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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Agroecosystems Management Research » Research » Publications at this Location » Publication #335390
Title: Nutrient composition, digestible and metabolizable energy content, and prediction of energy for animal protein by-products in finishing pig diets

Author
item Kerr, Brian
item JHA, RAJESH - University Of Hawaii
item URRIOLA, PEDRO - University Of Minnesota
item SHURSON, GERALD - University Of Minnesota

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2017
Publication Date: 6/8/2017
Citation: Kerr, B.J., Jha, R., Urriola, P.E., Shurson, G.C. 2017. Nutrient composition, digestible and metabolizable energy content, and prediction of energy for animal protein by-products in finishing pig diets. Journal of Animal Science. 95:2614-2626. doi: 10.2527/jas.2016.1165.

Interpretive Summary: Rendering is a process of grinding, heating, partial separation of fat, and drying of a wide array of inedible animal and carcass tissues, including blood, feathers, muscle, bones, fat, and offal. Within the U.S., the rendering industry processes over 22 million tons of raw animal components annually. Of the 4.5 million tons of animal derived protein products produced, about 85% are utilized as animal feed ingredients, and is an essential role that the rendering industry plays for achieving environmental and economic sustainability of animal agriculture. Animal protein by-products are concentrated sources of energy, AA, and minerals, which can be an important feedstuff in swine feed formulations depending upon its price relative to competing ingredients, but additional information is needed on their energy value to growing pigs. Consequently, the current study was conducted to determine the digestible and metabolizable energy content of animal protein by-products varying in chemical composition, and to develop energy prediction equations based upon animal protein by-products' chemical composition. Data from this experiment indicate that the energy value of animal protein by-products varied substantially among the animal protein by-products and sources, and that a variety of nutritional components can be used to accurately predict this energy value for finishing pigs. This information is important for nutritionists at universities, feed companies, and pig production facilities for the determination of the energy value of commonly used animal protein by-products in feed formulations, and provides a basis from which to assess their economic value.

Technical Abstract: An industry survey and an animal experiment were conducted to evaluate compositional variability and DE and ME content of animal protein by-products, and to generate equations to predict DE and ME content based on chemical analysis. For the 220 samples collected, the greatest concentration of CP was observed in blood meal (BM) and least in meat and bone meal (MBM), the greatest concentration of ether extract (EE) was in meat meal and least in BM, with ash content greatest in MBM and least in BM; with Ca and P levels being 36.1 and 16.3% of the ash content, respectively. For the balance experiment, a corn-soybean meal basal diet was used with test diets formulated by mixing 80% of the basal diet with 20% of the animal protein by-product, except for BM which was included at 10 and 20% of the test diets. Ten groups of 24 gilts (final BW = 92.5 ± 7.4 kg) were used, with gilts randomly assigned to the test or the basal diet within each group, resulting in 16 replications per animal protein by-product or basal diet, except for BM determinations (20 replications). Gilts were placed in metabolism crates and offered 2.4 kg daily of their assigned diet for 13 d, with total collection of feces and urine during the last 4 d. Gross energy was determined in the diets, feces, and urine to calculate DE and ME content of each ingredient by the difference procedure, using DE and ME content of the basal diet as covariates among groups of pigs. The DE content of the animal protein by-products ranged from 5,367 to 2,567 kcal DE/kg of DM, and ME ranged from 4,783 to 2,340 kcal ME/kg DM. Using all animal protein by-products, the best fit equations were as follows: DE, kcal/kg DM = -2,468 + (1.26 × GE, kcal/kg DM), with R2 of 0.84, SE = 390, and P < 0.01; ME, kcal/kg DM = -2,331 + (1.15 × GE, kcal/kg DM), with R2 of 0.86, SE = 327, and P < 0.01). The ATTD of Ca and P were also determined using the difference procedure, with the average ATTD of Ca and P for the animal protein by-products, excluding BM and FM, being 27.1 and 39.1%, respectively. These data indicate that DE and ME varied substantially among the animal protein by-products and sources, and that a variety of nutritional components can be used to accurately predict DE and ME for finishing pigs. In addition, it appears that high dietary inclusion rates of animal protein by-products may result in low ATTD estimates of Ca and P, which may be due to excessive concentrations of total Ca and P affecting digestibility.