Live Weight Gain Of Sheep Research Articles

High sugar ryegrasses for livestock systems in New Zealand

There has been mounting interest over the proposed production and environmental benefits from using perennial ryegrass cultivars bred to have higher water soluble carbohydrate content (high sugar grasses). Here, we objectively review published evidence, from the EU and New Zealand, of the effects of these on milk yield per cow, liveweight gain in sheep, N utilisation and wider trophic interactions. The literature reveals substantial variation in animal responses, though some of the uncertainty in interpretation can be resolved by combining the data from multiple trials, and showing this forms a continuum of response to diet quality. It also reveals variation in the degree to which the sugar trait has been expressed, possibly reflecting a gene x environment interaction. Achieving a more consistent, and probably greater than current, expression of the high sugar trait would be a valuable goal. We suggest 'proof of concept' has been shown, notably for the potential for improving N utilisation in the rumen, and so reducing the proportion of N intake lost in urine. The evidence suggests that this may be a greater challenge, albeit a more valuable goal, because of the relatively high N (crude protein) content forages that predominate in the New Zealand pasture industry. Keywords: animal performance, high sugar grass, Lolium perenne, perennial ryegrass, nitrogen utilisation, trait expression, water soluble carbohydrates

Sheep gain and species diversity: in sandy grassland, Inner Mongolia

A grazing experiment was conducted from 1992 to 1996 at a sandy grassland in the Horqin sandy land, located in the northeastern part of China. The grassland had been grazed by sheep for many years before the experiment at an intensity of 4.5 sheep ha−1. The experiment consisted of 4 grazing treatments: no grazing (0 sheep ha−1), light grazing (2 sheep ha−1), moderate grazing (4 sheep ha−1) and overgrazing (6 sheep ha−1). Plant species diversity, plant biomass, soil properties, and sheep liveweight under various grazing treatments were examined. Overgrazing resulted in considerable decreases in both species diversity and plant biomass. As a result, sheep liveweight gain decreased significantly in the last 3 years of the experiment in the overgrazing treatment. No grazing and light grazing treatments had higher species diversity as well as higher biomass production than moderate grazing and overgrazing treatments. The results indicate that light sheep grazing is sufficient for the recovery of overgrazed grassland in this region and for the maintenance of plant species diversity. The proper grazing intensity should be 2–3 sheep or sheep equivalents per hectare for the sandy grassland in Inner Mongolia.

Sheep gain and species diversity: in sandy grassland, Inner Mongolia

A grazing experiment was conducted from 1992 to 1996 at a sandy grassland in the Horqin sandy land, located in the northeastern part of China. The grassland had been grazed by sheep for many years before the experiment at an intensity of 4.5 sheep ha-1. The experiment consisted of 4 grazing treatments: no grazing (0 sheep ha-1), light grazing (2 sheep ha-1), moderate grazing (4 sheep ha-1) and overgrazing (6 sheep ha-1). Plant species diversity, plant biomass, soil properties, and sheep liveweight under various grazing treatments were examined. Overgrazing resulted in considerable decreases in both species diversity and plant biomass. As a result, sheep liveweight gain decreased significantly in the last 3 years of the experiment in the overgrazing treatment. No grazing and light grazing treatments had higher species diversity as well as higher biomass production than moderate grazing and overgrazing treatments. The results indicate that light sheep grazing is sufficient for the recovery of overgrazed grassland in this region and for the maintenance of plant species diversity. The proper grazing intensity should be 2-3 sheep or sheep equivalents per hectare for the sandy grassland in Inner Mongolia.

