An earlier study conducted at the Centre for Dairy Research (Phipps et al. 1996) using a total mixed ration (TMR) based on maize silage, showed that when distillers grains wheat and molassed sugar beet feed (MSBF) replaced cereal and protein supplements, milk yield and dry matter (DM) intake were maintained but there was a large and significant reduction in milk fat and a small but significant reduction in milk protein. This depression in milk protein was attributed to the high oil content of distillers grains, which would have reduced fermentable metabolisable energy intake which in turn may have adversely affected microbial protein synthesis and reduced milk protein content. The aim of the current study was to devise a nutritional regime using distillers grains maize (DGM) and MSBF in a TMR which would allow milk fat content to be substantially reduced without compromising either DM intake, milk yield or milk protein content.

High yielding cows require high quality diets to sustain milk yields and to minimise weight loss, metabolic disorders and fertility problems. Traditionally, these diets have contained fishmeal and soyabean meal, both widely regarded as good sources of high quality, digestible undegraded protein (DUP). However, there is increasing concern over the sustainability of world fish stocks and the BSE scare has increased public awareness to the extent that feeding animal protein to herbivores may become unacceptable in me future. This in turn has driven up the price of high quality imported vegetable proteins, such as soyabean meal. The aim of this study was to investigate whether fishmeal and soyabean meal could be replaced in the diet of high yielding cows, with protein sources grown in the UK

In a 12 week randomised block design experiment, 60 muciparous Holstein cows, on average 28 days calved at the start of the study, were fed total mixed rations based on grass silage and one of five protein mixtures. These were either 0.5 kg DM fishmeal + 0.7 kg DM soya + 2.5 kg DM rapeseed (PC), 1.3 kg DM soyabean + 2.3 kg DM rapeseed (PI), 3.8 kg DM lupins + 2.3 kg DM heat treated rapeseed (P2), 3.6 kg DM linseed + 1.4 kg DM rapeseed (P3) or 5.8 kg DM rapeseed (P4). Each diet was formulated to supply sufficient energy and metabolisable protein for maintenance + 43 litres and 0.75kg/d weight loss and to contain similiar levels of DUP (AFRC, 1993).

The rate of disimilation of the dietary protein fraction of fresh forages, especially fresh legumes, is rapid and often exceeds microbial requirements for ammonia [Beever, 1993]. Consequently total dietary nitrogen [N] utilisation is impaired due to increased absorption of ammonia from the rumen and excretion of urea via the kidneys. This experiment, as part of a larger co-ordinated study to examine N utilisation in alfalfa swards for milk production, considered the evaluation of different isoenergetic supplements formulated to contain contrasting carbohydrate components with respect to starch and fibre level and type, and water soluble carbohydrate content.

Forty multiparous Holstein cows in immediately post peak lactation were randomnly allocated to one of four alfalfa paddocks, and provided fresh daily allowances [13kg Dry matter (DM)/cow/d] by means of electric fencing. Cows were milked twice daily [0600&1500h] when 3.5kg DM concentrate was offered at each milking. At all other times cows were at pasture and intakes were estimated by measuring pasture DM on offer to and refused by the cows.

Rumen protected forms of methionine have been developed to facilitate rationing of dairy cows in term of digestible methionine. It is essential for rumen protected products that the proportion of the amino acid that resists ruminal degradation as well as the proportion available in the intestine is known. Methods based on the concentration of amino acid in blood have been developed to provide fast and effective assessment of protection / release coefficients. The objective of this trial was to test the efficiency with which four different sources of methionine could deliver methionine to the blood of dairy cows.

Two multiparous Friesian Holstein cows fitted with rumen and duodenal canulae and in their 10th week of lactation were used. They received a ration composed of corn silage ad libitum, soybean meal (2.5 kg/head/day) and concentrate (6.5 kg/head/day).

The objective of this work was to develop a simple method for screening feeds for their potential to increase rumen acid load. It is difficult to undertake in vivo experimentation on this subject owing to the dangers of acidosis as well as the animals’ ability to avoid major changes in rumen conditions. Additionally, the large number of samples involved make it desirable to develop a simple in vitro technique.

