The extent of rumen degradability of a feedstuff depends on the interaction between rate of degradation and residence time. In situ techniques require that substrates are ground to obtain a homogenous sample and to reduce result variability. However undegraded feed particle losses increase with bag pore size and fineness of grinding. If these particles are degraded at a similar or lower rate than the retained material, degradability, especially for short-term incubations, will be overestimated. In contrast if the feed particles lost are more readily degraded the degradability measurements obtained will be unaffected. Where improvements due to grinding have been recorded in situ these are assumed to result from variations in the proportion of fine particles that are immediately soluble or rapidly degradable. Gas-based in vitro feed evaluation systems offer the possibility of quantifying this effect directly and a study was therefore conducted to investigate the impact of particle size on the rate and extent of fermentation using the Reading Pressure Technique (Mauricio et al., 1999).

Members of the CAMDA cooperative group breeding scheme have expressed concern about the breeding values of imported sires, with a suggestion that their breeding value was underestimated. Analyses were conducted to examine changes in estimated breeding values for sires imported into the CAMDA nucleus flock

The project, conducted at ADAS Pwllpeiran, was based on mating individuals from several sources in Wales, using multiple ovulation and embryo transfer (MOET) to generate substantial numbers of progeny per sire and dam combination. The project represents the first attempt to create co-operative links between Welsh Mountain sheep breeding groups in Wales. The current analysis was conducted to determine whether sire and dam origins affected weaning weight.

Progressive inefficacy of chemoprophylactic therapy to control gastro-intestinal (GI) nematode infection in sheep has been a major contributory factor in stimulating research into the development of alternative means of internal parasite control. This research aims to investigate the possibilities for selecting UK sheep for increased genetic resistance to naturally acquired GI nematode parasite infections.

Behavioural studies of sheep have shown that poor maternal behaviour by the ewe immediately postparturition can lead to reduced lamb survival and ewe production (O'Connor et al., 1985). Under field conditions, behaviour may be quantified by the maternal behaviour score (MBS) - a six-point scale assessing ewe flight distance when lambs(s) are handled for the first time, within 24 hours of birth (adapted from O'Connor et al., 1985). Greater scores are awarded to ewes remaining closer to their lamb(s). The objectives of this study were (1) to investigate the factors affecting MBS in Scottish Blackface ewes; (2) to determine if MBS affects the average weight of lambs reared or the number of lambs dying before weaning; (3) to estimate genetic and phenotypic parameters for MBS and correlations between MBS and lamb performance.

Improvements in the level and quality of lamb output are required to help sustain the financial viability of hill sheep farming. In the lowland sector breed substitution has been shown to be an effective means of increasing ewe productivity and lamb carcass lean content. However, there is a lack of adequate contemporary breed comparisons for the hill sector to base breeding decisions on. Consequently, the objectives of this study were to investigate the effects of ewe and ram breed on lamb output under a range of hill environments.

Lowland sheep farmers in Northern Ireland depend heavily on the hill sector for replacement breeding ewes. Thus changes in the genetics of the ewes and rams used in the hills are likely to have major implications on the performance of lowland breeding ewes. Crossbred females were produced in the study by Carson et al. (2000) as a result of crossing Scottish Blackface and Wicklow Cheviot ewes with a range of sire breeds. The objective of this study was to provide information on the productivity of these crossbred females for lowland producers.

Some in-feed antibiotic growth promoters have been suspended from use within the EU. Alternatives to these antibiotics are actively being sought, especially ‘natural’ alternatives, such as essential oils, to try and maintain the performance advantage attributed to the use of these antibiotics. Some essential oils, e.g. thyme and origanum, have been shown to have anti-microbial activities (Hammer et al., 1999). The active compounds responsible for this property have been identified, and include cinnamaldehyde, cineol and eugenol. A specific formulation of essential oils reinforced with their active compounds has been combined into a form suitable for use as a feed additive (Multi-Functional Feed Additive, MFA). An experiment was conducted to determine the effect of this MFA on the food conversion ratio (FCR) of calves.

The degree of processing of protein-rich feeds affects their physical properties. Seeds which are less comminuted, whether cracked or rolled, may have properties which make their behaviour, in the rumen and postruminally, distinct from fine ground material and which may therefore alter their performance as feed proteins. The use of lupin seeds as a replacement for soya in ruminant diets has been demonstrated (Moss et al, 1997). This project aimed to assess whether the processing of lupin seeds, either hammer milling or rolling, affected the performance of young cattle fed the seed as their principal source of protein.

Sanda et al. (1999) studied the effects on crossbred steer liveweight gain of alternating the same quantities of napier grass and barley straw at five day intervals over a 40 day period. These animals lost significantly more weight (p<0.05) than animals on one and ten day frequencies of alternation and those receiving the same quantities of the two feeds mixed together at each meal. These responses could not be explained by differences in in vivo digestibility or intake. The present study was designed to test the hypothesis that there are gradual changes in the rumen environment as animals adapt to the intake of a given forage and that, during this adaptive phase nitrogen is not used efficiently, which could explain the poor performance.

