The principal objective to date in packaging dried forages into wafers, cobs or pellets has been to improve handling and storage. Over 80% of the dried forage produced in the UK is still used as a component in pig and poultry rations, for which a milled and pelleted product is the most suitable. However there is evidence that the different forms of package are not of the same nutritive value to ruminants. With the increasing interest in the use of dried forages for ruminant feeding it is important to examine packaging in these dual rôles, as both mechanical and nutritional treatments.

In the winter feeding phase of a lifetime study of spring-born cattle managed in a 20-month beef system, a total of four feeding treatments were imposed by increasing the level of concentrate supplement offered with ad libitum grass silage. The objective was to achieve a difference in live weight at the end of the winter of about 25 kg between food treatments. A multifactorial design was used with three animal factors — maturity (early maturing Hereford crosses v. late maturing Charolais crosses), sex (heifer v. steer) and method of rearing (suckled calves v. bucket-reared calves).

There were no significant differences between breeds but highly significant (P < 0·001) differences for method of rearing and sex. As a consequence live-weight differences at the end of the winter between breed types (18 kg) were less than the difference between the sexes (23 kg) and for method of rearing (25 kg) although all were highly significant. Although suckled animals had significantly lower growth rates they were still significantly fatter at the end of the winter as were heifers and Hereford crosses. Differences in dry-matter intake were reflected in growth rate.

Plane of winter nutrition had a highly significant effect (P < 0·001) on live weight and condition score at the end of the winter resulting in increments of about 23 kg and 0·12 units of condition for each level of feeding.

Interactions between the main production variables were not significant with the exception of feeding level and method of rearing. Suckled animals showed a significant (Y < 0·001) reduction in winter gain (proportionately 0·85 for that of bucket-reared animals) when offered the same diet. This reduction ranged proportionately between 0·25 and 0·08 for the lowest and highest daily levels of concentrate supplementation respectively. An extra 1 kg concentrates per day was required for suckled animals to achieve similar live-weight gains to bucket-reared animals.

Groups of five Yorkshire ♂ x Landrace ♀ gilts were either exposed (BE) or not exposed (NE) to a mature boar commencing at 140, 147, 154 or 161 days of age. Each group of BE gilts was slaughtered 10 days after initial boar exposure, for examination of the reproductive tract, with one of the four NE groups killed at a corresponding age.

NE gilts remained prepubertal throughout. Boar exposure induced ovulation in one gilt at 140 days, two gilts at 147 days, two gilts at 154 days and one gilt at 161 days. Boar exposure also increased uterine weight (P < 0·001). There were no effects of age either on the number of gilts ovulating or on uterine weight. There was a significant positive effect of body weight on uterine weight which was greater in BE gilts than in NE gilts. These results suggest that body weight may be a determinant of the response to boar exposure by gilts between 140 and 170 days of age.

Twenty-six pregnant Holstein-Friesian × zebu heifers, arranged in pairs according to age, body weight, expected calving date and amount of zebu breeding, were allocated at random to two nutritional regimens during the last 12 weeks before calving. If was planned that the animals in treatment A should calve at a pre-calving live weight of 480 kg and those in treatment B should calve at 380 kg. The diet consisted of maize silage or elephant grass silage, soya-bean meal and minerals. During the first 21 days of the post-partum period both groups were given 6 kg concentrate per head daily. After this period, the feeding level was adjusted every 14 days according to the current milk yield. The mean total milk yields were 2132 kg and 1283 kg (P < 0·05) and the lengths of lactation were 239 days and 156 days (P < 0·01) for cows in treatments A and B, respectively. There was no statistically significant difference between treatments in the intervals from calving to first heat or calving to conception.

Thirteen dairy cows between 7 and 20 days post partum were fitted with catheters in both the jugular vein and caudal vena cava, the latter with the tips anterior to the junction with the ovarian veins. Blood samples were taken from nine control cows from both sites at 15-min intervals for periods of between 8 and 16 h. Four more cows were sampled for 13 h and given 4 × 2·5 ug GnRH intravenously at 3-h intervals starting 1 h after sampling began. Plasma oestradiol-17(3 concentrations were significantly higher in the vena cava than in the jugular vein in the two cows in which they were compared. Twenty-eight LH pulses occurred in the nine control cows during the sampling periods. These were followed within 1 h by increases in caval oestradiol-17β concentrations in 26 cases. LH pulses occurred after 14 of the 16 GnRH injections and with one exception were associated with oestradiol pulses in the vena cava. Oestradiol concentrations generally peaked 15 to 45 min after each LH peak. It is concluded that ovarian follicles are responsive to LH pulses by releasing oestradiol pulses early in the post-partum period.

