大河乌猪采食特性与生长性能的关联性分析

为研究大河乌猪采食特性与生长性能的相关性,选择云南富源县大河种猪场饲养的日龄相近、体重30 kg左右的50头大河乌猪为试验对象,随机分为5组,每组10头,每头均打上电子识别耳标,进入测定舍测定,试验猪100 kg体重结束试验。试验期间饲喂相同饲粮,自由采食和饮水。结果显示:1)30~50 kg与50~100 kg体重阶段日采食量差异不显著,总耗料量、日增重及料重比均差异显著(P0.05)。2)双变量分析表明,30~50 kg体重阶段大河乌猪的日采食量与日增重、料重比呈强度相关(r=0.960;r=0.932);总耗料量与日增重、料重比呈强度相关(r=0.988;r=0.861);日增重与料重比呈强度相关(r=0.845)。50~100 kg体重阶段大河乌猪的日采食量与日增重、料重比呈强度相关(r=0.981;r=0.990);总耗料量与日增重、料重比呈强度相关(r=0.978;r=0.984);日增重与料重比呈强度相关(r=0.969)。3)30~50 kg和50~100 kg体重阶段日采食量、总耗料量、日增重与料重比之间均呈极显著正相关(P0.01)。     

产蛋期蛋种鸭色氨酸需要量的研究

本研究旨评估产蛋期蛋种鸭色氨酸(Trp)的需要量。选择504只22周龄龙岩麻鸭随机分为6个处理组,每个处理6个重复,每个重复14只鸭,单笼饲养,试验周期为16周。饲粮总色氨酸处理水平分别为1.00、2.00、3.00、4.00、5.00和6.00 g/kg的饲粮。随着饲粮色氨酸水平的提高,22-37周龄种鸭的产蛋量、蛋重和采食量呈线性和二次增长((P<0.05),料肉比(FCR)呈二次下降(P<0.05)。随着饲粮色氨酸水平的提高,试验第8周和第12周种蛋的蛋白高度和哈夫单位呈线性和二次降低(P<0.05),而种鸭的体重、输卵管的绝对重量与相对重量、卵泡数(POF)以及卵泡比例均呈线性(P<0.01)和二次增长(P<0.001)。小型黄色卵泡重量占卵巢重量的比例呈线性和二次下降(P<0.01)。随着饲粮色氨酸水平的提高,试验的第16周种鸭血清白蛋白含量和谷丙转氨酶活性呈线性和二次下降(P<0.05),肌酐含量呈线性和二次上升(P<0.01)。由回归分析可知,基于产蛋性能、蛋重和料重比三个方面,产蛋期蛋种鸭Trp最优水平分别为3.14 g/kg、2.93 g/kg、2.92 g/kg。综上所述,不同饲粮Trp水平(1~6g/kg)对种鸭生产性能、蛋品质、生殖器官卵泡发育和血清生化指标均有显著影响,推荐产蛋期(22-37周龄)蛋种鸭色氨酸需要量为2.9~3.1 g/kg。     

秦川牛主要体尺、体重与剩余采食量主成分分析

为揭示秦川牛的生长发育规律,选择30头成年秦川牛进行主要体尺、体重和剩余采食量统计分析,选择累计贡献率达81.06%的5个主成分进行分析。结果显示:秦川牛之间采食量差异不显著(P0.05),其中剩余采食量、胸深和胸围变异幅度较大,选育潜力大;体重与体高、平均日增重呈极显著正相关(P0.01),体高、腹围与平均日增重呈极显著正相关(P0.01),剩余采食量与采食量呈极显著正相关(P0.01);从主成分的特征值与累计贡献率来看,第1主成分反映体型外貌特征,第2主成分主要反映后驱特征,第3主成分主要反映采食特征。本研究为阐明秦川牛体尺体重和剩余采食量之间的关系,为秦川牛的选种选育提供参考依据。     

