The system of feeding beef bulls on a “storage regime” based on silage has been developed at Rosemaund Experimental Husbandry Farm. The gross margin obtained from this planned and disciplined system of production has shown figures comparable to milk production.

The introduction of the hormonal implant,oestradiol - 17 β in a slow release form (Compudose 365 Elanco) offers the benefit in an “18 month” beef system of improved live-weight gain of steers at grass, continued during the final finishing period without further handling and cost. In this trial the persistence of the benefit over a 12 month period and of any interaction with the level of protein fed in the compound diet during the last 4 months of winter feeding was examined.

Implants are widely used with both steers and heifers over the 100 days before slaughter. They are known to increase the growth rate and improve the carcasses of the cattle. Results were presented to this Society last year (Proceeding Winter Meeting 1983 paper 102) which showed that repeat implantation with Zeranol in steers weighing initially 55 or 175 kg produced worthwhile improvements in daily gain. The object of this work was to obtain information on the effect of a single implant of oestradiol 17 β with repeat implantation using Zeranol at 90 day intervals.

Recent reports have suggested that growth in entire male cattle (bulls) may be increased by implantation with the growth promoter zeranol. It is well known that given similar nutrition bulls grow faster than castrate male cattle (steers). This effect may be attributed to the presence of testicular steroids in bulls which stimulate lean tissue deposition and hence greater live-weight gain. A major objective of this study was to provide further information on the effects of zeranol implantation on growth and blood concentrations of endogenous hormones and metabolites. Effects on concentrations of the endogenous steroids, testosterone and oestradiol-17β were of particular interest.

Dairy- and suckler-bred cattle of several breed types and sex either overwintered in yards prior to grass finishing or finished in yards during the winter of 1982/3 were involved in farm trials to determine the effect of Salinomycin sodium on daily gain. To a large extent breed and sex were confounded with farm group. Overall 520 winter finished and 728 overwintering cattle were involved (Table 1).

Virginiamycin, discovered and manufactured in Belgium (De Somer, 1955) from a naturally occuring mould, is a steptogramin type antibiotic (Cocito, 1979). Steptomyces virginiae produces two antibiotic factors, M and S. Factor M is a cyclic lactone and is present as 60-70 per cent of Virginiamycin. It has been demonstrated that there is a synergism between these two factors (Chabbert, 1971) whose combined activity is three or more times that of the individual components. The mode of action in monogastric animals has been well documented in pigs (Henderickx, 1979) and this work has lead to recorded data on the influence of Virginiamycin on the absorption Of nutrients by these animals (Dierick, 1980). The advantages of supplementing broiler, layer, turkey and pig feeds with Virginiamycin have been recorded (Barber 1978, Krider 1978, Pellura 1980, Leibetseder 1980, Harnisch, 1980, Canale 1980, Korthas 1979 and Phillip, 1978). The producers of veal and beef calves have also used Virginiamycin and shown improved daily gain and feed conversion (Parigi-Bini, 1979). These data promoted the trials in growing cattle detailed in this paper.

Feed additives are widely used in beef production systems. Two series of trials were carried out during a 2 year period on several farms in the N.E. of Scotland to determine the effects of the feed additives, Salinomycin, Flavomycin, Romensin and Avotan on the growth rate of beef cattle. In the first trial which was carried out on 27 farms, there were 1650 steers and heifers which were on an ad-libitum diet of grass silage and a rolled barley supplement. The additives were pre-mixed with 1 kg ground barley and fed once daily to the groups of cattle as part of their concentrate allowance. The additives compared were Salinomycin 150, Flavomycin 40, Romensin 200 and Avotan 150 mg/head/day. All cattle were weighed at 0, 42, 84 and 126 days. The responses in terms of daily gain and the persistency of those responses were measured for the various feed additives. In the second trial which was carried out on 13 farms, there were 470 bulls which were in cereal-beef units. The additives used were premixed and fed in a similar manner to that in trial 1. The same additives were compared at similar dose rates to the other trials. All cattle were weighed at 28-42 day intervals and daily gains were recorded. On one farm, feed intake was recorded for each group of bulls given the different feed additives. The data from each farm was analysed using the analysis of variance technique. The mean gains on each farm were subjected to further analysis using least squares techniques to provide overall mean values with appropriate standard errors.

