The principle role of α-tocopherol is to protect the polyunsaturated fatty acids of membrane lipids against peroxidation. The biological activity of α-tocopherol is very important in meat quality. Supplementation of cattle and pig diets with α-tocopherol acetate results in the production of meat which has an extended shelf life, greater colour stability and reduced drip loss (Vega et al 1994, Monahan et al 1994). Supranutritional supplementation with quantities of α-tocopherol acetate as high as 4000 mg d-1 have been reported in cattle (Arnold et al 1993). These high levels of supplementation have been shown to improve meat quality significantly. However, it is not clear if all of this α-tocopherol is absorbed or if the absorption of α-tocopherol becomes saturated leading to excretion of unabsorbed α-tocopherol. The present study was designed to measure the digestibility of α-tocopherol acetate in sheep when given at moderate and high levels.

Computer tomography (CT) has the potential to measure body composition and form in live farm animals accurately and objectively in ways not possible with longer established assessment methods. Preliminary reports (Young, Logan, Nsoso and Beatson, 1996) verified that this is so but concluded that registration errors and subjective interpretation of tissue boundaries during image analysis affect accuracy. However, their study did not allow an assessment of the relative significance of these effects. The trial reported here was designed to quantify such effects by determining the repeatability of CT scan measurements.

Breeding leaner sheep is a desirable goal provided reductions in fatness do not compromise survival and productivity, particularly in harsh environments. Whether some energy stores are more labile than others, the internal fat depots in particular, is not clear. Genetic variation in this trait could be usefully exploited in hill sheep where carcass fat is undesirable but energy reserves are important. Patterns of change in body energy stores need to be examined to determine when it is best to assess energy stores in animals. X-ray computer tomography (CT) provides a means to examine depletion and repletion of body energy but scans are not cheap. In order to use CT in a cost effective way, a number of variables need to be assessed from just a few scans. This report presents results of a study designed to define such a scanning approach in terms of which scans were most informative and which produced most accurate predictions of tissue size.

The introduction of new forage maize hybrids has provided feed raw materials with a range of nutritional characteristics. The objective of this experiment was to investigate the impact of feeding different hybrids of forage maize on the overall digestibility of feed components and rumen degradability of starch in sheep.

Four forage maize hybrids from different sites within the UK[NANCIS(A) and EMA(B)] and France[Hybrid 6196 High Oil (C) and Volgata Waxy(D)] were ensiled in sealed drums with no additives. The resultant silages were used as the basis for a digestibility trial using four fistulated Suffolk X wethers in a 4 X 4 factorial design. Sheep were fed twice daily with total intake of 900 g DM of silage plus 150g Soya Bean Meal. After an adaptation period (21d) a 5 day total collection of faeces was carried out followed by a rumen degradability study.

Parameters from in vitro gas production and in situ degradability are often used to predict digestibility and intake in vivo. However, these methods use dried ground feed samples and cannot be expected to estimate the effect of changes in physical form or particle size. Previous work (Romney and Gill 1998) has indicated that short term intake rate (STIR) values showed potential to rank a variety of feeds in terms of their ad libitum dry matter intake, rate of passage and digestibility. Since STIR values are determined on feeds “as offered” it is likely they will reflect the effects of physical structure on in vivo parameters. The present work examines whether measurement of STIR values can be used to predict in vivo responses to changes in particle size distribution in chopped forages.

Differences in sheep management and breeding programmes lead to variations in carcass fatness. It is necessary to investigate the relationships between breed, growth and composition on different feeds in order that leaner carcasses may be produced. The purpose of this experiment was to investigate these relationships in two breeds of sheep, and their cross, when fed either a food considered non-limiting to growth or a food that was restrictive by virtue of its bulk.

Suffolk (S), Scottish Blackface (B) and reciprocal cross (X) lambs were born over a 4 week period beginning late February. The lambs were weaned at a weight (0.20 estimated mature size) or no later than 8 weeks of age and following an adjustment period, individually penned.

One major consequence of the presence of the nematode parasites in the gastrointestinal tract (GIT) of ruminants appears to be an elevated flow of endogenous N component from the small intestine, leading to adverse changes in host productivity (MacRae, 1993). However, many of these aspects have remained speculative because of a lack of appropriate methodology to quantify the influence of parasites on GIT protein metabolism. In the present study oxidation of leucine sequestrated from arterial blood and digesta-derived leucine during “first pass” metabolism in the GIT of lambs subjected to subclinical T. colubriformis infection were quantified directly, using trans-organ catheterisation procedures coupled with stable isotope tracer kinetics.

