密度和垫料对农大3号节粮小型蛋鸡行为的影响

本研究选取农大3号节粮小型蛋鸡为试验对象,采用两种饲养模式:单层栖架系统与自由散养。研究单层栖架系统中密度和垫料对农大3号节粮小型蛋鸡行为的影响,并与自由散养模式下舍外运动场中蛋鸡的行为进行对比,从而为单层栖架系统中适宜的饲养密度和合适的垫料提供参考。试验结果表明,在5.5只/m2、9.7只/m2、13.8只/m2三种密度中,刨垫料、沙浴、抖身、梳羽和啄羽等行为均可以得到满足,当饲养密度为13.8只/m2时,进攻啄发生率最低;在砂土、沙子和稻草三种垫料中,刨垫料、沙浴、抖身、梳羽和啄羽等行为均可以得到满足,当沙子作为垫料时,进攻啄发生率最低。单层栖架系统不设运动场,刨垫料、沙浴、抖身、梳羽和啄羽等行为可以基本得到满足,与自由散养模式相比,进攻啄行为显著减少(P<0.05)。

育成期不同体重农大3号蛋鸡器官发育研究

本试验旨在比较育成期不同体重农大3号蛋鸡器官发育的差异,为农大3号蛋鸡标准体重的确定奠定基础。试验采用单因子设计,选用36只120日龄农大3号蛋鸡,根据体重分为6组,分别为(0.72±0.01)kg、(0.81±0.02)kg、(0.93±0.02)kg、(1.01±0.01)kg、(1.10±0.02)kg、(1.21±0.03)kg,每组6只,进行屠宰测定。结果表明:不同体重农大3号蛋鸡胸肌、腹脂、胰腺、卵巢、空肠、回肠、肝脏、心脏、肌胃、脾脏重量和胫骨长度均具有显著差异,并随体重增加呈线性增加;不同体重农大3号蛋鸡胸肌、腹脂、卵巢、十二指肠、心脏相对重量及胫骨和小肠各段相对长度均差异显著,胫骨和小肠各段相对长度及十二指肠、回肠、心脏、肌胃相对重量随体重增加均呈线性降低,但腹脂相对重量呈线性增加,卵巢和胸肌相对重量呈二次曲线变化;卵巢相对重量在平均体重为1 009 g时最大,胸肌相对重量在平均体重为977 g时最小。根据胸肌、卵巢发育状况可知,120日龄农大3号蛋鸡标准体重范围应为950~1 000 g。

Effect of Time and Fatty Acid Composition in Eggs of White Leghorn Hens Supplemented with Tuna Oil

The study evaluated the effect of time and fatty acid (FA) composition in eggs of laying hens supplemented with tuna oil (TO). Two hundred White Leghorn hens 30-week were divided into 5 treatments with 4 replicates of 10 birds each. Treatments were assigned randomly and consisted of 0%, 0.75%, 1.50%, 2.25% and 3% TO in commercial sorghum-soybean meal diets, in which the soybean oil was partially replaced. The experiment was conducted for 90 days. At days 28, 56 and 84 of the experiment, 10 eggs per replicate were collected for chemical analysis. Feed intake, egg production rate, egg weight, and feed conversion were not influenced by dietary treatment. FA content was significantly altered (P < 0.05) by TO, showing a progressive increase in egg n-3 FA (especially docosahexaenoic [DHA] and eicosapentaenoic [EPA] acids) when TO was added. Levels of EPA and DHA were higher (P < 0.05) in the egg lipids of TO fed hens than those in the control group. This was correlated (P < 0.05) with the concentration of TO in the diet. However, no significant differences were observed either in egg weight or percent of egg lay between groups. There was a high correlation (P < 0.05) between TO inclusion level in the diet and the incorporation of EPA (r = 0.96) or DHA (r = 0.92) into the egg yolk and an overall decrease in n-6 FA. There was a high correlation (P < 0.05) between TO inclusion level and the incorporation of linoleic acid (LA, r = -0.95) or arachidonic acid (AA, r = -0.96) into the egg yolk. The highest incorporation (P < 0.05) of total n-3 FA content in eggs was obtained with 3% TO/kg. This increase was proportional to TO inclusion levels in the diets (r = 0.95). The results indicate that the n-3 FA content in eggs can be increased by dietary supplementation with TO, and that TO can serve as a reasonable alternative feed ingredient in layer diets to produce a healthier choice of egg.

