A new technique was used to analyse data from an experiment involving sequential measurements on the same experimental units. Results may be inconclusive if analysed in several univariate analyses of variance, one for each occasion, because the successive measurements contain the cumulative effect of treatments.

An experiment was carried out in which two pre-weaning herbage allowances and four ages of weaning were applied to 80 lambs and their live weights recorded twice-weekly until 25 weeks of age. The direct and residual treatment contrasts were evaluated over time using a response surface equation. The continuous variation of treatment effects over time was demonstrated simply by plotting the treatment contrasts and fitting the most appropriate equations to them. Treatment effects were tested by analyses of orthogonal regression coefficients over time, evaluated within each sex of each treatment group by multivariate analysis of variance.

Fitted equations of treatment contrasts were used to demonstrate the continuous variation of effects of pre-weaning herbage allowance on live weights of unweaned lambs, the residual effect of pre-weaning allowance on the weights of weaned lambs, and, separately, the effects of weaning and weaning age on live weights of the lambs.

All the live-weight data recorded in the experiment were used in the analyses. The assumptions made for the application of the method were satisfied and the results were much more informative than those of several univariate analyses of variance.

Increasing public interest and more anti-pollution legislation sharpen the need to avoid pollution. Soil, water and air are at risk.

Apart from plant nutrient considerations, secondary effects of water-logging and oxygen depletion of the soil can occur. Slurry tankers can cause damage to the field surface by rutting. Some tankers exert pressures of 70 psi on the soil and then are often used on wet soils. Such malpractices create extra costs to rectify extra problems created.

To mimic the abnormal patterns of follicular growth in the early post-partum period, heifers were injected with 15 mg oestradiol and 37•5 mg progesterone every 12 h for 7 days starting on day 15 of the oestrous cycle. Control and treated animals (no. = 8 per group) were monitored by daily ultrasonography and plasma hormone measurements. Five treated animals had quiescent ovaries for 11 days during which period oestradiol concentrations exceeded 30 pg/ml. After this, the first post-treatment follicular wave produced a normal ovulatory follicle. The other three heifers had quiescent ovaries for 17 days during exposure to high oestradiol values but this was followed by the formation of persistent follicles. The prolonged exposure to oestradiol probably disrupted normal LH surges in the latter animals. Growth rates and internal diameters for normal, ovulatory and prolonged persistent follicles were similar for the first 6 days after emergence, but the persistent follicles grew larger (P < 0·05) than normal follicles over the next 20 days. Luteinization of a subsequent persistent follicle was observed in one heifer. For 2 to 3 days prior to follicular growth, FSH concentrations were similar in controls, and heifers with ovulatory or persistent follicles (P > 0·05). When follicles first emerged and for the next 4 days, oestradiol concentrations were greater in follicles which later persisted (P < 0·05). For the second half of the life-span of persistent follicles, oestradiol concentrations were basal, thus the structure remained for many days after endocrine function had declined. These observations allow new interpretation of previously confusing findings in subfertile cattle presented to veterinarians.

The variations in the incidence of mastitis and infection with stage in lactation of dairy cattle have been the subject of a number of investigations (Oliver, 1955) but until recent years the udder health of dry cows has been given little attention. This is surprising, because many cows are dry for almost three months in each year and the dry period is immediately followed by a few weeks when the incidence of mastitis is high (Oliver et al .,1956a).

During the last ten years a study has been made at this Institute of the importance of the dry period to the control of mastitis in dairy cattle. The object of this article is to review the progress made.

There have been many attempts to use the measurement of cell wall fractions to predict the digestibility in vivo of untreated and alkali treated straws (see far example Sundstøl et al, 1978; Reid and Ørskov, 1987). All these attempts have shown this approach to have very low predictive ability for straws. Accordingly extensive use has been made of digestibility measurements in vitro using either rumen fluid (eg Sundstøl et al, 1978) or cellulase type enzymes (eg Jewell et al, 1986).

Whilst in vitro methods appear to be useful predictors of digestibility in straws, they are slow and relatively expensive. The work reported here has compared their predictive power with that of near infra-red reflectance spectroscopy (NIR).

