The combined addition of branched-chain volatile fatty acids (BCVFAs) and folic acid (FA) could improve growth performance and nutrient utilization by stimulating ruminal microbial growth and enzyme activity. This study was conducted to evaluate the effects of BCVFA and FA addition on growth performance, ruminal fermentation, nutrient digestibility, microbial enzyme activity, microflora and excretion of urinary purine derivatives (PDs) in calves. Thirty-six Chinese Holstein weaned calves (60 ± 5.4 days of age and 107 ± 4.7 kg of BW) were assigned to one of four groups in a randomized block design. Treatments were control (without additives), FA (with 10 mg FA/kg dietary DM), BCVFA (with 5 g BCVFA/kg dietary DM) and the combined addition of FA and BCVFA (10 mg/kg DM of FA and 5 g/kg DM of BCVFA). Supplements were hand-mixed into the top one-third of total mixed ration. Dietary concentrate to maize silage ratio was 50 : 50 on a DM basis. Dietary BCVFA or FA addition did not affect dry matter intake but increased average daily gain (ADG) and feed conversion efficiency. Ruminal pH and ammonia N were lower, and total volatile fatty acids (VFAs) concentration was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition did not affect acetate proportion but decreased propionate proportion and increased acetate to propionate ratio. Total tract digestibility of DM, organic matter, CP and NDF was higher for BCVFA or FA addition than for control. Dietary BCVFA or FA addition increased activity of carboxymethyl cellulase and cellobiase, population of total bacteria, fungi, Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes and Prevotella ruminicola as well as total PD excretion. Ruminal xylanase, pectinase and protease activity and Butyrivibrio fibrisolvens population were increased by BCVFA addition, whereas population of protozoa and methanogens was increased by FA addition. The BCVFA × FA interaction was significant for acetate to propionate ratio, cellobiase activity and total PD excretion, and these variables increased more with FA addition in diet without BCVFA than in diet with BCVFA. The data indicated that supplementation with BCVFA or FA increased ADG, nutrient digestibility, ruminal total VFA concentration and microbial protein synthesis by stimulating ruminal microbial growth and enzyme activity in calves.

This experiment was carried out to determine the effects of the usage of dried brewing yeast in quail diets on laying performance, egg traits and blood parameters. A total of 240 Japanese quails (Coturnix coturnix japonica) aged 10 weeks were randomly allocated into one control group and three treatment groups. Each group was divided into five replicates as subgroups, comprising 12 quails each. Dried brewing yeast (Saccharomyces cerevisiae) was used at the levels of 1.5%, 3.0% and 4.5% in the diets of the first, second and third treatment groups, respectively. Soyabean meal was replaced with dried brewing yeast. The diets were formulated to be isocaloric and isonitrogenous. The experimental period lasted 18 weeks. Dietary treatments did not significantly affect body weight, daily feed intake, daily protein intake, egg production, egg weight, feed efficiency, mortality, egg shell thickness, egg albumen index, egg yolk index, egg Haugh unit, the percentages of egg shell, albumen and yolk, excreta moisture and small intestinal pH. Inclusion of 3% and 4.5% dried brewing yeast in diets reduced egg yolk cholesterol concentration as mg per yolk and mg per g yolk (P < 0.01). Blood serum cholesterol of groups fed diets with dried brewing yeast was significantly lower (P < 0.01) than that of the control group. Feeding diets containing 3.0% and 4.5% dried brewing yeast resulted in significant increases (P < 0.01) in blood serum levels of total protein, alanine aminotransferase at the end of the experiment. Blood serum levels of uric acid, triglyceride, aspartate aminotransferase and alkaline phosphatase were not affected by dietary dried brewing yeast. It is concluded that dried brewing yeast can be used up to 4.5% in the diets of laying quails without adverse effects on the measured parameters.

Two synthetic lines of rabbits were used in the experiment. Line V, selected on litter size, and line R, selected on growth rate. Ninety-six animals were randomly collected from 48 litters, taking a male and a female each time. Richards and Gompertz growth curves were fitted. Sexual dimorphism appeared in the line V but not in the R. Values for b and k were similar in all curves. Maximum growth rate took place in weeks 7 to 8. A break due to weaning could be observed in weeks 4 to 5. Although there is a remarkable similarity of the values of all the parameters using data from the first 20 weeks only, the higher standard errors on adult weight would make 30 weeks the preferable time to take data for live-weight growth curves.