日粮代谢能、粗蛋白水平对5～8周龄东北肉鹅生长性能及胴体品质的影响

选取4周龄、体重相近的东北肉鹅(莱茵鹅♂×双城本地鹅♀)216只,随机分成9个组,采用2因素3水平完全随机试验设计,研究日粮代谢能和粗蛋白水平对东北肉鹅生长性能和胴体品质的影响。结果表明:日粮代谢能水平对平均日采食量、料重比、腹脂率影响极显著(P<0.01),对半净膛率影响显著(P<0.05);日粮粗蛋白水平对料重比影响极显著(P<0.01),对平均日采食量、腿肌率影响显著(P<0.05)或极显著(P<0.01);代谢能和粗蛋白互作对料重比影响极显著(P<0.01),对腿肌率影响显著(P<0.05)。综合评定生长性能和胴体品质,推荐5～8周龄东北肉鹅日粮适宜的ME、CP分别为12.3MJ/kg和16%。     

酵母硒对吉林芦花鸡蛋品质及生产性能的影响

为研究添加不同浓度的酵母硒对吉林芦花鸡生产性能、蛋硒含量、蛋品质、鸡蛋胆固醇含量的影响,试验选用健康的21周龄吉林芦花鸡96只,平均体重1622 g。随机分成4组,每组6个重复,每个重复4只鸡。对照组饲喂基础日粮,其他3组分别添加0.3、0.6、0.9 mg/kg的酵母硒。预试期5 d,正式期21 d。结果表明:各组间料蛋比、采食量、哈氏单位、鸡蛋颜色无显著差异(P>0.05);0.3 mg/kg酵母硒组的平均蛋重极显著低于其他3组(P<0.01),产蛋率、软破壳蛋率均极显著高于其他3组(P<0.01);0.6 mg/kg酵母硒组的蛋黄比率、软破壳蛋率极显著低于其他3组(P<0.01);0.9 mg/kg酵母硒组胆固醇含量极显著低于其他3组(P<0.01);料蛋比(P=0.087)和胆固醇(P=0.061)随着酵母硒添加量的增加有降低的趋势。0.6 mg/kg酵母硒组蛋硒含量极显著高于对照组和0.3 mg/kg酵母硒组(P<0.01),显著高于0.9 mg/kg酵母硒组(P<0.05)。综上,在本试验条件下,酵母硒适宜添加量为0.6 mg/kg。     

日粮添加枸杞渣对蛋鸡生产性能与蛋品质的影响

为研究日粮中添加枸杞渣对蛋鸡生产性能与蛋品质的影响,以240只23周龄蛋鸡为试验对象,将蛋鸡随机分成4组,每组60只。Ⅰ组为对照组,饲喂基础日粮;Ⅱ、Ⅲ、Ⅳ组为试验组,分别在基础日粮中添加2.5%、5.0%、7.5%枸杞渣。结果显示:与对照组相比,Ⅲ、Ⅳ组平均产蛋率分别提高了1.85%和3.99%,Ⅱ、Ⅲ、Ⅳ组日采食量均极显著降低(P<0.01),Ⅲ组料蛋比显著降低(P<0.05),Ⅳ组料蛋比极显著降低于Ⅰ、Ⅱ其他各组(P<0.01)。Ⅱ、Ⅲ、Ⅳ组蛋黄颜色极显著提高(P<0.01),Ⅱ、Ⅲ组蛋重显著下降(P<0.05),试验组蛋壳强度、蛋白高度、哈氏单位和蛋壳厚度与对照组无显著差异(P>0.05)。结果表明,日粮中添加5.0%、7.5%枸杞渣可以提高蛋鸡的产蛋率,并能降低料蛋比;日粮中添加2.5%、5.0%枸杞渣即可显著降低蛋重,改善蛋黄颜色。     