A total of 123 cereal straws were used. These included 54 wheat, 43 barley and 4 oat straws all untreated and the 9 wheat, 9 barley and 4 oat straws oven-treated with ammonia previously described by Mason et al (1988).

Since the early 1980's there has been a growing interest in the Italian Piemontese breed as a crossing sire breed for use on dairy cows in the United Kingdom. Early interest was centred on ease of calving, growth performance and carcass yields but more recently there have been claims that the Piemontese breed produces meat which ranks highly for tenderness. The aim of this study was to evaluate carcass and meat qualities of Piemontese - sired cattle out of the British dairy herd by comparing these characteristics with similar and contemporaneous Charolais - sired cattle.

A considerable amount is now known about the endocrine and neuro-endocrine control of parturition. Far less is understood however about the effect of events which may be considered stressful on the parturition process, despite its broad relevance to animal welfare and farm animal production. There is evidence that stress can have highly disruptive effects during parturition. For example, it has been suggested, that in pigs the behaviourally restricting farrowing crates used in commercial farming practice give rise to increased inter-piglet birth intervals and piglet mortality (Vestergaard and Hansen, 1984). Recent work on rodents has suggested that inhibtion of oxytocin secretion mediated by endogenous opioids, might be responsible for prolonged parturition following an acute stress such as a mid-partum change of environment. The aim of the present work was to extend the study of the effects of stress at parturition to a large animal model. We report two studies on the effects on parturition and oxytocin secretion of movement in mid-parturition to a novel environment (environmental disturbance). In Experiment 1 the effect of this disturbance on inter-piglet interval was investigated. In Experiment 2 a fuller investigation was made of the effects of environmental disturbance on a range of measures including inter-birth interval, behaviour of the sow and plasma oxytocin and Cortisol levels. The role of opioids was investigated in both experiments by administration of the opioid antagonist naloxone.

Precise, unbiased estimates of genetic parameters, such as heritability and genetic covariance, are necessary to optimise breeding programs and to predict rates of change for various selection schemes. A classical method of estimation is to use high and low selection experiments. We consider two generation selection experiments when observations in the parental generation are only taken on one sex, resulting in half-sib family information. We consider cases of two standardised traits, with zero mean and unit variance, and assume that the traits are normally distributed. The genetic and phenotypic variance-covariance matrices for the traits are denoted by G and P respectively. The genetic variances and covariances of the standardised traits are then heritabilities and co-heritabilities.

The construction of other designs is examined, assuming the phenotypic correlation of rp between traits is known. For simplicity, comparisons of designs are developed by considering the variance of the genetic variances when the traits are uncorrelated both phenotypically and genetically.

The indigenous sheep breeds of Greece, which are used mainly for milk production, produce lambs which are killed at weaning to provide carcasses (including the head, pluck, liver, spleen and the omental and mesenteric fat) of 5 to 9 Kg. The production of heavier carcases could be of benefit if they are acceptable to consumers and if they could be economically produced. The purpose of this experiment was to characterise the growth and development of the entire males and females of three Greek breeds under conditions presumed to be non-limiting.

Animals. From each of three breeds, Boutsiko (B), Serres (S) and Karagouniko (K), 20 lambs of each sex were used in a serial slaughter experiment. Four animals of each breed/sex combination were killed at live weights which were 25, 35, 50, 70 and 100% of the estimated mature values. All sheep were weaned at 6 weeks of age and the males were entire.

Although there is some understanding of the effects of immediate levels of nutrition on ovulation rate and embryo wastage, it is not yet possible to predict the reproductive performance of ewes at pasture in the autumn. In many situations sward height declines over the pre- and post-mating period but herbage intake and reproductive performance under these circumstances have not been described. Furthermore, responses in reproductive performance to supplementary feeding at pasture in the autumn have been variable. It may he possible to explain some of this variation in terms of sward height and the substitution rate of herbage by the supplement. This paper reports 2 experiments which were conducted to describe (1) the herbage intake by ewes grazing swards at different heights and when supplements were offered, and (2) the reproductive performance of ewes given supplements as sward height declined.

