A previous investigation, reported at the Winter Meeting 1985, showed significant effects of growth promoters on carcass composition and on the eating quality of sirloin steaks. The growth promoters investigated factorially were (a) hormonal implants (heifers, Zeranol; steers, Zeranol + Trembolone acetate), (b) feed additive (Avotan) and (c) fishmeal. The experiment was repeated during the winter of 1984/85, with the eating quality investigation expanded to cover some 192 households, using sirloin steaks from all 64 cattle involved in the investigation. In addition, the rate of carcass cooling in the left-hand side of each animal was measured using electronic probe thermometers placed in the longissimus dorsi immediately after slaughter. This data was used to test the hypothesis that rate of carcass cooling was negatively related to the fat content of the carcass and with overall eating quality due to the effects of cold shortening.

In 1984 the water authorities reported 2961 serious cases of freshwater pollution caused by farming, ca 75% by dairy farming. Liquor from insufficiently wilted silage, farmyard runoff and slurry washed off land or escaping from overflowing or leaking lagoons have all been implicated. The effects of these rich organic wastes on life in streams are described below.

Farm wastes can place an enormous demand on the dissolved oxygen (DO) content of the stream water. Cow slurry is 40-80 and silage liquor 200 times stronger than untreated domestic sewage, so that one volume of silage liauor is capable of completely deoxygenating 40 000 volumes of previously air-saturated water. The wastes also (i) increase turbidity, which reduces the effective penetration of light and thus restricts photosynthesis and primary productivity, (ii) smother the stream bed with a layer of decomposing silt or solids resistant to degradation and (iii) are toxic due to ammonia.

Increasing public interest and more anti-pollution legislation sharpen the need to avoid pollution. Soil, water and air are at risk.

Apart from plant nutrient considerations, secondary effects of water-logging and oxygen depletion of the soil can occur. Slurry tankers can cause damage to the field surface by rutting. Some tankers exert pressures of 70 psi on the soil and then are often used on wet soils. Such malpractices create extra costs to rectify extra problems created.

The environmental or polluting aspects of nitrogen in relation to livestock farms are gaseous losses to the atmosphere, nitrate leaching into water supplies and the eutrophication of surface waters. Gaseous losses of ammonia by volatilisation from organic materials and denitrification losses from soil as nitrogen and nitrous oxide have been at various times implicated in acid rain, photochemical smogs and effects on the ozone layer although the latter is now largely discounted. Nitrate leached from soil may pass rapidly into surface waters where it can affect quality for drinking or encourage algal blooms. Over porous strata nitrate may take many years to percolate downwards so as to pollute groundwater supplies. Restrictions may face livestock farmers in the arable areas of eastern England to restrict nitrate leaching from their land.

Pollution problems caused by silage are mainly odour and effluent production.

Odour can be virtually eliminated by ensuring a satisfactory silage fermentation, i.e. a low pH and a low ammonia concentration in the total nitrogen. This can be achieved by following the basic rules of good silage making, including the correct use of an effective acid additive.

Effluent is the major problem, particularly when it enters drains and water courses. This is because a typical effluent will have a pH of approximately 4.0 and a high 5-day biological oxygen demand (BOD5) up to 90 000 mg O2, per 1. This compares with BOD5, values of 5000 and 500 mg O2 per 1 in cow slurry and untreated domestic sewage respectively. Thus silage effluent in water courses removes the dissolved oxygen and will kill fish and other aquatic fauna. Effluent from a silo containing 300 t of low dry matter (DM) silage is equivalent in BOD5 to the daily sewage from a town of 80 000 people.

The principal reasons for measuring herbage intake are (1) to understand the relationships between sward attributes such as structure or composition and herbage intake, and (2) to explain differences in animal performance associated with different grazing systems or management strategies. These two objectives may require the use of different techniques, as will be outlined below, but all techniques require to meet the criteria of having a precision suitable for the purpose of the measurement, producing minimal disturbance to grazing acitivity, giving unbiased results and being as undemanding of labour and thus as inexpensive as possible. Animal-based estimates have the advantage over other methods in that they allow an examination of between-animal variation.

Intake of herbage by grazing animals is determined by the weight of herbage harvested per bite and the number of bites taken. A knowledge of ingestive behaviour can, therefore, play a valuable role in understanding animal responses to changes in sward conditions and management practices and thus aid the interpretation of results from grazing experiments. This paper will firstly consider briefly some methods of recording behaviour and, secondly, present some results illustrating the use of behaviour recording within a grazing experiment.

Direct observation is the most frequently used method of recording behaviour. It is, however, laborious and often carried out under unpleasant conditions; it is difficult to record activities continuously and in some cases it is not possible to directly observe a particular behaviour. These limitations have led to numerous attempts to record grazing behaviour automatically.