Caucasian clover/ryegrass produced more legume than white clover/ryegrass pastures in a grazed comparison

The potential of caucasian clover to improve the legume content of lowland New Zealand pastures should result in enhanced animal performance. Liveweight gains from eight flocks of ewe lambs rotationally grazing irrigated ryegrass pasture with caucasian or white clover at two levels of soil fertility (Olsen P values 10 or 22) were compared during years 2 (1998/1999) and 3 (1999/2000) of an ongoing grazing experiment in a lowland environment. Clovers were sown in December 1996 and ryegrass in March 1997 into the pure clover swards. Lamb liveweight gains were similar in year 2 (1130 kg/ha/yr), but in year 3, gains were greater on pastures sown with caucasian than on those sown with white clover (1290 vs. 1110 kg/ ha/yr). Spring liveweight gains per head per day averaged 170 g/hd/d in year 2, and in year 3 were greater from caucasian than white clover pasture (180 vs. 160 g/hd/d). Caucasian clover pastures had more legume on offer than pastures sown with white clover in year 2 (26% vs. 17%) and year 3 (19% vs. 12%). In year 3, 39% of the total legume on offer in caucasian clover pastures was volunteer white clover. Soil fertility had little influence on results. Early years of this grazing experiment showed that caucasian clover can establish as well as white clover if sown alone, and that sowing caucasian clover can result in lowland pastures with an increased total legume content which may improve liveweight gains. Keywords: legume content, Lolium perenne, pasture production, sheep liveweight gain, Trifolium ambiguum, T. repens

The effect of supplementation with ficus leaves on the utilization of cassava peels by sheep

The objectives of this experiment were to determine the effects of dried Ficus exasperata leaves supplementation on voluntary feed intake, digestibility of nutrients and liveweight gain of sheep given ad libitum access to dried cassava peels. A total of 48 Djallonké wethers and ewe lambs (avg. wt 13.5 kg ± 1.2 kg), housed individually and given ad libitum access to dried cassava peels were randomly allocated to one of six dietary treatments comprising 0, 50, 100, 150, 200 and 250 g d −1 of dried F. exasperata leaves. Supplementation increased ( P < 0.05) daily dry matter (DM) intake from 44.0 g kg −1 LW 0.75 for animals that received no supplement to 81.2 g kg −1 LW 0.75 for animals that received 250 g d −1 of supplement. Digestibility coefficients of DM, organic matter and acid detergent fibre in the diets were depressed ( P < 0.05) as a result of supplementation. However, intake of the basal diet increased ( P < 0.05) from 44.0 g kg −1 LW 0.75 d −1 for control animals, to 55.1 g kg −1 LW 0.75 d −1 for animals that received 200 g d −1 of supplement. Animals which received 250 g d −1 of leaves had the fastest growth rates (53.6 g d −1) followed by those that received 200 and 150 g d −1 ( P < 0.05). Although the supplement was less digestible than the basal feed, it promoted a higher DM intake and growth rate, presumably due to the supply of nitrogen and other nutrients.

Vitamin E treatment of weaner sheep. II. The effect of vitamin E responsive subclinical myopathy on liveweight and wool production

Nutritional myopathy occurs as both a clinical and subclinical disease in weaner sheep in Western Australia during summer and autumn. The effect of subclinical nutritional myopathy (SCNM), caused by vitamin E deficiency or combined vitamin E and selenium deficiency, on liveweight and wool was investigated. During the period of SCNM there was no significant difference in liveweight gain in sheep with and without the disease in any of the experiments. Initial liveweight in one experiment was significantly (P &lt; 0.05) higher in sheep that were to develop SCNM during the course of the experiment. In vitamin E deficient-selenium adequate SCNM, there was no difference in wool growth over the period of the disease and no differences in any of the wool measurements at shearing. At 2 sites, the greasy and clean fleece weights were significantly (P &lt; 0.05) greater in a group of sheep diagnosed with more severe SCNM compared with sheep without SCNM. It was concluded that unlike the clinical disease, SCNM was unlikely to cause any economic loss.

