Effect of level of beef cow milk production on pre- and postweaning calf growth

Three groups of beef cows that were similar in growth and mature size, but different in genetic potential for level of milk provided to their calves, were studied. A procedure for fitting grafted polynomials based on calf suckling data was used to estimate the total amount of milk produced by each cow during 205-d lactations. Estimated 205-d milk production of the high milk group exceeded that of the medium and low milk groups by 186 and 561 kg, respectively. Differences in milk production of the three groups tended to increase as dams got older. The pooled, within milk-group correlation between calf gain to 205 d and milk intake was .60. Calves suckling dams with low milk production relied earlier and to a greater extent on alternative food sources of lower nutritional value than milk. Calves suckling high milk-group dams had 16.9 kg greater 205-d weaning weight than those suckling low milk-group dams, solely because of differences in maternal environment. Calves from the high milk group maintained 63% of the advantage over those in the low milk group in 205-d weight through a fairly rapid postweaning growth period to slaughter.     

An economic evaluation of the differences between intensive and extensive beef production systems

A model to evaluate economic criteria involved when cattle are raised on high-forage diets prior to finishing or finished directly after weaning was developed using data from two experiments. In Exp. 1, each year for 3 yr, 136 Charolais-cross calves were weaned and allotted to either an intensive system, in which they were immediately finished on a high-grain diet, or an extensive system, in which they were wintered on crop residues, grazed on summer pasture and finished on a high-grain diet. In Exp. 2, 160 British breed steers were wintered, in one of eight different wintering systems utilizing crop residues, using supplemental protein and(or) alfalfa hay. After wintering, the steers grazed summer pasture and then were finished on a high-grain diet. Overall cost of gain and final "break-even" price were lower for cattle finished through the extensive system except when the price of corn was very low in relationship to other inputs. Interest costs were higher for cattle in the extensive system. Increasing the feeder calf purchase price had almost no effect on differences between the systems. Corn price and purchase price affected both systems similarly, whereas interest rate, wintering yardage and finishing yardage affected each system differently. Because of the additional weight produced through the extensive system, it yielded lower final "break-even" prices in most situations.     

莫能菌素对奶牛产奶性能的影响

本试验旨在研究莫能菌素对奶牛产奶性能的影响。将24头泌乳后期中国荷斯坦奶牛随机分为2组,试验组日粮中添加300g/d·头的莫能菌素。结果表明:在炎热的夏季,莫能菌素可提高奶牛的采食量,且奶牛产奶量比试验前提高了1.24%,比对照提高了15.91%,具有可观的经济效益;但对乳蛋白和乳糖的影响效果不显著。     

莫能菌泰对奶牛产奶性能的影响

本试验旨在研究莫能菌素对奶牛产奶性能的影响。将24头泌乳后期中国荷斯坦奶牛随机分为2组．试验组舀粮中添加300g/d·头的莫能菌素。结果表明：在炎热的夏季，莫能菌素可提高奶牛的采食量，且奶牛产奶量比试验前提高了1．24％，比对照提高了15．91％，具有可观的经济效益；但对乳蛋白和乳糖的影响效果不显著。     

Age of calf at weaning of spring-calving beef cows and the effect on cow and calf performance and production economics

Over a 5-yr period, spring-calving cows were used in a carry-over design experiment to evaluate effects of calf age at weaning on cow and calf performance and production economics. Weaning management groups were early (n = 60, calf age 150 d, EW), traditional (n = 60, calf age 210 d, NW), and late (n = 60, calf age 270 d, LW). Cow body condition score (BCS) and weights at the last weaning date were different (P < .05) for EW (5.8, 583 kg), NW (5.5, 560 kg), and LW (5.2, 541 kg) management groups. Pregnancy rates among groups were similar. Days on feed for groups differed (P = .001) and was 247 for EW, 204 for NW, and 164 d for LW steers. Average daily gain in the feedlot differed (P = .01) among groups and averaged 1.5 kg for LW, 1.4 kg for NW, and 1.3 kg for EW steers. Dry matter intake while steers were in the feedlot was greater (P = .001) for LW than for NW and EW calves. Hot carcass weight was greater (P = .01) for EW (328 kg) and NW (332 kg) calves than for LW (321 kg) steers, and fat depth was greater (P = .05) for EW and NW steers than for LW steers. When carcass data for the NW and LW steers were adjusted to the fat depth of EW steers, carcass characteristics among groups were similar. Net income per steer at slaughter for the feedlot phase was greater (P < .001) for the EW ($75.36) and NW ($62.16) steers than for the LW ($10.09) steers. Again, when carcass data for the NW and LW steers were adjusted to the same fat depth of the EW steers, net income differences among groups were reduced. Replacement heifers were developed in a drylot and costs were higher (P < .001) for the EW than for NW and LW heifers. Annual cow costs were greater (P < .10) for the LW ($443.45) than for the EW ($410.09) and NW ($421.35) groups. Break-even for each system on a steer financial basis was not different between the NW and LW groups, and both the NW and LW groups had lower (P = .08) break-evens than the EW group. Age of the calf at weaning affects cow weight and BCS. Net income in each system is influenced by cow costs, month of the year that steer calves are purchased into the feedlot and finished steers are sold, month of the year cull cows are marketed, and replacement heifer development costs.     

