Freeman S R, Poore M H, Huntington G B, Middleton T F
Department of Animal Science, North Carolina State University, Raleigh 27695, USA.
J Anim Sci. 2008 Jan;86(1):146-58. doi: 10.2527/jas.2006-0698.
Finding appropriate disposal techniques for waste products is one of many challenges facing the poultry-processing industry. One waste generated in significant quantities is dissolved air floatation sludge, a product of wastewater treatment. Converting dissolved air floatation sludge into a dry feed product (meal) for incorporation into livestock feed appears to be a viable solution. This meal, called secondary protein nutrients (SPN), is high in protein (45% CP), fat (28% crude fat), and minerals. The protein consists of 85% B(2) and B(3) fractions, which are moderately to slowly degradable in the rumen, and therefore may potentially escape ruminal degradation and be available for digestion in the lower gastrointestinal tract. The goal of this research was to evaluate SPN as an alternative to traditional protein sources for ruminants by substituting it on an equivalent N basis for soybean meal in cattle and meat goat diets (0, 25, 50, 75, and 100% for cattle; 0, 20, and 40% for goats). When included in corn silage-based steer diets, increasing SPN resulted in linear and quadratic declines in both DMI and ADG (P < 0.001). Dry matter intake diminished with inclusion rates above 50%, and ADG were reduced after inclusion of SPN reached 25% of added N. Feed efficiency (the reciprocal of the efficiency of gain, which is represented by G:F) declined linearly (P < 0.001) with each incremental increase in SPN. Addition of up to 40% added N as SPN in goat diets caused no change in DMI, digestibility of DM or fiber, or N retention. Ruminal VFA concentrations showed little variation in either species. Increasing the proportion of SPN in the feed caused linear declines in ruminal NH(3) in steers (P < 0.001). Increasing SPN in goat diets, however, resulted in only a trend toward reductions of this parameter (P = 0.14). The decreases observed may have resulted from decreasing ruminal protein degradability or increasing fat caused by increasing the proportion of SPN in the feed. Urinary urea N as a percentage of urinary N showed significant declines in cattle, but not in goats, over the ranges of SPN offered. These results indicate that SPN can be included in diets for ruminants to supply up to 40% of supplemental N with little negative impact on animal performance.
为家禽加工行业的废弃物找到合适的处理技术是该行业面临的众多挑战之一。大量产生的一种废弃物是溶解空气浮选污泥，它是废水处理的产物。将溶解空气浮选污泥转化为用于掺入牲畜饲料的干饲料产品（粕）似乎是一个可行的解决方案。这种粕称为二次蛋白营养素（SPN），蛋白质含量高（45% 粗蛋白）、脂肪含量高（28% 粗脂肪）且富含矿物质。该蛋白质由85% 的B(2) 和B(3) 组分组成，这些组分在瘤胃中降解程度适中或缓慢，因此可能会逃过瘤胃降解，并可在下消化道进行消化。本研究的目的是通过在牛和肉山羊日粮中以等量氮为基础用SPN替代豆粕，评估SPN作为反刍动物传统蛋白质来源替代品的效果（牛的替代比例为0、25、50、75和100%；山羊为0、20和40%）。当将SPN添加到以玉米青贮为基础的阉牛日粮中时，随着SPN添加量的增加，干物质采食量（DMI）和平均日增重（ADG）呈线性和二次下降（P < 0.001）。当添加比例超过50%时，干物质采食量下降，当添加的SPN达到添加氮的25%后，平均日增重降低。饲料效率（增重效率的倒数，用料重比表示）随着SPN的每一次增加而呈线性下降（P < 0.001）。在山羊日粮中添加高达40%添加氮的SPN，对干物质采食量、干物质或纤维消化率以及氮保留均无影响。两种动物的瘤胃挥发性脂肪酸（VFA）浓度变化不大，但在阉牛日粮中增加SPN比例会导致瘤胃氨态氮（NH(3)）呈线性下降（P < 0.001）。然而，在山羊日粮中增加SPN仅导致该参数有下降趋势（P = 0.14）。观察到的下降可能是由于饲料中SPN比例增加导致瘤胃蛋白质降解性降低或脂肪增加所致。在所提供的SPN范围内，牛尿液中尿素氮占尿液氮的百分比显著下降，而山羊则没有。这些结果表明，反刍动物日粮中可以添加SPN来提供高达40%的补充氮，且对动物生产性能几乎没有负面影响。
