1. Wessex Saddleback sows were fed 4 lb. or 2 lb. of a balanced meal per head per day during the first 13 weeks after mating with a Large White boar. All sows received 6 lb. of meal for the last 3 weeks of pregnancy, and approximately 14 lb. (4 lb. plus 1 lb. for each piglet) during lactation. From mating to weaning half the sows on each feeding treatment had access to small soil pens, and the other half to range grazing of lucerne or grass/clover swards.

2. During the first 3 months of gestation sows on soil receiving 2 lb. of meal gained 20 lb. while those on grazing gained 40 lb., equal to the gain of sows fed 4 lb. of meal.

3. Approximately 10·5 piglets were born per sow under all treatments. Piglet mortality was highest with sows which had been fed 4 lb. of meal during pregnancy and were confined in small soil pens, because this treatment produced the greatest number of over-fat sows. Mean piglet weight at 3 weeks (≏ 12 lb.) and 8 weeks (≏ 39 lb.) and total creep-fed meal consumption per piglet (≏ 30 lb.) were similar for all treatments.

4. In a preliminary trial 3½ lb. of dried grass plus ½ lb. of meal per head per day was fed to gilts during the second and third months of pregnancy without adversely affecting farrowing results.

5. From these experiments and the published work it is suggested:—

(a) Pasture alone would probably have been sufficient during the second and third months of pregnancy of the sows used in these trials.

(b) Feeding standards for pregnant sows of 250-350 lb. live-weight may be too generous, and produce ‘fat not fit’ sows at farrowing.

(c) In practice the reduction of meal feeding and the greater dependence on grazing should be applied individually to each sow according to her condition and response.

The objective of this study was to assess the effect of dietary saponins, extracted from the plant Quillaja saponaria, on the concentrations of immunoglobulins in sow colostrum and milk, and additionally to observe any effect on piglet performance. Twenty-two sows were allocated to each of two dietary treatments on day 72 of gestation, balancing for parity, fatness and past reproductive performance. Treatments were : control (C) and supplemented (Q; 2.5 g saponin per day as a top-dressing). Sows received 2.5 kg food once per day throughout gestation. Between days 72 and 93 of gestation Q sows received a saponin top-dressing as described. After day 93, all sows were given the same diet and managed in an identical manner. Colostrum samples were taken from all sows at farrowing on delivery of the first piglet then 4, 8, 24 and 72 h later and again on day 21 of lactation. A group of eight sows from each treatment were also blood sampled at farrowing, day 3 and day 21 of lactation. Concentrations of immunoglobulins IgG and IgA in the colostrum, milk and blood were not affected by sow treatment during gestation at any sampling point. Fat, lactose and cell counts were also similar across treatments in colostrum and milk. Protein tended to be higher in milk on day 3 but lower on day 21 (P < 0.1) in Q sows. Piglet performance was not affected by sow treatment during week 1 of lactation. However pigs suckling Q sows grew more slowly between days 8 to 14 (P < 0.05) and days 15 to 21 (P < 0.1). Q sows also had fewer stillborn piglets in their litters at farrowing (7.67 v. 13.25%, P < 0.05, s.e. = 1.93). It is concluded that dietary quillaja saponin given during this time period has no influence on sow lacteal immunoglobulin secretions. However an adverse effect on performance of the sucking piglet was observed, the reasons for which are unclear, but may be related to reduced milk protein concentrations. Dietary quillaja saponin during gestation does however appear to reduce the incidence of stillborn piglets.