Inbreeding effects on postweaning production traits, conformation, and calving performance in Irish beef cattle

The objective of this study was to quantify the effect of inbreeding on carcass quality, growth rate, live conformation measures, and calving performance in purebred populations of Charolais, Limousin, Simmental, Hereford, and Angus beef cattle using data from Irish commercial and pedigree herds. Variables analyzed are reflective of commercial farming practices. Inbreeding was included in a linear mixed model as either a class variable or a linear continuous variable. Nonlinear effects were nonsignificant across all traits. Inbred animals had decreased carcass weight and less carcass fat. The effects of inbreeding were more pronounced in the British beef breeds. Effects for carcass weight ranged from -0.87 kg (Charolais) to -1.90 kg (Hereford) per 1% increase in inbreeding. Inbred Charolais and Hereford animals were younger at slaughter by 3 and 5 d, respectively, per percentage of increase in inbreeding, whereas the effect of inbreeding on age at slaughter differed significantly with animal sex in the Limousin and Angus breeds. Inbred Limousin and Angus heifers were younger at slaughter by 5 and 7 d, respectively, per percentage of increase in inbreeding. Continental animals were more affected by inbreeding for live muscling and skeletal conformational measurements than the British breeds; inbred animals were smaller and narrower with poorer developed muscle. Calf inbreeding significantly affected perinatal mortality in Charolais, Simmental, and Hereford animals. The effects were dependent upon dam parity and calf sex; however, where significant, the association was always unfavorable. Dam inbreeding significantly affected perinatal mortality in Limousin and Hereford animals. Effects differed by parity in Limousins. Inbred first-parity Angus dams had a greater incidence of dystocia. Although the effects of inbreeding were some-times significant, they were small and are unlikely to make a large financial effect on commercial beef production in Ireland.     

硒对牛生产性能影响的研究进展

硒(Se)是动物必需的微量元素.缺硒会引起一系列疾病,硒过量则会导致硒中毒,而适量补硒则具有多方面的有益影响.硒在牛生产中的作用重大.日粮补硒不仅可以提高血液、牛奶及牛肉的硒含量,还能改善牛的繁殖性能、增强机体免疫力,同时改善牛肉品质.日粮补硒的效果受牛的生理状况、补硒前的硒状况、补饲硒的形态及补饲量的影响.目前,补硒...     

活酶宝对泌乳奶牛产奶量及乳成分的影响

本试验选用60头中国荷斯坦奶牛,按照胎次、体况及产奶量随机分成对照组和试验组。对照组饲喂原有全混合日粮(TMR);试验组在此基础上,每天每头牛在精料中添加17g的活酶宝。结果表明,活酶宝可以提高奶牛的产奶量、乳脂肪率、乳蛋白率、乳糖率、干物质率和脂蛋比(P>0.05),并降低体细胞数(P>0.05)。与对照组相比较,试验组泌乳量、乳脂肪率、乳蛋白率、乳糖率、干物质率的值分别相对提高1.7kg、0.23、0.12、0.09和0.27;体细胞数相对下降26.16百万个。     

Performance of spring-calving beef suckler cows and their progeny to slaughter on intensive and extensive grassland management systems