Patterns of oestrous cycle activity in the first breeding season were studied in 30 Suffolk × Mule ewe lambs, Twenty-eight reached puberty and the mean date of first oestrus was 27 November (s.d. 13·6 days). Mean live weight at first oestrus was 37·7 (s.d. 3·63) kg. The mean number of oestrous cycles was 3·3 (s.d. 1·6), 0·92 (65) being normal length single cycles (14 to 19 days), 0·03 (2) long single cycles (20 to 26 days) and 0·05 (4) multiple cycles (> 26 days).

Plasma progesterone profiles before and after the breeding season were studied in 10 randomly selected animals. All showed profiles suggesting one or two silent ovulations preceding the first oestrus but none showed any indication of silent ovulations following the last oestrus.

Plasma progesterone profiles were also studied on the four animals showing multiple cycles and on the two animals that did not reach puberty. These suggested that, in all four animals showing multiple cycles, one or two silent ovulations had occurred between the two overt oestrous periods. Of the two animals that did not reach puberty, one showed three abnormal silent cycles and the other showed no change in progesterone concentration from a low basal level.

Cows (no. = 11) were classified from liver biopsies taken 7 to 10 days after calving as having mild (FL1, no. = 6), or moderate (FL2, no. = 5) fatty infiltration of the liver. Blood samples were collected from the jugular vein: (1) three times weekly and assayed for progesterone and oestradiol; (2) at 10-min intervals for 8-h periods on three occasions during the early post-partum period and assayed for LH; (3) every 2 h, with ovarian palpation performed every 4 h around the second or third post-partum ovulation, and assayed for LH and oestradiol.

Mean weekly concentrations of oestradiol were not significantly different between FL1 and FL2 cows. FL2 cows tended to have short (< 17 days) first cycles (3/4 FL2 v. 0/5 FL1) with significantly lower concentrations of plasma progesterone (P < 0·05). Mean basal concentrations of LH in the samples collected at 10-min intervals tended to be lower in FL2 than in FL1 cows; however, the difference was significant only in the 2nd week of sampling (P = 0·05). Mean basal concentrations of LH were significantly higher in weeks 3 and 4 than in week 2 in FL1 but not in FL2 cows (P < 0·05). The frequency and amplitude of LH pulses were not affected by week of sampling or by fat content of the liver. The total area under the profile of LH during the pre-ovulatory surge was lower in FL2 than in FL1 cows (P < 0·05) but peak plasma concentrations of pre-ovulatory oestradiol and timing of ovulation after the LH surge were similar.

In a 20-week experiment beginning at week 3 post partum, autumn-calving dairy cows were offered either a flat rate of concentrates in which all the cows received the same daily amount throughout the experiment (G). or a flat rate based on their individual milk yield at 2 weeks post partum (I). Two amounts of concentrates were compared and grass silage was available ad libitum. The amounts of concentrate were 6 kg/day (6) and 12 kg/day (12). In the I treatments the ranges of individual inputs were 4 to 8 and 9 to 15 kg/day for the 6 and 12 kg/day treatments respectively. For treatments 6G, 61, 12G, and 121 respectively, mean milk yields were 25·5, 25·7, 28·9 and 27·6 kg/day; mean live-weight changes +0·05, +0·04, +0·19 and +0·27 kg/day; and mean silage dry-matter intakes 11·1, 11·2, 8·1 and 7·5 kg/day. The differences between systems of allocation were not significant, but differences between amounts of concentrate offered were significant. The system of allocation had no significant effect on milk composition. In the residual period (2 weeks indoors and 19 weeks grazing) there were no significant effects on performance. The mean 305-day milk yields for 6G, 61, 12G and 121 respectively were 6376, 6422, 6720 and 6597 kg.

