饲粮中添加铬——烟酸复合物对肉鸭生产性能、胴体成分及血液生化指标的影响

选择1日龄樱桃谷母鸭240只 ,随机分为3组 ,每组5个重复 ,每个重复16只 ,饲养49天。在各组鸭的饲粮中分别添加0、100、200μm/kg铬量的铬—烟酸复合物 ,研究铬—烟酸复合物对肉鸭生产性能、胴体成分及血液生化指标的影响。试验结果显示 :(1)饲粮中添加铬 -烟酸复合物显著(P<0.01)提高肉鸭体重和日增重 ,显著(P<0.01)降低料肉比 ,对日采食量无影响(P>0.05) ;(2)添加铬 -烟酸复合物显著(P<0.05)提高肉鸭瘦肉率和胴体粗蛋白质含量 ,显著(P<0.05)降低肉鸭皮脂率和胴体粗脂肪含量 ;(3)添加铬 -烟酸复合物显著(P<0.01)降低肉鸭血清总脂、葡萄糖、总胆固醇、三酰甘油和尿素氮含量 ,显著(P<0.01)提高血清总蛋白含量。试验结果表明 :饲粮中添加200μm/kg铬量的铬 -烟酸复合物不仅可促进肉鸭生长、降低料肉比 ,而且可提高屠宰性能 ,改善胴体品质     

Stress parameters and immune response of layers under different cage floor and density conditions

The aim of the experiment was to investigate the effects of cage floor and cage density on stress parameters of laying hens. A total of 162 brown laying hens (Hyline Brown), aged 34 weeks, were used in the experiment. Compact-type battery cages, with three floors, were used. Hens were allocated as one, three or five hens in each of 18 cages to obtain three different cage density groups of 1968, 656 and 393.8 cm² floor area per hen, respectively. The same number of cages with different cage density were allocated to three different battery floors (first floor=top, second=middle, third=bottom) systematically. Values for body weight, mortality rate, egg weight, egg production, egg quality characteristics, egg yolk cholesterol content, the levels of blood plasma corticosterone, serum glucose, total cholesterol and triglycerides, the ratio of heterophils to lymphocytes (H-L ratio), antibody titers, claw length score, foot health score, plumage score and throat skin injuries were taken as indicators of stress. The values for egg weight (P<0.01) at the first floor were greater than the other floor levels. The group with five hens per cage had significantly lower mean estimates (P<0.01) than other groups with respects to body weight (P<0.001), egg production (P<0.001), egg weight (P<0.001) and plumage score (P<0.01), while significantly higher mean estimates for egg albumen index (P<0.01), Haugh unit (P<0.01), serum glucose (P<0.001), and H-L ratio (P<0.001). Serum cholesterol was higher in cages with one hen than that with five hens, whereas plasma corticosterone was lower. Antibody titers in cages with one hen was similar to that with three or five hens; however, those with three hens had higher titers than those with five hens. Values for egg breaking strength, yolk index, egg cholesterol content, and foot health score were not affected by cage density or floor. The results suggest that the allocation of three hens per cage had no measurable effect on health and welfare.     

Estimation of genetic and crossbreeding parameters for daily milk yield of Ayrshire × Sahiwal × Ankole crossbred cows in Burundi

The pedigree of 317 cows of which 184 were controlled for milk production has been used to estimate crossbreeding parameters for daily milk yield of Ayrshire, Sahiwal and Ankole crosses in the Mahwa station. Lactating cows belonged to one of 6 different genetic groups defined on the basis of the mating system used to produce them. REML estimates of the genetic parameters were obtained with a repeated animal model using daily milk records. Estimated heritability (h²) and repeatability (r²) were 0.27 and 0.36, respectively. The genetic group effects were used to estimate crossbreeding parameters following Dickerson's genetic model. Estimates for the additive effects for daily milk yield of Ankole, Sahiwal and Ayrshire breeds were − 1.66l, − 0.48l and 5.22l, respectively. Estimates of direct heterosis for daily milk yield for Sahiwal × Ankole, Ayrshire × Ankole, and Ayrshire × Sahiwal crosses were 1.97l, 2.30l and − 2.33l, respectively.     

Bayesian estimation of variance partition coefficients adjusted for imperfect test sensitivity and specificity

The variance partition coefficient (VPC) measures the clustering of infection/disease among individuals with a specific covariate pattern. Covariate-pattern-specific VPCs provide insight to the groups of individuals that exhibit great heterogeneity and should be targeted for intervention. VPCs should be taken into consideration when planning study designs, modeling data and estimating sample sizes. We present a Bayesian discrete mixed model for the estimation of covariate-pattern-specific VPCs when measurement of the infection/disease is based on an imperfect test. The utility of the presented model is demonstrated with three applications. In all cases, imperfect tests biased VPC estimates towards the null but corrected estimates could be obtained by modeling the sensitivity and specificity of the test procedure with beta distributions. The comparison of adjusted VPCs between the intercept only and the fitted models with higher level covariates explained the portion of heterogeneity in the data that was accounted for by the covariates.     