In a few published papers the utilised mstabolisable energy system for recording grassland productivity has been extended to calculated herbage intakes by grazing animals from records of their performance. First the energy needed to sustain the measured level of performance by the animals is calculated using published energy allowances for maintenance, lactation, growth etc. Then the amount of herbage that will provide the calculated energy requirement is estimated. Although there are considerable variations in the factors used to calculated energy allowances in the systems used in different countries, papers published in Britain recently have used the MAFF (1975) allowances to make these calculations.

Research into the conversion of grazed forages to milk and meat by ruminants has concentrated on factors influencing crop growth and utilization, whilst knowledge regarding the nutritive value of grazed pasture and the processes involved in the conversion of ingested forage to animal products is limited. The purpose of this paper is to review recent research findings with respect to the utilization of ingested forage by ruminants, to identify how these may be affecting animal performance, and to offer possible means for improving the nutritive value of, and animal output from, grazed pasture.

In large scale commercial pig production the programmed replacement of culled sows by pregnant gilts is a major problem. Techniques for heat synchronisation in groups of gilts have been explored by a number of workers using a variety of materals such as methallibure, gonadotrophins and progesterone. One promising method involves the use of allyl-trenbolone as an agent for oestrous synchronisation (Varley, 1983; Stevenson and Davis, 1981). Another approach is to use a combination of gonadotrophins (PMSG and HCG) to induce ovulation and new oestrous cycles.

The purpose of this study was to compare the value of these two techniaues under the same commercial conditions.

Melatonin has been shown to be effective in advancing the breeding season of the ewe when given either orally or by subcutaneous implantation. We have demonstrated that it is also effective when given as an intravaginal implant containing melatonin in silastic tubing. Such implants have the advantage that they are much easier to insert and remove than subcutaneous implants. Rate of implant loss is extremely low. The present abstract summarises the result of several experiments which have examined the effectiveness of melatonin implants when given at different times of year. Animals used were either Mule ewes or their Suffolk cross offspring. All were kept outside under normal management conditions. Groups of in ewes were given implants on either 12 April, 13 May, 18 July, or 21 December. Control ewes received empty implants. Blood samples were taken twice Weekkly for progesterone analysis to estimate the tire of onset of ovarian activity.

It has previously been shown (Robinson et al., 1985) that the normal breeding season of Greyface and Scottish Blackface ewes can be advanced by the daily administration of the indoleamine melatonin; the administration of the melatonin beginning midway during the anoestrous period. If melatonin is administered towards the end of the normal breeding season, oestrous activity can be extended, but only for a period of about six weeks until the ewe becomes refractory to the melatonin treatment (Nett and Niswender, 1981). There is no information on the administration of melatonin at the beginning of the anoestrous period.

In the following experiments we report results for the influence on the subsequent breeding activity of Greyface ewes of the oral administration of melatonin at the beginning of their normal period of anoestrus. We also report the results of an investigation on the effects of melatonin in advancing the breeding season of Scottish Blackface ewes maintained on either a high or low plane of nutrition. The experiments were carried out under natural daylength conditions at 57°N.

Hill gimmers typically perform below the flock average and are reluctant to take supplementary feed. This paper reports an attempt to evaluate the effects in the first breeding season of training young flock replacements to eat supplementary feed in the form of either concentrate pellets or feedblocks.

Four hundred and fifty-five ewe hoggs were allocated to two groups on return from away-wintering on 1 April. Untrained hoggs (U) were put to the hill immediately. The remainder were trained to feed (T) for one week before rejoining their contempories. Training and subsequent mating treatments are summarised in Table 1.

The objective of the study was to assess the potential benefits of using real-time ultrasound scanning in a hill sheep flock where the incidence of twinning is low. A high hill hirsel of some 320 Scottish Blackface ewes, typically lambing in the range 0.6-0.9 lambs per ewes mated, was divided across age into two groups. One group was scanned, colour marked and subsequently managed according to foetal number (the SCANNED flock). The other group was also scanned but not colour marked, and therefore managed irrespective of foetal number (the UNSCANNED flock).

The objective of the commercial pig breeder is, normally, profit per sow place per annum. Pigs reared per sow place per annum must be optimised to cover the fixed and variable costs of the business and leave an acceptable financial surplus. “Optimising output” is emphasised because in the late 1970s and early 1980s conmercial pig breeders were often encouraged to maximise sow output at any cost. The efficiency parameter “pigs reared per sow place per annum” takes into account the fact that many units run below capacity increasing the costs both fixed and variable carried by the sows actually in the herd. In a herd producing 20 pigs per sow per annum each 5% shortfall in herd size is equivalent to a reduction of one pig per sow per annum.

