饲养密度对饲养环境及肉牛生产性能的影响

摘要

为探究适宜肉牛生长的最佳饲养密度,提高肉牛场经济效益,该文研究了饲养密度对肉牛生产性能,行为活动及经济效益的影响.在江西省高安市肉牛试验站选取体质量182~282 kg的杂交牛,在固定圈舍面积(18 m2)内分别饲养3、4、5、6、9头肉牛,对应占地面积为6.0、4.5、3.6、3.0、2.0 m2/头,饲养密度依次增加.由于肉牛体型较大,每个处理2个重复.结果显示,2.0 m2/头的试验组每头牛日采食量为11.90 kg显著高于其他处理组(P<0.05),但每头牛日增质量仅为1.09 kg;3.6 m2/头时,每头牛日采食量处于居中水平为10.96 kg,每头牛日增质量最佳,达到1.41 kg.随着饲养密度的增加,舍内二氧化碳浓度分别为1056.38、1108.44、1172.65、1200.89、1398.19 mg/m3,呈上升趋势;占地面积为2.0 m2/头时,舍内氨气浓度最高达3.23 mg/m3,而6.0 m2/头时仅为1.13 mg/m3;不同处理组之间有害气体浓度存在显著性差异(P<0.05).2.0 m2/头处理组1 d内站立时间(含打斗)为11.84 h,站立时间最长,脏污程度评分为2.09,体表最脏,3.6 m2/头试验组在打斗时间及体表清洁度方面均处于居中水平.综合上述指标,182~282 kg的每头牛适宜占地面积为3.6 m2,此时饲料转化率高,动物福利水平较好,利于农场取得较好经济效益.%In order to figure out the optimum stocking density for beef cattle growth and seek the improvement of economic benefits in beef cattle farms, related experiments were carried out at the beef cattle experimental station of Gao'an City, Jiangxi Province from December 26, 2016 to January 22, 2017. In the beef barns with the fixed area of 18 m2, we respectively selected 3, 4, 5, 6, and 9 heads of hybrid cattle with initial body weight between 182 and 282 kg, and thus area per calf was designed as 6.0, 4.5, 3.6, 3.0, and 2.0 m2/head correspondingly. Each treatment with different stocking density was repeated 2 times to obtain exact conclusion. The results of this experiment showed that the feed intake per calve per day which was fed in group of 2.0 m2/head was 11.90 kg, which was significantly higher than that fed in the other treatment groups (P<0.05). Although it held the highest feed intake, frustratingly we found that the weight gain effect was poor, only 1.09 kg per head per day for the 2.0 m2/head group. Calves held in 3.6 m2/head treatment group, which had the middle-level feed intake of 10.96 kg per calve per day, turned out that they gained the best effect of weight gain of 1.41 kg everyday. We figured out the weight gain increased by 29% compared with those treatments that were designed as 2.0 m2/head, respectively. During this experiment, we also surveyed related environmental index to help us evaluate the best stocking density for calves. We found that there were no significant differences in indoor temperature, relative humidity or average velocity between different treatments, but when it came to deleterious gas concentration, especially for carbon dioxide concentration and ammonia concentration, results were different. The conclusions were drawn that with the increase of stocking density, the indoor carbon dioxide concentrations were determined as 1056.38, 1108.44, 1172.65, 1200.89, and 1398.19 mg/m3 respectively, showing an upward trend. The calves fed in 2 m2/head treatment group reached a maximum value of ammonia concentration of 3.23 mg/m3, which was 1.44, 1.60, 2.10 and 2.86 times that of the treatments with area per calf of 2.0, 3.0, 4.5 and 6.0 m2/head, respectively, while in 6 m2/head treatment group , ammonia concentration was only determined as 1.13 mg/m3. Different experimental groups held notable differences (P<0.05), and in summary the concentration of harmful gas production was positively related to the number of livestock. For 2 m2/head treatment group, the standing time (including fight time) was determined as 11.84 h per day, and with the decrease of stocking density, standing time reduced. As for the dirt degree, the score was evaluated as 2.09 for the 2 m2/head treatment group, and therefore cattle's bodies in this treatment group seemed to be the dirtiest among all the experimental groups. As for fight time and dirt degree, 3.6 m2/head held the middle state. These findings suggest that the 3.6 m2/head treatment group, which leads to a high feed conversion rate and results in a middle-level animal welfare, is the optimum feeding density for beef cattle with a weight of 182-282 kg and holds great advantage to cattle farm developing.