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。     

Performance of second-season grazing cattle following different levels of parasite control in their first grazing season

A 3-year grazing trial was performed during 2003-2005 on a commercial steer-producing farm in Sweden to study performance of second-season grazing (SSG) cattle following different levels of parasite exposure during their first grazing season. Initially, groups of 10 first-season grazing (FSG) cattle were each year assigned to four parasite control strategies: (1) turn-out onto pasture that during the previous year was grazed by SSG cattle, followed by a mid-July move to aftermath, (2) supplementation with concentrate and roughage for 4 weeks after turn-out, (3) no treatment, or (4) anthelmintic treatment (injectable doramectin) every fourth week. All animals were set stocked, except for those in group one. Next spring and following housing the cattle were turned out for their second grazing season onto approximately 25 ha communal pasturelands as a common mob. Weighing, faecal sampling and blood collection were performed at turn-out and then every 4 weeks for the 20-week grazing season. Faecal samples were also collected on day 10 after turn-out for detection of coccidian oocysts. Antibodies to Dictyocaulus viviparus were analysed at the time of their second housing period, and when elevated levels were recorded, stored serum samples from seropositive animals were analysed retrospectively. Results showed early-season weight losses of up to 47 kg in the SSG cattle. However, faecal egg counts were generally low and there was no correlation between SSG performance and treatment history as FSG cattle. Still, cumulative egg counts were significantly higher in animals that had been treated with anthelmintic as FSG cattle but serum pepsinogen concentrations showed no significant differences and the output of Eimeria alabamensis oocysts seldom exceeded 10,000 oocysts per gram faeces. Antibodies to D. viviparus were observed from July 2004 and from June 2005 but not in 2003. In 2004 and 2005, 64% and 83% of the animals, respectively, were seropositive for D. viviparus. It is concluded that weight gain penalties resulting from different levels of parasite infections the first grazing season remained during the second grazing season in 2004 and 2005 but no differences in weight gain could be identified in SSG cattle that had experienced different parasite control measures during their first grazing season. This was under conditions where the level of pasture infectivity was low to moderate during the second grazing period. However, D. viviparus was demonstrated in SSG animals during the two last years of the study and was an important confounding factor.     

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。     

Growth performance and meat characteristics of hair lambs grazing stargrass pasture without supplementation or supplemented with concentrate containing different levels of crude protein

Abstract

Forty crossbreed hair lambs (19.1 kg body weight; 8 months of age) grazing on a Cynodon plestoctachyus pasture without supplementation or supplemented with 300 g of concentrate containing different levels of crude protein (CP) were randomly assigned to treatments defined as follows: control (without supplementation); CP130 (concentrate 130 g CP/kg), CP150 (concentrate 150 g/kg), CP170 (concentrate 170 g/kg), and CP190 (concentrate 190 g CP/kg). Lambs fed supplements had higher final body weight (BW), total gain, average daily gain (ADG), total dry matter intake (DMI), total tract digestion, and carcass dressing than lambs in control treatment. Final BW, total gain, ADG, total DMI, feed conversion, and total tract digestion were improved linearly as protein level in concentrate increased. Meat of lambs fed supplements was lighter, redder, and less yellow than meat of lambs in control treatment. It is concluded that supplementation improved ADG, feed conversion, carcass dressing, and meat color.     

Energy to protein ratios in supplements for grazing heifers in the rainy season

Tropical Animal Health and Production - This study evaluated the effect of energy and protein supplementation on the nutritional characteristics, ingestive behavior, and productive performance in...     

Supplementation of suckling beef calves with different levels of crude protein on tropical pasture

The effects of supplementation with different levels of crude protein on performance, intake and nutrient digestibility and efficiency of microbial protein synthesis in suckling beef calves on pasture were assessed. Fifty-five calves, with an average age of 100 days and an initial average body weight of 110?±?7.5 kg and their respective dams, were used. The experimental design was completely randomised with five treatments and 11 replications. The experimental treatments for calves were as follows: control = calves received only mineral mixture; supplementation levels = calves received supplement containing 8, 19, 30 or 41 % of crude protein (CP, at a rate of 0.5 % of body weight (BW)). The cows received only mineral mixture ad libitum. Supplemented calves had higher (P?<?0.1) average daily gain (ADG). Protein levels showed a quadratic effect (P?<?0.1) on average daily gain (ADG) of calves. There was no difference in total dry matter (DM) intake (P?>?0.1). However, intake of dry matter forage (DMF) presented cubic profiles (P?<?0.1), with CP levels in the supplements. Supplementation increased (P?<?0.1) the digestibility of nutrients, except for the digestibility of neutral detergent fibre. Supplementation increased (P?<?0.1) the production of microbial nitrogen and N losses in urine. It can be concluded that multiple supplementations optimise the performance of beef calves on creep feeding. The intake of supplements with CP levels between 8 and 30 % partially replaces of the pasture ingested by calves and increases the digestibility of the diet.     