Records ivere collected on Romanov (R), Finnsheep (F), and Booroola Merino (B); first cross; and backcrosses of these breeds with a new synthetic breed of Dorset, Leicester and Suffolk (DLS). The data covered the period from the birth of ewes to weaning of their progeny. The heaviest lambs at birth were the B backcross and R first and backcrosses (4·1 to 4·0 kg) and the lightest were pure R (3·0 kg). The fastest pre-weaning average daily gain was that ofR crosses. R purebreds were more fertile (109%, P < 0·01) than F (81%) and B (62%). They were also more prolific at birth and at weaning (2·44, 2·13) than F (2·04, 1·71, P < 0·01) and B (2·36, 2·09, P > 0·05) purebreds, respectively. Similarly, first-cross R ewes were more prolific than first-crosses of F and B (1·99 v. 2·86 and 1·70), also backcross R ewes were more prolific than backcrosses ofF and B (1·63 v. 1·45 and 1·42, P > 0·05), respectively. R first-cross ewes had heavier litters (6·31 and 26·1 kg) than B (5·17 and 20·3 kg, P>0·01) and F (5·52 and 24·4 kg) at birth and at day 50. The lambs born to DLS ewes were the heaviest at birth and at day 50 compared with those from prolific ewes. Fleece weight in B and its crosses was significantly higher than in R. Crosses showed generally positive heterotic effect in weights, prolificacy and wool production compared with pure breeds. In two data sets, additive direct effect ofR was higher than that ofF at birth (by 0·11 and 0·10 kg) and at day 50 (by 0·57 and 0 kg) but was similar at day 100 and day 365. The additive direct effect of both R and F was non-significantly different to that of B at birth in both data sets, but in only one data set was it higher (P < 0·001) at day 50 (by 2·29 and 1·72 kg), at day 100 (by 5·24 and 5·30 kg) and at day 365 (by 8·7 and 8·4 kg, respectively). Maternal direct effects ofR was higher (P < 0·05) than F in lamb weights at day 1 and 50, and higher than B in lamb weight at day 50. Individual heterosis between both R and F and DLS were -3·7 and -3·6% in weight at birth, 1·46 and 2·09% in weight at day 50 respectively. The corresponding maternal heterosis were, -2·9, -5·2, 1·46 and -0·02%.

Energy metabolism during flushing of mink (Mustela vison) in relation to a control group was studied by means of combining pooled data from balance and respiration experiments carried out in 1993 (experiment I) and 1994 (experiment II) and some blood metabolites from experiment II. The experiments, which were divided into six 1-week balance periods, started on 7 February and continued until 22 March. Flushing was performed by restricted feeding in periods 2 and 3 and refeeding in periods 4 and 5. Each balance period included a 24-h measurement of heat production by means of indirect calorimetry in open-air circuit respiration chambers. In experiment II blood samples were taken at weekly intervals and analysed for total triiodothyronine, total thyroxine, free thyroxine, glucose, insulin and fructosamine. Generally, intake of digestible nutrients and energy metabolism measurements within the flushed group were strongly influenced by period (energy supply), whereas they remained stable in the control group and differences between treatment groups over the total experiment were non-significant. The fluctuation in energy status induced by flushing did not involve major changes in body weight. Blood metabolites reflected the food intake by being fairly stable in the control group and decreasing during restriction and increasing during refeeding in the flushed group (P < 0·05). As an effect of flushing the number of corpora lutea increased significantly (P < 0·05).

Juice was extracted from a ryegrass silage after fermentation times of 0, 51 or 291 h. Three solutions of D/L lactic acid were prepared to have the same neutralizing values (NV) as the silage juices. Experiment A measured the mtakes by sheep of dried silage residues remaining after juice extraction. Experiment B measured the effect of adding each of the juices and lactic acid solutions (1·5 l/kg) on intake of unmolassed sugar-beet nuts. Intakes were measured daily and also over 3 h following an overnight fast.

Fermentation time had no effect on the composition or intake of the residues (P < 0·05). Increasing fermentation time from 0 to 51 to 291 h reduced silage juice pH (5·07, 4·96 and 4·10), increased lactic acid (gfl 6·2, 7·1, 18·7), NV (meq/l 29, 40, 157) and osmolality (mosmol/l 1000, 1010, 1390). Corresponding values for the lactic acid solutions were 2·82, 2·74, 2·41 (pH), 3·1, 4·3,18·3 (lactic), 26, 38,154 (NV) and 32, 42,176 (osmolality).