Effects of treating rice straw with urea or urea and calcium hydroxide upon intake, digestibility, rumen fermentation and milk yield of dairy cows

Three, multiparous Holstein crossbred dairy cows with initial body weight of 385 ± 19 kg were randomly allocated to 3 treatments of rice straw (T1 = untreated rice straw; T2 = 5.5% urea-treated rice straw (5 g urea in 100 ml water to 100 g air-dry (91% DM) straw); T3 = 2.2% urea + 2.2% calcium hydroxide treated rice straw (2.0 g urea and 2.0 g Ca(OH)₂ in 100 ml to 100 g air-dry (91% DM) straw) according to a 3 × 3 Latin square design. Each period lasted for 21 days in which feed, feces and rumen fluid were collected during the last 7 days for chemical analyses. The findings revealed significant improvements in dry matter intake and digestibility by using 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw. Ruminal pH and NH₃-N were found higher (P < 0.05) as compared with urea-treated rice straw fed group, while blood urea nitrogen and milk urea nitrogen were in normal ranges. Volatile fatty acid concentrations especially those of acetic acid were decreased (P < 0.05) and those of propionic acid were increased (P < 0.05), thus acetic acid:propionic acid was subsequently lowered (P < 0.05) in cows fed with 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw, respectively. Moreover, ruminal viable and cellulolytic bacterial counts were enhanced by urea and calcium hydroxide treatments. Milk protein and fat concentrations were additionally increased by respective treatments while 3.5% fat-corrected milk was highest; ranking from 2.2% urea + 2.2% calcium hydroxide treated rice straw, 5.5% urea-treated rice straw and urea-treated rice straw fed groups. Based on this study, implications could be made that using 2.2% urea + 2.2% calcium hydroxide treated rice straw for straw treatment could be an alternative treatment to 5.5% urea treatment with regards to its effectiveness and treatment cost for lactating dairy cows.     

利用体外培养法建立饲料营养成分与瘤胃丙酸产量的回归模型

根据美国康乃尔净碳水化合物和蛋白质体系 (CNCPS) ,分析测定了 4类 2 4种饲料的营养成分 ,利用体外批次培养技术测定了它们在体外培养一定时间后的丙酸产量 ,并由此建立了饲料中产丙酸的营养成分和瘤胃丙酸产量的回归方程     

蓝山灰鹅生态之研究

对湖南省蓝山县的地方良种灰鹅进行了研究,测定了体重、体尺、体温、脉搏、呼吸次数、血液学参数、产蛋性能、屠宰率、羽绒产量等。经对该县不同生态环境中的灰鹅进行比较,发现山区灰鹅在体形外貌、成年体尺、体重、体温、脉搏、呼吸及血液学指数等方面与平原地区灰鹅没有明显差异,但生长发育较慢(P<0.05)、开产迟(p<0.05)、产蛋率低,但羽绒产量和孵化率皆显著高于平原地区(P<0.01和P<0.05),母鹅利用年限也较长(P<0.05)。     

不同光增方式和周期对蛋鸡蛋品质和血液生化指标的影响

研究光增方式和光照周期对蛋鸡蛋品质和血液生化指标的影响。将20周龄海兰褐商品蛋鸡320只,随机分为8组,每组4个重复,每个重复10只鸡。试验光照周期采用渐增和骤增2种,光周期设11L∶13D、13L∶11D、15L∶9D、17L∶7D4个水平。结果表明:①不同光增方式对蛋形指数和哈氏单位有显著影响(P<0.05),以渐增条件下较好。不同光增方式对血液生化指标没有显著影响(P>0.05)。②不同光照周期对蛋黄颜色有显著影响(P<0.05),以15L∶9D处理组蛋黄颜色最好。不同光照周期对血液生化指标有一定影响,以13L∶11D处理组较好。     

Physiological responses of transported goats treated with ascorbic acid during the hot-dry season

The aim of the present study was to determine the physiological responses of transported Red Sokoto goats (RSG) treated with ascorbic acid (AA). Ten RSG treated orally with ascorbic acid served as experimental subjects, while seven goats treated with sterile water served as the control. The goats were transported for 8 h. The ambient temperature and relative humidity during the study period fluctuated between 21 and 38°C and 51 and 91%, respectively, which indicated that the season was thermally stressful and did not favor transportation of goats. The rectal temperature obtained in the control goats was significantly higher (P < 0.01) than the value in the experimental goats after transportation. There was a significant decrease (P < 0.05) in eosinophil counts and an increase (P < 0.01) in neutrophil counts and neutrophil : lymphocyte ratio recorded in the control goats after transportation, which suggested that the control goats were physically and emotionally stressed. The control goats lost 11.9% of their initial liveweight, while the experimental goats lost only 1.04% after transportation. Multiple stresses, including extreme meteorological factors, acted upon the transported goats and impaired their homeostatic mechanism. In conclusion, AA administration in goats reduced the adverse effects of road transportation stress.     

黄河首曲—玛曲高寒湿地生态系统服务功能价值估算

结合试验和调查,综合运用市场价值法、替代费用法和影子工程法,从11类服务功能方面对黄河首曲—玛曲高寒湿地生态系统服务功能进行了定量估算,旨在为该地区经济发展及科学合理地保护和利用湿地资源提供依据。结果表明:玛曲高寒湿地生态服务功能总价值达159.42亿元/a,是该地区国民生产总值的36.65倍。其中以水文调节功能最大,为57.72亿元/a。其次为水源补给、文化科研、营养循环与储存和气候调节功能,分别为32.43亿、12.50亿、12.38亿和11.37亿元/a,环境净化、物质生产、生物多样性保护、土壤形成与保护和大气组分调节功能,分别为9.24亿、8.48亿、8.31亿、5.67亿和1.09亿元/a,休闲娱乐功能最低(0.23亿元/a)。充分说明,玛曲高寒湿地是"中国西部高原之肾",是黄河上游重要水源补给区和蓄洪区,是黄河上游生态系统的绿色生态屏障,对保证中下游地区生态安全具有重要的战略地位。