Nutritional research on commercial farms is difficult to carry out due to the problems associated with measuring individual animal dry matter intake (DMI). This research was aimed at developing a satisfactory method of estimating DMI from routine farm records, supplemented by cow body condition score and height at withers of the cow.

Earlier studies (e.g. Dewhurst et al., 1996, 1999) have shown marked declines in forage voluntary intake as calving approaches. The resultant reduction in nutrient supply may compromise performance in the next lactation, because it coincides with a period of intense metabolic activity in preparation for the next lactation. Feeding concentrates to dry cows did not overcome this problem (Dewhurst et al., 1999). The objective of the current experiment was to investigate alternative dry cow strategies, using only high-quality grass silage, to minimise the severity and consequences for subsequent milk production of the reduction in nutrient supply in this period.

Many farmers apply slurry to grassland as a fertiliser or a means of waste disposal. There is evidence that winter slurry application leads to higher losses of nitrogen due to leaching subsequently reducing the efficiency of slurry N utilisation when compared with spring applications (Smith et al 1995). This suggests that slurry applications should be undertaken in spring, but the effect of timing on the extent of grass contamination is unknown. When grassland is used for silage production, contamination of the sward can lead to reduced silage fermentation and acceptability (Boxem and Remmelink 1987). A study was conducted to investigate the effect of timing of slurry application on fermentation and dry matter intake of first and second cut grass silage.

Cattle in the tropics mostly depend on pastures. During dry periods the forage available is usually mature, constraining both intake and digestion. These constraints need to be understood, for intake and digestibility define productivity. Intake depends on the rumen space made available by fermentation and outflow. Markers such as PEG (liquid phase), and chromium mordanted fibre (solid phase) can be used to measure rumen volume and outflow, but have limitations. The objective of this experiment was to measure intake, digestibility, and rumen kinetics of cattle fed ad libitum forages with very different degradation characteristics, and also to compare rumen volumes measured with markers with those obtained by manual emptying.

A previous study (Syed and Leaver, 1999) showed that offering maize and grass silages alternately either within days or between days resulted in higher intakes of maize than grass silage, and lower total intakes than when fed mixed together. The factors influencing the choice of forages are not well researched. The hypothesis tested was that as maize and grass silages are similar in ME value but very different in crude protein, nutrient demand for protein, and protein level in the supplement would influence forage selection. This experiment examined the influence of the milk yield level of the cow and the protein level of a supplement.

The objective of this study, which formed part of a larger project, was to investigate the effect of feeding high levels of urea on the reproductive function of the lactating dairy cow. Increasing dietary protein intake can increase milk production, but may reduce reproductive performance (Laven and Drew 1999). McEvoy et al (1997), based on work which fed urea to sheep, suggested that this effect on fertility may be caused by ammonia. However, there is little information on the effect of feeding quickly degradable nitrogen (QDN) on the concentration of plasma ammonia in the dairy cow and the accurate measurement of plasma ammonia is difficult. The measurement of a more stable metabolite, such as urea, may be more useful, if it can be shown to be correlated with plasma ammonia.

In a previous study, spring calving dairy cows exhibited considerable milk yield responses when given access to spring grass for short periods (Sayers and Mayne, 1998). The current study seeks to examine the performance of autumn calving (later lactation) dairy cows when given access to spring grass. In addition, this study seeks to identify if winter management system (forage or concentrate based systems) influences the response achieved.

An increasing acreage of forage maize is being grown in the north of England and south of Scotland as an alternative to grass silage for dairy cows. Previous work has shown that molassed sugar beet pulp (MSBP) can be ensiled with maize to minimise effluent production and ensiling losses (Hameleers et al) from low dry matter (DM) maize. This experiment was designed to evaluate the effects of feeding 'Pulp'n'Maize' on intake, milk yield and milk composition in dairy cows.

As more farmers try to improve the efficiency of their production systems by sourcing safer and cheaper dietary energy and protein from home grown feeds, the importance of cereal-legume bi-crops for winter-feeding of UK livestock may increase. However, little is known about the production, conservation, feeding value and animal performance from such bi-crops in the UK. This study measured the feed intake and milk production from dairy cows fed pea-wheat bi-crop silages.

The extent and type of in-silo fermentation has a profound influence on the composition of nutrients absorbed from the digestive tract of dairy cows (Choung & Chamberlain, 1993; van Vuuren et al. 1995). The amount of amino acids absorbed from the small intestine decreases when the extent of in-silo fermentation is increased due to reduced efficiency of microbial protein synthesis. The ratio of lipogenic to glucogenic VFA increases when in-silo fermentation is restricted, since silage lactic acid generally increases propionate in rumen VFA, whereas WSC in silage increases acetate, butyrate or both. The purpose of this study was to estimate quantitative relationships between silage fermentation characteristics and milk production using data based on mean treatment values of production parameters and silage fermentation characteristics.

Current thinking suggests that the saturated fatty acids myristic (C14:0) and palmitic (C16:0) are major risk factors in cardiovascular disease compared to longer chain fatty acids such as stearic (C18:0) and oleic (C18:1). Milk fat is rich in C14:0 and C16:0 because these fatty acids can be manufactured in the bovine mammary gland from glycerol and free fatty acids. Rapeseed oil is a rich source of oleic acid, and feeding whole rapeseed to dairy cows has been shown to increase the C18:1 content of milk fat (Murphy et al, 1995). However, increasing the unsaturated fat content of milk has led to suggestions that oxidative stability may be effected. Feeding high levels of a natural antioxidant such as vitamin E may enhance milk stability and improve its' nutritive value. This study investigated the effect of feeding various amounts of whole cracked rapeseed and vitamin E on animal performance, and the levels of fatty acids and vitamin E in milk fat.

Increasing the n-3 polyunsaturated fatty acid (PUFA) content of ruminant products is widely accepted as a potential means of reducing the incidence of cardio-vascular disease in man. However, after ingestion dietary PUFAs are extensively hydrogenated in the rumen. Whole linseed is particularly high in a-linolenic acid (C18:3 n-3) and the feeding of whole seeds with an intact seed coat has been reported to double the duodenal supply of C18:3 in wether lambs (Wachira et al. 1998). This supply may be further enhanced by treating the whole seed with formaldehyde (Gulati et al. 1997). The objective of the experiment was to investigate the effect of untreated and formadehyde treated whole linseed on the performance and fatty acid composition of milk produced by Friesland ewes.