The metabolisable protein system (AFRC, 1992) requires the measurement of the dynamics of the degradation of protein in the rumen. However many drying techniques used during sample preparation cause protein damage and denaturation which may affect the subsequent assessment. The objective of this work was to compare the dry matter and nitrogen degradation profiles of samples of grass silage dried using a range of techniques.

One kilogram samples of first cut grass (Lolium perenne) silage (156 g CP/kg DM) were air dried (AD), freeze dried (FD), dried at 50 (OD50) or 100°C (OD100) in a still air oven or dried in a microwave oven (MD) on the ‘defrost’ setting. In sacco degradability was assessed in fistulated yearling wether sheep, using a 5x5 Latin square and incubation times of 3,6,12,24 and 48 hours. Bags size was nn x nn cm with a sample size of 3 g. Bags were rinsed and frozen upon removal, mechanically washed and dried at 60°C before analysis. Dry matter and nitrogen disappearance data for each sheep was fitted to the model y = a + b(1-e-ct) using non-linear regression.

Three trials, each involving 24 pigs, were conducted to assess the value of Hormonexa as a feed supplement for pigs slaughtered at 90 kg live weight. Rations were compounded from a variety of feeding stuffs to different protein levels and the pigs were fed on various nutritional planes. Hormonexa was added to these rations at the rate of 1·32 kg per 1000 kg meal.

In all three trials growth rate and food conversion efficiency were not affected significantly by the addition of the supplement. There was a tendency for the pigs receiving the supplement to be slightly leaner but in only 1 out of 39 measurements of fat thickness was the difference between control and supplemented pigs statistically significant (P< 0·05).

No benefit from this feed supplement has been demonstrated in terms of animal performance or carcass quality under a range of feeding systems.

The selection of lactic acid bacteria for use as silage additives is normally based upon their ability to dominate the silage fermentation and not upon benefits in animal performance. The object of this study was to investigate whether two lactic acid bacteria selected for fermentation characteristics would support the same animal performance as an established silage inoculant.

On 5 June 1989, first cut, predominantly perennial ryegrass (Lolium perenne) was ensiled direct with no wilting in plastolene silos of 2 tonne capacity. The herbage was harvested with a precision chop forage harvester and the following additive treatments were applied: None, control (C); Formic acid (Add-F, BP Nutrition, 850g/kg; 3 litres/tonne), (F); inoculant E. (Ecosyl, ICI Pic, 106Lactobacillus plantarum /g): inoculant A, (Pediococcus sp, 10 /g); inoculant B (L. plantarum 106 /g). The silages were fed to 6 wether sheep (Suffolk x Halfbred), initial live-weight, 40.1 kg (s.d. 2.22kg). Because the silages were unstable aerobically and restricted quantities of each silage were available, all sheep were fed the silages in the same (random) order.

Quantitative water intake and excretion, urinary osmolality and urinary excretion of Na, K and cortisol were studied in an experiment with nine adult male mink. The experiment comprised four periods each of 3 days, and ambient temperature (Ta) was increased from 5°C to 20 °C (periods 1 to 2) and, after an interval of 1 day, continued at 20°C and then decreased to 5°C (periods 3 to 4). Three different water supplies were given, namely E: extra water in the food, N: normal ad libitum water supply or R: restricted, free access to drinking water twice daily. Intake of metabolizable energy (ME) was calculated, and the water intake and excretion data were related to ME intake. The effect of Ta on quantitative water intake and excretion was evident, with the greatest response recorded when Ta was decreased. Intake of drinking water was highest at 20 °C, as well as the total water balance. The water supply had some, but not a profound, influence on water intake and excretion, with tendencies for reduced drinking water intake and water excretion in urine for R mink. Intake of ME decreased during period 3 at 20 °C and then increased when Ta was decreased to 5°C, which was reflected by an increased 24-h excretion of Na and K as well as an increased osmolality of the urine. Therefore, it was concluded that water intake and excretion were affected by combined effects of Ta and ME intake. Generally, it was shown that the mink responded rapidly to changes in Ta, and within 24 h significant effects of the change could be recorded for several of the traits studied.

