复合益生菌对奶牛免疫及抗氧化功能的影响

研究复合益生菌（乳酸菌、酵母菌和芽孢杆菌等）对奶牛免疫及抗氧化功能的影响。对照组不饲喂益生菌,低剂量益生菌组和高剂量益生菌组分别一次性饲喂50和100 ml/（头·d）益生菌液。各处理组基础日粮相同,试验期为60 d。结果表明：与对照组相比,高剂量益生菌组血清IgG含量显著升高,过氧化氢酶水平则极显著升高,丙二醛含量极显著降低,其他各项指标则与对照组相比差异不显著。饲粮中添加一定剂量的复合益生菌制剂对奶牛免疫功能和抗氧化功能均有一定促进作用。     

牛至油、香芹酚、柠檬醛和肉桂醛的抗氧化性能研究

采用DPPH（1,1-二苯基-2-三硝基苯肼）法、BCB（β-胡萝卜素漂白）法和TBARS（硫代巴比妥酸）法对牛至油、香芹酚、柠檬醛和肉桂醛的抗氧化性能进行研究。结果表明,BHT、牛至油、香芹酚、柠檬醛和肉桂醛的DPPH自由基清除反应速度很快,清除能力随其浓度升高而显著增强,并逐渐趋于稳定,其IC50分别为1.2、4.3、3.7、7.2、3.1g/L;采用BCB法测定抗氧化性能时,BHT、牛至油、香芹酚和肉桂醛均表现出优良的抗氧化性能,并且随着浓度的增大,抗氧化性能增强,其IC50分别为0.1、2.2、3.4、1.9g/L;采用TBARS法测定抗氧化性能时,BHT、牛至油、香芹酚、柠檬醛和肉桂醛也表现出较好的抗氧化性能,并且其抗氧化指数随其浓度的增加而提高。由此可知,牛至油、香芹酚和肉桂醛可以作为天然抗氧化剂应用于食品加工中。      

牛至油对东北白鹅生长性能和屠宰性能的影响

研究了东北白鹅日粮中添加牛至油对东北白鹅生长性能和屠宰性能的影响.对照组饲喂基础日粮,试验组在基础日粮中分别添加50、100和150 mg/kg的牛至油预混剂,测定28 d和70 d的生长性能指标及70 d的屠宰性能指标.结果表明:添加不同水平的牛至油制剂均可提高平均日增重(前期提高0.86%～5.78%,整个生长期2.92%～8.93%),降低料重比,改善屠宰性能.前期150 mg/kg增重效果显著,整个生长期100 mg/kg效果最佳;添加牛至油对腹脂率的降低效果较为明显.     

脂肪酸钙与苜蓿干草对热应激奶牛产奶性能和血液指标的影响

选择2～4胎次泌乳中期的荷斯坦牛48头,配对分为4组,每组12头:CK(基础日粮)、Ⅰ组(基础日粮+400 g脂肪酸钙)、Ⅱ组(基础日粮+2.5 kg苜蓿干草)和Ⅲ组(基础日粮+400 g脂肪酸钙+2.5 kg苜蓿干草),于7～9月进行50 d的饲养试验,以研究添加脂肪酸钙或(和)苜蓿干草对热应激奶牛生产性能和血液指标的影响。结果表明:(1)添加脂肪酸钙或(和)苜蓿干草可以减缓热应激条件下奶牛产奶量的下降,提高产奶量,其中,Ⅲ组产奶量极显著高于CK(P0.01);(2)添加脂肪酸钙或(和)苜蓿干草有提高乳脂率的趋势(P0.05);(3)有提高血清T_4和COR水平的趋势(P0.05),且Ⅲ组血清T_3含量显著高于CK(P0.05)。     

α-硫辛酸对育肥猪生产性能和抗氧化功能的影响

研究日粮中添加α-硫辛酸对肥育猪生产性能和抗氧化功能的影响.对照组饲喂基础日粮,试验组在基础日粮中分别添加300、600和900 mg/kg的旷硫辛酸,试验期28 d.结果表明:与对照组相比,添加600、900 mg/kgα-硫辛酸降低了平均日增重(P＜0.05)和平均日采食量(P＜0.01),而各组料重比差异均不显著(P＞0.05);900mg/kgα-硫辛酸组总抗氧化能力增加显著(P＜0.05),谷胱甘肽过氧化物酶活性极显著增强(P＜0.01).α-硫辛酸添加组血清中丙二醛含量均显著降低(P＜0.05).α-硫辛酸的适宜添加水平为600 mg/kg.     