The effects of melatonin implants, administered during anoestrus, on the time of onset of oestrus, conception rate and litter size in indigenous (Capra prisca) and crossbred dairy goats were studied on commercial farms in a hill region of northern Greece. In the 1st year, 192 indigenous and 86 crossbred does on one farm (farm 1) were each separated into treated (T) and control (C) groups. The T groups from each breed type were given implants of melatonin on 17 April and 6 May, respectively. Bucks were re-introduced to both T and C groups 5 weeks after implantation. Mean mating dates for indigenous goats were 6 July (s.e. 0·15) (T) v. 13 July (s.e. 0·24) (C). Corresponding dates for crossbreds were 31 July (s.e. 0·61) (T) v. 14 August (s.e. 0·87) (C). Treatment did not significantly affect conception rate. Mean kidding dates (from first service) were 6 December (s.e. 0·18) (T) v. 14 December (s.e. 0·28) (C) for indigenous and 31 December (s.e. 0·64) (T) v. 13 January (s.e. 0·82) (C) for crossbred goats. Litter size was higher in both T groups but the difference was not significant. In the 2nd year the indigenous flock on farm 1 was supplemented by two similar neighbouring farms. Farm 1 had both treated does and control does; farm 2 were all treated and farm 3 were untreated control does. In this year all bucks used on treated does were also implanted. All implants were given on 21 April. Mean mating dates were 21 June (s.e. 0·23) (1/T) v. 9 July (s.e. 0·36) (1/C), and 28 June (s.e. 0·09) (2/T) v. 19 July (s.e. 0·15) (3/C). Conception rate was high in all groups. Corresponding mean kidding dates were 22 November (1/T) v. 11 December (1/C) and 29 November (2/T) v. 22 December (3/C). Litter size was higher (F > 0·05) in T than in C groups.

Sixteen healthy ewes of the Marwari breed were randomized and four ewes allocated to each of the following treatments: control, 0·5%, 1·0% and 1·5% sodium chloride in the drinking water. Blood volume, total body water, extracellular fluid volume, intracellular fluid volume and interstitial fluid volume were determined. The results showed that Marwari sheep have a remarkable tolerance to saline water. There were no significant changes in body water compartments accompanying the changes in salinity of the water. It was also concluded that sheep can subsist on drinking water containing concentrations of up to 1·5% sodium chloride for a period of 6 months or more without exhibiting signs of change in body water distribution.

The proportion of ewes lambing of those exposed to the ram, litter size and weight at lambing, and at weaning, pre-weaning lamb mortality and changes in ewe weight during suckling, were studied in 326 ewes (931 lambings) representing two pure breeds, Oxford and Suffolk, and four crossbreds, Oxford♂ × Suffolk♀, Suffolk♂ × Oxford♀, North Country Cheviot♂ × Oxford♀ and Cheviot♂ × Suffolk♀, mated to purebred and crossbred rams during 9 years. The proportional fertility in the Oxford and Suffolk ewes (0·82 and 0·85 respectively) was lower than that of Suffolk × Oxford (0·93), Oxford × Suffolk (0·94), Cheviot × Oxford (0·88) and Cheviot × Suffolk (0·88) ewes. Litter sizes of Suffolk ewes at birth and at weaning were 1·6 and 1·3 lambs, 0·3 (0·22) and 0·3 (0·27) lambs largeir than those of the Oxford ewes, respectively. The corresponding figures for litter weight were 1·29 kg (0·22) and 11·8 kg (0·36). Oxford ewes lost 0·10 of their weight during nursing compared with 0·14 for the Suffolk and the two reciprocal crosses. The estimates of heterosis in litter size and litter weight at birth were 0·085 and 0·082, and at weaning were 0·13 and 0·18 respectively.

The results showed that Oxford crosses were better in performance than the pure Oxford, whereas the Suffolk crosses were similar in performance to the pure Suffolk, except in the proportion of ewes lambing of those exposed and pre-weaning mortality, in which the crosses were 0·07 and 0·20 superior to the pure Suffolk, respectively.