鸭茅╋白三叶型混播放牧草地肉牛生产系统优化研究

在鸭茅（Dactylis glomerata）+白三叶（Triflium repens）草地型肉牛放牧系统内,实施全日制划区轮牧、载畜量季节性调控、维持肥施用、草地除杂、枯草期补饲等优化措施,对草地的土壤养分、牧草生长强度、现存量、组分、养分及肉牛体质量、日增体质量等指标进行了监测。结果表明,采用全日制放牧,在草地年平均载畜量1.4牛单位/hm2下,牧草的生长量超过8 077 kg/hm2,肉牛体况得到明显的改善,单位草地面积经济效益可达1 135元/hm2,草地实现可持续利用。同时,针对草地肉牛放牧系统中存在的问题,提出了有效改进的合理化建议。     

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。     

不同水平DL-蛋氨酸铜对肉牛瘤胃纤维代谢的影响

选用4头平均体质量（420±20）kg,年龄2.5岁的中国西门塔尔阉牛,采用4×4拉丁方设计,以混合精料和风干玉米秸秆为基础日粮,研究1.3倍维持水平下,日粮中添加不同水平（0、8、16和24mg/kg干物质）铜（以DL-蛋氨酸螯合铜形式添加）对玉米秸瘤胃降解率的影响。结果表明,日粮中添加铜均降低了玉米秸干物质（DM）、中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）的瘤胃降解率及动态降解率,并且都达到显著水平。研究结果表明,试验中添加任何剂量的铜都降低了玉米秸的瘤胃降解率。     

Investigation of osteochondrosis in grazing beef cattle

Severe lameness attributed to osteochondrosis is described in an extensively managed Brahman herd grazing on improved native pasture. Clinical signs were observed in five animals, three of which were necropsied. The most prominent lesions were in the elbow and stifle joints. There was multiple fissuring and ulceration of thickened articular cartilage with numerous osteochondral bodies present in the joint spaces. All affected animals were entire males sharing a common ancestral sire. Inheritance and gender were suspected to be contributing factors in the development of the disease.     

Nutritional and dietary interrelationships with diseases of grazing beef cattle

This article describes current methods of controlling acute bovine pulmonary emphysema (ABPEE) and edema, lungworm and gastrointestinal nematodes, and bloat in grazing beef cattle. Success in handling outbreaks of these conditions and in their prevention depends on an understanding of their epidemiology and pathogenesis. Supplementation with ionophore antibiotics is effective in prevention of ABPEE and bloat and may also prevent other diseases of cattle that graze lush pastures.     

Digestion criteria in nursing beef calves supplemented with limited levels of protein and energy.

This study was conducted with grazing nursing calves (197 kg) to determine the effects of 1) limiting creep feed intake and 2) increasing the concentration of ruminal escape CP in creep feed at a limited level of creep feed intake on fescue and milk intake, ruminal NDF digestion, and total tract digestibility in calves fed high-quality, freshly harvested fescue. The treatments were 1) control (no creep feed), 2) limited intake of creep feed (.60 kg/d) having a moderate concentration of CP (13%), 3) limited intake of creep feed (.60 kg/d) having a high concentration of CP (35%), and 4) unlimited (high) intake (1.62 kg/d) of the same creep feed fed in Treatment 2. Forage OM intake was negatively correlated (r = -.995, P less than .05) with level of creep feed OM intake, whereas milk OM intake was not affected by level of creep feed intake. Decreases in ruminal fiber digestion and total tract NDF digestion caused by unlimited creep feeding were partially avoided by limiting creep feed intake. Digestible OM intake increased by .47 kg per kilogram of creep feed OM intake.     

