【作者】 彭焕伟；

【导师】 张克英； 陈代文；

【作者基本信息】 四川农业大学 ， 动物营养与饲料科学， 2005， 硕士

【摘要】 本试验选用15头35kg左右的长×大二元杂交猪,考察饲喂褪黑激素对猪生产性能、胴体品质以及肉质的影响。采用单因子试验设计,设两个水平MT添加组(低MT组:1.5mg/kgBW/d,高MT组:3.0mg/kgBW/d)和一个对照组,每组5个重复,每个重复1头猪。 试验结果为: (1) 对于生产性能:前期(0-50d,猪体重从35kg～80kg左右),高MT组ADG和ADFI分别比对照组降低11.31%(P<0.01)和13.53%(P<0.01),F/G有下降趋势;低MT组F/G比对照组降低5.85%(P<0.05),ADFI有下降趋势,而ADG与对照组无明显差异。后期(50-75d,猪体重80-95kg左右),猪ADG各处理间没有显著差异,两个MT处理组猪ADFI都显著下降,高MT组降低了12.88%(P<0.05),低MT组降低了19.31%(P<0.01);低MT组F/G比对照下降了21.39%(P<0.05),高MT组与对照间差异不显著。从全期来看,ADFI高MT组降低12.94%(P<0.01),低MT组降低了9.41%(P<0.01);ADG高MT组降低8.93%(P<0.01),低MT组略有提高,但差异不显著;F/G高MT组降低4.73%(P<0.05),低MT组降低11.04%(P<0.01)。 (2) 对于养分消化率:低MT组猪对饲料粗蛋白的表观消化率有提高的趋势,而高MT组有下降的趋势,低MT组比高MT组提高了3.09%(P<0.05)。高MT组粗脂肪表观消化率比对照组降低了6.19(P<0.05),低MT组比对照组降低了5.27%(P=0.056)。高MT组猪对碳水化合物表观消化率有提高的趋势。MT对饲料能量和总有机养分表观消化率没有显著的影响。 (3) 对于胴体品质:低MT组猪胴体重有提高的趋势,高MT组猪胴体重有降低的趋势,而低MT组比高MT组提高了13.66%(P=0.131)。两个MT处理组的屠宰率都有所提高,其中低MT组比对照提高了7.61%(P=0.082)。高MT组的眼肌面积显著低于低MT组和对照组,分别比对照组和低MT组降低了34.62%和38.41%(P<0.05),而低MT组与对照没有显著差异。高MT组猪的背膘厚比对照降低了2.11%(P=0.084),低MT组也有降低的趋势。各MT处理组猪的平均板油重都降低,与对照相比高MT组降低了25.71%(P=0.187),低MT组降低了12.74%(P=0.571)。各MT处理对板油率都有所降低,其中高MT组比对照降低了17.72%(P=0.268)。 (4) 对于肉质指标:两个MT组猪屠宰后45min背最长肌肌肉的pH值与对照组相更多还原

【Abstract】 To test the effects of oral melatonin on performance, nutrients digestibility ,carcass and meat quality of growing-finishing pigs, 15 pigs (Landrace×Yorkshire) (initial weight 35kg approximately) were employed and divided into 3 groups with 5 replicates of 1 pig . One group were fed high level melatonin (3.0mg MT/kg body weight/d), one group were fed low level melatonin (1.5mg MT/kg body weight/d), and one group as the control were fed basal diet without melatonin. The results showed that:(1) Effects of MT on performance:For phase Ⅰ (from 35kg to 80 kg approximately): high level MT reduced the average daily gain (ADG) and feed intake (ADFI) of pigs by 11.31%(P<0.01) and 13.63% (P<0.01) respectively, and the feed to gain ratio (F/G) also was reduced (P>0.1) compared to the control. The ADG and ADFI of pigs in low level MT group were similar to the control, but the feed to gain ratio (F/G) reduced significantly by 5.85%(P<0.05).For phase Ⅱ (from 80kg to 95kg approximately): there was no difference in ADG among treatments. The ADFI of pigs in the high or low level MT group decreased by 12.88% (P<0.05) or 19.31% (P<0.01) respectively compared to the control. The feed to gain ratio(F/G) in high level MT group were similar to the control, while decreased by 21.39% (P<0.05) in low level MT group compared to the control.For total phase (from 35kg to 95kg approximately):The ADG , ADFI and F/G in high level MT group reduced by 8.37% (P<0.01) ,12.94% (P<0.01) and 4.73%( P<0.05) respectively compared to the control. In low level MT group ,the ADFI and F/G also reduced by 9.41% (P<0.01) and 11.04% (P<0.01) respectively, but the ADG had no difference compared to the control.(2) Effects of MT on nutrients digestibility:Two levels of MT had no significant influences on apparent digestibility of feed gross energy and total organic nutrients for pigs, but the apparent digestibility of crude fat(CEE) was reduced by 6.19%( P<0.05 )and 5.27%(P=0.056) for high and low level MT respectively compared to control .Apparent digestibility of crude protein(CP) was reduced in high level MT group, but improved in low level MT group, and there was significant different between high level and low level MTgroups. The apparent digestibility of carbohydrates had the tendencies to be improved in high level MT group.(3) Effects of MT on carcass quality:There was no significant difference in carcass weight between the two levels of MT group and the control. But there were the tendencies that low level MT increased the carcass weight, high level MT reduced the carcass weight. While the carcass weight of low level MT group was increased by 13.66%(P=0.131) compared to that of high level MT group. The slaughter ratios of the two levels of MT group were improved to some extent, especially the low level MT group with 7.61% (P=0.082) increased . The loin muscle area of high level MT group was 34.62% and 38.41%(P<0.05 Mower than those of control group and low level MT group respectively , while there was no notable difference in loin muscle area between low level MT group and control group. The thickness of back fat of high level MT group was reduced by 2.11% (P=0.084) compared to the control, and low level MT also trended to reduce thickness of back fat. The MT of two levels both reduced the leaf fat weight of pigs. The leaf fat weight of group were fed high and low level MT were respectively reduced by 25.71%(P=0. 187) and 12.74% (P=0. 571) compared to the control. The two levels MT both reduced the leaf fat to carcass weight ratio of swine, which of high level of MT group was reduced by 17.72%(P=0.268) .(4) Effects on parameters related to meat quality:The significant difference in pH45(the detected pH value of loin muscle at 45min post- slaughter) were not observed among treatments, but higher pH24(the detected pH value of loin muscle at 24h after post-slaughter) were observed in the two levels MT groups, and the <dpH(pH45-pH24) in high or low level MT group and the control were 0.38,0.28 and 0.58 respectively. The color of loin muscle detected at 45min post-slaughter were similar among the three groups, which displayed similar detected L, a and b values of loin muscle. At 24h post-slaughter, the a value of loin muscle in high (P<0.05) or low(P> 0.1) level MT group lower than that of the control, and the b values of loin muscle in high level MT group tend to be lower(p=0.07). The drip loss of loin muscle in high or low level MT group increased by 87.82% (P=0.083) and 33.33%(P>0.1) respectively compared to the control. There were no difference in marbling score, intramuscular fat contents and MDA levels of loin muscle among three treatments.It can be concluded that oral 3.0 mg/kg BW/d or 1.5mg/kgBW/d MT could affect performance, digestibility of feed CP and CEE for growing-finishing pigs. The oral MT could decrease the deposit of body protein and fat of pigs, which might improve the pH24 and drip loss of meat, decrease the a and b values of meat detected at 24h post-slaughter.更多还原