Breed of sire had a significant effect on litter weight at birth and at weaning, whereas the interaction breed of sire × breed of dam was a significant source of variation on litter size and litter weight at birth and at weaning. Litter performance at birth was significantly lower in 2-year-old ewes and in ewes sired by 3-year-old or older rams than in other age groups

'Clean’ grazing is accepted as a successful method of overcoming poor performance in lambs and young cattle caused by nematode parasites of the alimentary tract and would virtually eliminate the need for regular anthelmintic treatment. However,it is impracticable on many grass farms and especially where sheep predominate. ‘Safe’ grazing offers a realistic alternative but has not been fully tested under field conditions. Two 2.8 ha paddocks of a predominantly perennial ryegrass sward were managed during the spring and summer of 1985 to produce two different levels of pasture nematode infestation for weaned lamb grazing during the Autumn of that year. Both areas were grazed by non-lactating mature ewes until 5 February 1985. The safe area(S) was then closed for two silage cuts and grazed for 11 days during early August by replacement dairy heifers. The contaminated area(C) was set stocked with 21 cross-bred ewes and their May born Suffolk x lambs per ha between 29 April and 28 August. Dung samples were collected from lambs grazing C at 8,12 and 16 weeks of age. Herbage and dung samples were collected from S and C at weaning (28 August) and 14 day intervals until lambs were removed from trial on 31 October. 138 lambs were divided into two groups by weight and condition at weaning and set stocked at 25/ha on S and C following an anthelmintic treatment. Lambs were selected for slaughter to produce carcasses of MLC fat class 2 or 3.

It is well known that the process of ensiling forage has a deleterious effect on intake. It is likely that the soluble constituents, produced during the fermentation, are responsible for a major part of this effect, although studies of infusion of constituents into the retlculo-rumen have shown that there Is no simple post-ingestive mechanism. Studies on feeding behaviour have shown that ruminants eat silage more slowly than unensiled forage and from this it has been concluded that ruminants may be aversive to the taste, smell or sight of silage. The question, however, of whether is this aversion to silage could explain reduced intake, when silage is the only food offered, remains. To provide a more definitive test of this question, soluble constituents were added to a high-quality low dry matter silage in combinations and levels typical of those reported in the literature. The effects of these additions on intake by sham-fed sheep was measured.

The effect of contrasting white clover contents on diet selection by grazing sheep provides an insight into grazing behaviour mechanisms. When sheep have a choice between ‘strips’ containing either 70% white clover or 100% grass they consistently choose to graze the former. When clover is intermingled with grass in normal sheep-grazed swards evidence for selective grazing is less clear. The objectives of this experiment were, firstly, to define the pattern of discrimination in response to variation in the contrast in clover content between alternative swards. And, secondly, to test whether the pattern is affected by the mean clover content about which the range is established.

The ‘base’ levels of clover content: 30 and 60% together with 7 ‘contrast’ levels from -30 to +30% of ‘base’ level were planned. Swards of equal content were included as controls. Thus the 30% base was contrasted with 0, 10, 20, 30, 40, 50 and 60%; and the 60% base with 30, 40, 50, 60, 70, 80 and 90% white clover. Each combination of treatments was repeated at two nitrogen levels: C and 30 kg N/ha and the whole replicated twice. The experimental area was at Grasslands Division, Palmerston North, New Zealand. The pasture comprised well-established Ruanui ryegrass - Huia white clover with some weed species. Fifty-six plots (5.6 x 3.5 m), each containing 2 ‘contrast’ areas at 2.8 x 3.5 m were sprayed with different herbicides on 29 July 1983 to achieve the above contrasts.

