The effects of level of winter feeding and buffer-feeding during the grazing season on the milk production of January/February calving dairy cows.

Buffer-feeding of grazing dairy cows, by allowing cows access to forage for a few hours each day, has been widely advocated as a means of maintaining high animal performance whilst enabling efficient sward utilization. However, in practice, responses to buffer-feeding with January/February calving cows have been extremely variable. The objective of this study was to examine if part of the variability in response could be explained by differences in the level of nutrition during the winter feed period.

The use of diets containing high levels of copra meal for growing/finishing pigs

Copra meal is a by-product of the coconut oil industry and is a potential source of protein and energy in the diets of pigs and poultry in the tropics. However, previous studies with pigs have suggested that its use may be limited because of poor growth performance associated with levels of inclusion above 300 g/kg (Creswell and Brooks, 1971). The experiment reported here and conducted under tropical conditions at the University of the Philippines at Los Banos was designed to study possible ways of feeding copra meal at levels of inclusion greater than 300 g/kg in the diets of pigs while maintaining acceptable animal performance.

An intraruminal soluble glass bolus containing melatonin — a potential system for early lamb production

Seasonal changes in daylength (photoperiod) are effectively monitored by the eye transmitting a neural signal to the pineal gland which responds by secreting a hormone, melatonin, during the hours of darkness. Decreasing daylength is accompanied by an increase in the duration of melatonin secretion and stimulates breeding activity in sheep.It has been demonstrated that both timed (afternoon feeding and injection) and continuous (subcutaneous and vaginal implant) administration of supplementary melatonin to ewes in mid-summer mimics the effect of short or decreasing photoperiod and can advance the onset of breeding activity. Such treatments can also increase relative fecundity at early mating by phase-advancing the mid-breeding season peak in ovulation rate. As the U.K. is not sufficient in lamb production and bearing in mind the economic pressure for early lamb marketing, effective melatonin treatment offers considerable potential for commercial application.

An optimal dietary amino acid pattern for growing pigs

An animal's rate of protein accretion (or nitrogen retention) is determined by the most deficient (or first limiting) amino acid in the diet, in a perfectly balanced (or ideal) protein all essential amino acids and the sum of the non-essential amino acids are equally limiting. If a dietary protein had any amino acids in excess of the ideal pattern, then the removal of any of the excess should not affect nitrogen retention. This principle was used to determine the ideal dietary amino acid pattern for growing pigs.Three nitrogen balance trials were carried out with a total of 64 gilts of weight from 30 to 55 kg. Casein and a mixture of amino acids were used in the semi-purified diets. The animals were given the diets at the rate of 93 g/kg BW0.75/d in three equal meals mixed with 0.3 L water. The feeding times were 08.30, 12.30 and 17.30. All pigs received their experimental diets for 7 days, made up of 3 days preliminary and a 4-day collection, except that the preliminary period before the first collection in the first period was 7 days. Before the first collection bladder catheters were introduced.

Effect of concentrate to silage ratio and hoof trimming on lameness in dairy cows

Lameness in dairy cows has both important animal welfare and economic implications. High concentrate to silage ratios may be an important predisposing factor, whilst trimming has been advocated as an effective preventative measure. This trial examined the effects of these two factors on locomotion, incidence of lameness and hoof measurements.

In Vitro Fertilization of Bovine Oocytes Matured In Vitro

The development of an efficient laboratory procedure which would enable cattle ovarian oocytes to be matured in vitro, fertilized and cultured in vitro to the blastocyst stage of development could have important practical and scientific implications. The commercial exploitation of certain embryo transfer techniques applicable in cattle (eg., twinning by embryo transfer) might be facilitated by the development of such a procedure and there would be many advantages to having a cheap source of embryos available for research purposes. The present report deals with some of the studies recently carried out in this laboratory aimed at utilising follicular oocytes recovered from the ovaries of cattle slaughtered for beef at the abattoir. Such studies have been undertaken over a period of almost twenty years, starting with the work of Sreenan (1968)* but it now realised that the oocytes of farm mammals are incapable of normal development until after the completion of complex changes during maturation.

Options at the fundamental level for growth regulation in farm livestock

New developments in immunological techniques and increasing expertise in genetic manipulation, especially by gene transfer, have opened up a wide variety of approaches to the manipulation of the growth and metabolism of farm livestock. However, the most effective use of these techniques and the design of new pharmacological agents for growth promotion and nutrient “repartitioning” might well rest on a greater understanding of the factors and cellular mechanisms that coordinate growth and protein anabolism. It is this coordidnation that must be disturbed if persistent gains are to bke made. This greater understanding may well result from an examination of the mechanisms whereby currently available anabolic agents and techniques exert their effects and this paper will draw on these experiences. Growth is clearly a closely coordinated process and this has hampered many attempts to maintain accelerated protein deposition for long periods. For example forced increases in hormonal concentrations often induce hormonal insensitivity. It is possible that understanding and reducing the constraints on growth for example by reducing the levels of suppressive factors rather than concentrating on the active stimulation of anabolic factors may be more effective.

The effect of antisteroid antibodies upon the mating performance of early lambing mule ewes also treated with progestagen sponges and PMSG

The importance of a high lambing percentage in early lambing flocks is well recognised as is the variability of the dose response to PMSG of early lambing ewes. It was hoped that the integration of the immunogen ovandrotone-albumin (Fecundin ® Coopers Animal Health) into such a system would give a reliable increase in ovulation rate without the danger of superovulation caused by higher doses of PMSG. Unfortunately, last year Logue, Gill and McClelland (1986) and Keeling, King and Gunn (1986) independently reported that although Fecundin treatment in early lambing flocks (using progestagen sponges with and without PMSG)gave an increased litter size over controls there was a considerable reduction infertility which negated this advantage. These groups employed a regime of a sensitising injection, a boosting injection 28-30 days later, and ram introduction to an induced oestrus after a further 28 days(i.e. a Boost Tupping Interval (BTI) of 28 days) for the second group and 35 days for the first.

Effect of timing of intrauterine insemination with frozen-thawed semen on conception rates in ewes

The widespread use of artificial insemination (AI) in the United Kingdom sheep industry has been limited by the poor conception rates obtained after cervical insemination of frozen-thawed semen. The major problem in this respect is the impairment of sperm transport through the cervix, particularly when AI is used in conjunction with oestrus synchronisation.Previous studies (Killeen and Caffery, 1982; Maxwell, 1984) have indicated that a laparo-scopic technique for intrauterine insemination in ewes may overcome such limitations. At the moment, however, sufficient data on the optimum time of insemination and sperm doses required to maximise fertility in British breeds are not available. The present study was conducted to establish the optimum time of intrauterine insemination using frozen-thawed semen.

The effect of body condition, feed level and temporary calf separation on the post-partum anoestrous period and LH and FSH levels in beef cows

Compared with other species of farm livestock the reproductive performance of beef cows is poor. Mating and calving periods are frequently extended to avoid having a large proportion of barren Cows. vs. For example the ‘average’ MLC recorded herd has a calving period of over 4months. This makes management of beef cow herds difficult and has a deleterious effect on biological efficiency and profitability.One of the major limitations to improvement of reproductive efficiency in beef cattle is the extended post-partum anoestrus. Beef cows have longer post-partum anoestrous periods than dairy cows. In one study of three different herds (Peters and Riley, 1982) the mean length of the anovulatory period ranged from 24 to 88 days.