The objective of this study was to estimate genetic parameters and breeding values of sires for different definitions of length of productive life in Swedish Red and White dairy cattle. The data consisted of 534 016 daughters with initial calvings between 1988 and 1996. These cows were daughters of 1266 sires (55 of which were considered proven bulls, and treated as fixed effects). The model for the hazard included: a random time-dependent effect of herd-year-season (hys), a fixed time-dependent effect of year-season, a fixed time-dependent effect of parity by stage of lactation, a fixed time-dependent effect of the cow’s peak yield as deviation from her herdmates in that herd-year, a fixed time-independent effect of age at first calving, and random and fixed effects of sire. The hys effect was assumed to follow a gamma distribution and the random sire effect a normal distribution with mean zero and variance Aσ2s, where σ2s is the variance among sires and A the relationship matrix. Length of productive life was defined as the number of days from first calving to culling or end of data. Two types of length of productive life were studied: (1) functional productive life (PL), all cows that were culled before the end of data were considered as uncensored; (2) fertility determined productive life (FPL), only cows that were culled for fertility problems were considered as uncensored. Heritability estimates were 6·9% and 6·1% for PL and FPL, respectively. The approximated genetic correlation estimates between fertility measures in first lactation and FPL was higher than the corresponding estimates with PL. In conclusion, it was feasible to use the trait fertility-determined length of productive life, its heritability was almost as large as for PL, and the genetic correlation with fertility was higher than for PL. However, the expected selection response in fertility from indirect selection on FPL was lower than from direct selection.

To access the fermentative response of equine caecal microbial population to nitrogen availability, an in vitro study was conducted using caecal contents provided with adequate energy sources and nitrogen as limiting nutrient. Two nitrogen (N) sources were provided, protein (casein) and non-protein (urea). Caecal fluid, taken from three cannulated horses receiving a hay–concentrate diet, was mixed with a N-free buffer–mineral solution. The influence of four N levels (3.7, 6.3, 12.5 or 25 mg of N in casein or urea) was studied using the gas production technique. Total volatile fatty acids (VFA), NH3-N and gas production were measured after a 24-h incubation period. Microbial biomass was estimated using adenine and guanine bases as internal markers, and ATP production was estimated stoichiometrically. Microbial growth efficiency (YATP) and gas efficiency (Egas) were estimated. Fermentation with casein as the sole N source was generally characterized by lower total VFA, NH3-N, total gas production and higher acetate : propionate (A : P) ratio and YATP than with urea. Results herein presented indicate that, under these in vitro conditions, caecal microbial population does in fact use urea N, but less efficiently than casein in terms of microbial growth.

An experiment was carried out to investigate the effects of compound composition and silage characteristics on silage intake, feeding behaviour and productive performance of dairy cows during the first 25 weeks of lactation. Over a period of 3 years, 36 lactating British Friesian cows (12 per year), in their third or later lactations, were divided into two groups. The cows in each group received either compound S, in which the principal energy source was cereal starch, or compound F containing a mixture of high quality digestible fibre. Cows given compound F ate 2·2 kg more silage dry matter per day (P < 0·05). The type of compound had no effect on the frequency of silage feeding and the time spent eating was significantly different only over weeks 10 to 25 of lactation (P < 0·05), with cows on compound F spending on average 20 min longer feeding per day. Cows on compound F produced 1·7 kg more milk per day than cows on compound S. Although there were no significant differences in the concentration of milk constituents, compound F was associated with higher yields of milk constituents. Significant differences were found between the years of experiment in the frequency of feeding (P < 0·05) and also in the concentration of milk protein and milk fat. There were no significant differences in the magnitude of live-weight change between treatments or year of experiment.

