Purpose To evaluate the effects of substituting walnut cake for soybean meal on growth performance, carcass traits, muscle quality, and economic benefits of a new line of Diqing Tibetan pigs, providing empirical support for the development of geographically-specific unconventional protein feed resources.
Methods A total of 72 barrows of the new line of Diqing Tibetan pig with an average body weight of (69.60±1.60) kg were randomly divided into four groups, and were fed with walnut cake instead of soybean meal at 0% (control group), 25% (experimental group Ⅰ), 50% (experimental group Ⅱ), and 100% (experimental group Ⅲ) substitution levels, respectively. The fattening process was concluded when the average body weight reached approximately 130 kg, and then the growth performance, carcass performance, muscle quality, and economic indicators are measured.
Results The average daily feed intake of group Ⅲ was extremely significantly higher than that of the control group (P<0.01), while average daily gain of group Ⅱ was extremely significantly higher than that of group Ⅲ (P<0.01). The average backfat thickness of the experimental groups was lower than that of the control group, with groups Ⅱ and Ⅲ reaching an extremely significant level (P<0.01); the backfat thickness between the 6th and 7th ribs of groups Ⅱ and Ⅲ was significantly lower than that of the control group (P<0.05). The small intestine length of all experimental groups was extremely significantly increased (P<0.01); the large intestine length of groups Ⅱ and Ⅲ was significantly increased (P<0.05, P<0.01). The lean meat percentage of group Ⅱ was significantly increased (P<0.05), and the fat percentage of group Ⅱ and Ⅲ was extremely significantly decreased (P<0.01). The unit feed cost of the experimental groups was reduced by 1.16% to 9.91%, and the output-to-input ratio was increased by 5.38% to 16.94%.
Conclusion Replacing soybean meal with walnut cake significantly promotes intestinal development, reduces body fat deposition, and improves carcass composition in the fattening new line of Diqing Tibetan pigs. Considering growth performance and the output-to-input ratio, the optimal substitution rate of walnut cake is 50%.
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