Practical dietary levels of canola oil and tallow have differing effects on gilt and barrow performance and carcass composition

Abstract

Previously we demonstrated that barrows produced leaner carcasses when fed 5% versus 2% canola oil. The present trial was conducted to determine if the same would be true for gilts or when feeding beef tallow (a source of saturated fatty acids). Four diets were fed (2 or 5% canola oil or digestible energy equivalents of tallow), and 27 gilts and 27 barrows were fed each diet. Experimental diets were fed from 49.4 to 113.5 kg body weight. Barrows fed 2% canola oil had similar average daily gains (ADG) relative to gilts (P > 0.05) fed any diet, but grew slower than barrows fed 5% canola oil (0.99 vs. 1.08 kg d-1; P < 0.05) and tended to have lower ADG relative to barrows fed diets containing tallow (P < 0.10). Barrows fed 2% canola oil had poorer feed conversion efficiency (kg feed kg-1 gain) relative to animals fed any other diet (P < 0.05). For barrows, feeding the 2% canola oil resulted in more subcutaneous fat relative to feeding 2.16% tallow (+18 g kg-1 lean cuts; P < 0.05), but the anticipated decrease in barrow subcutaneous fat when feeding 5% canola oil was not significant (-4 g kg-1 lean cuts; P > 0.05). No practical differences in pork quality were noted when feeding any diet, but backfat became more unsaturated when feeding canola oil and led to softer backfat (P < 0.05). When feeding canola oil to barrows, it may therefore be more practical to feed higher levels than lower levels due to improvements in animal performance without changes in body composition, but care must be taken so that fat softness does not become an issue. Key words: Canola oil, tallow, barrow, gilt, carcass composition, average daily gain, feed conversion