Relative sheep liveweight gain on perennial lupin, red clover and alsike

Young Merino wethers set stocked from November to April, over 5 years, on developed high country legume pastures, at Lake Tekapo at 50 kglhafyr superphosphate, showed daily liveweight gain on perennial lupin and alsike clover that were 53% and 70%; respectively, of that on Pawera red clover (110 g/day). Keywords: high country, Lupinus polyphyllus, Trifolium hybridum, T. pratense, sheep weight gains

The comparative performance of Holcus lanatus and Lolium perenne under sheep grazing in the Scottish uplands

AbstractAn experiment was conducted over 3 years (1983‐85) to assess the performance of Holcus lanatus German Commercial and cv. Massey Basyn compared with Lolium perenne cv. Perma on a gley soil under sheep grazing in the Scottish uplands. All grasses were sown together with Trifolium repens cv. Grasslands Huia. The swards were rotationally grazed at similar herbage allowances. During the first harvest year, the swards were grazed hard to a low mass (500 kg DM ha−1). In the second harvest year, post‐grazing herbage masses of 500 and 1000 kg DM ha−1 were compared.Perma ryegrass had a higher level of herbage production than both H. lanatus cultivars in the first and second harvest years after sowing and hence had a greater number of sheep grazing days. The ryegrass sward consisted of 25% more green sown grass (85 cf. 60%) but 12% less white clover (4 cf. 16%) compared with both H. lanatus cultivars in the establishment and first harvest years. The persistence of all three grasses was poor although ryegrass had a higher presence (36%) than either Massey Basyn (22%) or German Commercial (13%) at the end of the. second harvest year.At a similar herbage allowance, there were no significant differences in the herbage intake and liveweight gain of sheep. Ryegrass had a higher organic matter digestibility and lower neutral and acid detergent fibre and lignin contents than either of the H. lanatus cultivars.In the second harvest year, although herbage production was greater at the higher herbage mass, there was no difference in the proportion of sown grass.It was concluded that ryegrass is a superior grass to H. lanatus on upland soils with high N status, moderate P status and a high pH.

Conditions under which flavomycin increases wool growth and liveweight gain in sheep

Flavomycin, a glycolipid feed additive, was evaluated for its potential to improve wool growth and liveweight gain in sheep of two ages and from two different sources. Sheep came from two locations in the Mediterranean climatic region of Western Australia's agricultural area-Mount Barker, with a relatively high rainfall and Wongan Hills with a relatively low rainfall and shorter pasture growing period. Forty weaner sheep, from each source, initially eight months of age and with a mean liveweight of 29 kg (s.e. � 0.3) were studied. There were also 40 adult sheep, from each source, initially 20 months of age with mean liveweights (Wongan Hills) 42 kg (s.e. �0.5) and (Mount Barker) 51 kg (s.e. � 0.7). All animals were housed individually in the one shed and fed a pelleted ration at a level equivalent to 3.1% (weaner) and 3.5% (adult) of each animal's liveweight. The pelleted ration was based on wheat and lucerne chaff, lupin grain and fishmeal. Flavomycin was included at 20 mg/kg pellets and there were 16 sheep of each age and source fed this medicated diet. Twenty-four sheep were fed the unmedicated diet. Wool growth was increased by flavomycin by 14.5% (P &lt; 0.05) but only in adult sheep from Mount Barker. Inclusion of flavomycin in the diet increased liveweight gain in sheep of both ages and from both sources. There was no significant effect of flavomycin on fibre diameter of wool in sheep from the different age groups and sources.

Effect of dry or hydrated bentonite on the wool growth and liveweight gain of sheep fed wheat chaff