A simple in vitro method was developed for estimation of the rumen acid load, based on the dissolution of calcium from calcium carbonate after a period of rumen fermentation. The method was based on the first stage of the method of Tilley and Terry (1963) with some modification to the buffer (which contained MgCl2 instead of MgSO4, 0.025% (w/v) Cystine monohydrochloride and was diluted to 20% in strength). At the end of each incubation, a 2 ml sample was taken, mixed with 0.05 g CaCO3 and centrifuged at 4000 rpm for 10 minutes. The supernatant was analysed for calcium using a Sigma kit (method No. 587) on a discrete analyser. The concentration of calcium (mg per 100 ml) in the supernatant has been termed the acidogenicity value (AV). A series of pilot experiments were conducted to investigate the effects of duration of incubation, buffer concentration, buffer pH and source of rumen liquor.

Falling prices for cereals and beneficial effects on milk protein concentrations may promote greater inclusions of rapidly fermented ingredients in dairy rations. There is, however, a limit to the inclusion of these feeds into dairy rations beyond which performance declines due to sub-acidosis and related disorders. The feed compounder will need to be able to set limits on levels of feeding concentrates according to these risks. The objective of this experiment was to evaluate the effect of feeds of different acidogenicity (Wadhwa et al., 1998) on lactation performance of dairy cows offered diets based on grass- or maize-silage.

Twelve multiparous Holstein-Friesian cows in the third month of lactation were used for this experiment. The experimental design involved adaptation and covariance recording on a standard diet (grass silage and 10 kg concentrates per day), followed by three 21-day experimental periods arranged as four 3x3 Latin Squares. The Latin Squares were constrained to a single forage to avoid difficulties in changeovers between grass silage and maize silage.

There is now considerable evidence of residual effects of both energy and protein supply during the dry period on performance in the next lactation. Changes in forage intake and eating/rumination behaviour in the dry period have been implicated in predisposition to metabolic disorders in the subsequent lactation. In particular, there is a close association between intake either side of calving (Grummer, 1995). The primary objective of this experiment was to identify the effects, and interactions, of pre-partum energy and protein supply on forage intake and particle size reduction (as an index of rumination behaviour) of cows in the dry period.

Fifty-two Holstein-Friesian cows, calving from September to November 1996, were used in a continuous design experiment The cows were dried off 8 weeks before their anticipated calving date and grazed on bare pasture for one week before training to use Calan gates (using grass silage only).

The dry period nutrition of the dairy cow can significantly affect subsequent milk production. It has been suggested that part of this effect can be attributed to the animal's use of labile body protein in support of early lactation nutrient requirements. If this is so, then there may be endocrine changes to signal nutrient partitioning. This experiment was designed to investigate the effect of offering diets differing in protein content during the dry period on changes in the endocrine profiles of animals over that period and during the first 21 weeks of lactation.

Forty-eight multiparous Holstein-Friesian cows were offered one of three different dry period diets for 6 weeks before predicted calving (16 animals per treatment): A) grass silage only, B) a grass silagetoarley straw mix (60:40 on a dry matter basis), or C) grass silage plus 0.5 kg/d high protein maize gluten meal. Diets A, B and C differed in the amounts of protein supplied: medium, low and high respectively. After calving, all animals were offered the same diet of ad libitum grass silage and concentrates at a stepped fixed rate.

Many sheep in the United Kingdom are grazed on pastures deficient in cobalt and selenium. Proprietary products for selenium and cobalt supplementation often contain copper, which in certain breeds can induce copper toxicity. A soluble glass bolus has been manufactured to supply long term sustained release of cobalt and selenium similar to the commercially available Cosecure, but with the copper content being replaced by zinc. Sub clinical zinc deficiency has been suggested to be involved in disease conditions such as broken mouth periodontitis, footrot and mastitis. Therefore a long term continuous supply of zinc may be beneficial in these situations. This trial was designed to examine the effect of administering a zinc, cobalt and selenium soluble glass bolus on trace element status of over-wintered ewe lambs.