The performance of rotationally grazed beef suckler cows and their progeny to slaughter on two lowland grassland management systems differing in stocking rate (SR) and fertiliser nitrogen (N) level was compared over eight years. The two Systems were 1) Intensive (INT): SR of 0.56 (bull production) or 0.71 (steer production) ha cow^? 1 unit, 211 kg fertiliser N ha^? 1, two silage harvests, and 2) Extensive (EXT): SR of 0.69 (bull production) or 0.88 (steer production) ha cow^? 1 unit, 97 kg fertiliser N ha^? 1 and one staggered silage harvest. A cow unit was defined as a cow plus progeny to slaughter. On the silage harvesting area, the mean application rate for fertiliser N was 110 and 80 kg ha^? 1 for first and second harvests, respectively. Herbage dry matter digestibility both pre- and post-grazing was similar (P > 0.05) for the two systems, whereas herbage crude protein concentrations were generally significantly lower for the EXT than the INT system. There was no difference (P > 0.05) between the Systems in cow live weight, body condition score or their changes or in calf live weight gain from birth to weaning. Post-weaning, live weight gain, slaughter weight, carcass weight, kill-out proportion, estimated carcass gain, carcass conformation score or carcass fat score did not differ (P > 0.05) between the systems for heifer, steer or bull progeny. It can be concluded that similar animal performance levels can be expected in an extensive grassland-based suckler calf-to-beef system compatible with the EU, Rural Environmental Protection Scheme as that attained in a more intensive System comprising of both a moderately high SR (~ 1.25 higher) and fertiliser N application (~ 2.1 higher).     

短期使用碘化酪蛋白对奶牛产量的影响

选择 2 0头泌乳期相近中国荷斯坦奶牛 ,随机分成 5组 ,每组 4头 ,对照组饲喂基础日粮 ,试验组在喂基础日粮的基础上添加 15 g/头·d碘化酪蛋白 ,为期 30d。结果表明 ,试验组牛产奶量比对照组平均升高 10 .73% (P <0 .0 5 ) ,牛奶密度变化不大。不论是逐渐撤去还是突然撤去饲料中的碘化酪蛋白 ,都不能有效地阻止奶产量的迅速下降     

The effect of concentrate level and concentrate composition on the performance of growing dairy heifers reared and finished for beef production

Abstract

The objectives of the study with growing dairy heifers were to determine the effects on animal performance of (1) concentrate level and (2) the concentrate composition in the grass silage-based diet. Animals (30 heifers) were randomly assigned to three feeding treatments: (1) low level (1.75 kg dry matter (DM)/d) of rolled barley (LB); (2) low level (1.75 kg DM/d) of commercial pelleted concentrate (LC); and (3) medium level (3.5 kg DM/d) of commercial pelleted concentrate (MC). All animals were also offered grass silage and hay. The commercial concentrate contained more crude protein than barley grain (135 g/kg DM vs. 205 g/kg DM). The data were analysed using analysis of variance and differences between the treatments were tested by orthogonal contrasts: LC vs. MC and LB vs. LC. The growth of the heifers increased and carcass conformation improved with increasing concentrate level. Commercial concentrate did not improve animal performance compared with barley grain.     

不同添加比例的两种纤维素酶对奶牛产奶量及乳品质的影响

试验选用100头胎次、产奶量、泌乳期相近的奶牛,随机分成5组(每组20头),在试验1组、试验2组、试验3组和试验4组饲料中分别添加纤维素酶A50g/t、纤维素酶A100g/t、纤维素酶B80g/t、纤维素酶B160g/t。测定5组奶牛产奶量及乳品质,研究其对奶牛产奶量的影响。结果表明,与试验前相比,不同纤维素酶组产奶量均呈上升趋势;与对照组相比,纤维素酶组在试验全期产奶量高于对照组(P>0.05);在本试验条件下,纤维素酶可有效提高奶牛产奶量,提高经济效益,对乳品质的影响效果不明显。     

