Live Performance of Weaner Pigs fed Canola Seed

C.J. Brewster, G.R. Furley1, D.P. Collins1, R. Jeffrey2, N.L. Gallagher2, P.J. Cartwright3, R.J. Mailer4, P.C. Wynn2 and L.R. Giles1

NSW Agriculture, Yanco Agricultural Institute, Yanco, NSW 2703. 1NSW Agriculture, Elizabeth Macarthur Agricultural Institute, Camden, NSW 2570. 2 Faculty of Veterinary Science, The University of Sydney, Camden, NSW 2570. 3Pine Park’, Temora, NSW 2666. 4NSW Agriculture, Wagga Wagga ARI, Wagga Wagga, NSW 2650.

Whole canola seed contains up to 40% oil and a reasonable quality protein. Canola seed has potential as an alternative energy and protein source in pig diets depending on price and availability of traditional ingredients. However, canola seed contains small amounts of anti-nutritional factors (e.g., glucosinolates and sinapine) that may depress thyroid function and/or affect food intake in pigs. This study was designed to assess the growth and metabolic implications of using milled canola seed in weaner pig diets.

Thirty male Large White x Landrace crossbred piglets, 8.5 * 0.30 kg live weight (mean ± SEM), were allocated to a randomised block experiment consisting of three dietary treatments each containing 0.8 g available lysine and 15 MJ DE per kg. The three diets included a). a triticale-based diet supplemented with a solvent extracted canola meal (64.2 g/kg) and canola oil (30 g/kg); b). a triticale-based diet supplemented with milled canola seed (100 g/kg); and c). a commercial diet (Eziwean; Ridley AgriProducts) that contained no canola ingredients. Levels of protein (215g/kg), oil (400g/kg) and glucosinolates (7 mmol/kg) were estimated in the whole canola seed using near-infrared reflectance and used in diet formulation.

The pigs were housed in individual weaner cages. Food and water was available ad libitum and room temperature was maintained at 27oC. The experiment was conducted for 21 days. Measurements included food intake and live weight at the start and finish of the experiment. At the end of the experiment a blood sample (8 ml) was collected from each pig to assess thyroid activity (T3, tri-iodothyroxine and T4, thyroxine).

Table 1. Mean (± SEM) live performance1, and serum concentrations of tri-iodothyroxine (T3) and thyroxine (T4) for piglets offered diets containing either canola meal + canola oil, milled canola seed or a commercial diet containing no canola.

Treatment	Canola meal + oil	Milled canola	No Canola	SEM	Sig²
Daily intake638 (g)	638	644	767	29.0	**
Daily gain (g)	462	462	568	17.0	**
Feed gain (g/g)	1.46	1.47	1.41	0.040	NS
T3 (ng/ml)	1.1	1.0	1.3	0.05	**
T4 (ng/ml)	43.4	34.6	59.6	2.30	*

1Mean live performance adjusted for initial live weight. 2Significance. a,b,cMeans in rows with different superscripts differ significantly at *P<0.05 or **P<0.01.

There was no significant difference in daily gain or feed:gain between pigs fed diets containing either canola meal plus canola oil or milled canola seed. However, daily feed intakes, and consequently growth rates were depressed by 20% in pigs fed diets containing canola ingredients compared to the commercial diet with no canola ingredients. Pigs fed diets containing canola ingredients also exhibited a significant decline in serum T3 and T4 concentration compared to pigs fed the commercial diet. Further research is required to establish the significance of thyroid function on feed intake and growth in pigs fed diets containing canola meal and/or canola seed.

Canola seed is an acceptable alternative energy and protein source for pig diets. However, the results suggest that anti-nutritional factors in canola affect thyroid function in weaner pigs, reducing serum T3 and T4 concentrations, which in turn may affect food intake. Nutritionists need to consider the metabolic and growth implications of including canola meal and/or canola seed in weaner pig diets.
Supported in part by the Pig Research and Development Corporation.