不同能量蛋白水平对褐壳蛋鸡生产性能的影响

试验选用23周龄伊莎褐648只,根据体重随机分成3个处理组,每个处理有7个重复。日粮分别为高能低蛋白(能量11.28MJ/kg,蛋白15.60%),高能高蛋白(能量11.28MJ/kg,蛋白16.50%)和低能高蛋白(能量10.60MJ/kg,蛋白17.50%)。试验从25周龄～55周龄,一共217d,分为2个阶段:25周～40周和41周～55周。高能低蛋白组,高能高蛋白组和低能高蛋白组在各试验期的试验结果分别为:试验前期:产蛋率81.11%、81.37%和77.58%。体增重138.3g、94.2g和61.9g;采食量126.4g、127.3g和124.1g;蛋重61.7g、62.2g和62.7g;料蛋比2.52、2.53和2.54;经统计分析,各组间产蛋率、体增重、采食量、蛋重和料蛋比差异都不显著(P>0.05);试验后期:产蛋率81.75%、83.59%和82.96%;体增重177.5g、147.3g和120.8g;采食量117.8g、121.2g和127.7g;蛋重65.7g、65.6g和65.7g;料蛋比2.18、2.20和2.34。经统计分析,除高能低蛋白组,高能高蛋白组的采食量与低能高蛋白组差异显著(P<0.05)外,各组间产蛋率、体增重、蛋重和料蛋比差异都不显著(P>0.05);在整个试验期内的试验结果分别为:产蛋率81.43%、81.48%和80.27%;体增重315.8g、241.5g和182.7g;采食量122.1g、124.2g和125.9g;蛋重63.8g、64.0g和64.3g;料蛋比2.35、2.38和2.44。经统计分析,除高能低蛋白组的体增重?     

品种对肉兔断奶后窝生长性状的影响

本研究旨在明确影响肉兔断奶后窝生长性状和料肉比的重要因素。利用一般线性模型分析了来自5个不同肉兔品种(新西兰白兔,加利福尼亚兔,比利时兔,青紫蓝兔和福建黄兔)的909只173窝肉兔断奶后窝生长和料肉比性状。结果表明,品种和断奶数对断奶窝重(5周龄窝重),窝增重,窝上市体重(10周龄窝重),个体平均上市体重,窝采食量和料肉比的影响极显著(P<0.01)。出生月份对窝采食量影响极显著(P<0.01),对断奶窝重和窝上市体重的影响显著(P<0.05)。比利时兔的断奶窝重、窝增重、窝上市体重、窝采食量和平均上市体重显著高于其他品种,而福建黄兔的上述5项指标显著低于其他品种(P<0.05)。断奶数与断奶窝重、窝采食量、窝增重、窝上市体重和料肉比的回归系数为正且显著。品种、断奶数和出生月份是影响肉兔断奶后窝性状和料肉比的重要因素。本研究的结果为将比利时兔作为杂交的终端父本提供重要依据。     

不同品种蛋鸭蛋品质比较分析

为比较不同品种蛋鸭蛋品质的差异性及相关性,试验随机选取300日龄绍兴鸭、山麻鸭、缙云麻鸭和攸县麻鸭四个品种鸭蛋各30个,进行蛋品质测定。结果表明:四个品种的蛋形指数之间没有显著性差异(P0.05);绍兴鸭的平均蛋重、蛋黄色度显著高于缙云麻鸭(P0.05);绍兴鸭的蛋壳强度极显著高于山麻鸭(P0.01),显著高于缙云麻鸭和攸县麻鸭(P0.05);绍兴鸭的蛋壳厚度极显著高于山麻鸭、缙云麻鸭、攸县麻鸭(P0.01);山麻鸭的蛋黄比例显著高于绍兴鸭(P0.05);山麻鸭的蛋壳厚度极显著高于缙云麻鸭和攸县麻鸭(P0.01);缙云麻鸭的哈氏单位显著高于绍兴鸭(P0.05);四个品种相比绍兴鸭的蛋壳质量为最优,缙云麻鸭的新鲜度为最优。相关性分析结果表明:绍兴鸭和缙云麻鸭蛋形指数与哈氏单位呈极显著正相关(P0.01);缙云麻鸭和攸县麻鸭蛋壳强度与蛋壳厚度呈极显著正相关(P0.01);攸县麻鸭色度与哈氏单位呈显著负相关(P0.05);缙云麻鸭哈氏单位与蛋黄比例呈显著负相关(P0.05),不同品种间存在不同差异。     