The effect of ensiling grass and supplementing the resulting silage with water-soluble carbohydrate in the form of sucrose and undegradable dietary protein (UDP) in the form offish meal on forage intake and milk production and composition were evaluated in an experiment involving 63 mid-lactation Holstein-Friesian cows. Herbage from the primary growth of a predominantly perennial ryegrass sward was zero-grazed (ZG) from 19 April to 16 May 1993. The herbage was mown and picked up with a precision-chop harvester and offered as the sole diet, twice daily, to 18 cows which were on average 186 days into lactation. On 13 May, herbage from the same sward was harvested identically to the ZG herbage and ensiled, treated with formic acid at a rate of 2·85 lit grass. At 53 days after ensiling the silage was offered either as the sole diet (SO) or supplemented with sucrose at 10·3 g/kg fresh silage (SS) or supplemented with sucrose and fish meal each at 10·3 g/kg fresh silage (SSF) to 15 cows per treatment which were on average 164 days into lactation. The feeding period was 28 days for ZG and 21 days for the SO, SS and SSF treatments, and the last 7 days were the main recording interval. Prior to going on to the experimental diets all animals were offered a common silage ad libitum and supplemented with 5 kg of a 180 g/kg crude protein concentrate. Dry-matter intakes (DMI), milk yields and milk composition were recorded during the pre-experimental period and subsequently used as covariates in the statistical analysis. For diets ZG, SO, SS and SSF, forage DMI (kg/day), total DMI (kg/day), milk yields (kg/day), fat concentration (g/kg) and protein concentration (g/kg) were 14·4,14·0,13·7 and 13·9 (average s.e.d. = 0·55); 14·4,14·0,14·5 and 15·4 (average s.e.d. = 0·59); 15·4, 14·4, 14·5 and 16·7 (average s.e.d. = 0·42); 36·6, 38·6, 38·6 and 37·5 (average s.e.d. = 2·67); 33·0, 30·7, 32·2 and 32·8 (average s.e.d. = 0·75). Nitrogen (N) digestibility was higher on SO and SSF (P < 0·05) relative to ZG with SS being intermediate, otherwise treatment did not alter (P > 0·05) diet apparent digestibility. Ensilage increased the immediately soluble N fraction (a value) and degradability of N (P < 0·001) relative to ZG. It is concluded that ensilage had no effect on forage DMI but decreased milk yield and protein concentration relative to the parent herbage. The positive response in milk yield due to supplementation of the silage-based diet with sucrose and fish meal and the lack of response to sucrose supplementation alone suggests that nutrients absorbed from the digestive tract of cows offered silage-based diets are more limiting in protein or specific amino acids supplied by fish meal than in energy. The decrease in animal performance due to ensiling may be overcome by supplementation of silage-based diets with UDP at sufficient levels to equate that of the parent herbage.

Biohydrogenation of C18 fatty acids in the rumen of cows, from polyunsaturated and monounsaturated to saturated fatty acids, is lower on clover than on grass-based diets, which might result in increased levels of polyunsaturated fatty acids in the milk from clover-based diets affecting its nutritional properties. The effect of forage type on ruminal hydrogenation was investigated by in vitro incubation of feed samples in rumen fluid. Silages of red clover, white clover and perennial ryegrass harvested in spring growth and in third regrowth were used, resulting in six silages. Fatty acid content was analysed after 0, 2, 4, 6, 8 and 24 h of incubation to study the rate of hydrogenation of unsaturated C18 fatty acids. A dynamic mechanistic model was constructed and used to estimate the rate constants (k, h) of the hydrogenation assuming mass action-driven fluxes between the following pools of C18 fatty acids: C18:3 (linolenic acid), C18:2 (linoleic acid), C18:1 (mainly vaccenic acid) and C18:0 (stearic acid) as the end point. For kC18:1,C18:2 the estimated rate constants were 0.0685 (red clover), 0.0706 (white clover) and 0.0868 (ryegrass), and for kC18:1,C18:3 it was 0.0805 (red clover), 0.0765 (white clover) and 0.1022 (ryegrass). Type of forage had a significant effect on kC18:1,C18:2 (P < 0.05) and a tendency to effect kC18:1,C18:3 (P < 0.10), whereas growth had no effect on kC18:1,C18:2 or kC18:1,C18:3 (P > 0.10). Neither forage nor growth significantly affected kC18:0,C18:1, which was estimated to be 0.0504. Similar, but slightly higher, results were observed when calculating the rate of disappearance for linolenic and linoleic acid. This effect persists regardless of the harvest time and may be because of the presence of plant secondary metabolites that are able to inhibit lipolysis, which is required before hydrogenation of polyunsaturated fatty acids can begin.

The paper describes the results of the analysis of over 3000 records of Cambridge sheep kept on 11 farms over a 12-year period. The heritability of the number of lambs born per ewe increased from a low value for the 1-year-old ewes to a high value for the 3-year-old ewes; the multiple age value for 2-, 3- and 4-year-old ewes was 0·33 (s.e. 0-121). Heritability estimates for number of lambs surviving were lower, but showed the same trend of increasing values with increasing ewe age. This trend in heritability was also evident for the mean 50-day lamb weight, as a trait of the ewe, which had a multiple age value of 0·20 (s.e. 0·151). The estimates of heritability of various measures of early lamb mortality were relatively low. Date of first oestrus showed a variable heritability although the multiple age value was 0·42 (s.e. 0·149).

