were introduced to a vasectomized boar for 30 min each day, and were subsequently mated at the second oestrous period. The interval from boar introduction to puberty was 15·2 and 19·0 days respectively for gilts having first boar contact at 190 and 160 days of age, these intervals being significantly shorter (P<0·05) than the 34·3 days for the 135-day group. However, the mean ages at puberty of the 135- and 160-day groups (169·4 and 178·2 days respectively) were not significantly different but these gilts were significantly younger at puberty than the 190-day group (205·3 days). There were no significant differences between treatments for gilt live weight at puberty or first litter size.

Branched-chain volatile fatty acids (BCVFA) supplements could promote lactation performance and milk quality by improving ruminal fermentation and milk fatty acid synthesis. This study was conducted to evaluate the effects of BCVFA supplementation on milk performance, ruminal fermentation, nutrient digestibility and mRNA expression of genes related to fatty acid synthesis in mammary gland of dairy cows. A total of 36 multiparous Chinese Holstein cows averaging 606±4.7 kg of BW, 65±5.2 day in milk (DIM) with daily milk production of 30.6±0.72 kg were assigned to one of four groups blocked by lactation number, milk yield and DIM. The treatments were control, low-BCVFA (LBCVFA), medium-BCVFA (MBCVFA) and high-BCVFA (HBCVFA) with 0, 30, 60 and 90 g BCVFA per cow per day, respectively. Experimental periods were 105 days with 15 days of adaptation and 90 days of data collection. Dry matter (DM) intake tended to increase, but BW changes were similar among treatments. Yields of actual milk, 4% fat corrected milk, milk fat and true protein linearly increased, but feed conversion ratio (FCR) linearly decreased with increasing BCVFA supplementation. Milk fat content linearly increased, but true protein content tended to increase. Contents of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0 and C15:0 fatty acids in milk fat linearly increased, whereas other fatty acids were not affected with increasing BCVFA supplementation. Ruminal pH, ammonia N concentration and propionate molar proportion linearly decreased, but total VFA production and molar proportions of acetate and butyrate linearly increased with increasing BCVFA supplementation. Consequently, acetate to propionate ratios linearly increased. Digestibilities of DM, organic matter, CP, NDF and ADF also linearly increased. In addition, mRNA expressions of peroxisome proliferator-activated receptor γ, sterol regulatory element-binding factor 1 and fatty acid-binding protein 3 linearly increased, mRNA expressions of acetyl-coenzyme A carboxylase-α, fatty acid synthase and stearoyl-CoA desaturase quadratically increased. However, lipoprotein lipase mRNA expression was not affected by treatments. The results indicated that lactation performance and milk fat synthesis increased with BCVFA supplementation by improving ruminal fermentation, nutrient digestibility and mRNA expressions of genes related to milk fat synthesis.

Corn silage (CS) is associated with a reduction in milk fat content. The fact that CS is constituted of a grain and a forage fraction could explain this effect. This experiment evaluated the effect of grain fraction of CS on rumen fermentation, production performance and milk composition. Earless CS (ECS) was harvested after manually removing corn ears from the plant. Whole CS (WCS) was harvested from the same field on the same day. Eight (four ruminally fistulated) multiparous Holstein cows (84 days in milk) were utilized in a double 4 × 4 Latin square with 21-day periods. Treatments were (dry matter (DM) basis) (1) 23.0% WCS; (2) 12.4% ECS plus 10.6% high moisture corn (HMC) to obtain reconstituted CS (RCS); (3) 23.0% ECS; and (4) 23.0% timothy silage (TS). Diets were formulated to be isonitrogenous and were fed as total mixed ration once a day. DM intake (DMI), milk yield, 4.0% fat-corrected milk (FCM), as well as protein concentration and yield were higher for WCS than ECS. Compared with WCS, cows tended to eat less with RCS, and produced less milk and milk protein. However, yield of FCM was similar between WCS and RCS. Milk fat concentration and yield, as well as the specific ratio of t11 18:1 to t10 18:1 in milk fat did not differ among diets. Milk urea-N tended to be higher for ECS than WCS and TS, whereas ruminal NH3-N was higher with ECS than TS. Rumen pH decreased linearly with time after feeding but was not different between treatments. Higher acetate and lower propionate concentration resulted in greater acetate to propionate ratio with ECS compared with WCS. In conclusion, removing grain fraction from CS decreased milk production and modified rumen fermentation without affecting milk fat concentration and yield. Moreover, despite some differences in DMI and total ruminal volatile fatty acid concentration between WCS and RCS, the restoration of FCM yield, using HMC in RCS diets, to a level of production similar to WCS highlights the importance of energy and nutrients supplied by the grain fraction of CS to support milk yield.