Disagreement exists within the scientific community with regards to the level of competition for feed between sheep and kangaroos in the Australian rangelands. The greatest challenge to solving this debate is finding effective means of determining the composition of the diets of these potential grazing competitors. An option is to adopt a non-invasive approach that combines faecal collection and molecular techniques that focus on faecal DNA as the primary source of dietary information. As proof-of-concept, we show that a DNA reference data bank on plant species can be established. This DNA reference data bank was then used as a library to identify plant species in kangaroo faeces collected in the southern rangelands of Western Australia. To enhance the method development and to begin the investigation of competitive grazing between sheep and kangaroos, 16 plant species known to be palatable to sheep were initially targeted for collection. To ensure that only plant sequences were studied, PCR amplification was performed using a universal primer pair previously shown to be specific to the chloroplast transfer RNA leucine (trnL) UAA gene intron. Overall, genus-specific, single and differently sized amplicons were reliably and reproducibly generated; enabling the differentiation of reference plants by PCR product length heterogeneity. However, there were a few plants that could not be clearly differentiated on the basis of size alone. This prompted the adoption of a post-PCR step that enabled further differentiation according to base sequence variation. Restriction endonucleases make sequence-specific cleavages on DNA to produce discrete and reproducible fragments having unique sizes and base compositions. Their availability, affordability and simplicity-of-use put restriction enzyme sequence (RES) profiling as a logical post-PCR step for confirming plant species identity. We demonstrate that PCR–RES profiling of plant and faecal matter is useful for the identification of plants included in the diet of kangaroos. The limitations, potential and the opportunities created for researchers interested in investigating the diet of competing herbivores in the rangelands are discussed.

The reports which appeared last January from the English and Scottish Hill Sheep Farming Committees have shown that the economic utilization of our extensive areas* of high lying land has thrown up a number of closely inter-related problems, some technical, some administrative, others legal, social, or political. I have to select from this complexity those aspects of the hill sheep industry which most properly fall within the scope of the Society’s interests and which can be presented within the space of half an hour. It is not easy.

Digestibility (DE) and metabolizability (ME) of a single pelleted diet was examined with growing Angus and Holstein cattle. One hundred and ninety-one individual digestion trials were conducted with bulls, steers and heifers. Food was offered ad libitum or restricted with a daily meal frequency of four. Data were analysed by two covariate models. The first included relative dry matter intake (RDMI) defined as the ratio of DMI to body weight (M0·73). In the second model, covariates were defined by genetic-size scaling; the first covariate scaled DMI by mature weight (A) raised to the power 0·73 (DMI/A0·73) and the second covariate was degree of maturity (μ) defined as body weight divided by A. Model 2 also allowed separation of size and DMI effects. No breed differences were detected. There was a consistent trend for increasing ME and ME/DE from heifers to steers to bulls which was significant between heifers and the average of bulls and steers (575·3 v. 589·3 and 832·8 v. 844·3 J/kJ for ME and ME/DE, respectively). Independent of animal effects, DE, ME and urinary energy (UE) decreased and ME/DE and faecal energy (FE) losses increased as RDMI or DMI/A0·73 increased. Per unit rise in RDMI equivalent to maintenance, the corresponding changes for DE, ME, ME/DE, FE and UE were –33·9, –13·6, 21·3, 34·1 and 9·6 J/kJ, respectively. DE increased 1·5 and ME increased 0·8 J/kJ GE for each 01 unit increase in degree of maturity.

This study used individual weekly results for 160 non-lactating Holstein–Friesian dairy cows in the last 5 weeks of gestation to develop regression equations based on forage NDF content and individual body condition score (BCS) for predicting dry matter (DM) intake. Results were used from treatments in which cows received the same forage and no concentrates throughout the dry period. Ten different conserved forages, either grass silages or mixtures of grass silage and barley straw, were fed in six different experiments and forage NDF ranged from 452 to 689 g/kg DM. On average cows gained 390 g live weight per day, which is less than conceptus growth at this stage – suggesting some mobilisation of maternal tissues to support conceptus growth. BCS remained unchanged at 2.5 over the dry period. DM intake declined from 10.79 kg/day 5 weeks before calving to 9.32 kg/day in the week before calving, with half of this decline occurring in the final week before calving. Intake as a percentage of live weight was moderately predicted (R2 = 0.61 for the entire period) from measures of diet composition (NDF) and cow state (BCS). There were highly significant negative effects of forage NDF and increased BCS on DM intake. The effect of BCS on DM intake was greatly reduced in the week before calving, possibly as a result of a change in metabolic priorities from gaining to losing body reserves.

