The genetic improvement of fertility in post-partum dairy cows is hampered by its age-limited and sex-limited expression since it can only be measured on adults and in the female. However improvement is further hampered by the low heritability of the traits that are commonly used as selection criteria (typically estimated ≤0.05), such as time to first insemination (T1), conception to first service (P1), number of inseminations per conception (NI) and days open (DO). Thus despite its undoubted economic importance in dairy cattle management, especially if the scheme is tied to an annual cycle, fertility does not receive a large weight in any aggregate selection index, since the weight in the index depends not only upon the economic importance but also upon how well genetic merit can be identified. Nevertheless significant opportunities may exist to improve fertility providing the appropriate traits are measured and recent evidence (Darwash et al. 1997) suggests that traits such as the interval to commencement of luteal activity postpartum (CLA) may have moderate heritability (0.21, s.e. 0.07) and be related to fertility (Whitmore et al. 1974). The present study was therefore undertaken with the objective of examining whether such a finding in the heritability of CLA is consistent with the published evidence on the low heritabilities of commonly measured criteria of fertility.

The in vitro gas production (GP) technique was developed using strained rumen fluid (SRF) as an inoculum. This requires the use of surgically modified animals and it is questionable whether maintaining cannulated animals for this purpose can be justified. Faeces (FAE) have been used as an alternative inoculum, but while total gas volume tends to be the same, the rate of gas production is usually slower. This is probably because of a lower microbial activity in FAE. If the initial activities of the two inoculum sources were controlled, the differences between them may be reduced. The objective of this experiment, therefore, was to compare the GP profiles obtained when different concentrations of SRF and FAE were used, and the initial activity of the inocula equalised.

Post Mid Term Review of the Common Agricultural Policy, beef production must survive in a subsidy-free, market led environment. It is essential that producers increase final carcass value by achieving cost effective performance from birth to slaughter. The aim of the present study was to evaluate the effects of plane of nutrition during the growing and finishing indoor feeding periods, and stocking rate and concentrate supplementation at pasture on the performance of steers and heifers from weaning to finishing.

Variety and location of production can affect the nutritive value of barley grain (Valaja et al 1997). Riviera and Dandy are the most commonly produced varieties of barley in Northern Ireland and it was an aim of this study to compare their nutritive value and to examine the effect of location of production. The growing and harvesting conditions have been shown to affect chemical and physical properties of cereal grain (Rogel et al 1987). A further aim was therefore to compare the nutritive value of Riviera and Dandy produced in 1998 (McCann et al 2000) and in 1999.

In animal production significant losses occur due to parasitism (Coop et al. 1985). The classic means of treating animals against parasites is with anthelminthic drugs. However, the recent years resistance to anthelminthic drugs has become a major problem in many countries. Novel ways of overcoming the problem of nematode parasites have been proposed. One of them is breeding for resistance to parasites (Bishop and Stear, 1999). The aim of this study was to estimate the genetic parameters needed to devise strategies to breed against nematode parasites. Faecal egg counts (FECs) are used as the indicator trait of resistance to parasites.

Nematodes are a particular challenge to animal health and productivity in organic sheep systems, where the prophyllactic use of anthelmintic is prohibited. The peri-parturient rise in faecal egg output, a consequence of relaxation of host immunity in late pregnancy and early lactation, is potentially a key factor in the epidemiology of parasitic gastro-enteritis on organic sheep farms. Coop and Kyriazakis (1999) developed a hypothesis to explain the relationship between nutrition and periparturient breakdown of immunity to parasites, and there is now an increasing body of evidence for the involvement of dietary protein (Houdijk et al 2001). The objective of this study was to test this hypothesis in organically managed ewes carrying a mixed, naturally acquired infection, grazing on grass/clover in early lactation, and to examine the potential for a nutritional approach to parasite control in commercial practice.

The use of fully slatted flooring and absence of bedding for finishing pigs are being questioned for welfare reasons at Council of Europe level and have already been made illegal in some EU member states. Part slatted flooring offers an alternative, but their success depends to a large extend on the correct use of functional pen areas by the pigs: dunging should take place on the slats, lying on the solid floor. Pen lay-out has a large effect on the degree of pen fouling. The effects of straw provision on the solid floor area are less well documented. The present study tests the hypothesis that pen fouling in a converted standard Dutch pig pen is not affected by straw use, but by the position of the single space feeder as well as the position of a 40 cm chain (toy).