Every producer should assess the resources at his disposal namely capital, labour, buildings, stock, etc. and then optimise sow output within the limitations imposed by those resources. Output from the breeding herd is dependent on pigs born alive per litter, piglet survival rate, the interval from weaning to successful service, lactation length and the ability to maintain herd size.

An examination of the influence of nutrition on the series of chronological events in the breeding lifetime has suggested that satisfactory breeding animals can be produced on a range of regimens in early life. For example, nutrition during the rearing phase has to be fairly severe (50% of ad libitum or less) to significantly delay puberty.

Nutrition needs to serve the immediate reproductive needs of the animal and to ensure that the animal is in satisfactory body condition to reproduce throughout its breeding lifetime. Consequently, at certain stages there will be competition for energy and nutrients between the products of conception or lactation on the one hand and the maternal body tissues on the other.

The Starch Equivalent (SE) system devised by Kellner for expressing the energy requirements of ruminants and the energy value of feeds was used in Britain from 1912. Metabolizable energy (ME) was proposed (Agricultural Research Council, 1965) and adopted (MAFF, DAFS and DANI, Technical Bulletin 33, 197S), as a basis for a new system relating diet to the energy requirements of animals. Additional information was incorporated in the extensive Technical Review (The Nutrient Requirements of Ruminant Livestock, 1980). Metabolizable energy was retained, and animal performance it was claimed, was predicted more precisely with ME than SE. Results presented in this paper are for the comparison, and interpretation, of observed and predicted (Technical Bulletin 33) rates of gain, and other components of the ME system, for growing lambs and cattle fed forage and mixed forage and concentrate diets.

Fixed amounts of roughage and concentrate can be allocated to growing ruminants in a number of different ways e.g. a) a mixed diet containing equal parts of roughage and concentrate b) split feeds, roughage being given alone until exhausted, then concentrate alone c) a mixture changing . progressively from all roughage to all concentrate d) half the animals given roughage and half concentrate. The results of these alternatives can be predicted from computer models based on current feeding standards. Recent evidence (Ørskov et al, 1981a; Williams et al, 1984) suggests that in cattle carcasses of similar weight and composition can be obtained by giving a fixed amount of roughage and concentrate as either a mixed diet, or as separate feeds, (i.e. alternatives (a) and (b), above)even though animals on (b) took significantly longer. (Ørskov et al (1981a) concluded that improved efficiency of energy utilisation in the split group could be accounted for by a decrease in the maintenance requirement of the animals, or an increase in the efficiency of energy utilisation during realimentation following a period of reduced nutrition. The results could also be explained by differences in carcass composition of the animals, since no measurement of the protein and fat content of the carcasses was made. Williams et al (1984) found no significant difference in carcass composition between the two groups, as determined by specific gravity measurements and concluded that associative effects caused a reduction in the energy available from straw when offered with barley in a mixed diet.

Lameness in dairy cattle can result in significant economic loss. High protein levels in the diet have been implicated as a cause of lameness, whilst trimming has been advocated as an effective preventative measure. This trial examined the effects of these two factors on locomotion, hoof measurements and incidence of lameness.

Forty eight autumn calving cows in a continuous design experiment, lasting from weeks 3 to 26 of lactation were allocated to 4 treatments: LT (161 g/kg DM crude protein in the total diet, hooves trimmed); LUT (161 g/kg DM, untrimmed), HT (198 g/kg DM, trimmed) and HUT (198 g/kg DM, untrimmed). The protein levels in the complete diet were adjusted by substituting barley for soya. Daily ME intakes were maintained at the same level for all treatments by adjusting the high protein diet intake to that of the low protein, which was offered ad libitum. The cows feet were shaped and trimmed to a toe length of about 7 cm, 4 months before calving. Cows were scored for their locomotion weekly on a scale of 1 to 5 high scores indicate lameness. Hoof shape, growth, wear and hardness were recorded every 8 weeks on the right hind claw.

Partial storage feeding (grazing during the daytime and housing overnight) is becoming an established management system after turnout in the spring. Ad libitum grass silage is the most common overnight feed. However, some farmers do not have adequate silage available and a straw mix is a possible alternative feed. There is little information available concerning the optimum energy content of straw mixes (or other forages) used for partial storage feeding. In this experiment 3 straw mixes were fed with different energy contents.

In a continuous design experiment lasting 8 weeks (18 April to 12 June 1985) 60 autumn calving Friesian dairy cows and heifers were set stocked together during the daytime at 10 cows/ha. They were housed overnight and straw mixes, with low (L), medium (M) or high (H) metabolisable energy (ME) contents, were fed ad libitum each to 20 cows. In addition an average of 2.3 kg concentrates were offered daily. The grazing area was a perennial ryegrass ley which received 224 kg N, 13 kg P2O5 and 13 kg K2O/ha. The mean composition of the straw mixes, herbage and concentrate are given in Tables 1 and 2.