Prolificacy was strongly correlated with various measures of early lamb mortality although the correlation with the final number of lambs weaned was positive. Prolificacy was positively correlated with the ewe's mature weight and the ewe's date of first oestrus and the genetic correlation with mean 50-day lamb weight was slightly positive.

The effect of increases in prolificacy on numbers of lambs weaned was markedly curvilinear with maximum numbers of lambs weaned at an intermediate level of prolificacy.

Angiogenin is a member of the ribonuclease A superfamily of proteins that has been implicated in stimulating angiogenesis but whether angiogenin can directly affect ovarian granulosa or theca cell function is unknown. Therefore, the objective of these studies was to determine the effect of angiogenin on proliferation and steroidogenesis of bovine granulosa and theca cells. In experiments 1 and 2, granulosa cells from small (1 to 5 mm diameter) follicles and theca cells from large (8 to 22 mm diameter) follicles were cultured to evaluate the dose-response effect of recombinant human angiogenin on steroidogenesis. At 30 and 100 ng/ml, angiogenin inhibited (P<0.05) granulosa cell progesterone production and theca cell androstenedione production but did not affect (P>0.10) granulosa cell estradiol production or theca cell progesterone production, and did not affect numbers of granulosa or theca cells. In experiments 3 and 4, granulosa and theca cells from both small and large follicles were cultured with 300 ng/ml of angiogenin to determine if size of follicle influenced responses to angiogenin. At 300 ng/ml, angiogenin increased large follicle granulosa cell proliferation but decreased small follicle granulosa cell progesterone and estradiol production and large follicle theca cell progesterone production. In experiments 5 and 6, angiogenin stimulated (P<0.05) proliferation and DNA synthesis in large follicle granulosa cells. In experiment 7, 300 ng/ml of angiogenin increased (P<0.05) CYP19A1 messenger RNA (mRNA) abundance in granulosa cells but did not affect CYP11A1 mRNA abundance in granulosa or theca cells and did not affect CYP17A1 mRNA abundance in theca cells. We conclude that angiogenin appears to target both granulosa and theca cells in cattle, but additional research is needed to further understand the mechanism of action of angiogenin in granulosa and theca cells, as well as its precise role in folliculogenesis.

When crossbred offspring are used for production of an agricultural commodity profit is a function of three genotypes, that of the sire, the dam and the crossbred offspring. Heterosis in the component traits of profit, in any of the above genotypes, affects profit. Thus only when the final product is a four-way cross can we get crossbred parents plus a crossbred progeny and a full use of the available heterosis.

When the contributions of the sire and dam to profit are unequal, there is a justification for the breeding and use of specialised sire and dam lines, even though the component traits may be genetically additive. Multiple crosses (three- and four-way) may improve profit over two-way crosses only when there is heterosis in one or more of the component traits.

When profitability is presented as a function of productivity and repro-ductivity, five heterosis factors of the component traits may affect profit. These are: (a) Improved efficiency of production in a crossbred ‘commercial offspring’, (b) Improved viability (a component of reproductivity) in a crossbred ‘commercial offspring’, (c) Improved ‘female fertility’ in a crossbred dam. (d) Improved efficiency of the ‘commercial offspring’ through heterosis for maternal effects in the crossbred dam. (e) Improved male fertility through heterosis in the crossbred sire.

When the profit equation is non-linear, the same degree of heterosis as that measured on the component traits may have quite a different effect on profit, depending on the level of performance of the traits. By crosses and backcrosses between the parental lines the location and composition of the heterosis factors may be altered favourably.

Graphic and algebraic procedures were outlined for finding sire-dam combinations that maximise profit in the presence of heterosis when a group of genetic stocks is available.

Sirtuins, NAD-dependent histone deacetylase (HDAC), are correlated to aging and antioxidant. The aim of this study was to determine breed differences of porcine Sirtuins expression and antioxidant capacity in brain between Jinhua pigs (a fatty breed of China) and Danish Landrace pigs (a leaner breed). Effect of age on Sirtuins’ expression was also investigated. At the age of 180 days, the mRNA levels of Sirt1, as well as Sirt2 and Sirt4, in Jinhua pigs were greater, but the mRNA levels of Sirt3, Sirt5, Sirt6, and Sirt7 of Jinhua pigs were lower compared with Danish Landrace pigs. Likewise, at the same BW of 64 kg, the mRNA levels of Sirtuins, except Sirt5 and Sirt7, in Jinhua pigs were greater than Danish Landrace pigs. Meanwhile, Jinhua pigs possessed higher antioxidants activity than Danish Landrace pigs either at the same age or at the same BW. Furthermore, mRNA levels of Sirtuins were decreased with age in brain of the two breeds from 30 to 120 days. The results indicated that Sirtuins expression in brain was different between fatty and lean pigs, and Sirtuins expression may be correlated to antioxidant capacity. In addition, age could down-regulate Siruins expression in porcine brain.