丙三醇对肉牛生产性能和胴体品质的影响研究

选取杂交母牛(体重421.6kg±28.9)373头,饲喂含纯天然丙三醇的日粮,其中丙三醇含量分别为0、2%、4%、8%、12%、16%。牛的蒸汽压片玉米为主的日粮包括:6%的苜蓿干草、1.2%的尿素、300mg/kg的莫能霉素、90mg/kg的泰乐菌素、0.5mg/kg的醋酸美仑孕酮。每个牛栏中大约有6～7头牛,每组9个牛栏。从对照组饮食过渡到添加丙三醇的日粮持续10d,饲喂丙三醇的时间持续85d。结果显示,当丙三醇添加量从0增加至2%时,肉牛干物质采食量(DMI)也呈线性增加(P0.001)。肉牛饲喂含有0、2%、4%、8%、12%、16%的丙三醇,其平均日增重(ADG)分别增加1.19、1.34、1.29、1.25、1.17和1.03kg;料重比(F/G)呈显著二次方效应,且当丙三醇添加量为2%时,其料重比最高(P=0.046),当丙三醇增加至2%、4%和8%时,体重相应增加12.7、8.1和5.3kg;当丙三醇比例增加到12%和16%时,体重却分别减少1.9kg(一次线性,P=0.009)和14.3kg(二次方,P=0.006)。当丙三醇含量增加时,背最长肌面积也有所增加(P0.013),饲喂丙三醇也可降低牛肉皮下脂肪和大理石花纹评分等级(P=0.045)。当丙三醇含量不高于干物质含量8%时,肉牛日粮中添加丙三醇可以提高牛体重和饲料转化率。     

胡萝卜对奶牛产奶量及乳成分的影响

试验通过在产奶牛日粮中添加胡萝卜,研究胡萝卜不同饲喂量对舍饲奶牛的奶产量和乳成分的影响。试验牛选用中国荷斯坦奶牛,体重500~600 kg,胎次为头胎、泌乳100 d左右的健康荷斯坦奶牛30头,采用完全随机区组设计,分为3个处理组,试验1组为对照组(基础日粮),试验2组(基础日粮+5 kg胡萝卜)、试验3组(基础日粮+7.5 kg胡萝卜)为试验组,基础日粮由全株青贮玉米、羊草和精料组成。研究结果显示,奶牛在添加胡萝卜后能够显著提高产奶量,90 d后试验2组的产奶量比对照组提高了11.94%(P<0.05),试验3组的产奶量比对照组提高了16.17%(P<0.05),牛奶的风味也得到很大的改善。     

Factors affecting the calcium, magnesium and phosphorus content of beef cow milk.

This paper reports the calcium, magnesium and phosphorus content of milk from Shorthorn cattle during the five month calf nursing period as well as the effect of prepartum administration of a single intramuscular dose of vitamin D3 or of 25-hydroxyvitamin D3 on the milk mineral constituents. The colostrum of the group which received 25-hydroxyvitamin D3 was found to contain a higher percentage of calcium on the second and third day than the colostrum of control cows or those receiving D3. No differences occurred in colostrum magnesium or phosphorus contents due to prepartum treatment. Calcium, magnesium and phosphorus concentrations were all high in the first day of lactation, but declined until the third day after parturition. Milk calcium, magnesium and phosphorus content of individual cows was not uniform throughout the lactation and the variation was different for different cows.     

挤奶频率对奶牛生产性能的影响

文章介绍了挤奶频率对奶牛泌乳性能、繁殖性能、健康与福利等方面的影响。     

Evaluation of life-cycle herd efficiency in cow-calf systems of beef production

A deterministic beef efficiency model (BEM) was used to evaluate life-cycle herd efficiency (LCHE) in cow-calf beef production systems using four breed groups of beef cattle. The breed groups were Beef Synthetic #1 (SY1), Beef Synthetic #2 (SY2), Dairy Synthetic (DS), and purebred Hereford (HE). The LCHE was defined over the lifetime of the herd as the ratio of total output (lean meat equivalent) to total input (feed equivalent). Breed differences in LCHE were predicted with the larger/slower maturing DS being most efficient at each age of herd disposal and reproductive rate. This was mainly because, at any average age at culling, the dams of DS breed group were less mature and so had been carrying relatively lower maintenance loads for shorter periods and positively influencing LCHE. Higher LCHE was predicted with improvement in reproductive performance if there were no associated extra costs. However, this declined markedly if there was a delay in marketing of offspring. As average age at culling increased from 4 to 6 yr, efficiency declined sharply, but it began to recover beyond this age in most breed groups. We concluded that the slower maturing DS breed group may be more efficient on a herd basis in cow-calf systems and that improvements in reproductive rate not associated with extra costs improve life-cycle efficiency. Culling cows soon after their replacements are produced seems efficient.