Tail docking of new born lambs is a routine practice in the United Kingdom. It has been used as a strategy to reduce the impact of myriasis (blowfly strike). There is only a limited period of time after birth (up to seven days) during which lambs can be docked without the use of anaethesia. Tail docking may have a detrimental effect on the ewe-lamb bond if the process leads to significant and sustained pain. French, Wall and Morgan (1994) suggested lambs suffer acute pain immediately after the procedure of docking but this potential disturbance of normal behaviour during the first few days of life did not seem to affect the long-term performance of lambs. The study reported in this paper considers the effect of tail docking on the behaviour of lambs during the first 90 minutes after docking and on lamb performance to slaughter.

Intensively reared early weaned lambs are conventionally fed a high energy concentrate diet in order to maximise daily gain and feed conversion efficiency. This reduces both the time required to reach slaughter weight and the overhead costs. However, it is estimated that feed costs in intensive lamb systems amount to 0.24 of the total output value (MLC 1998) and that the profitability is sensitive to relatively small changes in the lamb price to feed cost ratio. The objective of the work was to investigate the effects of various alternative feeds consisting of molassed sugar beet feed (MSBF), distillers products and the whole barley or grainbeet (200 g/kg MSBF and 700 g/kg brewers grain) on the performance and profitability of intensively reared lambs.

Peptides are intermediates in the conversion of ingested protein to ammonia in the rumen and their accumulation depends upon the nature of dietary protein (Mesgaran & Parker, 1995). In addition, It has been demonstrated that the hydrolysis rate of peptides was influenced by peptide structure and that proline containing peptides were hydrolysed more slowly by rumen fluid (Mesgaran & Parker, 1996). The objective of the present experiment was to investigate the effect of altering the sources of protein, in diets with similar effective rumen degradable protein (ERDP), on the ruminal peptide-N concentrations.

Four Iranian Baloochi lambs weighing 33±1.3 Kg, each with a permanent rumen fistula, were fed twice daily with diets differing in protein sources in a 42 latin square design. The diets consisted of a basal diet of chopped lucerne, barely and sugar beet pulp (190, 230 and 170 g DM d–1, respectively) which was supplemented with lucerne (L), cottonseed meal (C), soybean meal (S) or molasses+urea (M+U) (210, 118, 84 and 80+9 g DM d–1, respectively).

The wilting of grass prior to ensiling is an effective method of reducing the moisture content of the grass and improving the fermentation quality of the silage (Wilkinson et al., 1996). The effects of wilting grass on voluntary intake, digestibility and animal performance are variable, potentially reflecting the losses of nutrients from the crop during the wilting period. Three methods of swath treatment to accelerate the loss of water from the mown crop are currently used in northern Europe, wilting in the swath, spreading the crop to 1.0 of ground area and tedding swaths. The aim of the experiment reported here was to investigate the effect of swath treatment and duration of field wilting on the voluntary intake and digestibility of wilted silage offered to lambs.

A study was undertaken to evaluate the performance of male and female of Sangsary sheep, a native Iranian breed. Rouzbehan et al. (1996) detailed the growth rate and body composition of male lamb of this breed. In this summary, the production potential and carcass characteristics of female lamb were reported.

Forty four 9 month (m) old female lambs, mean initial weight 22.9 kg (±2.5) were used. The two diets, which consisted of concentrae and roughage, had a similar protein content (150 g/ CP/kg DM) and metabolisable energy of either 10.6 MJ/ kg DM (diet A) or 9.2 MJ/kg DM (diet B) were each fed ad libitum to 22 lambs. The animals were grouply penned. At the start and end of the study, the animals were weighed on two consecutive days. Throughout the study, live weight gain (LWG) and dry matter intake (DMI) were recorded weekly.

There are conflicting reports in the literature about the benefits of defaunation, the removal of ciliate protozoa from the rumen, in ruminant production. Ciliate protozoa are not essential for proper functioning of the rumen nor for the life of the host and that their contribution to microbial protein flowing to the lower gut is small (Williams and Coleman, 1992). Protozoa ingest and digest bacteria in the rumen decreasing the flow of microbial protein from the rumen, and inserting an energy wasting step in the net synthesis of bacterial protein in the rumen (Williams and Coleman, 1992). However, protozoa also play an active role in ruminal fibre digestion and up to 50% of ruminal carboxymethylcellulase activity is associated with the protozoal fraction (Williams and Colemans, 1992). Thus the effect of defaunation on animal productivity will be a balance between the increase in the supply of microbial protein leaving the rumen and any decrease in ruminal fibre digestion. The aim of this work was to determine the effect of defaunation on microbial protein supply and fibre digestion in sheep fed a poor quality tropical diet.