The experiment assessed the effects on performance from calving to the 20th week of lactation of milking cows three times daily (3 × ) compared to milking twice daily (2 × ). After 20 weeks all cows were milked 2 ×. Each treatment consisted of 18 cows and 11 heifers. The mid-calving date was 21 September 1979.

Complete diets of the same composition were offered separately to each group in quantities equivalent to 1040 g/kg of their previous intake. The diet for the first 18 weeks of lactation was estimated to have an energy concentration within the range 11·0 to 11·3 MJ metabolizable energy per kg dry matter. After 18 weeks, the diet was reformulated to reduce the energy concentration to 10·3 MJ per kg dry matter. Total food intakes for the 20 weeks of treatment were 2352 kg dry matter (3 ×) and 2241 kg dry matter (2 ×). From 8 April 1980 the cows were turned out to grass to complete their lactations.

During the 20 weeks the mean daily milk yields of heifers were 19·3kg (3×) and 171kg (2×) (P<005). Cow yields were 28·4 (3×) and 23·9 kg (2×) (P< 0·001) during the same period. After 3× daily milking ceased, there were some positive carry-over effects on milk yield and food intake.

Lactation yields from heifers were 4881 (3 ×) and 4498 kg (2×), whilst for cows the equivalent yields were 6485 (3 ×) and 5694 kg (2 ×) (P<0·01). There were no significant differences in milk quality. At 20 weeks after calving the cows milked 3 × daily had gained less weight, but by 44 weeks from calving the weight gains were similar at 42 (3 ×) and 45 kg (2 ×).

Machine vision can be used to collect images of pigs and analyse them to identify and measure specific areas and dimensions related to their growth, shape and hence conformation. This information could improve the stockman’s ability to maximize production efficiency and also to monitor health by detecting abnormalities in growth rates. This work introduces fully automated algorithms which find the plan view outline of animals in a normal housing situation, divide the outline into major body components and measure specified dimensions and areas. Special attention is paid to determining whether the results are sufficiently repeatable to be useful in estimating these parameters. Problems in compensating for changes in the optical geometry are outlined and methods proposed to deal with them. The repeatability of the image analysis process coupled with the subsequent signal processing for outlier rejection gives s.e. values on areas of < 0·005 and on linear dimensions of < 0·0025. For example, the plan view area less head and neck (A4) can be used to predict the weight of the group of pigs at 34 kg, 66 kg and 98 kg with standard errors of 0·25 kg, 0·17 kg and 0·39 kg respectively when using manual weighing results to calibrate the system. If an individual pig is weighed once at 75 days (e.g. 34 kg) to calibrate the A4-to-weight relationship, subsequent A4 measurements can be used to predict its weight when 125 days old (approx. 80 kg) to within 1 kg. This matches the accuracy of the manual weighing system used in the trials. The effect of pig gender on the area to weight relationships is not significant (P = 0·074), but there is a small yet significant gender effect with the linear dimensions.

