The nutritional objective for pigs weaned at 3 weeks of age is to enable the most economical transition from sows milk to predominantly cereal/soya based diets in the grower/finisher period. Conventional ‘complex’ diets given to early weaned pigs usually consist of a range of high quality, and therefore relatively expensive, ingredients such as skim milk powder, fishmeal and cooked cereals. Often the aim is to provide a more than adequate supply of highly digestible proteins with a view to maximising weight gain over this initial period. An alternative strategy is to provide the weanling pigs with a low-cost cereal/soya diet which is balanced, in terms of Its amino acid complement, in a manner similar to the ideal protein. A variation on this theme is to use a more conventional diet as a ‘pre-starter’ diet for the first two weeks after weaning, before the introduction of a cereal/soya diet, as there is often a check in growth rate associated with simple diets during this period. The aim of this experiment was to evaluate these alternative dietary regimes with pigs weaned at 3 weeks of age.

A test of the theory that animals seek to eat what they need, is to offer them a choice of two feeds with different protein contents but similar energy yields. The animals, treated in this way, are expected to eat that combination of the two feeds which Just meets their protein and energy requirements. However, in a previous experiment (Kyriazakis, Emmans and Whittemore, 1987), when pigs were offered a choice between two feeds, a high variation in the choices of individuals was observed. This was attributed to the need for an initial learning period, where animals obtain information about the feeds before making “correct choices”. The purpose of this experiment was to compare different ways of giving the opportunity to the animals to learn about the feeds on offer, and to measure their effects on the diets selected by young pigs given choices between the same pair of feeds.

Dried unmolassed sugar beet pulp contains complex polysaccharides which are highly fermentable in the growing pig and the neutral detergent fibre fraction is highly digestible. Fermentation in the hind gut of the pig is dependent on a supply of carbohydrate and nitrogen. The amounts of nitrogen available could limit microbial metabolism and hence sugar beet pulp digestibility at high levels of intake. The alms of the experiment were to examine:

1. 1. The effect of the level of protein on the digestibility of fibre from sugar beet pulp.

2. 2. The effect of the level of sugar beet pulp on nitrogen digestibility, nitrogen retention and nitrogen excretion.

There have been a number of reports that voluntary feed intake (VFI) of modern pig genotypes may be the limitation to their growth performance. It has been suggested that selection for leanness (Fowler et al. 1976) and breeding for faster growth may have reduced appetite.

In addition there is only limited information about the effect on VFI, performance and carcass characteristics of pigs fed ad libitum to liveweights greater than 100kg. A study was therefore undertaken to compare VFI and energy intake of improved genotypes with predicted intakes based on earlier genotypes (ARC, 1981). The associated effects on performance and carcass characteristics at heavier slaughter weights were also studied.

The ability to detect oestrus in cattle is important where artificial insemination, superovulation or embryo transfer techniques are being used. Even where oestrus is synchronised or controlled, knowlege of the occurrence of oestrus can increase success rates and reduce costs. A testosterone treated female fitted with a chinball marker (Signoret, 1975; Kiser, Britt and Ritchie, 1977) has been shown to be a useful aid to detection of oestrus. A preliminary experience using such females in conjunction with maiden heifers supported these claims and a subsequent trial provided a more formal evaluation of the technique.

To investigate possible factors influencing ease of calving in heifers, records from 392 calvings of replacement heifers on 10 research farms were analysed. Sire breeds were classified as either British or Continental, the majority of the Continental sires used being Limousin. Calving difficulty was recorded on a 1-3 scale. The data were analysed by regression analysis, dropping factors until the minimum r.s.d. value was obtained. Heifers in-calf to Continental bulls were mated at heavier weights, had heavier post-calving weights and greater pregnancy gains. Continental sires increased birth weights (3 ± 0.6 kg), gestation length (3.8 ± 2.55 days) and calving difficulties (calving score 1.14 and 1.41 ± 0.063 for British and Continental sires respectively). Birth weight was the major factor influencing calving difficulty (0.04 ± 0.012) with pregnancy weight gain the next most important. The effect of calf sex, gestation length and sire breed on calving difficulty were non-significant. This can be explained by the influence of birth weight, which alone accounted for most of the variation in calving difficulty.

The ability of growing animals to exhibit compensatory growth after a period of undernutrition is well documented (O'Donovan 1984). However, in cattle most information is on calves born in spring, underfed during the post-weaning winter and showing compensatory growth during the following grazing season. Little information is available on post-weaning compensatory growth in autumn born suckled calves.

The energy density of diets can be increased by the inclusion of fat containing long chain fatty acids which may have antimicrobial activity. Their interaction with antibiotic feed additives is unknown. This study was designed to investigate the effects of monensin sodium (Romensin - Elanco Products Ltd) an antibiotic feed additive, and supplementary fat (BP fat prills - BP Nutrition Ltd) when fed either alone or together in the diets of barley-beef bulls.