Total daily DM intake (g/kg live weight1·473) was unaffected by NV but was significantly higher overall (P < 0·05) for the silage juices (7·49) than for the lactic acid solutions (6·64) although this difference was mostly due to the extra dry matter (DM) contained in the added silage juice. Short-term DM intake (g per 3 h per kg live weight1·473) decreased with increasing NV, being significantly lower (P < 0·05) for the highest NV than for the others (3·58, 3·34 and 3·11) but lactic acid and silage juice gave similar responses (P > 0·05). Effects on short-term intake were influenced mainly by NV and suggested effects on immediate feedback mechanisms or palatability.

The Maasai of Kenya are typical of many pastoral communities in that they rely on milk as a major part of their diet. Milk production in three herds of Maasai cattle was studied from 1991 to 1996. Weekly measurements of milk extracted for human consumption were used to estimate lactation length, total offtake and mean daily production. Calf live-weight data were used to estimate total milk yield. Least-mean squares regression and analysis of variance tests were adopted to assess the effect of a number of variables on milk production parameters.

Data from a total of 650 lactations and 383 calvings were collected. Mean daily offtake was 891 ml. The length of lactation of frequently milked cows was 372 (s.e. 7·96) days. Total lactation offtake was estimated at 305 I. Herd, parity level and year of calving differences were observed. Multiple regression analyses indicated that some of the variation in daily offtake could be explained by stage of lactation, season of milking, herd, parity and year of calving. An average total yield of 2·73 I/day was estimated for the first 90 days of lactation. Of this, approximately 0·4 was used for human consumption. Overall, seasonality was seen as the major variable influencing production.

1. Nitrogen balance studies have been conducted on eight early-weaned calves receiving four diets containing, respectively, groundnut meal, groundnut+lysine, groundnut+lysine+methionine and white-fish meal as the major protein source.

2. There were no significant differences between groundnut meal diets i n any of the measurements examined. On the fish meal diet all measures of nitrogen retention tended to be higher than the corresponding values for groundnut meals.

3. Daily live-weight gains were significantly higher on the fish meal diet than on any of the groundnut diets (P<0·05).

4. It is suggested that the supplementary amino acids, being highly soluble, were rapidly deaminated by rumen micro-organisms.

Two studies were conducted to examine the effects of selection for milk-fat yield on pancreatic responses to exogenous glucose, as measured by circulating insulin concentrations following an intravenous glucose load, in heifer calves. The first study involved 6-month-old Friesian heifers, eight each from the Massey University high breeding index (HBI) and low breeding index (LBI) lines. Average breeding indices (BI) for milk-fat yield of the calves based on ancestry BI were 136 (s.d. 2) and 112 (s.d. 2), respectively. Oestrous cycling of the heifers was controlled by intravaginal insertion of progesterone-impregnated controlled internal drug-releasing devices (CIDRs). Challenges of glucose (0, 75, 150 and 300 mg/kg live weight) and insulin (0, 0·1, 1, and 10 fig/kg live weight) were administered via indwelling jugular cannulas and were followed by serial blood sampling to measure responses. Plasma insulin concentrations immediately following the glucose challenge were significantly (P < 0·05) greater in HBI than in LBI heifers, peak insulin concentrations (above baseline) in the HBI group being approximately twice those in the LBI group. Plasma glucose concentrations were marginally lower in HBI heifers, probably due to the secondary effect of the relatively greater hyperinsulinaemia in this group. Although the exogenous insulin challenge significantly reduced circulating glucose concentrations in all heifers, there was no difference between the lines in the magnitude of insulin-induced hypoglycaemia.

The second study was designed to determine whether insulin responses to an exogenous glucose load were influenced by stage of the oestrous cycle in heifers of the two lines. In this study, eight yearling HBI heifers and eight LBI heifers (with BI of 135 (s.d. 4) and 111 (s.d. 1) respectively) were administered an intravenous glucose load (150 mg/kg live weight) on tivo occasions, the first being after 17 days of CIDR treatment (simulating the luteal phase of the oestrous cycle) and the second 46 h after withdrawal of the CIDRs (when the heifers were expected to be in oestrus). HBI heifers again showed significantly greater circulating insulin concentrations than LBI heifers following the glucose challenge but the magnitude of this effect was not influenced by time relative to CIDR withdrawal. It is concluded that heifers selected for high milk-fat yield have an increased pancreatic response to exogenous glucose which is apparently independent of the stage of the oestrous cycle. This difference may provide a useful means of identifying heifers of superior genetic merit for milk-fat production prior to their first lactation.