The effects of energy source and level of digestible undegraded protein (DUP) in concentrates on silage intake and performance of lactating dairy cows, offered one of a range of grass silages differing in digestibility and intake characteristics, were evaluated in a partially balanced change-over design experiment involving 48 cows. Four silages were prepared using differing management practices prior to and during ensiling. All silages were treated with an inoculant additive. For silages A, В, С and D, dry matter (DM) concentrations were 199, 320, 313 and 223 (s.e. 4.6) g/kg, pH values 3.82, 4.03, 4·03 and 5·27 (s.e. 0.056), ammonia nitrogen (N) concentrations 58, 122, 66 and 356 (s.e. 13.2) g/kg total N and in vivo DM apparent digestibilities 077, 0.75 , 0.60 and 0.60 (s.e. 0·013) respectively. When offered as the sole diet to 12 dairy cows in a partially balanced change-over design experiment, silage DM intakes were 14.7, 14.7, 12.7 and 10.5 (s.e. 0·36) kg/day respectively for silages А, В, С and D. Six concentrates containing three starch concentrations, each at two levels of DUP, were formulated to have similar concentrations of crude protein, metabolizable energy (ME) and fermentable ME. For the low and high starch concentrates and low and high levels of DUP, starch concentrations were 22·5 and 273 g/kg DM and DUP levels were 44 and 60 g/kg DM respectively. Silages were offered ad libitum supplemented with 10 kg fresh concentrate per head per day. For silages А, В, С and D, DM intakes were 10.8, 11.2, 10·7 and 9·1 (s.e. 0·26) kg/day and milk yields 29.0, 27.6, 27.1 and 25.7 (s.e. 0.69) kg/day respectively. With the exception of milk protein concentration there were no significant (P > 0.05) silage type by concentrate energy source and/or level of DUP interactions on silage intake, milk output or composition. Concentrate energy source had no effect (P > 0.05) on silage DM intake, the yields of milk, fat, protein or fat plus protein or milk fat concentration. However, increasing starch concentration increased milk protein concentration (P < 0·001), urinary allantoin concentration (P < 0·01) and diet apparent digestibility (P < 0·001). Altering concentrate DUP level had no effect (P > 0·05) on silage DM intake, yields of milk, protein, fat or fat plus protein, milk f at concentrations or diet apparent digestibility. Increasing the level of DUP decreased milk protein (P < 0·05) concentration. It is concluded that with silages of varying digestibility, fermentation and intake characteristics, there were no concentrate energy source and/or level of DUP by silage type interactions on silage intake, milk yield or composition, or diet apparent digestibility with the exception of a silage type by concentrate level of DUP interaction on milk protein concentration. With out-of-parlour feeding of concentrates the results of the present study suggest that there is no evidence to justify the formulation of concentrates differing in energy source or level of DUP to complement individual silage types.

The influence of four diets and two remating intervals (1 or 9 days after parturition) on several milk and production traits was studied in 73 lactations of 46 Californian C? × New Zealand $ does. Three diets were formulated to provide increasing levels of fibre concentration (180, 202 and 238 g acid-detergent fibre per kg dry matter (DM)); a fourth diet contained added pork lard (35 g/kg) at the lowest level of fibre. The energy: protein ratio was maintained between 72 and 84 kj digestible energy (DE) per g digestible protein.

The DE intake increased significantly when fat was included in the diet but was not affected by dietary fibre concentration. An increase in the DE content of the diet tended to decrease food conversion ratio at a mean rate of 0·16 kg/kg per MJ/kg DE. Fat addition also improved milk yield, litter weight at 21 days and survival index, mainly when litter size was higher than nine pups born alive. Neither live-weight gain nor prolificacy of does were affected by any of the variables studied.

The type of diet did not affect milk DM, crude protein, fat and energy concentrations, the mean values being 287·8, 116·1, 134·2 g/kg and 27·73 MJ/kg, respectively. The proportions of short- and medium-chain fatty acids in milk fat were not affected by type of diet. The effect of fat addition on milk fat composition was limited to the long-chain fatty acids, mainly C18: 0 and C18: 1. These changes in addition to differences in milk intake could also affect the survival index of pups.

Does remated 1 day after parturition showed a lower total milk yield than those remated 8 days later, the decrease being more apparent at the end of lactation. Remating interval did not affect the other variables studied.

Starter feeding is usually used in lamb production to improve rumen development and to facilitate the weaning process, but molecular mechanism of which is not well understood. Therefore, the objective of this study is to investigate the effect of starter feeding on the expression of ruminal epithelial genes involved in cell proliferation, apoptosis and metabolism in pre-weaned lambs. We selected eight pairs of 10-day-old lamb twins. One twin was fed ewe milk (M, n=8), while the other was fed ewe milk plus starter (M+S, n=8). The lambs were sacrificed at 56 days age. Results showed that the lambs fed M+S had lower pH in the rumen and a higher concentration of acetate, propionate, butyrate and total volatile fatty acid (VFA). Compared with the M group, the concentration of β-hydroxybutyric acid in plasma had an increased trend, and the concentration of IGF-1 in plasma had an decreased trend in the M+S group. The length, width and surface of rumen papillae increased in the M+S group compared with the M group; this was associated with increased cell layers in the stratum corneum, stratum granulosum and total epithelia. Messenger RNA (mRNA) expression of proliferative genes of cyclin A, cyclin D1 and cyclin-dependent kinase 2 in the ruminal epithelia of M+S lambs was increased compared with M only lambs. The mRNA expression of apoptosis genes of caspase-3, caspase-8, B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) in the M+S group was decreased compared with M group, but the ratio of Bcl-2 to Bax were not changed between the two groups. Expression of IGF-1 mRNA was decreased, but the mRNA expression of IGF-1 receptor was higher in ruminal epithelia in the M+S group. Furthermore, the mRNA expression of VFA absorption and metabolism genes of β-hydroxybutyrate dehydrogenase isoforms 1 and 3-hydroxy-3-methylglutaryl-CoA lyase had an increased trend in the M+S group than in the M group, but the mRNA expression of 3-hydroxy-3-methylglutaryl-CoA synthase isoform 1, monocarboxylate transporter isoform 1 and putative anion transporter isoform 1 had a decreased trend in the M+S group than in the M group. These results suggest that starter feeding increased proliferation and inhibited apoptosis of ruminal epithelial cells, and may promote the VFA metabolism in ruminal epithelium in pre-weaned lambs. These findings provide new insights into improving rumen development by nutritional intervention strategies in pre-weaned lambs.

