The hypersensitivity of horses to culicoides bites in british columbia

Culicoides hypersensitivity is a chronic, recurrent, seasonal dermatitis of horses that has a worldwide distribution, but has only recently been reported in Canada. It is characterized by intense pruritus resulting in lesions associated with self-induced trauma.     

Electronic monitoring of mounting behavior in beef cattle on pasture

An automated heatmount detection system was employed to detect estrus for artificial insemination in 57 beef cows. First service conception rate was 84.2% and the pregnancy rate was 89.5% for a 42-day breeding season. Duration of estrus was 9.6 h, sx = 0.5 h and mounting activity was lowest during the dark part of the day.     

不同精料补饲水平对放牧肉牛生长性能的影响

试验选用健康的三江平原放牧肉牛50头,体重在320 kg左右,随机分成5组,每组10个重复,每个重复1头牛。肉牛放牧采食的同时,试验各组按牛重的0.6%、0.8%、1.0%、1.2%和1.4%每头每天分别饲喂1.9(A组)、2.5(B组)、3.3(C组)、3.8 kg(D组)和4.5 kg(E组)的精料补充料,预试期10 d,试验期60 d。旨在研究冬季放牧条件下,不同精料补饲量对放牧肉牛生长性能的影响。结果表明:(1)随着精料补饲量的增加,肉牛的平均日增重逐渐增加,B组显著高于A组(P<0.05),C、D、E组极显著高于A组和B组(P<0.01);(2)饲料转化率以C组最高,为35.63%,显著高于其他各组(P<0.05),并呈现先增加后降低的规律;(3)经济效益C组最高,C组60 d育肥收入较A组极显著提高176.42%,较B组显著提高80.12%,与C组和D、E组相比略有增加,但差异均不显著(P>0.05)。结果说明,按牛体重的1.0%补饲精料效果最好。     

Interactions between beef cattle and simulated tuberculous possums on pasture

Brushtail possums (Trichosurus vulpecula) were sedated with ketamine and placed within a fenced observation area with 17 Hereford cross steers. The behaviour of the sedated possums simulated that of terminally ill possums. Behavioural analysis was carried out during eight observation periods in which sedated possums were successfully released and interactions occurred. Cattle were attracted from over 50 m away by the movements of the possums, and for 34% of observation time cattle investigated the possums. Inactive animals engendered far less interest, and cattle investigated them for 3% of observation time. An average of seven to eight cattle came in physical contact with the possum in each of the observation periods. Cattle actively investigated the possum while following it as it moved, commonly close enough to be within aerosol transmission distance, and some sniffed the possum, touched it with their noses, and in many cases licked it extensively. All of these activities would expose the cattle to high risk of receiving an infective dose of Mycobacterium bovis, especially via the respiratory route. The type and duration of contact between individual steers and the possum varied between animals and observation period. The cattle exposed themselves to greater risk, overall, during the first week of observations, and there was evidence of habituation with increased contact. Although all 17 steers came within 5 metres of the possum at some point during the observation periods, some individual cattle behaved in ways which would put them at greater risk of contracting tuberculosis than did others. Cattle showed little interest in possum carcasses placed on pasture. These were unlikely to be a significant source of infection for cattle, although they could be for scavenger species.     

The effect of turn-out to pasture on blood plasma iron concentrations in beef cattle

Beef cows, bred to calve in the spring, were housed indoors over the winter. On May 25, 48 of the cows, and their calves, were put out to pasture while the other 24 cows and calves remained confined.Plasma iron concentrations in the pasture cows were higher (P<0.01) than the levels of the barn cows for several weeks after turn-out, but in September there was no difference (P>0.05). In contrast, the pasture calves showed significantly lower (P<0.01) levels than did the barn calves during the first two weeks, however, there was no difference (P>0.05) in September. No difference in plasma iron levels between male and female calves was found.     

人工草地纯种短角肉牛放牧系统优化研究

以云南省种羊场纯种短角肉牛群人工草地放牧饲养为对象,以年出栏100头种牛为目标,进行饲草预算和草畜动态平衡,充分利用人工草地的牧草生长量和营养物质,母牛怀孕后期适当补饲混合精料,全年牛群饲养量达375头,全年共需饲草料642．67t(DM),其中人工草地提供764t(DM),饲料地提供339t(DM)。经过优化牛群结构和饲草需求动态平衡,该系统尚有一定发展潜力。     

Efficiency of nitrogen metabolism in beef cattle grazing pasture and supplemented with different protein levels in the rainy season

Supplementation of animals in the rainy season is essential to maximise weight gain. Thus, the objective was to evaluate the effects of supplementation with low-, medium- and high-protein levels on nutritional parameters of grazing beef cattle in the rainy season. Eight rumen-cannulated Nellore bulls (437 kg body weight) were used in a 4?×?4 double Latin square design with four supplements and four experimental periods. The treatments were mineral supplement (ad libitum) and supplements with low-protein (LPSU), medium-protein (MPS) and high-protein (HPS) levels, providing 106, 408 and 601 g/day of crude protein (CP), respectively. There was no difference (P?>?0.05) between treatments for dry matter and forage intake, ruminal pH, ruminal ammonia nitrogen (RAN) at time 0 (before supplementation) and microbial protein yield. Animals on MPS had a higher (P?>?0.05) intake and digestibility of CP, higher RAN levels (3 and 6 h after supplementation), increased nitrogen intake and a better nitrogen balance than animals on LPSU. The HPS provided higher (P?>?0.05) RAN at time 6 and a better nitrogen balance when compared with MPS. We therefore infer that the high-protein supplement positively impacts nitrogen metabolism and efficiency in grazing beef cattle during the rainy season.     