Measurements of the m. longissimus and overlying fat at the last rib were taken on the live pig using ultrasonic machines of differing complexity: Sonatest (simple A-mode machine), Scanogram and His Observer (modified linear scanners), and Danscanner (‘real time’ scanner). These measurements were examined as predictors of the corresponding carcass measurements and percentage lean in the carcass.

Sonatest and Scanogram were compared using 143 purebred and crossbred pigs of different types. The analysis was pooled within breed-type and sex. The standard deviation for percentage lean was 3·94. Residual standard deviations for predicting percentage lean from live weight and best fat thickness were 2·72 (Sonatest) and 2·56 (Scanogram). Addition of m. longissimus depth (Sonatest) and m. longissimus area (Scanogram) reduced these to 2·69 and 2·29 respectively. The use of two or more fat measurements provided no extra precision over a single fat measurement.

Scanogram and His Observer were compared using a subset of 38 pigs. Scanogram was a better predictor of percentage lean using a single fat measurement but when a combination of measurements was used, there was little difference between the machines.

Scanogram and Danscanner were compared using a subset of 27 pigs. The standard deviation of percentage lean was 3·57. Residual standard deviations for predicting percentage lean from live weight, best fat depth and m. longissimus area were 2·18 (Scanogram), and 2·03 (Danscanner). Fat areas had similar predictive precision to fat thickness measurements.

Two experiments, each involving 48 British Friesian cattle, were carried out to examine the performance and carcass quality of bulls and steers implanted with one of three oestrogenic growth promoters in a semi-intensive system of beef production in which the animals were slaughtered at 14 to 17 months of age. The treatments used in experiment 1 were: (1) control steers (no implant); (2) steers implanted with 45 mg oestradiol in silastic rubber at 4·5 months of age and with 300 mg trenbolone acetate at 10·5 and 13·5 months; (3) steers implanted with 20 mg oestradiol and 200 mg progesterone at 95-day intervals from 4·5 months and with 300 mg trenbolone acetate at 10·5 and 13·5 months of age; (4) bulls (no implant). For treatments 1 to 4 respectively dry-matter (DM) intakes were 6·74, 7·24, 7·50 and 7·16 (s.e. 0·092) kg/day; carcass weights were 260, 283, 298 and 290 (s.e. 5·4) kg; and fat depths over m. longissimus were 6·5, 5·3, 6·3 and 3·4 (s.e. 0·53) mm. The same treatments were used in experiment 2, except that 36 mg Zeranol® was used in treatment 3 instead of 20 mg oestradiol plus 200 mg progesterone, and the bulls in treatment 4 were implanted with 36 mg Zeranol at 7·5, 11 and 14·5 months. For treatments 1 to 4 respectively DM intakes were 7·37, 7·85, 7·76 and 7·42 (s.e. 0·092) kg/day; carcass weights were 262, 285, 284 and 296 (s.e. 7·1) kg and mean fat depths over m. longissimus were 7·1, 5·9, 7·0 and 5·2 (s.e. 0·54) mm. Implantation of steers increased food intake but also improved food conversion efficiency and did not consistently affect carcass fatness or conformation. Repeated implantation with 20 mg oestradiol plus 200 mg progesterone produced a greater response in performance than a single implantation with 45 mg oestradiol-17β in a controlled-release silastic-rubber implant, while repeated implantation with 36 mg Zeranol produced a similar response to the single silastic-rubber implant. Bulls produced leaner carcasses and converted food to carcass gain more efficiently than implanted steers.

The effects of work stress and dietary supplementation on ovarian activity were determined in 16 multiparous Mashona cows in Sanyati Communal Area, which lies in a semi-arid environment of Zimbabwe. The cows were assigned to one of four treatments: supplemented working (SW), supplemented non-working (SNW), non-supplemented working (NSW) and non-supplemented non-working (NSNW) cows in a 2 × 2 factorial treatment arrangement with two dietary and two work levels. Cows in the SW and NSW groups pulled a cart with a 200-1 water drum for 18 km (9 km with drum empty, 9 km with drum full) every day for 5 days/week for a total of 12 weeks.

