A major constraint on smallholder dairy farms in Kenya is inadequate feed supply resulting in low productivity. In Kiambu district of the Central Highlands, principal feed resources are cultivated Napier grass, roadside grass and fodder from maize, including stover and higher quality thinnings cut during the growing period. An average farmer in Kiambu owns 0.8 ha of which 0.19 and 0.17 ha are dedicated to Napier and maize cultivation, respectively, and 2.2 cows producing 5.8 kg milk/day (Staal et al. 1998). Meeting the feed requirements of the dairy animals, while maintaining food production is already a challenge. There are indications that the maize crop will become increasingly important as a source of fodder (Staal et al. 1998). Methu (1998) showed that by planting 4 rather 2 maize seeds per hole, 1.9 t DM/ha of thinnings, with high energy and N content could be harvested without affecting significantly the yields of stover or grain. The present study explored further the potential of increasing production of good quality thinnings without jeopardising grain yield in a series of on-farm trials.

It is believed that there are time periods during the lifetime of an animal when inadequate nutrition may result in the animal not reaching its genetic potential. One sensitive period is during early foetal life at the time when muscle fibres are being formed from myogenic cells. The total numbers of muscle fibres for life are essentially set during this period. The aim of this study was to try and identify the ontogeny of muscle cell differentiation by quantifying the mRNA expression of ovine IGF-I, ovine IGF-II, and ovine myogenin, factors known to influence myoblast proliferation or differentiation. The aim was to gain an indication of the time period during gestation at which differentiation of the muscle cells commences. The period before differentiation (i.e. during proliferation) is potentially sensitive to external factors, such as nutrient supply. This information could be used to determine the time during pregnancy when adequate feeding is essential to ensure maximum muscle development of the offspring, and may allow the manipulation of diet to change muscle characteristics for meat production.

Feeding lowland sheep on straw-based systems during pregnancy (Davies and Chapple 1995) has shown that ewe and lamb performance can be satisfactory, providing adequate compound supplementation was fed. Whole barley and soya bean meal has been the standard ration. Experiments with March-lambing ewes (Chapple et al., 1997) has shown that feeds based on molassed sugar beet feed and maize distillers dark grains can replace a barley/soya supplement. The objective of this work was to evaluate the effects on ewe and lamb performance of feeding sugar beet feeds with higher levels of distillers grains to January-lambing ewes on straw-based and big-bale silage systems during pregnancy and early lactation.

Digestibility trials enable researchers to determine the amount of nutrients an animal absorbs and utilises from feed. There are a number of methods available, with the most common being the measurement of total feed intake and total collection of faeces. However, in situations where it is not practical to conduct a total collection trial, indigestible markers are used in conjunction with grab-sampling or sub-sampling techniques. To date, the most common marker used in dog studies has been chromium oxide (Cr2O3; Hill et al., 1996), with little data available on the suitability of other markers such as titanium dioxide (TiO2). A major problem in using Cr2O3 as an indigestible marker is poor repeatability and agreement between laboratories in the determination of Cr2O3. This has led to variable results due to incomplete and inconsistent recovery in excreta (Sales and Janssens, 2003). However work on other species comparing the use of TiO2 and Cr2O3, has demonstrated that TiO2 was a more accurate marker (Jagger et al., 1992). This study was performed to determine the digestibility of two diets, a low (LN) and a high nutrient (HN) diet using TiO2 or Cr2O3 as indigestible markers. The two different quality diets were used to investigate if digestibility affected marker recovery.

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.

Testing different pig genotypes on a single diet may constrain protein and lipid deposition or reduce the efficiency of nutrient utilisation by under- or over-supply of nutrients. If the ranking of genotypes is dependent on the diet used when performance testing animals, then genotype-specific nutritional regimes may be required by breeding companies to identify animals of high genetic merit and by producers to realise the benefits obtained by genetic improvement programmes. In the Edinburgh lean growth project, divergently selected lines for efficiency of lean growth (LFC), for rate of lean growth with animals performance tested on ad-libitum (LGA) or restricted (LGS) feeding or for daily food intake (DFI) have been established with seven generations of selection in a Large White population (Cameron, 1994). The selection lines provide an experimental resource to estimate the genotype with nutrition interaction for protein and lipid deposition rates as differences between selection lines will relate to the selection strategy since the lines were derived from the one base population.

