Canola meal can be used as a source of protein in swine diets, but conventional canola meal contains less protein than soybean meal. In recent years, new varieties of canola have been developed with seeds that contain more protein and less fiber than conventional canola seeds. The meal from these new varieties of canola has a protein content similar to that of soybean meal.

Previous research at the University of Illinois demonstrated that diets containing at least 30 per cent high protein canola meal (CM-HP) or conventional canola meal (CM-CV) could be fed to nursery pigs without reducing growth performance.

It has not yet been determined how much soybean meal can be replaced by conventional or high protein canola meal in diets for growing-finishing pigs without affecting growth performance or carcass characteristics. Therefore, an experiment was performed to determine the optimum inclusion rate of high-protein and conventional meal in diets fed to growing and finishing pigs.

Experimental Design

A total of 21 diets were formulated. Pigs were fed grower diets from approximately 25 to 60kg, finisher-1 diets from 60 to 95kg, and finisher-2 diets from 95 to 130kg.

In each phase, seven dietary treatments were used. One diet in each phase was a control based on corn and soybean meal. Three diets contained CM-HP in an amount that replaced 33 per cent (low), 66 per cent (medium) or 100 per cent (high) of soybean meal. The remaining three diets contained low, medium or high levels of CM-CV.

All diets were formulated so that the canola meal-based diets contained similar amounts of digestible amino acids, energy and phosphorus as the soybean meal-based diets.

A total of 280 pigs with an average initial body weight of 27.4kg were used. Individual pig bodyweight was recorded at the start of the experiment and at the end of each phase. Daily feed allotments as well as feed left in the feeders were recorded and used to calculate average daily feed intake and gain:feed ratio.

At the conclusion of the experiment, 10 pigs from each treatment group were randomly selected and their carcass characteristics measured.

Growth Performance

Final bodyweight was the same in pigs fed the control diet, the low level of CM-HP and any level of CM-CV.

In pigs fed diets containing medium or high levels of CM-HP, final bodyweight was less than in pigs fed the control diet.

Average daily feed intake (ADFI) was greatest in pigs fed the high level of CM-CV; feed intake did not differ between the control diet and any of the other canola meal diets.

No differences in average daily gain (ADG) or the gain:feed ratio (G:F) were observed between pigs fed any of the diets.

Table 1. Growth performance of growing-finishing pigs fed experimental diets
	Diet
	Control	Canola meal, high protein			Canola meal, conventional
		Low	Medium	High	Low	Medium	High
Initial bodyweight, kg	27.38	27.27	27.57	27.33	27.48	27.35	27.52
Final bodyweight, kg	114.16a	111.14abc	108.77c	110.19bc	113.36ab	112.21ab	113.12ab
ADG, g/d	0.935	0.922	0.893	0.910	0.946	0.934	0.938
ADFI, g/d	2.494bc	2.516bc	2.463c	2.522abc	2.575ab	2.598ab	2.628a
G:F	0.375	0.367	0.363	0.362	0.367	0.352	0.358
a-c Within a row, means without a common letter are different (P<0.05).

Carcass Characteristics

The carcass characteristics evaluated in this experiment were: bodyweight of pigs before slaughter, hot carcass weight, loin muscle quality (including marbling score, colour score, loin eye area, and loin muscle pH), and backfat quality (including backfat depth, lightness, redness, yellowness, and firmness).

Most characteristics were not different among pigs fed soybean meal, CM-HP or CM-CV diets.

Lightness of backfat linearly decreased (P<0.05) with increasing inclusion level of CM-HP in the diets, and was reduced (P<0.05) in pigs fed the highest level of CM-HP compared with pigs fed soybean meal.

Yellowness of backfat was less (P<0.05) in pigs fed the high level of CM-HP or the low or medium level of CM-CV than in pigs fed the low level of CM-HP and the high level of CM-CV.

Overall, yellowness of backfat in pigs fed any level of CM-CV or CM-HP did not differ from that in pigs fed soybean meal.

Table 2. Carcass characteristics of growing-finishing pigs fed experimental diets
	Diet
	Control	Canola meal, high protein			Canola meal, conventional
		Low	Medium	High	Low	Medium	High
Body weight, kg	116.57	114.15	115.48	111.58	117.68	115.53	112.72
Hot carcass wt., kg	90.92	89.52	89.72	87.25	92.49	90.40	87.75
Loin muscle quality
Marbling score1	1.3	1.3	1.2	1.4	1.3	1.3	1.6
Colour score2	3.0	3.0	2.9	3.1	3.0	3.0	3.2
Loin eye area, cm2	50.8	51.6	51.2	52.2	50.0	49.5	49.5
Loin muscle pH	5.48	5.47	5.51	5.53	5.51	5.51	5.52
Backfat quality
Back fat depth, inch	0.80	0.70	0.67	0.70	0.75	0.70	0.74
Lightness (L*)3	49.30ab	51.35a	47.72bc	46.69c	49.52ab	47.73bc	47.81bc
Redness (a*)3	7.81	8.57	8.22	8.48	8.49	7.68	8.96
Yellowness (b*)3	2.93ab	3.54a	2.91ab	2.45b	2.22b	2.42b	3.54a
Firmness	2.8	2.4	2.9	2.7	2.7	2.8	2.9
a-c Within a row, means without a common letter are different (P<0.05). 1 Marbling score; 1 = 1 per cent i.m. fat to 10 = 10 per cent i.m. fat (NPPC, 2000). 2 Colour score; 1 = pale pinkish grey to white to 6 = dark purplish red (NPPC, 2000). 3 Greater L*, a*, and b* values indicate greater lightness, more intense red colour, and more yellow colour, respectively.

Key Points

Conventional canola meal can replace up to 100 per cent of soybean meal in growing-finishing pig diets without any detrimental effects on growth performance.

Replacing 66 per cent or more of soybean meal with high-protein canola meal may result in reduced growth performance.

The inclusion of conventional or high-protein canola meal does not significantly affect most carcass characteristics compared with pigs fed soybean meal.

This report is based on unpublished data by Tanawong Maison, Yanhong Liu, and Hans H. Stein.

February 2014