Effect of ammonium sulfate fertilization on bahiagrass quality and copper metabolism in grazing beef cattle

To assess the impact of S fertilization on bahiagrass (Paspalum notatum) quality and Cu metabolism in cattle, two studies were conducted during the summer grazing season (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) received the same fertilizer treatment in each growing season, consisting of 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Forage sampling was conducted at 28-d intervals following fertilization by the collection of whole plants (four samples/pasture) in randomly distributed 1-m2 grazing exclusion cages and analyzed for CP, in vitro organic matter digestibility, S, P, Ca, K, Mg, Na, Fe, Al, Mn, Cu, and Zn. To determine the effect of fertilizer treatment on liver trace mineral concentrations in grazing cattle, random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period in 2000. Ammonium sulfate fertilization increased (P < 0.001) forage S concentration in both years. Plant tissue N concentrations were increased by N fertilization, regardless of source, in 2000, but not in 1999. Cows grazing AS pastures had lower (P < 0.05) liver Cu concentrations at the end of the study period in 2000 compared to AN and C. In Exp. 2, 37 Cu-deficient heifers grazing AS fertilized pastures were obtained from the same location and allocated to one of two treatments, consisting of supplements providing 123 mg/d of either inorganic (Cu sulfate; n = 12) or organic (Availa-Cu; n = 15) Cu. Treatments were delivered for 83 d. Liver Cu increased over time in all heifers regardless of treatment; however, heifers supplemented with Availa-Cu tended (P = 0.09) to have higher mean liver Cu concentrations than those receiving Cu sulfate. The results of these studies indicate that AS fertilization of bahiagrass increases forage S concentrations. When provided free-choice access to a complete salt-based trace mineral supplement, cows grazing AS-fertilized pastures had lower liver Cu concentrations than cows grazing pastures fertilized with AN; upon removal from high-S pastures, cattle were able to respond to Cu supplementation.     

Glucose and insulin responses to different dietary energy sources in Thoroughbred broodmares grazing cool season pasture

The objectives of this study were to characterize the glycemic and insulinemic responses of Thoroughbred broodmares fed late spring pasture only or a mixture of pasture and a high starch or low starch feed and to test hypotheses about differences in the glycemic and insulinemic effects of these dietary regimes. A group of 15 mares were divided into three treatment groups; pasture and high starch feed (PHS), pasture and low starch feed (PLS), and pasture only (PO) and maintained in these groups for 4.5 months prior to this study. These groups were maintained on a single pasture that was temporarily divided into three sections. The study protocol was conducted over two days. On day 1 the mares were fed their respective treatments and on day 2 all mares were allowed access to pasture only. On both days plasma glucose and insulin were measured in samples taken over a 7.5 h period. Baseline measurements for glucose and insulin were not different between any of the treatment groups on either day (P > 0.05). The baseline insulin concentrations of these pasture-kept mares (26.7 ± 8.3 mIU/L) were high compared to those reported from stall-kept horses. Plasma glucose and insulin on day 1 were influenced by treatment group, sample time, and an interaction between treatment and time (P < 0.05). On day 2 there was no significant influence of treatment group (P > 0.05). Glucose and insulin rose to higher (P < 0.01) peak concentrations in the PHS group on day 1 when compared to the PLS and PO groups, with no difference (P > 0.05) detected between the PLS and PO groups. These results are reflected in greater areas under the concentration-time curves for glucose and insulin in the PHS group on day 1 (P < 0.05). On day 2 there were no differences in any of the glucose and insulin characteristics for any of the treatment groups (P > 0.05). These results indicate a clear difference in the glycemic and insulinemic effect of the PHS feed compared to the PLS and PO groups. Of further interest are the glucose and insulin characteristics of these pasture-kept mares that indicate a low insulin sensitivity and high insulin secretory response. This study provides further information on factors influencing glycemic and insulinemic responses in horses.     