Many reports on the use of bentonite to increase wool growth indicate variable responses and it is often claimed that this variability is related to the chemical characteristics or the form in which the bentonite is fed. This paper describes 3 experiments in which there was consistency in the type and form of the clay. There was also comparison of the effects of dry and hydrated bentonite. In the first experiment, 64 sheep were individually penned and fed wheat chaff ad libitum. Thirty sheep were fed chaff only, 17 sheep received dry bentonite added to their chaff (20 g/kg chaff) and another 17 sheep had 23.7 g/day of bentonite added to their drinking water. Inclusion of bentonite in the drinking water significantly increased wool growth (P&lt;0.05, 14.8%) and increased chaff intake (P = 0.08, 6%). In the second experiment, 105 sheep were penned in groups of 7 and each pen fed wheat chaff ad libitum. Five pens of sheep had dry bentonite added to their chaff (20 g/kg chaff) while another 5 pens had bentonite added to their drinking water (23.7 g/sheep.day). There were 5 pens of sheep which received no bentonite. Inclusion of bentonite either in the drinking water or in the chaff, significantly increased chaff intake (P&lt;0.05, 6%), but had no effect on wool growth. In the third experiment, 60 sheep were divided into 12 groups and each group grazed individual 0.7 ha of cereal stubble. All groups were supplemented with the equivalent of 200 g of lupin grain/sheep.day fed twice weekly and 6 of the groups were watered by buckets containing hydrated bentonite (11.8 g bentonite/L). In experiments 2 and 3, inclusion of bentonite in the diet or in the drinking water had no effect on wool growth (P&gt;0.05) but liveweight gain was significantly increased (P&lt;0.05). It was concluded that the variability in the response to bentonite was not related to its chemical composition or the form in which it is administered and that, on balance, bentonite does not offer a practical or reliable means of increasing wool growth in sheep.

Grazing management studies with Australian cashmere goats. 2. Effect of stocking rate on the liveweight gain of sheep and goats grazing an oats-rye grass pasture

Australian cashmere goats and Border Leicester x Merino sheep grazing an oats-rye grass pasture were used to study the effects of stocking rate (20, 40, 60 animals/ha) on growth, intestinal parasite burdens and haematology of the 2 species and on the persistence and productivity of the crop grazed. Goats and sheep were either grazed alone or together over a 12-week period to determine the interaction between the species. Liveweight gain decreased with both stocking rate and time on experiment. At the highest stocking rate all animals lost weight between weeks 9 and 12. During the first 9 weeks of grazing, sheep had significantly (P&lt;0.05) higher liveweight gains than goats at all stocking rates; but the rate of decline in liveweight gain with increased stocking rate was similar in both species, whether they were grazed alone or together. Mean values for sheep were 161, 133 and 105 g/day, and for goats 101, 84 and 59 g/day at stocking rates of 20, 40 and 60 animals/ha. Under the same drenching regime, goats were more severely infested by intestinal parasites than sheep as indicated by significantly (P&lt;0.05) higher concentrations of parasite eggs in faeces and lower packed cell volumes and haemoglobin concentrations in blood. Oats was the major contributor to green feed available at all stocking rates, although rye grass yields increased in the later stages of the trial, particularly in high stocking rate paddocks. At the end of the trial, high yields of oat stem remained in the paddocks grazed by goats and goats plus sheep, suggesting that sheep grazed both leaf and stem but goats selectively grazed oat leaf. The availability of green leaf (oat + rye grass) per animal was closely related to liveweight gain in any period, although these relationships were different for sheep and goats.

Development of a simulation model of sulfur cycling in grazed pastures

A simulation model of S, P and N cycling in pastures was constructed as a conceptual and predictive tool to examine a range of possible fertilizer managements for improved pastures on the Northern Tablelands of N.S.W. The model successfully simulated pasture yield and clover content for a four-year superphosphate trial. It was used to calculate C and S fluxes between various pools for pastures with and without fertilizer S. Under a non-limiting P regime, which was S deficient, the model predicted a 3.6-fold increase in tops growth due to S fertilizaton, a 13-fold increase in sheep liveweight gain, and a 5-fold increase in wool production. These effects were due to a greater proportion of assimilate contributing to tops growth, and a much higher proportion of clover in the diet.