The response to repeat Zeranol implantation assessed in terms of LWG was evaluated under grazing conditions in both entire and castrated male kids, in order to determine wether the use of the anabolic was of economical importance under the system most widely used for goat meat production.

Forty five Spanish Granedine male kids aged 2 weeks were randomly divided in 3 groups. Group A remained as control, Groups B and C were implanted on weeks 0, 8 and 16 of the 24 week trial with 12 mg. of Zeranol and Group C was also castrated at the begining of this experiment.

The kids remained with their mothers on a Star grass plot for the first implantation period, afterwards they were weaned and their feeding depended only on grass pluss salt and minerals.

To avoid coccidiosis outbreaks the kids were given Amprolvet Super on a 0.006 concentration in the drinking water all through the trial. The animals were weighted fornightly.after a 18 hour fasting period.

Studies reported from this laboratory in the mid seventies showed that it was possible to achieve a conception rate of 73% to a single fixed-time insemination in the autumn breeding season in ewes previously treated with intravaginal progestagen and pregnant mare serum gonadotrophin (PMSG). The present work was aimed principally at an examination of the AI technique in commercial flocks when applied over a period of three years (1979–81) and when applied in sheep of different breeds (Galways and Suffolk-cross).

In the course of three successive breeding seasons, a total of 2,704 cyclic ewes in 87 farm flocks were bred to Texel or Suffolk rams by A.I. using a sperm dose of 400 million in 0.2 ml volume of a skim milk diluent; only semen samples showing a wave motion rating of 3.5 or higher were used and accepted samples were pooled. A further 525 ewes in 20 farm flocks were bred by natural service (ratio of 1 ram: 10 ewes) in one area covered by the AI work. Control of oestrus and ovulation was achieved by a 12-day treatment using commercially available progestagen sponges (Chronogest, Intervet. Ltd.; Veramix, Upjohn Ltd.); at sponge withdrawal a single intramuscular injection of 500 i.u. PMSG (Intervet. Ltd.) was administered.

One problem encountered in the widespread application of sheep artificial insemination (AI) is the rapid decline in fertility of fresh or liquid chilled ram semen. An effective deep-freezing procedure would enable semen to be collected and stored from selected rams throughout the year for subsequent use in controlled breeding programmes, as well as facilitating the import and export of semen.

Following some encouraging results from the use of pooled semen frozen by an Australian pellet method (Maxwell et al 1980), further field trials were conducted to investigate fertility of semen frozen from individual rams as well as pooled semen. The effects of season of freezing and number of inseminations on fertility were also investigated.

In 1980/81 the North of Scotland College of Agriculture and the Rowett Research Institute carried out collaborative trials on artificial insemination of ewes. The ewes were double inseminated at 48 and 60 hours after pessary withdrawal, using diluted, fresh semen chilled to 15°C. The average conception rate at synchronised oestrus was 70%.

Considerable interest was shown by farmers in the North East of Scotland resulting in on-farm trials. These were restricted to a 50 mile radius of Aberdeen in order to minimise time between collection and insemination and ensure viability of semen. However one trial entailed flying semen to the Orkney Island of Hoy and covered 250 ewes over two days of which 66% lambed to the synchronised oestrus.

Protein supplementation of silage diets using fishmeal can increase both the voluntary intake of silage and liveweight gain in young growing calves. In association with these responses, increases in ration digestibility have also been observed which are not predicted by ARC (1980) (Bax, J.A. and Offer, N.W., 1982). Similar unpredicted responses have also been observed in older cattle (Waterhouse, A., Laird, R., Holliday, R.J., 1983). ARC (1980) assumes that increases in digestibility following supplementation with RDP occur only if the basal diet provides less than 7.8 g RDP/MJ ME irrespective of the source of RDP. The objective of the present study was to subject the microbial requirements proposed in ARC (1980) to a critical evaluation.