用牛至油替代抗生素对仔猪生产性能的影响

选用刚断奶杜长大仔猪180头,根据窝别、性别和体重相近原则随机分成牛至油、金霉素和“金霉素 黄霉素”3个组,每组60头。牛至油组仔猪日粮中添加10%牛至油预混剂300 g/t,金霉素组仔猪日粮中添加15%金霉素1 000 g/t,“金霉素 黄霉素”组仔猪日粮中添加15%金霉素1 000 g/t和4%黄霉素100 g/t。结果表明:牛至油组仔猪日增重比金霉素组提高8.49%(P<0.05),比“金霉素 黄霉素”组下降1.05%(P>0.05)。牛至油组料肉比比金霉素组下降6.09%(P<0.05);比“金霉素 黄霉素”组高1.09%(P>0.05)。牛至油组的腹泻率为金霉素组的50%(P<0.01)、“金霉素 黄霉素”组的40%(P<0.01)。牛至油组死淘率均为金霉素组和“金霉素 黄霉素”组的33.4%(P<0.01)。牛至油组仔猪平均每头收益率比金霉素组和“金霉素 黄霉素”组分别提高了57.42%(P<0.01)和9.94%(P<0.05)。这说明,牛至油能明显提高仔猪日增重,降低料肉比,有效地降低仔猪腹泻率,能在仔猪日粮中替代抗生素使用。     

叶酸对泌乳牛产奶性能和瘤胃发酵的影响

为研究叶酸对泌乳牛产奶性能、瘤胃发酵、纤维分解菌数量和酶活力的影响,选取36头荷斯坦泌乳牛,按随机区组设计分为4组,进行100 d的饲养试验,各组(对照、LFA、MFA和HFA组)叶酸添加量分别为0、35、70和105 mg/d。结果表明,各组泌乳牛干物质采食量和体重变化无显著差异;叶酸添加组产奶量显著高于对照组(P0.05);MFA和HFA组乳脂率显著高于LFA和对照组(P0.05);MFA组乳蛋白率显著高于其余各组(P0.05);各组乳糖率无显著差异;MFA和HFA组料奶比显著低于对照组(P0.05)。叶酸添加组瘤胃pH值显著低于对照组(P0.05),总挥发性脂肪酸和乙酸浓度显著高于对照组(P0.05);各组丙酸浓度无显著差异;MFA和HFA组乙酸/丙酸显著高于对照组(P0.05)。MFA和HFA组羧甲基纤维素酶和纤维二糖酶活性及溶纤维丁酸弧菌和黄色瘤胃球菌数量显著高于对照组(P0.05);叶酸添加组木聚糖酶、果胶酶和α-淀粉酶活性与白色瘤胃球菌和产琥珀酸丝状杆菌数量显著高于对照组(P0.05)。叶酸促进了纤维分解菌的生长,改善了瘤胃发酵,提高了泌乳牛产奶性能;其最佳添加水平为70 mg/d。     

发酵黄芪粉对奶牛抗氧化性能及血液代谢的影响

研究发酵黄芪粉对奶牛抗氧化性能及血液代谢的影响。对照组奶牛饲喂基础日粮,试验Ⅰ、Ⅱ和Ⅲ组奶牛分别饲喂含10、20和30g/(头·d)发酵黄芪粉的基础日粮。结果表明:与对照组相比,添加适量发酵黄芪粉可显著降低奶牛血清丙二醛含量,提高血清总抗氧化能力、超氧化物歧化酶和谷胱甘肽过氧化物酶的活性,降低奶牛血清尿素氮含量;但对奶牛血清葡萄糖和白蛋白影响不显著。发酵黄芪粉以20g/(头·d)的添加量效果较好。     