When barley has been used as a supplement to straw in diets for finishing cattle the performance achieved has often been below target. A trial was made to measure whether substitution of sugar beet pulp, a fibrous source of energy, for barley in such diets would Improve performance. Forty-eight Frieslan-type steers weighing 370 kg were offered long, Spring barley straw (variety Doublet) ad libitum. The straw was either untreated or treated with ammonia. Ammonia treatment was carried out in an oven with 3% anhydrous ammonia for 21 hours. Supplementation of the straw was designed to give a daily live weight gain of 1 kg. Animals offered untreated straw received 5.5 kg per head daily of dry matter (DM) from supplementary concentrates whilst those offered ammonia-treated straw received 4.5 kg concentrate DM. Included in the concentrates was 0.23 kg DM from white-fish meal and 0.07 kg of a mineral/vitamin supplement. The animals offered untreated straw also received 0.09 kg per head daily of urea. The remainder of the concentrates consisted of either bruised barley, a mixture of equal parts of DM from bruised barley and dried molassed sugar beet pulp, or sugar beet pulp only.

Whilst it is predicted that for finishing cattle (over 350 kg at start) fed grass silage diets, rumen degradable protein (RDP) should provide all protein requirements, previous studies have shown very variable growth responses from protein supplementation of cereal or starchy concentrates fed with grass silage. The protein source usually used being white fish meal which is high in rumen undegradable protein (UDP). This experiment investigated the response to fish meal supplementation of an energy concentrate based on either barley (starchy) or sugar beet feed (SBF, fibrous) when fed with good quality (64‘D’) grass silage to cattle in the finishing period of a traditional 18 month semi-intensive system.

Forty two 15 month and twelve 14 month old Friesian steers were blocked by weight and allocated at random to treatments (weights as fed):

• 1. 2kg barley plus minerals (2B)

• 2. 1.8 kg barley plus 0.2 kg fish meal (2BF)

• 3. 2 kg sugar beet feed plus minerals (2S)

• 4. 1.8 kg sugar beet feed plus 0.2 kg fish meal(2SF)

• 5. 4 kg sugar beet feed plus minerals (4S)

• 6. 4 kg barley plus minerals (4B)

For successful rearing of purchased calves, healthy animals with good utiization of feed are main objectives for profitability. Growth rate feed conversion efficiency (FCE) and health are adversely affected by pathogenic bacteria and antibiotics or chemotheraputic agents have been used as feed additives for several years. These may depress useful, non pathogenic bacteria and certain strains of pathogenic bacteria may become resistant to antibiotics. Probiotics are becoming increasingly advocated as being of benefit to calf rearers as a feed additive to improve the growth rates and health of rearing calves. An experiment at Drayton E.H.F. investigated the use of Lactobacillus acidophilus as a probiotic agent during the rearing period of purchased calves.

The use of biological feed additives in animal production systems is becoming widespread, largely in response to consumer pressure and legislation concerning the use of antibiotics and hormone implants. Howewver, published data on their efficacy are limited. Yea-sacc,a high strength yeast culture, is one such product. A yeast-culture is a dry product composed of yeast and the media on which it was grown, dried in such a manner as to preserve the fermenting capacity of the yeast. The yeast used in Yea-sacc is a selected strain of Saccharomyces cerevisiae, and the yeast culture is produced using a high density fermentation technique. A trial was conducted to examine the effect of including Yea-sacc in the diet, on the performance of early-weaned calves.

In order to increase milk production per cow, Friesian cows are being bred to Holstein bulls. As yet, there are few pure-bred Holsteins in commercial production in Ireland but there are increasing numbers of Holstein x Friesian and Holstein x (Holstein x Friesian) calves available for beef production. The main difference between Holstein and Friesian steers is that the former have poorer carcass conformation. The use of anabolic agents and an increase in slaughter weight might improve carcass conformation. The objectives of the present experiment were (1) to compare the growth and carcass composition of 3/4 Holstein and Friesian steers, (2) to measure the effects of implantation with anabolic agents in both these breed types, (3) to determine the effects of a higher feeding level and delayed slaughter on carcass traits.

Previous studies conducted at Newcastle with a lactobacilli silage inoculant(Pioneer Brand 1177) had shown that when compared to an untreated control silage, the silage produced with the Inoculant had improved chemical composition. The benefits of applying the inoculant were further seen in improvements in nutritive value and voluntary food intake by sheep.

The addition to grass during ensiling of enzymes capable of hydrolysing forage polysaccharides has been shown to result in increased fermentation of dry matter within the silo (Jacobs & McAllan, 1987). Thus it appears that the enzymes promoted cellular breakdown within the silo. It is also possible that the enzymes may also have made available greater amounts of structural carbohydrate for utilisation within the rumen. Such an increase in available energy may be reflected in improved microbial activity in the rumen resulting in increased microbial protein synthesis. The present experiment examines the effects of enzyme treated silages on the flow of nitrogenous constituents at the duodenum of growing steers.