N.P. McMeniman

Assessment of the effects of supplementation with vitamin E on health and production of feedlot cattle using meta-analysis

Delivery of supplemental antioxidant vitamins to cattle placed in feedlots might be expected to improve health and performance outcomes by reducing the effects of oxidative stress to which these cattle are presumably exposed. Meta-analytic procedures were used in this study to assess published experiments on the effects of vitamin E supplementation in feedlot cattle. The health outcome of morbidity, and the production outcomes of average daily gain (ADG) and gain to feed ratio (G:F), were analysed. The currently available data do not support the use of supplemental vitamin E administered as an injection (morbidity risk ratio=1.17; P=0.17). The authors conclude that supplemental dietary vitamin E should be fed within the [NRC, 1996. National Research Council. Nutrient Requirements of Beef Cattle, 7th ed. Natl. Acad. Press, Washington, DC] recommended range.

Influence of body condition on ovulatory response to lupin (Lupinus angustifolius) supplementation of sheep

Fifteen mature Merino ewes were fattened with a maize grain/alfalfa chaff diet while an equal-sized group of similar ewes were maintained in store (score 2) condition (mean BW difference 11 kg). All sheep were then fed a maintenance diet of oat chaff. Following synchronization of all sheep with intravaginal sponges containing 40 mg progestagen, half of each group were fed a lupin (Lupinus angustifolius) grain supplement of 750 g/head/d from d 8 onwards of progestagen treatment. Ovulation rate following removal of the sponges was 64% higher (P 0.05) by the condition score of the ewes. Plasma glucose, plasma urea nitrogen and some plasma amino acids were higher (P<0.05) in the lupin-supplemented group. These results indicate that nutritional flushing may increase ovulation rate of ewes regardless of their body condition.

Voluntary feed intake and digestibility by red deer (Cervus elaphus) and sheep (Ovis ovis) of pangola grass (Digitaria decumbens) with or without a supplement of leucaena (Leucaena leucocephala)

Four yearling male red deer (Cervus elaphus) and four yearling male sheep were fed tropical grass (Digitaria decumbens) hay supplemented with or without 30% dried leucaena (Leucaena leucocephala) leaves. Voluntary feed intake (VFI), digestibility of dietary components, haematological parameters and serum thyroxine concentrations were determined. Leucaena supplementation reduced VFI of pangola grass by 8% but increased total DMI of both species by 30%. Digestibility of DM, OM and N was higher for both species when leucaena was fed but sheep digested these dietary components more efficiently than deer. Leucaena supplementation did not influence blood cell numbers or haemoglobin and thyroxine concentrations in either species. Deer had higher concentrations of red blood cells and lower concentrations of white blood cells than sheep. It was concluded that leucaena at 30% could be a suitable supplement for deer and sheep consuming sub-tropical pastures.

Effects of injectable vitamins A, D, E and C on the health and growth rate of feedlot cattle destined for the Australian domestic market

OBJECTIVE To examine the effects of injectable vitamins A, D and E at feedlot entry on health and growth rate and the effects of injectable vitamin C at the time of treatment for bovine respiratory disease (BRD) on cattle health. DESIGN Systematic allocation of 2465 cattle at feedlot entry to: a commercial vitamin A, D and E preparation at the label dose rate; commercial vitamin A, D and E at twice the label dose rate; a formulation with no vitamin D, a lower concentration of vitamin A and a higher concentration of vitamin E; and the oil-based carrier alone at volumes corresponding to the above treatments. Comparisons of growth rate, disease and mortality were made between the groups at the conclusion of the feeding period. In a separate experiment, 176 cattle were alternately administered injectable vitamin C at the time of treatment for BRD, or were not injected with vitamin C, and mortality was compared between the groups. RESULTS There were no differences between cattle administered vitamin A, D and E at feedlot entry and the controls in growth rate (P=0.11), all diseases (P=0.99), BRD (P=0.60) or mortalities (P=0.95). Cattle treated with the higher vitamin E and lower vitamin A preparation had a higher (P=0.02) incidence of anorexia than the other groups. Fewer cattle treated with 5 g of vitamin C by intramuscular injection at the time of treatment with antibiotics for BRD subsequently died (P=0.04). CONCLUSIONS The routine injection of cattle with vitamins A, D and E at feedlot entry is unlikely to result in improvements in health and growth rate where cattle are provided with these vitamins in their diets at concentrations equal to the National Research Council recommendations. Mortality rate in cattle diagnosed with BRD may be reduced by intramuscular injection of vitamin C at the time of treatment with antibiotics.

Effect of copra expeller pellet supplementation on the flow of nutrients from the rumen of sheep fed low quality pangola grass (Digitaria decumbens)

The effects of copra expeller pellet (CEP) supplementation on nutrient flow, the efficiency of microbial protein synthesis and degradability of CEP-nitrogen (N) in the rumen of sheep fed chopped pangola hay, were determined. Six sheep fitted with rumen and abomasal cannulae were given three diets; A (pangola hay ad libitum), B (A + CEP at 0.5% BW) and C (A + CEP at 1.0% BW) in a replicated 3 × 3 Latin square experiment. CEP supplementation did not affect intake of pangola hay when given at 0.5% BW, but was reduced (P × 0.05) when CEP supplementation was increased to 1.0% BW. Apparent DMD of the total diet was increased (P < 0.05) with CEP supplementation. Intake and digestibility of OM, DOM intake (DOMI), OM apparently digested in the rumen (ADOMR), OM truly digested in the rumen (TDOMR) and OM flow to the small intestines of sheep were not significantly affected by CEP supplementation. However, CEP supplementation increased (P < 0.01) total N intake, digestibility and flows of total non-ammonia N (NAN), microbial NAN and feed NAN to the small intestines of sheep. Degradabilities of CEP-N in the rumen of sheep fed CEP at 0.5% BW and 1.0% BW were 22% and 19%, respectively. Efficiency of microbial protein synthesis (g microbial NAN/kg ADOMR and TDOMR) in the rumen of sheep was increased (P < 0.01) with each increase in level of CEP supplementation. Mean values were 20.3, 29.9 and 37.1 g/kg ADOMR, 15.7, 21.3 and 26.0 g/kg TDOMR for diets A, B and C, respectively. It was concluded that CEP could be a suitable supplement for ruminants consuming tropical pastures.

Effect of supplementation with a by-product of molasses fermentation or a non-protein nitrogen/mineral mix on feed intake and microbial protein supply in sheep consuming chopped oat (Avena sativa) hay

Crossbred ewes, weighing 30-40 kg, were assigned to three groups of six animals. One group of sheep was fed chopped oat hay (control), the second group was fed the control diet plus 30 g per head per day spray dried residue from the fermentation of molasses and the third group was fed the control diet plus 30 g per head per day of a non-protein nitrogen/mineral mix. Voluntary feed intake, digestibility of DM, OM and nitrogen, nitrogen balance and microbial nitrogen flow to the intestines were significantly increased by supplementation but efficiency of microbial protein production was not affected