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The isoelectric behavior of food proteins has been well characterized in the food science literature. The isoelectric point (pI) of a protein is a pH at which the protein maintains a zero net electrostatic charge. In this state, protein-protein hydrophobic interactions overcome protein-water electrostatic interactions and the minimum solubility of proteins results. Consequently, several food science laboratories have begun active research on the application of the pI to recover functional muscle proteins, particularly fish myofibrillar proteins. Fish stocks are declining and several fisheries are currently over-exploited and may collapse by mid century. Fish processing by-products are considerable and include heads, frames, viscera, and etc. By-products are land-filled, ground-and-discarded or otherwise diverted from human consumption. By-products retain ample muscle proteins and oil. The oil contains omega-3 fatty acids. Due to the lack of commercially available technology to recover proteins and lipids from fish processing by-products or underutilized aquatic species, this tremendous resource is currently unavailable for human consumption. Fish proteins and oil from otherwise low-value by-products can be recovered using isoelectric solubilization/precipitation with recovery yields of approximately 90%. Recovered proteins and oil retain functionality and nutritional value for human food products. This article reviews the fundamental biochemical principles of food proteins and lipids as well as their structure and interaction with water in relation to the isoelectric behavior. Additionally, the most recent developments regarding application of isoelectric solubilization/precipitation to recover functional and nutritious proteins and oil from fish processing byproducts and underutilized aquatic species are addressed.

Primary Audience: Feed Mill Managers, Live Production Personnel, Nutritionists SUMMARYMeat birds fed high-quality pellets exhibit advantages in rate and efficiency of growth over birds fed poorer quality pellets. However, the associated feed manufacturing cost and reduced production rates to obtain high-quality pellets are viewed by the industry as offsetting the benefits in broiler performance provided by high-quality pellets. With the combination of increased costs for utilities in the feed mill and for feed ingredients, strategies are needed to conserve milling costs while optimizing the efficiency of broiler growth. In this study, we evaluated the effects of feed form on live performance and meat yield of broiler chickens during a 42-d production period. Four treatments were provided from 18 to 42 d of age: 1) high-quality pellets (88% pellet durability index), 2) low-quality pellets (66% pellet durability index), 3) a proportion of the formulated corn added post-pellet (89% pellet durability index), and 4) mash (corn was ground via a roller mill). Broilers fed the high-quality pellets had higher cumulative BW gain and consumed more feed than birds fed low-quality pellets. Mash-fed broilers had poorer growth performance and less meat recovery than birds in the other treatments. Adding corn post-pellet resulted in broilers having similar performance and meat yields compared with those fed high-quality pellets. In this study, we confirm that adding corn post-pellet does not negatively affect growth performance and meat yield. Feeding broilers high-quality pellets provides a benefit in growth rate over feeding low-quality pellets by increasing feed consumption.Means within a column without a common superscript differ (P < 0.05). 1 Values are least squares means of 8 replicate pens with 12 broilers per pen. 2 Yields are defined as grams of tissue/100 g of BW.

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The metabolisable energy of corn can vary by more than 400 kcal/kg in poultry. Chemical, rather than physical kernel characteristics may be more accurate for predicting nutrient and energy availability. Factors that affect variability include genetics, agronomic conditions, proximate composition, pre-and post-harvest processing variables, and the presence of anti-nutritional factors. Variation in the nutritional value of corn may be better identified when the relationship between protein and starch are considered rather than by total content or predicted digestibility values alone. Recently, the use of near-infrared reflectance spectroscopy has made rapid valuation of corn based on chemical kernel characteristics a possibility. Prediction equations may be useful for formulating diets to more closely approximate actual metabolisable energy content for poultry.

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Primary Audience: Feed Manufacturers, nutritionists, Researchers SUMMARYThe prices of fat and diet formulations with exogenous enzymes have caused a reduction in the amount of fat added to broiler diets. Although diets may be cheaper to produce, there is potential for nutrient and exogenous enzyme destruction with low inclusions of fat (0.5 to 1%) because of frictional heat and shear forces produced in the pellet die. Additionally, much of the added fat may be applied by using postpellet spray application, and the amount of fat added in the mixer may become negligible. Thermal inactivation of exogenous enzymes and the occurrence of unfavorable reactions (e.g., Maillard reaction, protein cross-linking) may be abated by increased levels of fat included at the mixer before pelleting [i.e., mixer-added fat (MAF)]. in this study, we evaluated the effects of MAF (1, 2.5, or 4%) with or without the addition exogenous enzymes (carbohydrase, protease, and phytase), and at different conditioning temperatures (82 or 85°C), on finisher phase feed manufacture, broiler performance variables, and processing yields. increasing MAF reduced the electrical energy usage required to manufacture broiler feed (P < 0.02). Feed intake during the grower and finisher phases and live weight gain during the finisher phase were increased with enzyme addition (P < 0.001). Enzyme addition, conditioning temperature and MAF interacted in their effects on FCR from 23 to 38 d of age (P = 0.009). Overall, enzyme addition decreased FCR, but the effect was greatest with 1% MAF and 82°C or 4% MAF and 85°C. increasing the MAF and conditioning temperature reduced abdominal fat pad yield (P < 0.03). no difference in breast or leg yield was due to any of the factors (P > 0.05). it is likely that increased MAF improved exogenous enzyme retention and nutrient utilization by broilers. Subject to current fat prices, increasing MAF may reduce the total cost of broiler production, particularly when the reduction of electrical energy usage is considered.

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