Tick control in small ruminants with a Cypermethrin ‘pour‐on’ in Kenya

Abstract Eleven young indigenous sheep and 11 goats in an extensive rangeland were kept virtually tick free for six months with a long acting synthetic pyrethroid ‘pour‐on’ formulation. Their performance in terms of liveweight gain (LWG) was compared with an untreated group. All animals in the trial were intensively dewormed. The total LWG in sheep was 0–7 kg and in goats 0·8 kg greater than the control groups (P = 1·0), despite the significantly different tick numbers they were carrying. Tick control did not increase productivity. The ‘pour‐on’ ectoparasiticide was a more economical and effective method than dipping. However, the results do not suggest any economic need for tick control on indigenous small ruminants in this environment.

The effects of artificially-induced fly-strike on food intake and liveweight gain in sheep

A single, artificially-induced fly-strike with Lucilia sericata larvae was associated with a rapid (decline in food intake in sheep, with a consequent reduction in liveweight. Loss of weight ranged from 0.5 to 5.5 kg over four to six days and recovery to pre-infestation liveweight took three to 36 days. Pair-fed, uninfested partners of these sheep also showed a reduction in liveweight, whereas uninfested sheep in some experiments fed ad libitum showed either little change or a gain in liveweight over the same period. In general, maggot infested sheep took less time to regain weight than did their pair-fed partners although the weight lost as a proportion of initial weight was similar in both groups. Loss of appetite alone would appear to account for these events.

A computer simulation model of ovine fascioliasis

A computer simulation model of ovine fascioliasis was developed. The simulated flock, comprising a maximum of 60 non-reproductive sheep, grazed on a perennial pasture with a suitable habitat for the intermediate host snail Lymnaea tomentosa at the low end of a ‘gradient’ across the simulated 2-ha area. The driving force for both herbage production and the life cycle of Fasciola hepatica is meteorological information—comprising maximum and minimum daily temperatures and moisture (rainfall and any water supplied by irrigation). The model simulates intake of both herbage and metacercariae, with sheep seeking green herbage, if available, in preference to dry material. This automatically produces seasonal variation in the grazing pattern and hence in access to metacercariae. The production of wool and liveweight gain in sheep are simulated and include the interaction with fluke burden. Flock replacement is also dealt with and is made to closely replicate commercial management practices. The life cycle of F. hepatica is simulated in detail and the role of the intermediate host is dealt with by permitting the snail production to be in one of three states of physical activity, only one of which is suitable for completion of the development and release of cercariae. From information arising from the simulation, an economic comparison of the control strategies under test was made and the results printed. The completed model was validated against the results of a field study conducted by the authors at Prairie, Victoria, Australia (Meek & Morris, 1979) using meteorological data which had been measured at the field site as the model's driving force and then comparing the predictions of the model with the actual field measurements. The model was also validated against the results of a field investigation conducted in New South Wales, Australia, by Boray et al. (1969). The degree to which the model conformed with expectations and with the actual field data was assessed. In two respects the agreement between model predictions and field data was inadequate. First, the model overestimated the weight gain of the simular sheep on irrigated pasture under conditions of severe drought; secondly, simular snails were unexpectedly sensitive to changes in soil moisture. These aspects require further examination. Sensitivity analyses were also performed on the model. It was determined that simular financial return was sensitive to both stocking rate and the proportion of the simular area defined as snail habitat. Therefore both these factors warrant consideration in the choice of control strategies. Various control measures were simulated, by means of the validated model, either singly or in combination, and were assessed by means of the expected annual margin over variable husbandry costs obtained over the course of a five-year simulation period, from a standard flock of 100 sheep. With respect to the phophylactic use of anthelmintics, the model provided a method of ranking various alternatives at each of a number of combinations of stocking rate and snail habitat size. Under almost all simular circumstances tested, five to six strategically timed treatments produced the greatest economic benefit from controlling the disease. The model predicted that it was possible to eradicate ovine fascioliasis from a closed system if the recommended treatment strategy were rigidly followed over a number of years. Simular results also suggest that molluscicides may be integrated to economic advantage with anthelmintics in instances where the grazier opts for an anthelmintic treatment strategy with fever than the recommended optimal number of treatments per annum. It is also suggested that integration of rotational grazing with the use of anthelmintics warrants further investigation to ascertain if its apparent benefits can be realised in practice. It was concluded that the computer simulation model provides a formal framework within which alternative control strategies can be assessed and that it provides a basis for informed decision-making about potential control methods. Its predictions can now be tested under practical conditions.