The nylon bag technique was used to determine the effects of offering to steers an allowance of turnips in a diet based on straw on the degradation of dry matter and acid-detergent fibre of the straw. Rumen-cannulated steers were offered basal diets of (a) sodium hydroxide (NaOH)-treated straw ad libitum, (b) NaOH-treated straw plus turnips (50 g dry matter per kg W0·73) offered once daily or (c) turnips ad libitum. Samples of straw, treated with NaOH, anhydrous ammonia (NH3,) or untreated straw were incubated in nylon bags in the rumen along with each of the basal diets. Additionally molasses (66 g dry matter per kg W0·75) was infused into the rumen of the steers offered the NaOH-treated straw. Dry matter and fibre losses of straw from nylon bags were in the order NaOH-treated > NH3,-treated > untreated; there was no interaction (P > 0·05) between method of straw treatment and effect of basal diet on 40-h or 72-h dry matter or fibre degradability. Supplementation of the basal straw diet with either turnips or molasses depressed (P < 0·01) degradability of both dry matter and fibre of the incubated straw at 40 and 72 h, molasses infusion producing a greater depression (P < 0·05) than offering turnips. There was a fall in rumen fluid pH shortly after steers consumed their turnip allowance or molasses was infused into the rumen, minimum pH values were 6·09 ± 0·241 and 5·75 ± 0·205 respectively. The pH of rumen fluid and degradability of dry matter and fibre of barley straw were depressed by the presence of carbohydrates in turnips and molasses. A reduction in the activity of cellulolytic bacteria may have been the cause of the depression in straw degradability.

A total of 142 pigs, born at four different times of the year, were slaughtered between 1 and 9 months of age to study the effects of season of birth and sex on heart weight and body weight in the equatorial climate of southern Nigeria.

Analysis of loge heart or body weight showed that season of birth influenced heart and body growth (P < 0·001). The differences occurred largely during the phase of rapid growth, with smaller differences at weaning and at 9 months. Pigs born during the high-rainfall period (May to September) showed stunted body and heart growth during the subsequent dry and warmer seasons. Those born during the dry seasons (November to March), but which passed their rapid-growth phase through the rainy, cooler seasons, were attaining market weights and adult heart weights earlier in life. However, all pigs with early growth reductions recovered, at least partially, later in life. The males had larger hearts at later ages than the females although the differences were not significant (P > 0·05). Allometric regression analyses for heart and body weight showed no seasonal effects but there was a small but significant sex effect (P < 0·001). The males had a smaller intercept and a larger slope when log, heart weight was fitted to log, body weight.

Pigs reared in this equatorial climate appeared to have higher heart weights relative to body weights than those reared in temperate regions. The highest recorded proportional value of 0·0032 is outside the range of 0·0023 to 00028 recorded in temperate regions. This suggests a probable physiological adaptation to increased work load on the heart under warm tropical conditions.

1. Eight-one British Friesian and 44 Jersey steers was slaughtered at 1. 12, 24, 48 or 72 weeks of age. Those aged 24 weeks and over were reared on a standard complete diet offered ad libitum, and individual food intakes were recorded until slaughter when carcasses were dissected on an anatomical basis.

2. From 1 to 72 weeks British Friesians were on average 50% heavier than Jerseys and consumed 47% more food. Total lean tissue (L) increased 11-fold to 137 + 6·4 kg in the British Friesians and 16-fold to 84 ± 4·7 kg in the Jersey. L as a percentage of live weight rose to 32% ±0·6 in the British Friesians and to 29% ±0·8 in the Jerseys. Breeds did not differ significantly in average efficiency of growth of lean tissue in any period.

3. From 24 to 72 weeks, an allometric relationship held between L and total food consumed postnatally, F. The two breeds had the same allometric coefficient of 0·61. Current efficiency, 0·61 L/F, was thus proportional to cumulated efficiency, L/F. Allowance was made for the prenatal input, Fo, required to produce the newborn calf. An optimum slaughter point at which overall efficiency, L/(F+F0), reached a maximum occurred in each breed when postnatal input was 58% higher than prenatal input (F = 1·58F0). When the breeds had equal maximum efficiency the British Friesian: Jersey ratios for prenatal input, total food consumed and total lean produced were all 2·6:1.