散养对产蛋鸡生产性能、蛋品质及繁殖系统发育的影响

本试验旨在研究散养对产蛋鸡生产性能、蛋品质、繁殖系统发育的影响。选取25周龄笼养海兰蛋鸡180只,随机分为2组,每组6个重复,每个重复15只,将其中1组放至地面进行散养,2组均自由采食,每天统计产蛋量和耗料量。试验第42天,每个重复随机取4只鸡屠宰、测定繁殖系统的相关指标,同时随机取6枚蛋测定蛋品质。结果表明,散养鸡期末体重、产蛋率极显著小于笼养鸡(P<0.01),料蛋比极显著大于笼养鸡(P<0.01),平均蛋重显著小于笼养鸡(P<0.05);散养鸡鸡蛋的蛋白高度、蛋壳厚度极显著大于笼养鸡(P<0.01),蛋黄颜色与笼养鸡鸡蛋相比有提高的趋势,蛋黄免疫球蛋白含量大于笼养鸡,但差异不显著(P>0.05);散养鸡输卵管重量、卵泡重极显著小于笼养鸡(P<0.01),输卵管长度显著小于笼养鸡(P<0.05)。由此可知,与笼养相比,产蛋期间散养降低了鸡体重,降低了繁殖性能,改善了蛋品质。     

笼养与平养蛋鸭蛋品质测定与相关性分析

试验旨在比较笼养和平养方式对不同品种蛋鸭蛋品质的影响,以期为评价不同饲养方式下的鸭蛋品质提供参考依据。随机选取40周龄笼养和平养的金定鸭（青壳蛋）和山麻鸭（白壳蛋）鸭蛋各30枚于产后24 h内进行蛋品质测定。结果表明,同一品种笼养蛋鸭蛋重极显著大于平养蛋鸭蛋重（P<0.01）,蛋重与蛋壳重、蛋白重和蛋黄重之间均存在极显著正相关（P<0.01）,但不同类型鸭蛋的蛋黄重之间差异不显著（P>0.05）。青壳蛋的蛋壳强度显著高于白壳蛋（P<0.05）,笼养青壳蛋的蛋壳强度亦高于平养青壳蛋（P<0.05）。蛋的比重与蛋壳厚度呈极显著正相关（0.503,P<0.01）,与蛋壳强度的相关系数亦达到0.536（P<0.01）。4种类型鸭蛋的哈氏单位均达到72以上。虽然蛋白重与蛋黄重之间呈极显著正相关（P<0.01）,但蛋白重与蛋黄比率之间却呈极显著的负相关（P<0.01）。蛋的比重与蛋黄重和蛋黄比率之间亦存在显著负相关（P<0.05）。以上结果表明,就蛋品质而言,蛋鸭养殖以采用笼养模式、选择青壳蛋鸭品种为宜。     

拉萨白鸡蛋品质的测定及相关分析

为研究拉萨白鸡蛋品质的相关物理性状,对43周龄拉萨白鸡所产的30枚新鲜鸡蛋进行了蛋品质测定及相关分析。结果表明,蛋壳重量与蛋壳颜色呈显著正相关（P〈0.05）;蛋壳强度与蛋重呈显著正相关（P〈0.05）;蛋白重量与蛋壳颜色呈显著正相关（P〈0.05）,与蛋壳重量呈极显著正相关（P〈0.01）,与蛋壳率呈显著负相关（P〈0.05）;蛋白率与蛋壳率呈显著负相关（P〈0.05）,与蛋白重量呈极显著正相关（P〈0.01）;蛋黄重量与蛋壳重量、蛋白重量呈极显著正相关（P〈0.01）,与蛋壳率呈显著负相关（P〈0.05）,与蛋白率呈极显著负相关（P〈0.01）;蛋黄率与蛋形指数、蛋黄重量呈极显著正相关（P〈0.01）,与蛋壳重量、蛋白重量、蛋白率呈极显著负相关（P〈0.01）;蛋黄比色与蛋壳强度呈显著负相关（P〈0.05）;哈氏单位与蛋壳颜色呈显著负相关（P〈0.05）,与蛋白高度呈极显著正相关（P〈0.01）;蛋壳厚度与蛋壳强度呈极显著正相关（P〈0.01）;血肉斑与蛋壳强度呈极显著正相关（P〈0.01）,与哈氏单位呈显著负相关（P〈0.05）,与蛋壳厚度呈显著正相关（P〈0.05）。其他性状间也有相关性,但差异不显著。该研究为拉萨白鸡今后的选育提供了理论依据。     