Sixty gilts by Landrace sires out of Large White × Landrace females were allocated on the basis of litter relationship and initial weight to six treatments involving the individual feeding of six dietary protein levels, 15·5%, 17·4%, 20·2%, 22·3%, 25·3% and 27·3% crude protein (CP), at a common energy level of approximately 3500 kcal/kg DE, from 23 to 59 kg live weight. Amino acid balance was maintained relatively constant with synthetic lysine, methionine and tryptophan. There were significant increases in growth rate and efficiency of feed conversion from the 15·5% to the 17·4% CP diets and significant reductions in both from the 25·3 % to the 27·3 % CP diets. Carcass lean by dissection increased linearly (r = 0·976) and fat decreased linearly (r = −0·992) with dietary protein increment over the full range studied. As best growth performance and maximum lean content were attained at different dietary CP levels, a combined measure of daily lean deposition was calculated; this indicated that maximum rate of lean growth and efficiency of feed conversion to lean were reached on the 22·3% CP level. In terms of efficiency of utilization of nutrients, maximum retentions of both DE and DCP in the edible part of the carcass appeared to be attained on the two lowest dietary protein levels.

Energy and nitrogen balances were carried out with four multi-porous Holstein/Friesian cows offered four diets in a Latin-square experiment to evaluate urea-treated whole-crop wheat as a partial grass silage replacement for lactating dairy cows. Grass silage (GS) was produced from the primary growth of a perennial ryegrass sward. Spring wheat (cv. Axona) was harvested at 603 g dry matter (DM) per kg and preserved with 20 (WCW-20) or 40 (WCW-40)kg urea per t DM. The diets were 6 kg DM of a dairy concentrate daily with one of four forage treatments offered ad libitum. The forage treatments were GS alone, a 2:1 DM ratio of GS with WCW-40 (2:1 40), or a 1:2 DM ratio of GS with WCW-20 (1:2 20) or WCW-40 (1:2 40). Each period lasted 4 weeks with energy and nitrogen balances being carried out in respiration chambers over 6 days in the last week. Replacement of GS by diets containing WCW resulted in significant increases in DM intake (P < 0·01). Changes in milk yield and composition were small and non-significant but yields of milk fat and protein were higher on WCW diets than on GS diets (P< 0·05). With increasing proportions of WCW in the diet there were significant linear falls in apparent digestibility of DM (P < 0·001), organic matter (F < 0·001), neutral-detergent fibre (F < 0·01), acid-detergent fibre (F < 0·01), starch (F < 0·001) and nitrogen (P < 0·01). Gross energy intakes (P < 0·01) and faecal (P < 0·001), methane (P < 0·05) and milk (P < 0·05) energy outputs were higher with the WCW diets than with GS but urine energy and heat losses were unaffected. In consequence there were no significant differences among the diets in digestible or metabolizable energy (ME) intakes. However dietary ME concentrations (MJ ME per kg corrected DM) fell with increasing WCW inclusion from 11·54 on GS to a mean of 9·96 on the 1:2 diets (P < 0·001). It was calculated that the ME concentration of the WCW was only 8·1 MJ/kg corrected DM at maintenance intake, considerably lower than values used conventionally. There were no significant diet effects on the partition of ME or on the partial efficiency of ME utilization for milk production (k1). The increasing inclusion of WCW increased N losses in urine (P < 0·05) and faeces (F < 0·01) with no net effect on N digested or retained though there was a small increase in milk N output (P < 0·01). It is concluded that low digestibility is the major cause of the small milk response to the partial substitution of urea-treated WCW for grass silage with no evidence of a reduction in the efficiency of utilization of ME.