Five Karan Swiss cows were allowed to calve spontaneously and served as controls (Group A), while another 10 were induced to calve about 1 month prior to expected term using either 25 mg dexamethasone alone (Group B) or 25 mg dexamethasone in combination with 25 mg stilboestrol dipropionate (Group C). Blood samples were collected prior to, and for 50 days following, parturition for subsequent hormone analysis, and observations were made on the occurrence of retained placentae.

Parturition was successfully induced in all treated cows within 72 h of drug administration. Placental membranes were retained for 24 h in all treated animals and were manually removed in the farm veterinary clinic. No incidence of placental retention occurred in control cows.

Mean plasma oestradiol-17β in control cows showed a gradual rise from days 30 to 5 pre partum, followed by a sharp increase to peak value 1 day before calving. The rise in mean oestradiol-17β levels in the 2 days before parturition in controls was significantly greater than that recorded for the treated animals. A precipitous drop in plasma oestradiol-17β level occurred following parturition in all groups, with the levels staying low for the rest of the sampling period. Drug administration to animals in groups B and C resulted in a rapid and significant drop in plasma progesterone concentrations to a level similar to that for control animals at parturition. Subsequently, the plasma progesterone remained low in all treatment groups. Mean plasma cortisol levels showed a significant but transient increase at calving in control cows, but were suppressed for at least 48 h following drug administration in treated cows before exhibiting a rebound phenomenon to reach high values after calving.

It is concluded that for normal placental expulsion, oestradiol-17β levels are more critical than progesterone, and that the rise in oestradiol-17β and fall in progesterone levels pre partum must be gradual.

The effects on reproductive performance of different strategies of pasture management designed to conserve herbage in situ during the late growing season for use during the pre-mating and mating period were studied in three experiments over 3 years with Greyface ewes. Two experiments with 341 ewes compared set-stocking of pasture at 12 ewes per ha on two initial levels of herbage mass with a conservation strategy which left half of the area ungrazed and grazed the other half of the area at 24 ewes per ha from late August until mid October (2 weeks before the start of mating) after which the total area was grazed at 12 ewes per ha. In a third experiment with 124 ewes, the conservation strategy left a quarter of the area ungrazed and varied stocking rate to a minimum of 12 ewes per ha to maintain two initial levels of herbage mass on the other three-quarters of the area and then compared set-stocking at six ewes per ha on this area with set-stocking at 18 ewes per ha on the previously ungrazed quarter of the area during the pre-mating and mating period.

Initial levels of herbage mass were within the range of 2000 to 2100 kg dry matter (DM) per ha (7 cm sward height; high) and 1500 to 1700 kg DM per ha (4 to 5 cm; low). Mean herbage accumulation rates between August and October were estimated to be 25 and 44 kg DM per ha per day in the first two experiments. Initial live weight and body condition score also varied considerably between years and subsequent response was influenced by herbage growth rate. Where mean ewe body condition was within the score 2·75 to 3·00, range over the mating period and herbage mass on set-stocked areas was not higher than 2200 kg DM per ha (8 cm sward height) in the pre-mating period or not lower than 1300 kg DM per ha (3·5 cm) at about 3 weeks after mating, the strategy of management did not influence reproductive performance in terms of the number of lambs born. Within these limits, however, reproductive performance was positively related to herbage mass in late August (low = 1·60, high = 1·94).

When herbage mass fell below the 1300 kg DM per ha level before or during mating, reproductive performance was improved by a herbage-conservation strategy which maintained ewe body-condition score within the 2·75 to 3·00 range. When herbage mass and growth rate were high, reproductive performance was also improved by a herbage-conservation strategy which restricted the development of excessive body condition before mating by avoiding the increase in barrenness shown to derive from very high levels of body condition.

