The effect of menhaden fishmeal on performance, carsass and sensory characteristics and fatty acid composition of finishing swine

Eighty (80) Landrace X Hampshire X Duroc crossbred pigs weighing approximately 65 kg were placed on a feeding trial which was terminated when pigs achieved a final weight of approximately 105 kg. Diets consisted of corn-soybean or com plus soybean and fishmeal present at 6%, 8%, 10%, or 12% of the diet. The highest level completely replaced soybean in the diet.

Throughout the experimental period feed samples of each treatment were collected and composited. The proximate composition, gross energy, calcium and phosphorus of each diet were determined.

Forty animals were slaughtered at the end of the feeding trial and carcass evaluation was done by a trained evaluator. Roasts, subcutaneous fat, and longissimus dorsi muscle samples were taken for sensory and chemical analyses. Selected fatty acids were determined by a gas chromatographic method using tricosanoic acid (23:0) as an internal standard. Thiobarbituric acid numbers were also determined on meat, fat and feed samples.

The results of this study indicate that performance of pigs during the finishing period was optimized when pigs were fed diets containing less than .8% fish oil from menhaden fish meal (MFM) at 8% of diet. The feeding of fishmeal at 8% of the diet elicited optimum performance during the first 6 weeks of the trial. The inclusion of up to 10% Menhanden fishmeal in the diet of finishing pigs did not result in the development of detectable off flavors. This research suggests that levels of 20:5w3 in feed greater than 739 ug/.5g lipid may enhance oxidation and rancidity in pork muscle and fat. In the future, improved methodology may permit stabilization of fish oil and therefore may reduce problems associated with oxidative rancidity and off flavors resulting from the inclusion of high levels of fishmeal in finishing pig diets.