Semester

Summer

Date of Graduation

2009

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Joe Moritz.

Abstract

Experiments were conducted to improve the physical and nutritional quality of pelleted feed. One experiment focused specifically on improvement of pellet quality using functional muscle proteins. A second experiment examined the effects of increasing mixer-added fat (MAF) on feed manufacture variables, broiler performance variables and carcass composition. In experiment 1, muscle proteins (myofibrillar and sarcoplasmic) were recovered using isoelectric/solubilization precipitation, and a functional paste (TPP) was formed by mixing recovered proteins with typical surimi additives. Trout protein paste was included in broiler diets at 0, 2.5 or 5%. A tap water treatment (3.9%) was included to match the moisture added by the 5% TPP treatment. Pellet manufacture variables, nitrogen-corrected true metabolizable energy (TMEn) and true amino acid digestibility were evaluated. Muscle protein inclusion improved pellet quality considerably, however 5% TPP decreased pellet mill throughput and increased relative electrical energy usage (REEU). Protein paste may be included in broiler diets below 2.5% to improve pellet quality without negative effects on pellet mill throughput and digestibility. Improving pellet quality is important because industry pellet quality is often low and our lab has demonstrated positive effects of feeding high quality pellets to broilers. Further experimentation revealed that nutrient availability may be reduced by adjusting feed manufacture strategies to improve pellet quality. Experiment 2 was conducted in order to determine if increasing mixer-added fat would improve broiler performance by maintaining nutrient availability in broiler diets pelleted at high temperature. Increasing MAF reduced the electrical energy usage required to manufacture broiler feed. Feed intake and live weight gain were increased with enzyme addition. Enzyme addition, conditioning temperature and MAF interacted in their effects on feed conversion ratio. Overall, enzyme addition decreased feed conversion ratio, but the effect was greatest with 1% MAF and 82°C or 4% MAF and 85°C. Increasing MAF and conditioning temperature reduced abdominal fat pad yield. There was no difference in carcass, breast or leg yield due to any of the factors. It is likely that increased MAF improved exogenous enzyme retention and nutrient utilization by broilers. While striving to achieve high pellet quality, nutritionists should consider increasing mixer-added fat to increase profitability because of improved nutrient and exogenous enzyme retention.

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