The fibrous roughages, wheat straw (WS) and cotton stalks (CS), were left untreated or treated with 30 g sodium hydroxide per kg, and residual alkali was either neutralized with sulphuric acid or left unneutralized. All roughages were pelleted and used either in complete feeds or separately. The effects of these treatments on the nutritive value of the roughages were examined in digestibility trials in vitro and in vivo, and in a 7·month feeding trial of a factorial arrangement of 2 × 3 × 2, in which the roughages constituted 350 g/kg of the diets. Approximately 150 g/kg of the neutral-detergent fibre (cell wall) constituents of both roughages was solubilized by sodium hydroxide treatment, while the changes in acid-detergent fibre components (cellulose and lignin) were much smaller, although evident.

In vitro-dry matter digestibility of wheat straw was 22 % higher than that of cotton stalks, and its increase due to NaOH treatment was 50% and 30% for wheat straw and cotton stalks, respectively. In vivo digestibility of organic matter of wheat straw was increased from 0·47 to 0·59, and that of cotton stalks from 032 to 037. The increase was evident in all components except protein, in which digestibility was reduced. The increase in the metabolizable energy values of wheat straw from 6·86 to 7·45MJ/kg dry matter and that of cotton stalks from 4·77 to 5·10MJ/kg dry matter following sodium hydroxide treatment was not reflected in daily live-weight or carcass-weight gain in the feeding trial. The animals offered NaOH-treated roughages had significantly more fat trim, and more fat in the large depots. Including roughages in complete feeds revealed no advantage in metabolizable energy conversion into live weight.

An experiment has been carried out at Bahia Blanca to estimate the trend in ovulation rate throughout the year shown by Corriedale ewes of similar live weight in the south-west district of the Argentinian pampa.

Five groups of 16 animals were each subjected to two 20-day observation periods and the 10 observation periods in the experiment were evenly spaced within a year.

The proportion of ewes showing oestrus and ovulation (OO), the frequency of twin ovulations (TO) and, hence, ovulation rate (OR) were estimated for each period by using vasectomized rams and performing laparatomies.

A significant and periodic relationship was found between each trait and the number of days elapsed from the longest day (×). In turn, changes in the values of ×, arising from the progress of the experiment, were to some extent associated with changes in nutrition and surgical interference. However, it was concluded that these factors could not have affected the similar and remarkable seasonality shown by each trait in this study, and that this seasonality was mainly associated with differences in the natural light regime to which the ewes were exposed before and during their corresponding observation periods.

The predicted maximum values for each parameter were reached 1 month before the shortest day. Prior to and after this date both OO and TO declined, so that the predicted OR values became zero for a period of approximately 2 months before the longest day

An experiment was undertaken to compare the carcass characteristics and meat quality of lambs from crossbred ewes produced by crossing Texel sires with Rouge de l’Ouest dams and Rouge sires with Texel dams, relative to lambs from purebred Texel and Rouge ewes. The ewes were crossed with Texel or Rouge sires and the relative performance of the sires assessed in terms of lamb carcass quality. Ewe and ram genotype had a significant effect on conformation classification. Lambs from Texel ewes had a greater conformation classification (4·0) than lambs from Rouge ewes (3·4, s.e. 0·09) (P <0·001) and Texel-sired lambs had a greater conformation classification (4·0) than Rouge-sired lambs (3·6, s.e. 0·06) (P <0·001). Fat depth was significantly influenced by ewe genotype with lambs from Texel × Rouge ewes having greater fat depths compared with lambs from Texel ewes (longissimus dorsi 2·3 and 1·9 (s.e.0·12) mm respectively) (P <0·05). Chemical composition of the carcass and meat quality measurements were unaffected by ewe or ram genotype. Significant heterosis effects on lamb live-weight gain (21 g/day; 15%) (P <0·01) from birth to slaughter, age at slaughter (–37 days; –12%) (P <0·01), weight of perinephric and retroperitoneal fat (76 g; 38%) (P <0·01) and fat depth over the longissimus dorsi (0·3 mm; 16%) and gluteus medius (0·5 mm; 17%; P <0·05) were obtained. The results from this study demonstrate that significant heterosis effects, particularly in terms of lamb growth rate, can be achieved by crossing Rouge and Texel breeds. In addition lambs from hybrid ewes have similar conformation characteristics to the Texel breed which has been intensively selected for carcass characteristics.