Improvement of herd life increases profitability due to lower replacement costs of heifers, higher proportion of mature cows that produce at their maximum potential and increased opportunity for voluntary culling. Functional productive life (PL) after adjustment for production is the ability of a cow to remain healthy and delay involuntary culling (Ducrocq et al 1988). Survival or failure time analysis has replaced linear model approaches for routine genetic evaluation of dairy cattle in several countries (Sewalem et. al. 2003). It allows proper treatment of censored data, inclusion of time-dependent covariates and skewed or non normal distribution of data. Approximate estimates of the heritability of longevity traits typically range from 0.05 to 0.10 and 0.15 to 0.20 using linear models and survival analysis, respectively (Vollema et al. 2000 and Caraviello et. al. 2004). The objective of this study was to apply survival analysis methodology for assessing the most important factor influencing PL, estimation of genetic parameters of productive life and genetic evaluation in Iranian Holstein dairy cattle.

Leptin is the 16 kDa product of the obese gene secreted by white adipose tissue in proportion to energy intake. In several species, plasma leptin levels correlate with, and may be and endogenous signal of, the extent of body fat reserves. Leptin acts via the hypothalamus to regulate feed intake in rodents and may control gonadal activity through this same axis. Significantly, the mutant ob/ob mouse lacks functional leptin and is both hyperobese and infertile. Leptin may be a useful diagnostic and/or therapeutic aid in high-yielding dairy cows in which infertility is rising inexorably and is anecdotally linked to the scale of the early post-partum negative energy balance. Our objectives were to recombinantly synthesise, and raise antibody to, a leptin-protein conjugate and to develop a useful and specific RIA for ruminant leptin.

In dairy cattle breeding programmes the knowledge of cow's lactation curve could be an effective tool to make selection decisions. In order to obtain an accurate shape of lactation curve a variety of mathematical models have been used in which parameters of production peak, inclining and declining phases of milk production over the course of lactation have been estimated by linear or non-linear techniques. The main purpose of this research was to compare four non-linear functions for the estimation of first lactation curve of Iranian Holstein dairy cows.

Ensiled grass is presently the major source of winter feed for dairy cows and other livestock in the UK. However, the quality and quantity of protein in grass silage tends to limit its use for milk production, which means that bought-in concentrate supplements must be fed to maintain high production levels. Whilst forage legumes such as red clover and lucerne appear to have potential as home-grown, protein-rich feeds for livestock (Frame et al., 1998), there is very little information available regarding their nutritive value when ensiled. The aim of this study was to compare the N balance of lambs offered red clover and lucerne silages harvested at two different growth stages.

Plasma protein is known to increase feed intake and growth rate in the first week following weaning (Coffey and Cromwell, 1995) although these benefits are not always evident some weeks later (Nessmith, et al., 1997). However, as most UK food retailers demand the exclusion of same species animal products from livestock diets, plasma products are excluded from UK piglet diets even though they are commonly used in several EU countries. The benefits of plasma protein are thought to result from its immunoglobulin content therefore alternative sources of specific immunoglobulins may be equally beneficial. One such source is egg protein derived from hens which have been vaccinated against specific pig pathogens (Kichura, 1997) eg Protimax (DuCoa, USA). The aims of this experiment were to estimate the potential loss of efficiency in the UK by the exclusion of porcine plasma protein from weaner diets and to determine whether egg protein containing specific immunoglubulins could produce similar piglet performance to plasma protein.