In three experiments, 16, 24 and 22, May-calving Aberdeen Angus × British Friesian cows were subjected either to single suckling of their natural calves or to single suckling in addition to ‘foster’ suckling for the first 8 to 9 weeks of lactation. Foster suckling was achieved by the removal of cows from pasture twice daily and suckling of male Friesian calves while cows were confined in a creep. Average milk yield per cow removed by foster suckling and milk secretion rates of individual cows were measured at intervals and cows were grazed at equal grazing pressure. Single plus foster suckling increased estimated total yield over single suckling proportionately by 0·55, 0·18 and 0·34 in the three experiments respectively. After foster calves were weaned, milk secretion rate of foster-suckling cows was always higher than that of naturally suckling cows. In addition to a mean yield of about 300 kg milk per cow to foster calves, single plus foster suckling increased calf gain in the natural calves in each experiment although the increases were not significant. The apparent conversion of extra milk consumed by natural calves in the single plus foster suckling treatment was generally low in relation to figures quoted in the literature.

A model is developed in which the metabolizable energy (ME) requirement for growth and maintenance of the foetus, uterus and udder are described explicitly for sheep. The efficiency of the use of ME for the growth of the products of conception (kp) is assumed to be the same as that for growth in non-pregnant animals. Using the results from the model to calculate the efficiency of the use of ME for conceptus growth (kc) in the conventional manner yields values with a similar magnitude and similar variation with food quality as those estimated experimentally. It is concluded that separately accounting for the growth and maintenance of the foetus, uterus and udder is preferable in models but unnecessary in feeding standards.

With an increase in the number of candidate genes for important traits in livestock, effective strategies for incorporating such genes into selection programmes are increasingly important. Those strategies in part depend on the frequency of a favoured allele in a population. Since comprehensive genotyping of a population is seldom possible, we investigate the consequences of sampling strategies on the reliability of the gene frequency estimate for a bi-allelic locus. Even within a subpopulation or line, often only a proportion of individuals will be genotype tested. However, through segregation analysis, probable genotypes can be assigned to individuals that themselves were not tested, using known genotypes on relatives and a starting (presumed) gene frequency. The value of these probable genotypes in estimation of gene frequency was considered. A subpopulation or line was stochastically simulated and sampled at random, over a cluster of years or by favouring a particular genotype. Line was simulated (replicated) 1000 times. The reliability of gene frequency estimates depended on the sampling strategy used. With random sampling, even when a small proportion of a line was genotyped (0·10), the gene frequency of the population was well estimated from the across-line mean. When information on probable genotypes on untested individuals was combined with known genotypes, the between-line variance in gene frequency was estimated well; including probable genotypes overcame problems of statistical sampling. When the sampling strategy favoured a particular genotype, unsurprisingly the estimate of gene frequency was biased towards the allele favoured. In using probable genotypes the bias was lessened but the estimate of gene frequency still reflected the sampling strategy rather than the true population frequency. When sampling was confined to a few clustered years, the estimation of gene frequency was biased for those generations preceding the sampling event, particularly when the presumed starting gene frequency differed from the true population gene frequency. The potential risks of basing inferences about a population from a potentially biased sample are discussed.

1. Three experiments are reported in which chromic oxide, administered as a component of shredded paper at 09·00 and 16·30 hr daily, was used in the estimation of the faecal output of steers fed on silage and barley.

2. Four Friesian steers of 160 kg live weight were used in experiment 1. They were fed on grass silage ad libitum with controlled allowances of concentrate supplement. ‘Absolute’ recovery of Cr2O3 in total collections was 85–91%, though it was apparent that some faeces may have been lost from the total collections. ‘Relative’ recovery in grab samples was 97%.

3. Diurnal variation in Cr2O3 excretion was investigated in experiment 2 with four yearling Friesian steers. Faeces were sampled in three 24-hr periods at each natural defaecation. A significant and consistent diurnal variation was observed, with the lowest concentration of Cr2O3 occurring during the night. Concurrent grab samples taken at 09.15 and 17.00 hr over four days gave estimates of cr2O3 in the faeces which were 16·27% higher than the mean concentration for the three 24-hr sampling periods.

4. Day-to-day variation in the Cr2O3 content of grab samples was examined in experiment 3 with eight yearling Friesian steers. Four steers received 3·63 kg/head per day of barley supplement and four received 1·81 kg. Both groups were offered silage of 25% dry matter ad libitum. Faeces were sampled per rectum twice daily at 09.15 and 17.00 hr over four-day sampling periods. The degree of day-to-day variation was small and tended to be random.