Low winter growth is a characteristic of male red deer and is caused, in part by a combination of reduced appetite and higher energy expenditure due to cold weather. This study aimed to determine whether housing during winter would reduce energy expenditure and increase the growth rate of male red deer calves. An additional aim was to investigate whether food restriction in winter would be compensated for by increased spring growth. In each of two consecutive years, 80 calves were randomly allocated to eight groups (no. = 10) comprising two replicates of four treatments during winter. Groups were housed inside (I) or outside (O) and given food either ad libitum (AL) or restricted (R) to maintain live weight. Winter treatments (southern hemisphere) ran from 22 May to 25 August (year 1) and from 5 June to 5 September (year 2). During these periods, animals were weighed weekly and group food intake recorded daily. At the end of winter animals were moved outside onto pasture and weighed monthly until the end of spring (27 November, year 1 and 7 December, year 2). In year 2 weighing continued during summer, until 4 April. The animals were slaughtered on 28 November and 18 January (year 1) and 5 April (year 2). The effect of housing on live-weight gain (LWG) and dry-matter intake (DM1) in AL groups was not significant in either year. However in R groups, O had a higher DMI than I in both years (P < 0·05) and a higher LWG than I in year 1 (P < 0·05). LWG was loiver in R than in AL groups in winter in year 1 (P < 0·05) and year 2 (P < 0·001) and live weight was lower in R than in AL groups at the end of winter in both years. Live weight was still lower in R than in AL groups at the end of spring in both years (P < 0·01). In year 2, this live-weight difference was not significant by the end of summer. Hot carcass weight (HCW) was greater in AL animals than R animals (P < 0·05) and dressing proportion was higher in R than in AL (P < 0·05) in year 1. GR (an index of body fatness) was greater (P < 0·05) in O than I in year 1 and was greater (P < 0·05) in AL than in R animals in year 2. Differences in GR between treatments were not significant in either year, with HCW as a covariate.

In conclusion, housing calves given food ad libitum during winter did not reduce DMI or increase growth rate. When normal growth rates were prevented by restricting food intake, housing lowered DMI requirement, although such a situation is unlikely to be a useful farm management practice as recovery from the growth check was slow. Annual variations in climate may determine both the food savings made by housing and the extent of compensatory growth of food-restricted animals in spring.

Relationships play a very important role in studies on quantitative genetics. In traditional breeding, pedigree records are used to establish relationships between animals; while this kind of relationship actually represents one kind of relatedness, it cannot distinguish individual specificity, capture the variation between individuals or determine the actual genetic superiority of an animal. However, with the popularization of high-throughput genotypes, assessments of relationships among animals based on genomic information could be a better option. In this study, we compared the relationships between animals based on pedigree and genomic information from two pig breeding herds with different genetic backgrounds and a simulated dataset. Two different methods were implemented to calculate genomic relationship coefficients and genomic kinship coefficients, respectively. Our results show that, for the same kind of relative, the average genomic relationship coefficients (G matrix) were very close to the pedigree relationship coefficients (A matrix), and on average, the corresponding values were halved in genomic kinship coefficients (K matrix). However, the genomic relationship yielded a larger variation than the pedigree relationship, and the latter was similar to that expected for one relative with no or little variation. Two genomic relationship coefficients were highly correlated, for farm1, farm2 and simulated data, and the correlations for the parent-offspring, full-sib and half-sib were 0.95, 0.90 and 0.85; 0.93, 0.96 and 0.89; and 0.52, 0.85 and 0.77, respectively. When the inbreeding coefficient was measured, the genomic information also yielded a higher inbreeding coefficient and a larger variation than that yielded by the pedigree information. For the two genetically divergent Large White populations, the pedigree relationship coefficients between the individuals were 0, and 62 310 and 175 271 animal pairs in the G matrix and K matrix were greater than 0. Our results demonstrated that genomic information outperformed the pedigree information; it can more accurately reflect the relationships and capture the variation that is not detected by pedigree. This information is very helpful in the estimation of genomic breeding values or gene mapping. In addition, genomic information is useful for pedigree correction. Further, our findings also indicate that genomic information can establish the genetic connection between different groups with different genetic background. In addition, it can be used to provide a more accurate measurement of the inbreeding of an animal, which is very important for the assessment of a population structure and breeding plan. However, the approaches for measuring genomic relationships need further investigation.