Our earlier studies with dry cows have highlighted a number of factors that affect performance in the subsequent lactation, including forage intake in the peri-parturient period, body condition at calving and supply of Metabolisable Protein (MP) (Moorby et al., 1996; Dewhurst et al., 2000). There is now increased interest in making more use of grazed grass, as a cheap feed, particularly through extending grazing into the late-autumn and winter. Dry cows are suited to extended grazing because they do not need to be brought in for milking each day. The high voluntary intakes of grass may be beneficial for dry cows, though the low MP supply from autumn-grass might be a disadvantage. This experiment evaluated the effects of extended grazing, compared with housing and silage-feeding of dry cows.

Nose ringing of outdoor sows is widely practiced to reduce pasture damage, but may have both short and longer term implications for animal welfare. This study was carried out to assess the effectiveness of different forms of nose ring and the extent of behavioural modification which they caused.

Six groups of 5 sows were allocated between three treatments: unrung (U), rung with three traditional boss-rings through the upper rim of the nasal disc (TR) or rung with a single bull-ring through the nasal septum (BR). Groups were placed in adjacent paddocks on undamaged grass leys at a stocking rate of 38 sows/ha. Pasture damage was assessed weekly by measuring proportions of grass, bare earth and overturned earth in 20 half-metre square quadrats per paddock on a fixed sampling pattern.

Thermal processing is carried out on commercial diets primarily to kill bacteria and reduce mould growth, although additional benefits have been shown such as an inactivation of trypsin inhibitors present in soyabean meal (McNaughton and Reece, 1980). However, heat treatment if too severe can produce negative effects, such as reduced apparent digestibility and increased viscosity of gut contents in broilers, an effect reversed by the addition of enzymes (McCracken et al, 1993). The aim of this study was to examine the effect of heat treatment during diet preparation on ileal and overall apparent digestibility of diets for growing pigs, made from two wheat varieties of different in vitro viscosity (8.8 vs 20.8 cps) with and without the addition of feed enzyme.

Porcine plasma is known to improve immediate post-weaning performance but this is often only evident in the first week to ten days after weaning (Toplis and Miller, 1999). Few if any studies have investigated whether there are any long term effects over the entire growth period. It has previously been shown that piglets in poor health situations (Coffey and Cromwell, 1995) demonstrate markedly greater responses to porcine plasma. The objective of this study was to determine whether porcine plasma produced long-term benefits and whether this was modulated by health challenge during the weaning period.

In Khorasan province of Iran about 1 million tonnes of tomatoes are grown annually. They are either directly sold to the customers as vegetable (200,000 tonnes) or further processed to products such as paste, ketchup, sauces etc. After the juice is extracted from fresh tomatoes, a residue primarily consisting of water, tomato seeds and peels is left. Tomato processing residues which is called tomato pulp accounts about one fifth of fresh weight or 160,000 tonnes in the area (ministry of Jahad-Agriculture, 2004). Fresh tomato pulp becomes sour and mould rapidly because it is traditionally processed during summer time and has high moisture content. Consequently, it is advisable to be ensiled or dried. Although it is commonly fed to ruminants but little data is available on its effect on milk yield, milk composition and dry matter intake in dairy cows.

A delay in the onset of puberty in gilts with intensive selection for efficient lean growth would have substantial implications for pig breeding programmes due to later first parity matings. Therefore the current study determined the responses in gilt traits at puberty to selection for components of efficient lean growth rate.

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.

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.

Maize distillers grains (MDG) is a high quality by-product feed containing 317 g crude protein (CP)/kg DM and 13.5 MJ metabolisable energy/kg DM, and as such is a valuable traceable feed resource. An earlier study conducted at the Centre for Dairy Research (Sutton et al. 2000) with cows in late lactation using a total mixed ration (TMR) based on maize silage, compared the protein value of MDG with that of soyabean meal (SB). The study showed that MDG could be used to replace SB on a total nitrogen (TN) basis without effecting feed intake or nutrient digestion in the rumen, or flow of non-ammonia nitrogen to the duodenum. The aim of the current study was to determine the effect of replacing SB with MDG on a TN basis, on DM intake and milk production in high yielding lactating dairy cows.