The in vitro gas production technique has been developed as a means of predicting the degradability of feeds. However, it was pointed out by Blümmel et al. (1997) that attention should be given to the other products of the incubation as well. Degraded feeds may be incorporated directly into microbial biomass, or they may be fermented to produce VFA and gas. One of the objectives of this experiment was to determine whether the proportion of degraded substrate that was partitioned to gas production varied with different feeds. Blümmel et al. (1997) observed a negative relationship between gas yield (ml gas produced/g substrate degraded) and microbial biomass yield (mg biomass/g substrate degraded) when poor quality forages were incubated. A second objective of this work was to determine whether this relationship was also observed when higher quality feeds were used.

It has often been observed that increasing silage DM through wilting increases DM intake, although digestibility and efficiency of utilisation of nutrients tends to decrease, resulting in poor responses in terms of milk yield. Rapid solubilisation of nutrients in the rumen may give rise to rapid nutrient absorption, activating satiety mechanisms and resulting in shorter meals. In the present trial the difference in DM content of the silages was high (>200g/kg). Supplements based on different energy sources were fed to determine whether synchronisation of release of nutrients from the silage and the supplement modified DM intake and feeding behaviour.

Aquaculture is a rapidly expanding and extremely diverse form of animal production. Aquaculture takes place in systems that cover an enormous range of levels of intensification from extensively managed low input static ponds to super-intensive high exchange rate silos with liquid oxygen injection. Appropriate nutritional strategies are required for each level of intensification.

My remarks explore the role of theory in making progress in science generally and particularly in ecology. I discuss what theory is (and isn’t). I argue that theory is a fundamentally important part of doing science efficiently, and I discuss some exciting new approaches for combining theory, data, and statistics to enhance scientific understanding. I illustrate these approaches using examples from work on foraging by mammalian herbivores.

The application of welfare science to the study of both domestic and wild animals raises important ethical questions which the science itself cannot answer, and my purpose in the paper is to give a framework for answering these questions. I shall also try to evaluate the contribution that welfare science can make to difficult questions of wildlife management.

Due to binding tannin with protein and cellulose, it was hypothesized that pistachio hull tannin can decrease the digestibility of protein and cellulose. Pistachio Hull (PH) is the main pistachio by-product produced from the pistachio dehulling process. PH contained 12.7, 5.7, 16.6, 25, and 20% ash, EE, CP, NDF, and ADF, respectively. The nutritional responses to high levels of dried pistachio by-product in the diet have not been clearly researched. The main objective of this experiment was to evaluate the effects of feeding pistachio Hull at high levels on feed intake, ruminal pH, N-NH3 and blood metabolites in Balochi sheep.

A key to long-term sustainable enhancement of viable livestock production is the introduction of genetic traits that ensure that fertility and meat quality characteristics are compatible with farming environments and market needs. For example, the sheep industry could benefit if daughters of hill-breed ewes were of a crossbred genotype that enhances both carcass characteristics and fertility traits. Use of sires that confer better conformation is an option but does not significantly boost prolificacy. Introduction of the ‘Inverdale’ fecundity gene could change this. On a flock basis in the Romney breed, mean ovulation is increased by 1.0 and litter size by 0.6 in adult ewes carrying a single copy of this gene (designated as FecXI because it is on the X chromosome; Davis et al. 1992). Carrier males transmit it to all of their female offspring, these being heterozygous carriers of the gene unless it also is maternally inherited. In the latter instance, young would be infertile the homozygous genotype confers an undesirable ‘streak ovary’ phenotype. Although a number of sheep breeds world-wide exhibit significant ‘single gene’ effects on ovulation and litter size (Montgomery et al. 2001), Scottish hill sheep breeds show no evidence of this. Consequently, all ewe lambs generated by crossing these hill ewes with a ram carrying the Inverdale gene should be heterozygous. To ascertain whether such animals exhibit enhanced fecundity, an on-farm study investigated ovulation incidence in cyclic ewe lambs born to Cheviot or Scottish Blackface ewes that had been bred to Texel rams carrying a single copy of the ‘Inverdale’ gene.