异位酸对泌乳牛产奶性能和饲料消化率的影响

为研究异位酸对泌乳牛采食量、产奶量、乳成分、日粮养分消化率和血液代谢产物的影响,选用48头荷斯坦泌乳牛,按随机区组设计分成4组(对照、LBFA、MBFA和HBFA组),分别在日粮中添加异位酸0、30、60和90 g/d,进行110 d的饲养试验和10 d的消化试验。结果显示,MBFA和HBFA组干物质采食量显著高于LBFA和对照组(P0.05);各组奶牛体重变化差异不显著;MBFA和HBFA组产奶量和乳脂率显著高于对照组(P0.05);异位酸添加组乳蛋白率显著高于对照组(P0.05),饲料转化率显著低于对照组(P0.05)。异位酸添加组干物质、有机物、蛋白质和中性洗涤纤维消化率显著高于对照组(P0.05);MBFA和HBFA组酸性洗涤纤维消化率显著高于LBFA和对照组(P0.05)。异位酸添加组血浆葡萄糖、总蛋白质、生长激素释放激素、生长激素和胰岛素样生长因子浓度显著高于对照组(P0.05);各组游离脂肪酸浓度无显著差异;MBFA和HBFA组乙酰乙酸和β-羟丁酸浓度显著高于LBFA和对照组(P0.05)。综上可知,异位酸提高了泌乳牛采食量、产奶量和饲料养分消化率;其最佳添加量为60 g/d。     

Three Times Daily Milking of Cows in California Dairy Herds

Twenty-eight California Holstein dairy herds were on twice daily milking for 3 to 17 mo and for 36 mo on three times daily milking. Effect of three times daily milking on yields of milk, fat-corrected milk, fat, and solids-not-fat, udder health, and reproductive performance was evaluated using Dairy Herd Improvement monthly herd summaries. Data for all cows in the herd and for first lactation cows were analyzed separately. Milk yield for the entire herd increased 12% above previous production on twice daily milking. Fat and solids-not-fat percentages were not affected by three times daily milking. First lactation cows milked three times daily yielded 14% more milk over previous twice daily levels. Fat percent was lower for first lactation cows on three time milking, but solids-not-fat percent did not change. Response to three time milking was not related to herd size or production while on twice daily milking. Udder health, evaluated by California Mastitis Test scores, and reproductive indexes were not affected by milking frequency.     

An Economic Evaluation of Three Times Daily Milking of Dairy Cows

A budgeting procedure using a micro-computer spreadsheet was used to compare the income over feed and variable costs of cows milked thrice and twice daily. Various percentage increases in milk yield, production per cow, milk and feed prices, and labor requirements were tested. With low feed prices, a 50% increase in labor requirements, and $12/ 45.4 kg milk, a 15.7% increase in milk yield was required for a herd producing 7727 kg milk per cow/yr for the income over feed and variable costs of thrice daily milking to equal that of twice daily milking. The percentage increases required for income over feed and variable costs of thrice daily milking to equal that of twice daily milking were lowered with a decreased labor requirement, lowered feed prices, and increased herd production. Small breeds required a larger increase in production from thrice daily milking to be as profitable as twice daily milking.     

Reproductive Performance of Crossbred and Purebred Dairy Cows

Analysis of 3095 records from purebred and crossbred dairy cows at five research stations of Agriculture Canada showed that the additive, maternal, and heterosis effects on kind of birth, placental condition, and percent of male or female dead calves were of minor importance.In 3108 records of purebred cows, the number of dead calves did not depend on whether or not the calf was purebred or crossbred or if it was born in first, second, third, or fourth lactation. However, 3080 records from cows of Holstein and Ayrshire lines and crossbred cows resulting from crossing the two lines gave results of higher mortalities of Holstein calves than of Ayrshire or crossbred cows. Holstein cows also had more abnormal births than cows in other genetic groups. Placental condition did not vary among the genetic groups of cows. Rebreeding rate, defined as percentage of cows pregnant for the second time based on the number of heifers calving for the first time, less the number of heifers culled for reasons other than reproduction, was 88% for Holstein and crossbred cows and 78% for Ayrshire cows. Reduction of cows in the herds from first to third lactation was the same for Holstein and crossbred cows (63%) but 77% for Ayrshires. Means of days to first service, number of services per conception, calving interval, and gestation period were almost identical for each genetic group of cows.     

牛奶体细胞数与产奶性能相关性分析

本试验运用2003年DHI报表体系,对西安市奶牛繁育中心的良种奶牛场110头左右的荷斯坦泌乳牛奶样进行分析,然后统计体细胞数和产奶性能的相关性.结果表明不同胎次,不同月份体细胞数与日产奶量和乳脂率负相关程度,和与乳蛋白率正相关的程度不同.其中,一胎牛体细胞数与日产奶量的相关系数差异极显著所占比例较大(60%);二月、八月、九月、十一月及十二月体细胞数与日产奶量相关系数差异显著和极显著比例较大(分别为75%、75%、50%、50%、50%);二月体细胞数与乳蛋白率相关系数显著比例较大(75%);八月、九月、十月及十一月体细胞数与乳脂率相关系数显著比例较大(分别为50%、75%、75%、75%).说明胎次对体细胞数与产奶性能的相关的影响相对较小,月份的影响相对较大.     