Influence of Replacement Time and Rate of Soybean Oil by Flax Oil in the Leghorn Hens＇ Diet on Polyunsaturated Fatty Acid Profile in Eggs

The study was aimed to evaluate the effect of replacement time and rate of soybean oil by flax oil （FO） on polyunsaturated fatty acid （PUFA） profile in egg of laying hens. Two hundred White Leghorn hens with 30 weeks of age were divided into five treatments with four replicates of l 0 birds each. Treatments were assigned randomly and consisted of 0.00%, 0.75%, 1.50%, 2.25% and 3.00% FO in commercial corn-soybean meal diets, in which the soybean oil was partially replaced. The experiment was conducted for 90 d. The main research findings were that feed intake, egg production rate, egg weight and feed conversion were not influenced by time and dietary treatment. Fatty acid content was significantly altered （P 〈 0.05） by FO, showing a progressive increase in egg n-3 fatty acid （especially docosahexaenoic acids （DHA） and eicosapentaenoic acids （EPA）） when FO was added. Levels of EPA and DHA were higher （P 〈 0.05） in the egg lipids of FO fed hens than those in the control group. However, no significant differences were observed either in egg weight or egg production among groups. The highest incorporation （P 〈 0.05） of total n-3 fatty acid content in eggs was obtained with 3% FO/kg. This increase was proportional to FO inclusion levels in the diets.

Dietary vitamin D_(3) deprivation suppresses fibroblast growth factor 23 signals by reducing serum phosphorus levels in laying hens

The present study was carried out to evaluate the effect of dietary supplemental vitamin D_(3) on fibroblast growth factor 23(FGF23)signals as well as phosphorus homeostasis and metabolism in laying hens.Fourteen 40-week-old Hy-Line Brown layers were randomly assigned into 2 treatments:1)vitamin D_(3) restriction group(n=7)fed 0 IU/kg vitamin D_(3) diet,and 2)regular vitamin D_(3) group(n=7)fed 1,600 IU/kg vitamin D_(3) diet.The study lasted for 21 d.Serum parameters,phosphorus and calcium excretion status,and tissue expressions of type II sodium-phosphate co-transporters(NPt2),FGF23 signals and vitamin D_(3) metabolic regulators were determined.Hens fed the vitamin D_(3) restricted diet had decreased serum phosphorus levels(by 31.3%,P=0.028)when compared to those fed regular vitamin D_(3) diet.In response to the decreased serum phosphorus,the vitamin D_(3) restricted laying hens exhibited:1)suppressed kidney expressions of 25-hydroxyvitamin D 1-a-hydroxylase(CYP27B1,by 52.8%,P=0.036)and 1,25-dihydroxyvitamin D 24-hydroxylase(CYP24A1,by 99.4%,P=0.032);2)suppressed serum levels of FGF23(by 14.6%,P=0.048)and increased serum alkaline phosphatase level(by 414.1%,P=0.012);3)decreased calvaria mRNA expressions of fibroblast growth factor receptors(FGFR1,by 85.2%,P=0.003,FGFR2,by 89.4%,P=0.014,FGFR3,by 88.8%,P=0.017,FGFR4,by 89.6%,P=0.030);4)decreased kidney mRNA expressions of FGFR1(by 65.5%,P=0.021),FGFR4(by 66.0%,P=0.050)and KLOTHO(by 68.8%,P=0.038);5)decreased kidney protein expression of type 2a sodium-phosphorus co-transporters(by 54.3%,P=0.039);and 6)increased percent excreta calcium(by 26.9%,P=0.002).In conclusion,the deprivation of dietary vitamin D_(3) decreased FGF23 signals in laying hens by reducing serum FGF23 level and suppressing calvaria and kidney mRNA expressions of FGF23 receptors.