A sustained-release rumen bolus system (‘Small-Trace’, Agrimin Ltd., Brigg DN20 0SP) consisting of two polymer-coated cylinders (55mm length, 18mm diam) containing a compressed mixture of normal inorganic trace elements and vitamins had been demonstrated to be an effective long-term copper and selenium supplement for calves > c. 70kg liveweight (Hemingway et al. 1996). A modification of the calf bolus system appropriate for ewes is described using a single bolus together with an inert grinder to promote bolus matrix erosion/dissolution in the reticulum/rumen.

The UK ruminant industry is currently reliant on soyabean meal and fishmeal as sources of high quality, digestible undegraded protein (DUP). However, there is increasing concern over the sustainability of fish stocks, and the world market price fluctuation and traceability of soya bean meal. There are a number of protein crops which will grow under UK conditions including sweet white lupins, peas, field beans and oilseeds (rapeseed meal and linseed meal). However, these proteins tend to be more rumen degradable than fish meal and soyabean meal (Moss and Givens, 1994). Heat moisture treatment has been shown to be particularly effective in reducing the rumen degradability of protein without reducing intestinal digestibility (Herland, 1996). This experiment was undertaken to determine the effect of feeding moist heat treated rapeseed meal, lupins and beans to dairy cows.

UK legislation dictates that all pigs shall have access to straw or other material or object suitable to satisfy their behavioural needs (Welfare of Livestock Regulations, 1994). However, it is unknown how much straw must be provided to be behaviourally rewarding, and whether pigs’ prior experience of straw can impact upon their subsequent behavioural needs. Therefore, the aim of the current experiment was to investigate these issues by exposing pigs which did, or did not, have prior experience of straw to four levels of straw bed depth.

Manipulation of energy- and protein supply during the dry period can affect milk production and composition in the next lactation (Moorby et al, 1996). These studies also demonstrated considerable between-animal variation in responses which may relate to previous nutritional history. This problem was addressed in the current experiment by (i) developing enhanced assessments of animal condition; and (ii) monitoring performance over successive lactations. The second half of the first lactation is a critical phase, particularly for young heifers, since they have to balance the competing demands of pregnancy, growth and a persistent lactation. Berg and Ekern (1993) showed that underfeeding heifers had a residual effect on milk production and composition in their second lactation.

Forty-five Holstein Friesian heifers, which calved from September to December 1994, were selected for this work; 23 of the animals calved at approximately 3 years of age (‘3’), 22 at approximately 2 years of age (‘2’). Thirty-eight animals completed the experiment (to the end of their second lactation) and data from these animals are used here. The animals were maintained on a complete diet until April 1995 when they were offered 8 kg/day of concentrate with ad libitum grass silage for 3 weeks of covariance recording.

Mastitis remains a costly health problem to dairy farmers despite a significant reduction in both clinical and sub-clinical mastitis over the last 25 years. This reduction has been due predominantly to the success of management control programmes. The continuing losses have raised the interest in breeding as a means to reduce mastitis incidence. Somatic Cell Counts (SCC) have been used since 1977 as an indirect means of monitoring mastitis within dairy herds. Since 1991 an optional individual cell count service has been offered by Milk Recording Organisations in the UK. The result is that 0.80 of recorded cows have SCC records. The Animal Data Centre has analysed the SCC data to establish genetic parameters and produced preliminary evaluations on bulls and cows (Mrode et al, 1996). As a forerunner to launching SCC evaluations it is important to determine whether SCC evaluations in the UK agree with similar evaluations overseas.

The Department of Health (1994) recommended people to reduce their intake of total fat and saturated fat and increase that of n -3 polyunsaturated fatty acids (PUFA) to 200 mg/d. The ratio of PUFA:saturated fatty acids (P:S ratio) in the total diet should be >0.4 with an n -6:n -3 ratio of <4. Since fish consumption, a major source of dietary long-chain n -3 PUFA, is low in the UK, research has focused on improving the fatty acid balance of other meats. The objective of this paper is to summarise studies by IGER and the University of Bristol on manipulating fatty acid composition of beef.