Alkali-Treated Forage for Early Lactation Dairy Cows: Effect on Lactation Performance and Nutrient Digestibility

Our objective was to determine the effect of sodium hydroxide treatment (4 g NaOH/100 g forage DM) of an alfalfa-orchardgrass forage and its subsequent utilization by early lactation dairy cows. Forage was harvested as hay. Complete mixed diets consisted of 55% control or treated hay and 45% concentrate (DM basis) and were fed to eight early lactation Holstein cows in a crossover design. Chemical composition of hays and complete diets were similar. Intake of dry matter was greater when cows were fed treated hay (23.4 vs. 22.2 kg/d), as was milk yield (32.3 vs. 30.9 kg/d). Yield of 4% FCM, however, did not differ between diets (27.8 vs. 27.4 kg/d). Cows fed the treated hay diet had increased concentrations of total rumen volatile fatty acids and ruminal acetate, decreased ruminal isobutyrate concentration and pH, and increased apparent digestibility of NDF, ADF, hemicellulose, and lignin. Sodium hydroxide treatment also increased the proportion of potentially digestible DM and NDF compared with that of untreated forage. Alkali treatment improved the utilization of medium quality forage in the early lactation dairy cow.     

Effect of Masonex and Forms of Cottonseed Hulls on Dairy Cows

Thirty-six lactating Holstein cows were in a 5 × 3 factorial partially balanced incomplete block design with three missing categories to study effects of different forms of cottonseed hulls and liquid supplements on milk production and composition. Roughages were regular cottonseed hulls, pelleted cottonseed hulls, pelleted cottonseed hulls with 9% fat, pelleted undelinted cottonseed hulls, and pelleted undelinted cottonseed hulls with 9% fat. Liquid supplements were 8% Masonex² (hemicellulose extract) and 8% cane molasses. Control had no supplement. All rations were adjusted to contain 30% cottonseed hulls. Roughages with added fat gave total rations of 2.5% added fat (air dry).Least square means for daily intake of dry matter, milk yield, and fat percent were regular cottonseed hulls 21.6 kg, 20.3 kg, 3.37%; pelleted cottonseed hulls 20.3 kg, 21.4 kg, 3.06%; pelleted cottonseed hulls plus fat 20.1 kg, 21.2 kg, 2.51%; pelleted undelinted cottonseed plus fat 19.4 kg, 20.9 kg, 2.73%. Pelleted cottonseed hulls increased milk yield, decreased dry matter intake and milk fat percent, but did not affect milk fat yields. Rations with pelleted undelinted cottonseed hulls resulted in higher milk fat percent and body weight than pelleted cottonseed hulls. Added fat decreased milk fat percent and yield because of high degree of unsaturation. Liquid treatments produced no detectable effects on dry matter intake, milk yield, or fat percent.     

Effect of Forage Maturity on Ration Digestibility and Production by Dairy Cows

Mixed grass-legume silages harvested at early and late maturities from the same field were evaluated in three trials to determine maturity effects on ration digestibility when forages were fed alone or in complete rations. In situ dry matter disappearance was examined using a rumen-fistulated steer. Rate of disappearance of potentially digestible dry matter was reduced for forage of greater maturity (−.0504 h⁻¹ for early versus −.0316⁻¹ for late cut silage). Nonlactating cows were used to determine forage digestibility. Apparent dry matter (69.2 versus 54.2%), acid detergent fiber (70.8 versus 52.7%), neutral detergent fiber (74.1 versus 55.9%), and crude protein (66.2 versus 45.6%) digestibilities were higher for early cut forage.Ration digestibility and milk production response were also measured. Concentrate to forage ratios necessary to meet energy requirements were 60:40 and 78:22 for diets containing early or late cut forage, respectively. Digestibilities of acid detergent fiber (60.2 versus 42.5%) and neutral detergent fiber (62.0 versus 52.7%) were higher for lactating animals consuming ration containing early cut forage. Milk yield and composition was not affected by diet. For each day of advancing forage maturity, approximately 1% more concentrate was needed in the total ration.