The present study was conducted to evaluate and compare the physiological responses of sheep and goats to water restriction using the deuterium dilution technique (D2O) to predict the total water intake (TWI) in both species. In two consecutive trials, 10 non-lactating Boer goats and 10 non-lactating German black-head mutton ewes were each randomly allocated into a treatment and a control group. In the control groups (n = 5, for each species), water was offered ad libitum, whereas the treatment groups (n = 5, for each species) received water 3 h/day on experimental days 8 to 14 and 6 h every 2 days on experimental days 15 to 22. The respiratory rate, rectal temperature, body mass and drinking behaviour were also recorded. The TWI was estimated by D2O for each animal. Water restriction for 21 h/day or 42 h/2 days had no significant (P > 0.05) effect on water intake (WI), feed intake, WI to dry matter intake ratio or body mass in both species. The absence of differences between species in their WIs was also confirmed using D2O. However, sheep had higher respiratory rates and rectal temperatures than goats in both control and treatment groups. Both species showed the ability to tolerate a moderate water shortage by activating several physiological mechanisms and behavioural strategies.

Acacia saligna and A. salicina phyllodes, harvested in autumn from young and mature trees, were fed as sole diets to goats (20·3 (s.d. 4·8) kg; no. = 16) and sheep (32·6 (s.d. 4·9) kg; no. = 16). Crude protein of phyllodes from mature trees was 111 g/kg dry matter (DM) and from young trees ranged between 121 and 132 g/kg DM. Condensed tannins and ash content were about twice as high in young trees as in old ones and gross energy was higher in old trees than in young ones. DM intakes by goats from both tree species were low: 24·8 and 13·7 g/kg M0·75 per day for mature and young trees, respectively. Corresponding intakes by sheep were 20·4 and 11·5 g/kg M0·75 per day. Metabolizable energy intakes were up to 125 and 99 kj/kg M0·75 per day for goats and sheep, respectively and were higher for phyllodes from mature trees than for young trees. Goats lost up to 219 glday and sheep up to 346 g/day and both species were in negative nitrogen balance. DM, organic matter and energy apparent digestibilities were low for all diets but were generally higher for goats than sheep. It is concluded that neither A. saligna nor A. salicina could be used as a sole food for small ruminants because of low intakes and negative nitrogen balances. This appears to be due to high tannin content.

The effect of frequency of feeding on the efficiency of utilization of L-lysine hydrochloride supplements was studied in 30- to 60-kg pigs. The feeding regimes were: (A) once daily, (B) twice daily, (C) four times daily between 08.30 and 20.30 h, (D) four times daily at 6-h intervals. The response criterion was urinary-nitrogen (N) excretion during 5-day periods. Linear improvements in N utilization were seen in response to lysine supplementation: (a) of a mineralized barley diet (4·0 g lysine per kg to levels of 5·0 and 6·0 g/kg (trial 1)), and (b) of a barley-soya diet (5·5 g lysine per kg to levels of 6·8 and 8·1 g/kg (trial 2)). In both trials the efficiency of N use averaged over the three diets was significantly poorer with once-daily feeding than for the other three treatments, which did not differ significantly from each other.

Two fats, soya-bean oil and tallow, were blended in the ratios 70: 30, 50: 50 and 30: 70. The ratios of unsaturated to saturated fatty acids (U/S) of the blends were 3·18, 2·08 and 1·49 respectively; values for soya-bean oil and tallow were 6·69 and 0·93. These five fat sources were each included into a basal diet at levels of 40, 80 and 120 g/kg. The digestible (DE) and metabolizable (ME) energy together with the apparent fat digestibility (AFD) of the experimental diets were measured in a metabolism trial based upon four 4 × 4 Latin squares using 16 gilts of 30 kg initial live weight. Linear equations relating dietary DE and ME values to level of inclusion of fat were extrapolated to 1000 g/kg to obtain values for the fats. DE values for soya-bean oil and tallow were 38·06 and 34·16 MJ/kg respectively. Corresponding data for ME were 35·63 and 32·53 respectively. These figures were used to calculate values of the mixtures. Data thus derived did not differ significantly from those determined directly, indicating that there was no synergism between the two fats. DE values of fats determined as the product of AFD of fats and their gross energy followed similar trends. The majority of the increase in values of fats was associated with a change in the U/S ratio from 0·93 to 2·08.

