Feeding Green Roasted Soybeans Does Not Affect Growth Performance and Carcass Quality

Table of Contents

1. Conclusion
2. Background
3. Objective
4. Results and Discussion

Conclusion

A small growth performance study was conducted to determine the effect of feeding green roasted soybeans to pigs. A total of 20 pigs were fed a finishing diet that contained either 15.0% regular roasted beans or 16.85% roasted green beans. No negative effects were observed when feeding green roasted beans to finishing pigs for any of the growth and carcass characteristics that were evaluated.

Background

The dry conditions we experienced in Ontario this summer, aggravated by long periods of extremely hot weather, sapped precious moisture and left many soybean fields without enough water to allow the soybeans to naturally reach maturity. The result is similar in some ways to an early frost, but without the usual problem of high moisture seeds that won't dry down. On harvest, producers saw dry soybeans that either had a green seed coat or were green throughout the entire soybean because of the presence of chlorophyll.

Whole soybeans typically contain 16 to 20 percent fat (dry matter basis). In the literature, drought-damaged soybeans, particularly green-colored beans, have been reported to have lower protein (anywhere from 25-38%) and fat (14-18%). Results to date, from this year's crop, indicate that protein and fat levels are running at the upper end of these ranges. However, due to variability in composition, soybeans should be analyzed for nutrient content before formulating rations.

A study conducted at South Dakota in 1992 determined the feeding value of frost-damaged soybeans for grow-finish pigs. In this study, diets were formulated based on analyzed nutrient content of the soybeans. Essentially, there was no difference in the feeding value of extruded frost-damaged soybeans or mature soybeans. Pigs fed extruded soybeans (either frost-damaged or mature) gained as fast as pigs fed a soybean meal-based diet, and there was no difference in carcass quality. Since nutritional value of frost-damaged soybeans may differ from drought-stressed soybeans, further research is necessary to determine the impact of high levels of green soybeans in swine rations on performance and carcass quality. Since there is the potential that the green chlorophyll may be incorporated into body fat, fat quality and colour should be monitored.

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Objective

· To assess the impact of feeding green soybeans on pig performance and carcass quality.

Experimental procedures

• Nutrient analyses were conducted on two samples of roasted green and regular soybeans. Both samples were roasted at Blythe Brae farms under very similar conditions.
• Two treatment rations were formulated on the basis of nutrient analysis of the roasted soybeans: roasted green vs. roasted regular soybeans (Table 1). Regular soybeans were included at 15% of the ration. The inclusion level of the green beans was slightly higher to supply a similar amount of fat from soybeans in the diet. These inclusion levels are slightly higher than the recommended maximum of 10%, to ensure that any negative impact of feeding green soybeans to finishing pigs on carcass quality could be noted. Rations were fed in a meal form.
• A total of 20 pigs were assigned to pens and treatments based on body weight, sex and litter. There were 2 pigs per pen, 5 pens per treatment and an equal number of barrows and gilts per treatment.
• Pigs were fed the rations ad libitum until they reached slaughter weight.

Observations and analyses

• Weekly body weight (per pig) and feed usage (per pen).
• Animals were observed daily for abnormalities in behavior or signs of disease or discomfort.
• Routine carcass evaluation: live body weight at slaughter, hot carcass weight, loin and fat depth, weight of cold carcass sides, meat colour, fat firmness and colour.
• Statistical analyses of all response variables

Results and Discussion

The pigs readily accepted and consumed the experimental diets. One pig on the regular beans showed lameness for about one week, which likely attributed to reductions in growth rate and feed intake in this pen of pigs. Data from this pen of pigs was excluded from statistical analyses of growth performance data.

As indicated in Table 2, pigs achieved high growth rates on both treatments and no differences (P>0.10) were observed between the two dietary treatments.

There were no effects of dietary treatments on any of the carcass characteristics that were evaluated. This was consistent with visual and subjective evaluation of carcass quality and meat color.

In conclusion, no negative effects were observed for any of the growth and carcass characteristics that were evaluated. There is no concern about feeding green roasted beans to pigs.

Acknowledgement:
Support provided by staff at the feed mill, swine unit and the abattoir at the University of Guelph is greatly appreciated.

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² Values are Least Square Means and adjusted for initial body weight in the statistical model
^# Initial body weight was not used as a co-variate in the model
⁺ SEM based on n= 5
^* Probability of treatment effect.

¹ Values are SAS Least Square Means and adjusted for Hot Carcass Weight in the statistical model.
^# Hot Carcass Weight was not used as a co-variate in the model.
⁺ SEM based on n= 20.
^* Probability of treatment effect.

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