苹果酸在肉牛生产上的应用研究

本试验研究在日粮中补充DL-苹果酸（MA）对肉牛干物质采食量（DMI）、甲烷（CH4）排放和瘤胃发酵的影响,采用二因素拉丁方设计。试验1,选取6头（年龄：19±1月）肉牛随机分成3组,每组日粮的MA（占干物质含量）分别为0、3.75%和7.5%;试验2,选取4头（年龄：48±1月）插有瘤胃瘘管的肉公牛,其日粮中的MA（占干物质含量）分别为0%、2.5%和5.0%。试验1结果表明,增加日粮中MA的含量可线性降低总干物质含量和肠道中总CH4的排放量（P〈0.001）;当MA含量为7.5%时,其CH4的排放量相比对照组要降低16%,占单位干物质CH4排放量也相应下降9%。在试验2中,随着MA水平的增加DMI和CH4排放量呈线性降低（P〈0.001）;随着日粮MA水平的增加乙酸、丁酸比例呈线性减少（P〈0.001）,丙酸呈线性增加（P=001）;随日粮MA水平的增加,瘤胃pH呈上升趋势（P=0.10）,原虫数呈线性减少（P=0.01）。总体来看,增加日粮中MA含量可降低CH4的排放,但同时DMI也有所减少,这可能对动物的生产性能带来负面影响。     

人工草地肉牛放牧系统夏季留茬高度试验

通过探索不同放牧强度对放牧系统人工草地优质牧草再生产力影响,在朗目山混播放牧草地牧草生长旺盛的6-8月开展了不同留茬高度对人工草地质量,牧草生长,牲畜采食量,牧草利用率等影响试验,结果表明,留茬10-12cm的牧草净产量,利用率,草地质量,牲畜采食量均最佳,是实现放牧系统人工草地合理利用和提高效益的理想留茬高度。     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71–237 nmol/l) for cattle and 118 nmol/l (67–227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75–185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Effects of three levels of alpha-tocopheryl acetate supplementation to feedlot cattle on performance of beef cuts during retail display

Retail packages (n = 288; 24 of each product in each treatment group) of inside round steaks, T-bone steaks (strip loin and tenderloin), top sirloin steaks, and ground beef were used to evaluate effects of dietary supplementation of vitamin E to cattle on product performance during retail display. Products from control animals and cattle fed 500 IU x animal(-1) x d(-1) or 1,000 IU x animal(-1) x d(-1) were evaluated. Except for ground beef, dietary supplementation of vitamin E increased (P < 0.05) alpha-tocopherol concentrations in beef muscle from cattle fed 1,000 IU x animal(-1) x d(-1). Although not all differences were statistically significant, retail display-life was greater for all steaks from cattle fed 1,000 IU x animal(-1) x d(-1) than for those from control cattle. Ten percent of the inside round and tenderloin steaks from cattle fed 1,000 IU x animal(-1) x d(-1) had mean overall appearance scores of 3 ("moderately undesirable") at 72 to 78 h and 54 to 60 h, respectively, whereas 10% of the inside round and tenderloin steaks from control cattle had mean overall appearance scores of 3 at 54 to 60 h and 42 to 48 h, respectively. Each of the retail cuts in this study (irrespective of the amount of alpha-tocopheryl acetate that was fed to the animal that generated it) was categorized as "high," "medium," or "low," based on the alpha-tocopherol concentration in the primal cut or ground beef batch from which it originated. Retail cuts in the medium a-tocopherol concentration category had increased retail display life of 4.0 h for ground beef (P < 0.05) over those in the low alpha-tocopherol category. Retail cuts in the high alpha-tocopherol concentration category had increased retail display life of 10.7 h for inside round steaks and 4.0 h for ground beef (P < 0.05) over those in the medium concentration category. Vitamin E supplementation of cattle at 1,000 IU x animal(-1) x d(-1) for at least 100 d can be used to increase retail caselife and to improve the overall color acceptability of steaks and ground beef products. Although far from a perfect relationship, these data strongly suggest that increasing the alpha-tocopherol concentration in a beef cut will increase its retail case life.     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and, 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71-237 nmol/l) for cattle and 118 nmol/l (67-227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75-185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Effects of rumen-protected oil supplementation on finishing grazing beef cattle

Tropical Animal Health and Production - The objective of this study was to evaluate the effects of rumen-protected oil (soybean and palm oil) in supplements for beef cattle during the fattening...