NEW ZEALAND PERENNIAL, RYEGRASS CULTIVARS IN MID-CANTERBURY

The perennial ryegrass cultivars 'Grasslands Ruanui', 'Grasslands Ariki' and 'Grasslands Nui' were sown with clover and compared at three levels of irrigation under rotational grazing with sheep. Ryegrass cultivar had little effect on total annual pasture production, although Nui pastures produced more total DM in autumn and winter. Nui was the most persistent cultivar and produced substantially more ryegrass than the orhers (6.1 t/ha, compared with 4.1 t/ha for Ruanui and 3.3 t/ha for Ariki) . Nui pastures produced less white clover, volunteer grasses and weeds. When grazed at the same stocking rate, sheep liveweight gain was similar regardless of ryegrass cultivar.

Optimum rate of application of formic acid during ensiling of unwilted lucerne

Abstract In two experiments lucerne was ensiled with the addition of 85% formic acid at rates ranging from 0 to 8 l/t. In tests made 8 months later, nitrogen, pH, and butyric acid values were similar in all formic acid-treated silages and lower than those in untreated ones. With increasing amounts of formic acid, ammonia levels decreased but water-soluble carbohydrate and water-insoluble nitrogen increased. In a quadratic relationship between lactic acid content and level of added formic acid the lactic acid maximum corresponded to a formic acid level of 4 l/t. Organic matter digestibility, voluntary intake, and live-weight gain of sheep increased with increasing formic acid. Over the practical range of lamb carcass values and formic acid costs the optimum level of formic acid was shown to be 5–6 l/t.

Sulphur as a nutrient for Merino sheep. 2. The utilization of sulphur in forage diets.

1. Estimates of sulphur retention by Merino sheep during growth, pregnancy and wool production, and of S excretion during lactation were obtained to derive estimates of the S requirements of Merino sheep.2. The S content of fifty Merino sheep was related by weighted regression analysis to age, live weight and (age × live weight). The quantity of S stored was calculated for varying rates of live-weight gain in sheep differing in age and live weight.3. The S contents of twenty-five samples of foetus, foetal membranes and uteruses were determined. Relationships between S content and days from mating were calculated, and differentiated to give daily net changes in S content during pregnancy.4. Milk production of twenty-seven Merino ewes was estimated on eight to ten occasions at approximately weekly intervals to the 84th day of lactation. The average S content was 472 mg/l; it increased on average by 1·0 mg/l per d of lactation. The mean S content of ninety-seven samples of wool averaged 34 g S/kg clean dry wool.5. It was concluded that wool represented the major demand for S by the Merino since approximately 70 g S were secreted in producing 2 kg clean wool, 50 g S in a lactation yielding 100 l milk and 8 g S in giving birth to a single lamb.

Comparison of the Effects of Crownvetch (Coronilla varia L.) and Alfalfa Hays on the Liveweight Gain of Sheep1

AbstractEarly cut crownvetch (Coronilla varia L.) and alfalfa hays of similar chemical composition were compared in a 70‐day feeding experiment, using 6‐month‐old crossbred wethers. The two forages in either pelleted or ground form were fed ad libitum as the sole diet. Liveweight gain was greater on alfalfa than on crownvetch and greater on pelleted forage than ground forage. Forage consumption was generally high. Consumption of pelleted forage was considerably greater than that of ground forage. Digestibility of crownvetch was generally less than that of alfalfa. Overall, the lesser liveweight gains on crownvetch were attributable to its lesser digestibility and, in the case of ground forage, to its lesser consumption as well. The differences in digestibility of the structural components of the two forages did not appear to be related to the degree of lignification of lignocellulose.