In the UK, 18-month beef finishing systems are common. Previous work has focused on the effects of the rate of gain during a winter store period on performance (Lowman et al., 1994) and carcass composition (Wright and Russel, 1991). However, few data are available relating the composition of gain during the winter store period to subsequent carcass characteristics. This study was designed to determine the effect of high and low body fat levels at the end of the store period on carcass characteristics, both in Spring, and after finishing on grass in Autumn.

Replacing grass silage with maize silage in the diets of finishing beef cattle can improve DM intake and performance even when starch content of the maize silage is low (McCabe, O'Mara and Caffery, 1995). The objective of this experiment was to investigate the response of beef cattle fed diets containing different proportions of maize silage and grass silage with the same level of concentrate supplementation.

In a previous experiment with dairy cows at this Institute, in which fodder beet was included as a third component of the diet along with grass silage and concentrate, fodder beet considerably increased metabolisable energy intake (MEI), but there was little effect on milk yield (unpublished data). The main objectives of the present study were to examine the effects of including fodder beet versus concentrate in a grass silage diet, on the digestibility of nutrients and the utilization of nitrogen (N) and energy at equal MEI in beef cattle.

It is generally accepted that diets for beef cattle containing a high proportion of grass silage compared to concentrates may result in poorer performance responses (intake, liveweight gain). Scollan et al. (1999) reported that in comparison to feeding grass silage alone, supplementing with additional concentrates increased growth rates, but the animals achieved the same amounts of carcass protein whilst depositing more fat. This study examined the effect of feeding a grass silage alone compared to silage and concentrate at the same level of metabolisable energy (ME) intake on animal performance and body composition.

Pulse chunies are byproducts obtained from processing of pulses while preparing dals and are available to an extent of 3 million tonnes annually in India. They contain broken seed coat, germ and small pieces of broken cotyledons constituting around 15-20% of total weight of pulses. Very little information is available in the literature on effective levels of inclusion of chunies in complete rations for ruminants. The objective of this experiment was to study the effect of inclusion of varying levels of green gram (Vigna radiata) Chuni in the concentrate mixtures for native buffaloes on the nutrient utilization.

High rates of decline in milk yield of >3.0% /week are common when dairy cows are grazing due to low herbage intakes. Under indoor feeding conditions rates of decline are often <2.0% /week. Behavioural factors control intake at grass, in particular the time spent grazing and the rate of intake. Low intakes produce high rates of decline in milk yield and potentially could lead to problems of poor fertility and welfare in high merit cows. The objective of this research is to examine the replacement of time available for grazing with time made available for eating forage-based diets indoors. This experiment was carried out in the spring.

Restriction of feed during the winter store period is an important part of current beef systems to exploit compensatory growth from cheap grazed grass. Previous studies have demonstrated that the composition of finished carcasses can be altered by the type of diet fed during the winter feed restriction period (Baker et al, 1985). The aim of this study is to examine the effects of body composition at the end of the winter store period on the composition of gain during the subsequent grass feeding period

Feeding of lowland sheep on straw-based systems during pregnancy and in early lactation has shown that ewe and lamb performance can be satisfactory, providing adequate compound supplementation is fed (Davies and Chapple, 1995). Whole barley and soya bean meal has been the standard ration. However, soya bean meal is imported and not fully traceable. Experiments with January- and March-lambing ewes have shown that traceable, homeproduced feeds based on equal quantities of molassed sugar beet feed and either maize or barley distillers grains can replace a barley/soya supplement when fed with straw or silage-based diets in late pregnancy (Chapple et al., 1998 and 1999). The objective of this work was to evaluate the effects on ewe and lamb performance of feeding sugar beet feeds with distillers grains to March-lambing ewes rearing twin lambs at pasture.

Fishmeal is a suitable protein source for pregnant and lactating ewes, providing higher levels of undegradable protein (UDP) than vegetable protein sources, with an improved biological value (Robinson, 1987). The lower amounts of UDP supplied by vegetable protein sources may however be improved by formaldehyde treatment. The objective of the current experiment was to compare the effects of feeding concentrates containing fishmeal with concentrates containing vegetable protein sources with or without formaldehyde treatment.

In adolescent sheep, high nutrient intakes to promote rapid maternal growth during pregnancy results in a major restriction in placental growth which leads to a significant reduction in lamb birthweight relative to moderate intake adolescents of equivalent gynaecological age (Wallace et al 1996). Placental hormones play a crucial role in the development, differentiation and function of the mammary gland and we have previously reported that maternal concentrations of progesterone, growth hormone and pregnancy-specific protein B are significantly reduced in high intake dams with growth restricted placentae (Wallace et al 1997 a,b). For newborn lambs, the ingestion of adequate quantities of nutrient dense colostrum is essential to provide fuel for heat production and to ensure absorption of maternal antibodies to give immunological protection against infection. The objective of the present study was to examine the effect of nutritionally-mediated placental growth restriction on colostrum yield, nutrient composition and immunoglobulin content.