Increasing sodium in herbage for grazing dairy cows can reduce the milk somatic cell count (Phillips et al., 1996), but the effects of providing salt supplements for cows fed conserved feeds indoors are less clear. Supplementary salt can also reduce oral stereotypic behaviour in individually-housed calves (Phillips and Youssef, 1994). Tethered dairy cows are also behaviourally restricted, demonstrate stereotyped behaviours and might similarly benefit from supplementary salt.

In experiment 1, 36 tethered Estonian Red cows were allocated for nine weeks to a randomised block experiment in which they received a daily restricted allowance of 7.5 kg DM grass silage, 6.6 kg DM grass hay and 2.2 kg DM barley/cow, with the addition of 0, 200 or 400 g NaCl. The salt supplements increased the Na content of the diet from 1 (control treatment) to 6 and 11 g/kg DM respectively. Milk yield was recorded every ten days and somatic cell count (SCC) by fluorescence microscopy. A blood sample was taken from the milk vein of each cow at the end of the experiment for mineral analysis.

Sub clinical zinc deficiency has been suggested to be involved in disease conditions such as broken mouth periodontitis, footrot and mastitis. However, although there is little risk of primary deficiency in the UK. there are large areas around the Mediterranean. Northern Africa and North America that are reported to be deficient in zinc. Therefore a method that could deleiver a long term continuous supply of zinc would be beneficial in these situations. This trial was designed to examine zinc availability from a zinc, cobalt and selenium soluble glass bolus administered to zinc deficient lambs fed on a low zinc diet throughout the trial.

Biotin is a water soluble vitamin, essential for post-absorptive metabolism in animals. A deficiency of the biotin has been associated with poor hoof horn formation in farm animals (Brooks et al., 1977). Biotin may be supplied from the diet or by microorganisms in the digestive tract. The objective of the present study was to evaluate the effect of dietary biotin supplementation on hoof growth and composition of hoof horn in goats (a) during pre-ruminant milk-feeding and (b) following the development of rumination and exposure to microorganisms in the digestive tract.

Pasture dusting with fine particle grade calcined magnesite (16kg Mg/ha) is an effective means for the prevention of hypomagnesaemia and clinical tetany in dairy cows, but almost double that rate was recommended for practical use as both leaf adherence and spreading distribution may be inefficient, (Todd and Morrison, 1964). Magnesium hydroxide powder has been demonstrated to have a significantly higher apparent magnesium availability and increased urine magnesium output for wether sheep than some granular calcined magnesites (Hemingway et al., 1997). Very fine particle size (0.95 ˂10μm) Mg hydroxide suspension (‘Neutramag 40’, Britmag Ltd, Hartlepool TS24 0BY) is available (405g dry matter (DM)/kg, 168g Mg/kg liquid suspension with S.G. of 1.3). The objective of the work was to examine the apparent availability and also the effectiveness of varying rates of application of this material in providing supplemental magnesium to grazing ruminants in spring.

Full rumination and feed dry matter (DM) intake require adequate recirculation of soluble phosphorus (P) and nitrogen (as urea) via saliva. Both decrease following periods of inadequate dietary intake, which may be prolonged for P with adults. Earlier studies, using 23 μm mesh nylon bags in cannulated cows, showed that rumen solubility coefficients of P in granular mono-calcium phosphate (MCP), powdered di-calcium phosphate (DCP) and granular defluorinated phosphate (DFP) were respectively 0.85, 0.14 and 0.03. This communication describes their relative ability to enhance plasma P and voluntary DM intake by ewes after lambing following development of aphosphorosis when given a low P diet (LP) throughout pregnancy (Parkins et al. 1998).

Beef cows given a diet severely inadequate in phosphorus (P) from 16 weeks before calving maintained appetite until 3-6 weeks after calving when plasma P concentrations were below 1.0 mmol/1 (Bass et al. 1981). The objective of this experiment was to compare the adequacy of ARC (1965) and AFRC (1991) dietary P inputs for ewes in relation to dry matter (DM) intake, plasma P concentration and early lamb growth.

Blackface ewes (˃ 3 lambings, n=87, mean liveweight (LW) 53.9, s.d. 5.1kg)) were mated to Border Leicester rams and then randomly allocated to three equal groups according to LW and expected lambing date.