Effect of selection for residual feed intake on feeding behavior and daily feed intake patterns in Yorkshire swine

Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between observed and predicted feed intake based on average requirements for growth and maintenance. The objective of this study was to evaluate the effect of selection for decreased RFI on feeding behavior traits and to estimate their relationships with RFI. Three data sets from the 4th and 5th generations of a selection experiment with a line selected for reduced RFI (LRFI) and a randomly selected control line (CTRL) were analyzed. Lines were mixed in pens of 16 and evaluated for feeding behavior traits obtained from a single-space electronic feeder over a growing period of ~3 mo before ~115 kg. The following traits were evaluated as averages over the entire test period and over the first and second half of the test period: number of visits per day and hour; occupation time per day, visit, and hour; feed intake (FI) per day, visit, and hour; and FI rate per visit. Models used included fixed effects of line and feeder, covariates of on-test age and FI per day, and random effects of pen, on-test group, sire, and litter. Repeated measures models were used to analyze feeding patterns during the day. The LRFI pigs had significantly less FI per day than CTRL pigs for all 3 data sets. With adjustment for FI per day, line differences of all traits were in the same direction for all 3 data sets but differed in significance and size. Feed intake per visit and hour and visits per day and hour did not differ between lines, but the trend was for LRFI pigs to have fewer visits, in particular during peak eating times. The LRFI pigs had a greater feeding rate and less occupation time per day, visit, and hour than CTRL pigs, but this was not significant for all data sets. Correlations of RFI with FI per day and visit and visits per day were positive. Average daily gain was positively correlated with FI per day and visit and occupation time per visit but negatively correlated with visits per day. Feed intake per day was positively correlated with backfat. In conclusion, feed efficiency may be affected by FI behavior because selection for decreased RFI has resulted in pigs that spend less time eating and eat faster.     

缠丝鸭蛋蛋品质及营养成分测定

为研究缠丝鸭蛋和普通鸭蛋在蛋品质及营养成分之间的差异,本试验随机选取300日龄左右鸭产的缠丝鸭蛋和普通鸭蛋各50枚,分别测定其蛋重、蛋壳厚度、蛋壳强度、蛋壳颜色、蛋白高度、蛋形指数、蛋黄色泽和哈氏单位等蛋品质性状及粗蛋白质、粗脂肪、钙、磷、锌和铁等营养成分含量。结果表明,与普通鸭蛋相比,缠丝鸭蛋的蛋重、蛋壳厚度、蛋壳颜色、蛋壳强度和蛋形指数差异均不显著(P>0.05),而蛋白高度、蛋黄色泽和哈氏单位极显著高于普通鸭蛋(P<0.01);蛋白质、钙、锌、铁含量较高,脂肪、磷含量较低。提示,缠丝鸭蛋蛋品质优于普通鸭蛋,营养物质含量比普通鸭蛋更丰富。     

Animals selected for postweaning weight gain rate have similar maintenance energy requirements regardless of their residual feed intake classification