Consumption of a highly fermentable, high energy density (ED) food by ruminants results in changes within the rumen environment including a fall in pH. It has been shown that such changes can influence subsequent intake and diet selection in sheep as they attempt to correct these changes through their feeding behaviour (Cooper et al, 1995). The addition of a buffer eg NaHCO3 to a previously consumed high ED food or offering the sheep a low ED food would assist in preventing changes in the rumen environment hence the ruminant would not need to modify it’s diet selection in an attempt to correct these changes. The objectives were to determine (i) whether or not sheep would make a continuous non random selection between 2 foods of different ED (Test 1), (ii) to determine what concentration of NaHCO3 should be added to a food to obtain the most beneficial effects on rumen pH combined with intake (Test 2), and finally (iii) the main objective was to determine what consequences the ED of a food and the supplementation of NaHCO3 to a food offered for a short period of time had on subsequent diet selection made by sheep (Test 3).

The benefits of long chain polyunsaturated fatty acids (PUFA) to human health, especially those of the n-3 series are now widely recognised. In a previous experiment (Wachira et al. 1998) supplementing diets with whole linseed or fish oil increased n-3 fatty acid levels in lamb muscle. To raise these further the whole linseed can be treated with formaldehyde to increase protection in the rumen. Dietary antioxidants such as vitamin E can control lipid oxidation but information on their effects on lamb performance and fatty acid composition is limited. The current experiments investigated the effects of different dietary PUFA sources and vitamin E levels on growth and fatty acid composition in two sheep breeds. Detailed results of the effects of vitamin E are presented in the accompanying abstract by Enser et al.

There is anecdotal evidence that certain sheep breeds, reared in a particular way, produce unusual or characteristic tastes in cooked meat. Such effects could be linked to differences in meat fatty acid composition associated with the consumption of different diets. This study investigated eating quality and fat composition in 4 distinctively different breed x feeding system groups.

Four groups of 20 ram lambs were obtained as follows: Pure Soays (SO) finished off grass in April from commercial breeders; Pure Welsh Mountain (WM) finished off upland grass in October from ADAS Pwllpeiran; Suffolk x Mules from Harper Adams College finished off concentrates (grains) (SC) in April; and Suffolk x mules from the same source finished off grass (SG) in May. The animals were transported to Langford where they were slaughtered in Bristol University's abattoir.

Ewes with extra teats can be found in many breeds but the amount of milk produced from these is only occasionally substantial. The aim of the breeding project was to investigate the possibility of developing a ewe with four functional teats.

A group of 15 ewes and four rams, all with four teats, together with five two-teated Cambridge ewes formed the initial nucleus group. Subsequently five four-teated Cambridge rams were used. The following measurements were recorded: (a) number of teats, (b) length of front (FL) and rear (RL) teats measured at 5 months of age, (c) distance between the front teat (FT) and front perimeter line of the fore udder (FU) measured post partum, (d) milk production from front (FM) and rear (RM) teats recorded over a 3h period at 2 to 4 days post partum using oxytocin to ensure complete let down.

The Animal Data Centre (ADC) is responsible for producing linear type evaluations for the Ayrshire, Shorthorn, Jersey, Guernsey, Jersey Island and Guernsey Island breeds. Along with publication of breeding values (BV's), it is important to provide farmers and organisations in the industry with information on genetic trends in conformation to establish the effect of selection and determine future selection strategies. As selection goals in conformation are not as clear as in production traits, it is important to analyse each trait to find out how breeds are developing. The objective of the study was therefore to analyse linear type evaluations in order to determine the trends in the traits classified.

The CAMDA group breeding scheme was established in 1976. Its objective is to increase lamb growth rate, mature size and maternal ability of the Welsh Mountain sheep while retaining their hardiness and breed type. The opportunity to achieve this goal depends on the extent of genetic variation within the breed for these traits. The objective of this study was to estimate the amount of variation in 18-week live weight attributable to the lamb genotype (direct) and dam maternal ability, both genetic and environmental, in Welsh Mountain sheep within this scheme.

A total of 12954 records of 18-week live weight of Welsh Mountain lambs collected between 1976 and 1995 from 4 flocks of the CAMDA scheme were considered. The data were edited for small contemporary groups and for incomplete performance or pedigree recording.

Two aspects of the CAMDA group breeding scheme is to improve lamb growth rate and the mothering ability of Welsh Mountain sheep. Genetic variation for these traits is present (Aslaminejad et al., 1999) but the rate of genetic progress depends on the selection decisions made within the scheme. The objective of this study was to estimate the genetic gain achieved in the nucleus and members’ flocks over the 20 years since the scheme began.

A total of 31887 records of 12 and 18-week live weight of Welsh Mountain lambs collected between 1976 and 1995 in 7 flocks of the CAMDA scheme were used in this study. Each flock was analysed separately fitting a univariate animal model with a direct and maternal random genetic effect. Genetic parameters were estimated using a derivative-free restricted maximum likelihood algorithm (DFREML; Meyer, 1993).