Rectal temperatures were recorded at specific points along the route to and from the river where the water was obtained. Blood samples were collected by jugular venipuncture once a week, before working, for the determination of plasma glucose and non-esterified fatty acids (NEFA). In addition, blood samples were collected once every 3 days for the determination of progesterone concentration. There were no differences (P > 0⋅05) in the rectal temperatures between SW and NSW cows. Cows in the NSW group had the highest decrease in glucose levels and also showed marked increases in NEFA concentrations. The incidence of ovarian activity was similar between SNW and SW cows (P > 0⋅05). The incidence of ovarian activity was least in NSW cows. We conclude that nutritional stress was more important in suppressing ovarian activity than work stress and that dietary supplementation can reduce the negative effects of draught on ovarian activity.

The variability in dairy cow gait characteristics, determined by measurements of footprints (trackway measurements), was analysed. Seven gait parameters were determined from 32 non-lame dairy cows during free-speed walking on a slatted concrete walkway. The footprints were revealed by application of a thin lime powder-slurry layer to the walkway surface. The cows were observed on two test occasions with a 3-week interval, with measurements from four consecutive strides used within each test session. The variance components for cow, test and cow–test interaction were estimated by a residual (restricted) maximum likelihood method. The percentage of each variance component was calculated to assess the relative impact of each factor on total variance. Between-test variation was generally low, suggesting that cows maintain the same average gait pattern, at least over a 3-week period. The proportion of within-test variation was considerable for most trackway measurements. Stride length, step angle, step width and tracking (overlap) showed low to moderate within-test variation (12% to 27%), whereas for mediolateral displacement of rear feet and step length it was rather high (54% and 62%, respectively). Within-test variation in step asymmetry was very high (77%), suggesting the occurrence of natural, non-systematic changes in inter-limb coordination in non-lame cows. For better understanding the gait pattern in non-lame cows, linear associations between the trackway measurements and with body size were assessed. It was concluded that trackway measurements were able to describe the gait pattern in walking cows under dairy farm conditions. However, considering the relatively high within-test variation in gait, several strides should be used to obtain a representative gait pattern.

Two studies, one using a trained taste panel and the other a consumer panel, were carried out to evaluate the eating quality of the Meishan breed. Entire male and female pigs of four genotypes: purebred Meishan (MS) and Large Wliite (LW) and the reciprocal crosses (MS♂ × LW ♀ and LW♂ × MS♀) were reared in single sex groups and given a commercial diet ad libitum from 35 kg live weight to slaughter at around 70 kg. For the taste panel, a loin joint was roasted under standard conditions and samples of fat and lean were presented to the panellists. There were no statistically significant differences between the genotypes for tenderness, juiciness, flavour, odour, incidence of boar taint or overall acceptability. Purebred Meishan samples had a higher incidence of abnormal odours but lower cooking losses and shear force values than the other three genotypes. Meat from gilts was judged to be significantly more tender and juicy, with a weaker pork flavour but a lower incidence of abnormal flavours and higher overall acceptability than that from boars. There were statistically significant interactions between genotype and sex for tenderness, abnormal odour and shear force which mainly involved the purebred Meishans and were of little practical significance. In the consumer study, loin chops and leg joints from purebred LW and the two crossbred genotypes were evaluated. Households received two samples of the same type of joint from the same sex in two separate distributions. Each household received an LW sample and a sample from one of the crossbred genotypes. In general, consumers found the appearance of the joints from the three genotypes to be equally acceptable. For eating quality, the within-household deviations of the crossbred compared with the LW suggested that MS♂ × LW♀ samples were considered to be of better eating quality, particularly for juiciness (deviation -0·71, s.e. 0·24, P < 0·01). In contrast, LW♂ × MS♀ samples were generally considered inferior, particularly in terms of juiciness (+ 0·59, s.e. 0·26, P < 0·05) and flavour (+0·63, s.e. 0·27, P < 0·05). However, the overall acceptability of both crossbreds was considered little different from the Large White. Overall, the results of this work suggest little benefit in eating quality for the Meishan under United Kingdom production conditions.