Data of comparative slaughter were used to determine Nellore bulls’ net energy requirements classified as efficient or inefficient according to residual feed intake (RFI) and selection lines (SL). Sixty-seven Nellore bulls from the selected (SE) and control (CO) lines of the selection program for postweaning weight gain were used. The animals underwent digestibility trials before being submitted to the finishing trial. Sixteen bulls were slaughtered at the beginning of the finishing trial, and their body composition was used as the baseline for the remaining animals. For body composition determinations, whole empty body components were weighed, ground, and subsampled for chemical analyses. Initial body composition was determined with equations developed from the baseline group using shrunk body weight, fat, and protein. The low RFI (LRFI) and CO animals had a lower dry matter (DMI) and nutrient intake (P < 0.05) than high RFI (HRFI) and SE animals, without alterations in digestibility coefficients (P > 0.05). During the finishing trial, DMI remained lower for LRFI and CO animals. Growth performance was similar between RFI classes, except for empty body weight gain that tended to be higher for LRFI than HRFI (P = 0.091). The SE animals had less fat content on the empty body (P = 0.005) than CO. Carcasses tended to be leaner for LRFI than HRFI (P = 0.080) and for SE than CO (P = 0.066) animals. LRFI animals retained more energy (P = 0.049) and had lower heat production (HP; P = 0.033) than the HRFI ones. Retained energy was not influenced by SL (P = 0.165), but HP tended to be higher for SE when compared to CO (P = 0.075) animals. Net energy requirement for maintenance (NE_m) was lower for LRFI than HRFI (P = 0.009), and higher for SE than CO (P = 0.046) animals. There was an interaction tendency between RFI and SL (P = 0.063), suggesting that NE_m was lower for LRFI+CO than HRFI+CO (P = 0.006), with no differences for SE (P = 0.527) animals. The efficiency of ME utilization for maintenance (k_m) of LRFI and HRFI animals were 62.6% and 58.4%, respectively, and for SE and CO were 59.0% and 62.1%, respectively. The breeding program for postweaning weight has not improved feed efficiency over the years, with RFI classification not being a promising selection tool for SE animals. Classification based on RFI seems to be useful in animals that have not undergone the breeding program, with LRFI animals having lower energy requirements than the HRFI ones.     

Determination and Correlation Analysis on the Egg Quality of Egg-laying Ducks Reared in Cages and on Floor

The purpose of this test was to evaluate the egg quality from two breeds of ducks reared in cages and on floor.30 eggs were chosen from each type of eggs,which were from Jinding (green shell) and Shan Partridge ducks (white shell)at 40 weeks-old reared in cages and on floor for egg quality evaluation.The results showed that the egg weight of caged duck was extremely significantly larger than the floor duck (P<0.01) in the same breed,there were very significant positive correlations between the egg weight and eggshell weight,egg-white weight and egg yolk weight (P<0.01),but no significant difference among the egg yolk weights of different types of ducks (P>0.05).The shell strength of green egg was obviously higher than that of white shell eggs (P<0.05),and the shell strength of green egg from caged ducks was higher than that of the green egg ducks on floor.The correlation coefficients of the egg specific gravity and eggshell thickness,the specific gravity and eggshell strength were 0.503 (P<0.01) and 0.536 (P<0.01) respectively.Haugh units of four types of ducks all reached 72 or more.Although there was significant positive correlation between egg-white weight and egg yolk weight (P<0.01),significant negative correlation was existed between egg-white weight and egg yolk ratio (P<0.01).There were significant negative correlations between egg specific gravity and egg yolk weight (P<0.05) and egg yolk ratio (P<0.05).In conclusion,the mode of cage feeding and the breed with green shell were appropriate choices in laying-egg duck production for high egg quality.     

北京油鸡剩余采食量与屠宰性能及肉品质的相关性分析

本研究旨在探讨北京油鸡剩余采食量（RFI）与屠宰性能和肉质性状的关系。试验测定了400只北京油鸡70~98日龄的RFI及98日龄屠宰性能和肉品质,并对RFI与屠宰性能和肉品质的相关性进行了分析。结果显示,试验公鸡的平均日采食量（ADFI）、平均日增重（ADG）极显著高于母鸡（P<0.01）,饲料转化率（FI/GW,FCR）极显著低于母鸡（P<0.01）。公鸡半净膛率、腿肌率和胸肌红度（a^*）极显著高于母鸡（（P<0.01）。公鸡的RFI与FCR、ADFI极显著正相关（P<0.01）,与腹脂率显著正相关（P<0.05）,与胸肌率和腿肌率极显著负相关（P<0.01）;母鸡RFI与FCR和ADFI极显著正相关（P<0.01）,与ADG显著正相关（P<0.05）,而与腿肌率极显著负相关（P<0.01）。公鸡RFI与胸肌亮度（L^*）极显著正相关（P<0.01）,与色度（C^*）显著正相关（P<0.05）;母鸡RFI与胸肌a^*和C^*极显著正相关（P<0.01）,与色调（H^*）和pH极显著负相关（P<0.01）,与L^*和黄度（b^*）显著正相关（P<0.05）。由以上结果可见,北京油鸡公鸡的饲料利用效率优于母鸡,且部分屠宰性状和肉质性状与RFI存在显著相关性。     