The influence of plane of nutrition and diet on the eating quality of fresh pork was investigated in a study involving 721 animals. Boars and gilts of three genotypes (0, 0·25 and 0·50 Duroc inclusion level) were reared from 30 to 90 kg on seven feeding regimens (combinations of diet formulation and feeding level) to achieve different rates of lean and fat tissue growth during two growth periods (30 to 60 or 75 kg; 60 or 75 kg to 90 kg), respectively. A diet of conventional energy and protein (CEP, 14·2 MJ/kg digestible energy, 205 g/kg crude protein, 10 g/kg lysine) was given using combinations of ad libitum and restricted feeding to produce six treatment groups with variation in lean and fat growth rates. An additional treatment group was given food ad libitum on a higher energy and lower protein diet (HELP, 14·7 MJ/kg digestible energy, 166 g/kg crude protein, 7·0 g/kg lysine) between 30 and 90 kg. Dissected carcass composition at 90 kg was predicted from equations based on P2 fat depth, which were developed from full-side and ham joint dissections on sub-samples of animals. Representative sub-samples of animals were dissected at start (30 kg) and at interim weights (60 or 75 kg) to allow lean and subcutaneous fat growth rates to be calculated for all or parts of the growth period. The feeding regimes produced substantial variation in live-weight gain (DLWG) (744 to 914 g/day) and lean tissue growth rate (LTGR 345 to 417 g/day) and subcutaneous fat growth rate (SFGR 81 to 97 g/day), between 30 and 90 kg, and in longissimus dorsi intramuscular fat content (10·37 to 23·87 g/kg). Pigs given the HELP diet had the highest intramuscular fat and the best eating quality. Pigs offered the CEP diet ad libitum throughout the growth period produced more tender but less juicy meat than those given food restrictedly (0·8 or 0·9 of ad libitum). The correlations between DLWG, LTGR and SFGR for the whole or parts of the growth period and sensory characteristics, although often positive, were generally low, suggesting weak relationships.

Grape proanthocyanidins (GPCs) are a family of naturally derived polyphenols that have aroused interest in the poultry industry due to their versatile role in animal health. This study was conducted to investigate the potential benefits and appropriate dosages of GPCs on growth performance, jejunum morphology, plasma antioxidant capacity and the biochemical indices of broiler chicks. A total of 280 newly hatched male Cobb 500 broiler chicks were randomly allocated into four treatments of seven replicates each, and were fed a wheat–soybean meal-type diet with or without (control group), 7.5, 15 or 30 mg/kg of GPCs. Results show that dietary GPCs decrease the feed conversion ratio and average daily gain from day 21 to day 42, increase breast muscle yield by day 42 and improve jejunum morphology between day 21 and day 42. Chicks fed 7.5 and 15 mg/kg of GPCs show increased breast muscle yield and exhibit improved jejunum morphologies than birds in the control group. Dietary GPCs fed at a level of 15 mg/kg markedly increased total superoxide dismutase (T-SOD) activity between day 21 and day 42, whereas a supplement of GPCs at 7.5 mg/kg significantly increased T-SOD activity and decreased lipid peroxidation malondialdehyde content by day 42. A supplement of 30 mg/kg of GPCs has no effect on antioxidant status but adversely affects the blood biochemical indices, as evidenced by increased creatinine content, increased alkaline phosphatase by day 21 and increased alanine aminotransferase by day 42 in plasma. GPC levels caused quadratic effect on growth, jejunum morphology and plasma antioxidant capacity. The predicted optimal GPC levels for best plasma antioxidant capacity at 42 days was 13 to 15 mg/kg, for best feed efficiency during grower phase was 16 mg/kg, for best jejunum morphology at 42 days was 17 mg/kg. In conclusion, GPCs (fed at a level of 13 to 17 mg/kg) have the potential to be a promising feed additive for broiler chicks.