Conception rate in ewes, mainly by reduction in early foetal mortality, have been improved by a range of individual supplementary trace elements (especially Se, but also Cu, Co, Mn and Zn) given prior to mating (Hidiroglou, 1979). Ritchie et al. (1997) has described significant improvements in liver copper concentration and blood glutathione peroxidase activity (GSHPx) in ewes given a single sustained-release multi-trace element and vitamin bolus which incorporates a grinder (‘Small-Trace’, Agrimin Ltd., Brigg DN20 0SP). This communication describes studies in the conception rate of ewes given this bolus at three grazing sites. Each flock was judged by the veterinary surgeon concerned to require routine trace element supplementation and which had previously been given by various combinations of injections, drenches, single element boluses and/or copper oxide needles.

Each bolus contained 5.3g Cu, 50mg Se, 90mg Co, lOOmg I, 4.7g Zn and 3.3g Mn with (iu) 268 x 103 vitamin A, 54 x 103 vitamin D and 800 vitamin E. About one-half of each nutrient is released in the first 6-8 weeks; thereafter the rate slows and the total life of the bolus is c. 7 months. (Ritchie et al. 1997).

In the last twenty years, some probiotics, such as Aspergillus oryzae or A. niger (Pioneer, 1989), yeast culture (Saccharomyces cerevisiae) (Wallace, 1994) and some microbial growth promoters (e.g. thiamine, niacin) (Shield, 1981), were used as feed additives in order to improve rumen conditions and cellulose digestion in the rumen and milk yield of dairy cows. The present study was planned to determine whether dietary supplemental baker's yeast and niacin would have individual and/or synergistic effects on milk yield and milk composition of dairy cows under our experimental conditions.

Previous work has suggested that assessing the trace element status of South American camelids (llamas) using cattle or sheep plasma values as reference norms could lead to incorrect diagnoses of sufficiency /deficiency (Illingworth et al.,1997). However there are no previous accounts of a direct comparison of the trace mineral status between a species of camelid and a conventional ruminant. This study directly compares the blood copper and cobalt status of guanacos and sheep grazing the same typical upland Agrostis / Festuca spp. dominated pasture.

Blood samples were obtained in May 1996 from the tail vessels of 10 mature, captive bred guanaco castrates and 9 mature barren ewes (Merino x Welsh Mountain) which had grazed the same upland pasture for 6 weeks with ad libitum access to trace mineral blocks (Wright Block - Standard) which both species were observed to consume.

A recent extensive review of the ‘bioavailability’ of magnesium (Mg) (Henry and Benz 1995) noted that the fractional efficiency of apparent absorption of Mg (AAMg) in ruminants could vary from -0.04 to +0.66. Little attempt was made to identify sources of variation, other than those between inorganic Mg supplements. Earlier, ARC (1980) had failed to find consistent differences between fresh herbage (FH) and dry diets but a reexamination of the literature suggested that AAMg was twice as high for mixtures of roughage and concentrate (R/C) as for FH and confirmed the marked inhibitory effect of dietary potassium (K) (Suttle, 1987). Since grass is usually richer in K than a dry diet, differences between diet types in AAMg may be largely attributable to differences in K concentration. The objective of the study was to identify systematic sources of variation in the absorbability of dietary magnesium (Mg) to sheep from published balance studies.

In ruminant diets, whole oilseeds are potential sources of polyunsaturated fatty acids (PUFA), which, because they are protected by the intact seed pericarp, may escape rumen biohydrogenation (Murphy et. al., 1990). Some seed coats are highly resistant to microbial and enzymic digestion and seed lipids may therefore be poorly degraded. Mild chemical treatment of oilseeds with sodium hydroxide has been suggested as a way to allow only limited ruminal lipid digestion but more extensive intestinal digestion of seed lipids (Aldrich et. al., 1997). Such treatments may allow the manipulation of milk composition by strategic use of selected oilseeds. Linseed is rich in C18:3n-3, an essential component of a healthy human diet which is normally only present at low levels in cows milk. This study evaluated the effect of inclusion of caustic-treated linseed in dairy cow rations on the protein, fat and fatty acid composition of milk