Feed conversion ratio,residual feed intake and cholecystokinin type A receptor gene polymorphisms are associated with feed intake and average daily gain in a Chinese local chicken population

Background: The feed conversion ratio(FCR) and residual feed intake(RFI) are common indexes in measuring feed efficiency for livestock. RFI is a feed intake adjusted for requirements for maintenance and production so these two traits are related. Similarly, FCR is related to feed intake and weight gain because it is their ratio. Cholecystokinin type A receptor(CCKAR) plays an important role in animal digestive process. We examined the interplay of these three parameters in a local Chinese chicken population.Results: The feed intake(FI) and body weights(BW) of 1,841 individuals were monitored on a daily basis from 56 to 105 d of age. There was a strong correlation between RFI and average daily feed intake(ADFI) and a negative correlation between the FCR and daily gain(r_g=-0.710). Furthermore, we identified 51 single nucleotide polymorphisms(SNPs) in the CCKAR and 4 of these resulted in amino acid mutations. The C334A mutation was specifically associated with FI and the expected feed intake(EFI)(P 0.01) and significantly associated with the average daily gain(ADG)(P 0.05). G1290A was significantly associated with FI and EFI(P 0.05).Conclusion: FCR is apply to weight selecting, and RFI is more appropriate if the breeding focus is feed intake. And C334A and G1290A of the CCKAR gene can be deemed as candidate markers for feed intake and weight gain.     

Circulating leptin and its muscle gene expression in Nellore cattle with divergent feed efficiency

Background: Leptin has a strong relation to important traits in animal production, such as carcass composition,feed intake, and reproduction. It is mainly produced by adipose cells and acts predominantly in the hypothalamus.In this study, circulating leptin and its gene expression in muscle were evaluated in two groups of young Nellore bulls with divergent feed efficiency. Individual dry matter intake(DMI) and average daily gain(ADG) of 98 Nellore bulls were evaluated in feedlot for 70 d to determinate the residual feed intake(RFI) and select 20 animals for the high feed efficient(LRFI) and 20 for the low feed efficient(HRFI) groups. Blood samples were collected on d 56 and at slaughter(80 d) to determine circulating plasma leptin. Samples of Longissimus dorsi were taken at slaughter for leptin gene expression levels.Results: DMI and RFI were different between groups and LRFI animals showed less back fat and rump fat thickness,as well as less pelvic and kidney fat weight. Circulating leptin increased over time in all animals. Plasma leptin was greater in LRFI on 56 d and at slaughter(P = 0.0049). Gene expression of leptin were greater in LRFI animals(P = 0.0022) in accordance with the plasma levels. The animals of the LRFI group were leaner, ate less, and had more circulating leptin and its gene expression.Conclusion: These findings demonstrated that leptin plays its physiological role in young Nellore bulls, probably controlling food intake because feed efficient animals have more leptin and lower residual feed intake.     

丝羽乌鸡蛋品质对种蛋受精率和受精蛋孵化率的影响

试验就丝羽乌鸡蛋品质因素对种蛋受精率和受精蛋孵化率的影响进行了研究.结果显示,哈氏单位和蛋白高度越大,受精率和受精蛋孵化率越高(P＜0.01);蛋重对受精率有一定的影响,蛋重与受精率呈一定正相关关系(r=0.0619,P＜0.1),随着蛋重增加,受精率也会增大;蛋壳强度与受精蛋孵化率呈一定负相关关系(r=-0.1808,P＜0.1),蛋壳强度太大的鸡蛋其受精蛋孵化率反而下降;蛋壳颜色与受精率呈强的负相关关系(r=-0.2848,P＜0.01),即蛋壳颜色越深的鸡蛋其受精率越高;而蛋黄颜色与受精蛋孵化率呈强的负相关关系(r=-0.2328,P＜0.05),即蛋黄颜色越浅的鸡蛋受精蛋孵化率越高;蛋形指数、蛋壳厚度、蛋比重等指标对受精率及受精蛋孵化率未有显著影响.