Spot measurements of methane emission rate (n = 18 700) by 24 Angus steers fed mixed rations from GrowSafe feeders were made over 3- to 6-min periods by a GreenFeed emission monitoring (GEM) unit. The data were analysed to estimate daily methane production (DMP; g/day) and derived methane yield (MY; g/kg dry matter intake (DMI)). A one-compartment dose model of spot emission rate v. time since the preceding meal was compared with the models of Wood (1967) and Dijkstra et al. (1997) and the average of spot measures. Fitted values for DMP were calculated from the area under the curves. Two methods of relating methane and feed intakes were then studied: the classical calculation of MY as DMP/DMI (kg/day); and a novel method of estimating DMP from time and size of preceding meals using either the data for only the two meals preceding a spot measurement, or all meals for 3 days prior. Two approaches were also used to estimate DMP from spot measurements: fitting of splines on a ‘per-animal per-day’ basis and an alternate approach of modelling DMP after each feed event by least squares (using Solver), summing (for each animal) the contributions from each feed event by best-fitting a one-compartment model. Time since the preceding meal was of limited value in estimating DMP. Even when the meal sizes and time intervals between a spot measurement and all feeding events in the previous 72 h were assessed, only 16.9% of the variance in spot emission rate measured by GEM was explained by this feeding information. While using the preceding meal alone gave a biased (underestimate) of DMP, allowing for a longer feed history removed this bias. A power analysis taking into account the sources of variation in DMP indicated that to obtain an estimate of DMP with a 95% confidence interval within 5% of the observed 64 days mean of spot measures would require 40 animals measured over 45 days (two spot measurements per day) or 30 animals measured over 55 days. These numbers suggest that spot measurements could be made in association with feed efficiency tests made over 70 days. Spot measurements of enteric emissions can be used to define DMP but the number of animals and samples are larger than are needed when day-long measures are made.

The aims of this study were to determine the presence and quantities of antioxidative status and oxidative stress (OS) variables in the seminal plasma and spermatozoa of bulls of varying age during cold and warm periods of the year, and to establish the correlation of these variables with semen quality parameters. The study was conducted on two groups each comprising nine Simmental bulls: one group contained younger animals (aged 2 to 4 years) and the second older animals (aged 5 to 10 years). Semen samples were collected using an artificial vagina for biochemical analysis. Seminal plasma and spermatozoa activities of total superoxide dismutase (TSOD), manganese superoxide dismutase (MnSOD), copper–zinc superoxide dismutase (CuZnSOD), catalase (CAT), selenium-dependent glutathione peroxidase, reduced glutathione and concentrations of total protein (TP), thiobarbituric acid reactive substances (TBARS) and protein carbonyl content (PCC) were determined. Several antioxidants in seminal plasma were also determined: total glutathione peroxidase (TGSH-Px), selenium-independent glutathione peroxidase (Non-SeGSH-Px), uric acid, albumins (ALB) and alkaline phosphatase (ALP). Significantly higher spermatozoa motility was observed during the cold v. warm period, and a significantly higher volume and total number of spermatozoa per ejaculate was observed in older than in younger bulls. Significantly higher values of ALP, TP and ALB were found in seminal plasma of older bulls than in younger bulls during the warm period. The seminal plasma of younger bulls showed significantly higher activities of TSOD, MnSOD, CuZnSOD, TGSH-Px and Non-SeGSH-Px. Younger bulls had significantly higher PCC concentration and activity of CAT in seminal plasma than older bulls during the cold period. Significantly higher concentrations of PCC and TBARS, and activities of TSOD, MnSOD and CuZnSOD were established in spermatozoa of the younger than in older bulls during the warm period. It could be concluded that antioxidative and OS variables differ significantly depending on bull age and time of year. Younger bulls were more sensitive to elevated ambient temperatures during the warm period, when the higher enzymatic antioxidative protection in seminal plasma and spermatozoa were insufficient to counteract the intensive oxidative processes in spermatozoa, which eventually resulted in decreased spermatozoa motility. The estimation of antioxidative and OS variables in seminal plasma and spermatozoa may have practical value for the assessment of bull semen quality.

Female pigs of the Pietrain and Large White breeds, 18 from each, selected to form a logarithmic weight range, were dissected into their major carcass tissues. Relative to carcass growth, fat was the fastest developing tissue in both breeds; fat and muscle grew at a rate higher, and bone at a rate lower, than the carcass. The growth of bone relative to carcass growth was faster in the Large White; differences between breeds in the growth of muscle and fat were not significant. Muscle weights and muscle: bone ratios, estimated at the same empty body weight, were greater for the Pietrain over the entire body weight range studied. There was no significant difference in muscle: bone ratio between the Large Whites used in the present study and those dissected by McMeekan over 30 years previously. The breed difference in the proportion of muscle and bone at the same body weight is attributed to a greater maturity of the Pietrain.