Digestibility of prairie hay diets supplemented with different levels of magnesium-mica by beef heifers

Four ruminally fistulated, nonpregnant, nonlactating heifers (515 +/- 7.9 kg) were offered chopped (10-cm screen size) prairie hay for ad libitum consumption with 1.8 kg/d of supplements to provide 0, 45, 113, or 181 g/d of magnesium-mica (MM) in a 4 x 4 Latin square design experiment. Heifers were adapted to diets for 7 d in drylot followed by a 19-d confinement period in individual stalls within a metabolism facility. Total feces and urine were collected for 5 d, daily intake and water consumption were monitored for 16 d, and in situ disappearance of fiber (prairie hay) and CP (soybean meal) were determined during the confinement period. Ruminal samples for fermentation product analyses were collected at feeding and every 2 h thereafter for 12 h on d 18, and rumens were evacuated at 1100 on d 19 to determine rumen fill. Cubic responses (P < .05) to MM level were observed for DM, OM, NDF, and ADF digestion and were characterized by a tendency for improved digestion with 45 g/d compared with the control diet, followed by a suppressive effect on digestion with 113 g/d, then little effect with 181 g/d MM. In situ NDF disappearance at 72 and 96 h tended (P < . 10) to be influenced quadratically by level of MM, but MM level had no apparent effect on ruminal fill and passage rate, ciliated protozoa counts, in situ rate of disappearance of fiber or CP, or nitrogen balance. Therefore, feeding MM at low levels to heifers consuming a prairie hay diet with a 20% CP supplement seemed to be beneficial for feed digestion with no measurable negative impact on intake or ruminal protein or fiber digestion.     

Selenium levels of beef cattle in southeastern british columbia relative to supplementation and type of pasture

Moderate to extremely low levels of selenium in hay were related to marginally deficient levels of selenium in sera from cattle in the Windermere Valley of southeastern British Columbia. Deficiency was most pronounced in cattle fed local hay during the winter or grazed on fertilized/irrigated pastures. Cattle on range had adequate levels of serum selenium. When sodium selenite was fed at 1.0 and 3.5 mg per head per day, serum selenium levels increased commensurate with the dose. Clinical observations indicated that a variety of clinical problems disappeared after injection or supplementation with selenium/vitamin E.     

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.     

Growth, carcass quality, and protein and energy metabolism in beef cattle with different growth potentials and residual feed intakes

Twenty-four beef steers (predominantly Angus x Hereford, 14 to 18 mo of age, 403 +/- 3 kg of BW), were housed and fed in individual pens for about 122 d. Twelve steers came from a herd that had been selected for growth (high growth; HG) and the other 12 from a herd with no selection program (low growth; LG). Another 6 steers (3 from each group) were slaughtered at the beginning to obtain the initial composition. All steers were fed the same corn-based diet (3.06 Mcal of ME/kg of DM, 13.6% CP) on an ad libitum basis. Two weeks before slaughter, total urine was collected for 5 d for estimation of 3-methylhistidine excretion and myofibrillar protein breakdown rates. Compared with LG steers, HG steers had less initial BW but greater final BW, DMI (7.52 vs. 6.37 kg/d), ADG (1.33 vs. 0.853 kg/d), G:F (0.176 vs. 0.133 kg/kg), ME intake (0.233 vs. 0.201 Mcal x kg of BW(0.75) x d(-1)), and retained energy (RE; 0.0711 vs. 0.0558 Mcal x kg of BW(0.75) x d(-1)); gained more fat (676 vs. 475 g/d); and tended to gain more whole body protein (100 vs. 72 g/d), with no difference in residual feed intake (RFI). Estimated net energetic efficiency of gain (k(g)) and ME for maintenance (ME(m)) did not differ between the 2 groups, averaging 0.62 and 0.114, respectively. The HG steers had greater HCW (350 vs. 329 kg), backfat (16.1 vs. 11.6 mm), and yield grades (3.53 vs. 2.80), with a similar dressing percent, KPH fat, LM area, and marbling score. Skeletal muscle protein gain (70.2 vs. 57.6 g/d) and fractional protein accretion rate (0.242 vs. 0.197%/d) tended to be greater in HG than in LG steers. Steers were classified into low (-0.367 kg/d) and high (0.380 kg/d) RFI classes. Compared with the high RFI steers, low RFI steers consumed less DM (6.61 vs. 7.52 kg/d) and ME (0.206 vs. 0.234 Mcal x kg of BW(0.75) x d(-1)) and tended to gain less fat (494 vs. 719 g/d), but were similar for initial and final BW, ADG, G:F, protein gain, HCW, dressing percent, backfat, KPH fat, LM area, marbling score, and yield grade, as well as for all observations related to myofibrillar protein metabolism. Residual feed intake may be positively [corrected] correlated with ME for maintenance. The maintenance energy requirement increased by 0.0166 Mcal x kg(-0.75) x d(-1) for each percentage increase in fractional protein degradation rate, confirming the importance of this process in the energy economy of the animal.