In general the energy supply is the main factor limiting the output of milk by the dairy cow from most food sources. Under Northern Ireland conditions grass produces a greater energy output per unit area than any of the other major crops grown there. Furthermore Lowe (1970) has estimated the relative production costs per unit of dry matter for cereals and root crops to be twice and eight times respectively those incurred with grass. Therefore it is apparent that both on a basis of energy output per unit area, and per unit cost input, grass must continue to provide the maximum possible proportion of the food supply for the dairy industry within Northern Ireland.

Feed barriers and mangers form an integral part of a cattle housing system. Their role is to prevent the animals’ wasting feed by scattering it or by walking and defecating over it. Feed barriers generally effect a better distribution of feed and should allow individuals adequate and ready access. Often they have a dual role and act as the side of a pen. These functions are often achieved with some regard to several managerial objectives; simplicity of feed distribution, labour economy, the regulation of excessive animal activity, minimal feed wastage and promotion of animal comfort.

Time spent at the feed barrier depends on the feedstuff, the rate of eating by the animal, space allocation, and the accessibility of the feed. Depending on the feed barrier design the animal may need to exert some force to reach the food. Injuries arise in those situations where large forces are exerted against the barrier and/or accommodating postures (ie kneeling or other) are adopted to reach the food. In extreme cases intake may be restricted. Thus, to assure maximum intake and minimise injuries the feed must be within the easy reach of the animal. Two trials with Friesian heifers compared the performance of 4 types of feed barrier.

The assessment of herbage intake using the n-alkane technique requires estimates of the n-alkane concentrations in the diet. The objective of the present study was a) to assess the magnitude of sampling variation in n-alkane concentrations among herbage samples taken from individual oesophageal fistulated wethers, b) compare n-alkane concentrations determined from oesophageal extrusa, hand plucked, and mechanically clipped herbage samples and c) assess the effect of errors in the estimates of herbage n-alkane concentrations on the accuracy of intake estimates.

A study was made of weaning weights in a beef herd, using a rotational crossbreeding system including the Boran breed (zebu) and two temperate beef breeds (Devon and Limousin), and a seasonal calving period spanning the onset of the rains.

Significant sources of variation in calf weaning weights were crossbred type, age at weaning, sex, dam's age, season of birth, year and a year × crossbred type interaction (all P < 0·001).

The adjusted mean weaning weight was 203 kg. Weaners sired by a temperate bull were generally 1·08 times the weight of those sired by a zebu bull. Steers were 1·06 times the weight of heifers. Marked increases in weaning weights occurred as dams increased in age from 3 to 6 years and slight increases continued up to 9 years of age. Weaners born to 9-year-old cows were 1·09 times the weight of those from first calvers.

Alternative methods for investigating the effect of season of birth were examined and the final choice was a covariate for time from birth to the onset of the rains. Calves born in the earliest part of the calving period were approximately 1·14 times the weight of those born just after the onset of the rains.

The primary aim of the calf rearer is to ensure a successful transition from non ruminant to ruminant status while achieving rapid growth and an early intake of solid food. Newbold, Blake and Hagges (1991), found that increasing the concentration of ME in either the starter or milk replacer will not promote more rapid growth, but will simply reduce the rate of starter consumption. This present study investigated the extent to which the energy density of a calf starter ration affected starter intake and liveweight gain in calves receiving a fixed allowance of a high energy milk replacer with ad libitum access to solid calf starter rations.

An investigation of the association of transferrin types with body weights at birth, 3, 6,12 months and first 6-monthly wool yield in Indian sheep showed that variation among transferrin types was a significant source of variation only for yearling weight. Sheep of Tf MB type had the highest yearling weight followed closely by Tf EC. Highest birth weight was recorded in sheep with Tf EM whereas 3-month weight was highest in sheep of Tf EE type. Tf EM sheep had the highest 6-month weight and fleece weight.