The effects of feeding total mixed ration (TMR) or pasture forage from a perennial sward under a management intensive grazing (MIG) regimen on grain intake and enteric methane (EM) emission were measured using chambers. Chamber measurement of EM was compared with that of SF6 employed both within chamber and when cows grazed in the field. The impacts of the diet on farm gate greenhouse gas (GHG) emission were also postulated using the results of existing life cycle assessments. Emission of EM was measured in gas collection chambers in Spring and Fall. In Spring, pasture forage fiber quality was higher than that of the silage used in the TMR (47.5% v. 56.3% NDF; 24.3% v. 37.9% ADF). Higher forage quality from MIG subsequently resulted in 25% less grain use relative to TMR (0.24 v. 0.32 kg dry matter/kg milk) for MIG compared with TMR. The Fall forage fiber quality was still better, but the higher quality of MIG pasture was not as pronounced as that in Spring. Neither yield of fat-corrected milk (FCM) which averaged 28.3 kg/day, nor EM emission which averaged 18.9 g/kg dry matter intake (DMI) were significantly affected by diet in Spring. However, in the Fall, FCM from MIG (21.3 kg/day) was significantly lower than that from TMR (23.4 kg/day). Despite the differences in FCM yield, in terms of EM emission that averaged 21.9 g/kg DMI was not significantly different between the diets. In this study, grain requirement, but not EM, was a distinguishing feature of pasture and confinement systems. Considering the increased predicted GHG emissions arising from the production and use of grain needed to boost milk yield in confinement systems, EM intensity alone is a poor predictor of the potential impact of a dairy system on climate forcing.

The timing in which supplements are provided in grazing systems can affect dry matter (DM) intake and productive performance. The objective of this study was to evaluate the effect of timing of corn silage supplementation on ingestive behaviour, DM intake, milk yield and composition in grazing dairy cows. In total, 33 Holstein dairy cows in a randomized block design grazed on a second-year mixed grass–legume pasture from 0900 to 1500 h and received 2.7 kg of a commercial supplement at each milking. Paddock sizes were adjusted to provide a daily herbage allowance of 15 kg DM/cow determined at ground level. The three treatments imposed each provided 3.8 kg DM/day of corn silage offered in a single meal at 0800 h (Treatment AM), equally distributed in two meals 0800 and 1700 h (Treatment AM-PM) or a single meal at 1700 h (Treatment PM). The experiment was carried out during the late autumn and early winter period, with 1 week of adaptation and 6 weeks of measurements. There were no differences between treatments in milk yield, but 4% fat-corrected milk yield tended to be greater in AM-PM than in AM cows, which did not differ from PM (23.7, 25.3 and 24.6±0.84 kg/day for AM, AM-PM and PM, respectively). Fat percentage and yield were greater for AM-PM than for AM cows and intermediate for PM cows (3.89 v. 3.66±0.072% and 1.00 v. 0.92±0.035 kg/day, respectively). Offering corn silage in two meals had an effect on herbage DM intake which was greater for AM-PM than AM cows and was intermediate in PM cows (8.5, 11.0 and 10.3±0.68 kg/day for AM, AM-PM and PM, respectively). During the 6-h period at pasture, the overall proportion of observations on which cows were grazing tended to be different between treatments and a clear grazing pattern along the grazing session (1-h observation period) was identified. During the time at pasture, the proportion of observations during which cows ruminated was positively correlated with the DM intake of corn silage immediately before turn out to pasture. The treatment effects on herbage DM intake did not sufficiently explain differences in productive performance. This suggests that the timing of the corn silage supplementation affected rumen kinetics and likewise the appearance of hunger and satiety signals as indicated by observed changes in temporal patterns of grazing and ruminating activities.