A method is described for the description of feeds and feed mixtures in terms of their ability to provide truly digestible amino nitrogen (N) for cattle. Total basal endogenous N (TEN) loss is assumed to be 0.35g N/kg bodyweight0.75 (Report of A.R.C, Protein Working Group).

Feedstuffs are analysed for total N (TN), non-protein N and detergent-insoluble N (neutral detergent, NDIN and acid detergent, ADIN, van Soest, 1982). The disappearance of N is measured from samples incubated in nylon bags in the rumen of dairy cows for 0, 4, 8, 18, 24 and (for forages) 48 hr. Residual N in nylon bags after 18 hr incubation is subjected to 48 hr pepsin digestion to give pepsin-insoluble undegraded dietary N (PSUDN). Digestibility trials are run using three sheep for each test feed and faecal N analysed according to a modification of the method of Mason (1969) into detergent-insoluble faecal N, soluble faecal N and bacterial and endogenous debris N. Urinary N has also been measured since 1983.

Sales of semi-skimmed milk in the USA and in many European countries are increasing, while those of whole milk are decreasing. Although consumption of whole milk in the U.K. is much higher than in other EC countries, sales have been declining in recent years. The amount of semi-skimmed milk sold in the U.K. is very small and in many parts of the country can only be obtained with difficulty. The object of this paper Is to compare changes in demands for liquid milk in the U.K. with those of other countries in an attempt to understand the relationship between the market for semi-skimmed milk and for whole milk.

Dried skimmed milk (DSM) is a common constituent of piglet creep rations. Liquid skimmed milk (ISM) is considerably cheaper per unit of feed value and if it could be fed successfully to young pigs as a substitute for DSM without adversely affecting performance, significant savings could be made in weaner rearing costs.

Twenty litters from Large White x Landrace sows, totalling 199 piglets, were offered one of two creep rations.

The incorporation of various organic acids into diets fed to weaned, growing pigs has been shown to improve growth performance. This research has concentrated on the response of pigs in the 5-110 kg liveweight range. The aim of the present study was to examine the response of piglets weaned at 10 days of age (approximately 3 kg live weight) to the inclusion of either 3% citric acid or 1.5% fumaric acid in their diet. A second trial was performed to elucidate the effect on diet palatability of including these organic acid additives.

Trial One: This involved 162 Large White x (Large White x Landrace) piglets which were weaned at 10 days of age. Following weaning, piglets were penned in litter-mate groups (2 groups/treatment) and allocated to one of three dietary treatments. The diets contained either 3% citric acid (CA), 1.5% fumaric acid (FA) or no additional organic acid (NA) , and were fed ad libitum in a pelleted form. The trial period extended from weaning for a period of 25 days. Piglets were weighed at weaning and at the completion of the period, water was available ad libitum.

An investigation was carried out to study feed intakes between 3 and 7 weeks of age for 3 week weaned piglets weaned into flat deck accommodation. Research has concentrated on the dietary requirements of early weaned piglets. Little information is available on the daily feed intake and liveweight gain of young piglets, on commercial units, over the initial post-weaning period.

The routine feeding of liquid replacer for sow milk (RSM) to either suckling or early weaned piglets is currently receiving some interest and several products of this type are now available commercially. Advantages claimed from the use of these products include reduced pre-weaning mortality, heavier weaning weights and faster post-weaning growth. An acidified whey-based RSM has been investigated at Newcastle and this report outlines two trials which have been carried out with this product(14% fat, 24% crude protein, pH 52).

There is considerable interest in using drinking water as a vehicle for the medication of early weaned piglets. A prerequisite of effective medication via drinking water is an accurate assessment of water intake. Unfortunately there is no published information on the water intake of early weaned piglets under modern systems of housing, feeding and management.