Preliminary Study On The Requirement Of Dietary Crude Protein In Growing-finishing Huai Pigs

As a group of Huanghuaihai Black pig, Huai pig is a high quality lean-fat type locative Chinese pig breed. However, studies about nutrient requirement of Huai pig were relatively rare. In this study experiments were made to examine the effects of dietary crude protein level on the growth performance, biochemical indexes, crude protein digestion and carcass characteristics as well as meat quality in Huai pig.Studies about dietary crude protein requirements of growing-finishing Huai pig were consisited of three feeding experiments including growing period, early-finishing period and later-finishing period of Huai pig. In each experiment, forty-eight Huai pigs were selected and equally divided into three treatments with4replicates according to their sex type and body weight. Crude protein level of the diet of experimental pigs were set mainly refering to the growth performance and the results of our previous studies and also refering to the Chinese lean-fat type pig nutrition needs standards (1983and2004). Initial body weight, diet digestible energy and crude protein level and test period in three feeding experiments were:the first period(growing period), average initial weights of experimental pigs were21.27±3.02kg, dietary digestible energy was3.05MJ/kg, dietary crude protein levels were14.53%,15.55%and16.62%, respectively. Duration of the experiment was49days; the second period(early-finishing period), average initial weights of experimental pigs were31.21±2.19kg, dietary digestible energy was2.98MJ/kg, dietary crude protein levels were13.10%,14.19%and15.00%, respectively. Duration of experiment was66days; the third period(later-finishing period), average initial weights of experimental pigs were53.71±2.23kg, dietary digestible energy was2.92MJ/kg, dietary crude protein levels were11.96%,13.04%and14.16%, respectively. Duration of the experiment was138days. The whole study consisted of three parts was shown as following:1The effects of dietary protein levels on growth performance of Huai pigsAt the begin and end of the experiment, each pig was weighted without feeding in the morning. Feed consumption was weekly recorded.On the growing period, Dietary treatment did not affect (P>0.05) ADFI, ADG and feed gain ratio(F/G).Compared with middle and high protein treatment, ADFI and F/G of low protein treatment respectively tended to decrease7.88%and2.56%,4.19%and8.63%. ADG of low protein treatment tended to increase9.09%which compared with high protein treatment.Each treatment of feed cost was11.68Yuan/kg,12.13Yuan/kg and12.76Yuan/kg.On the early-finishing period, Compared with middle and high protein treatment, ADFI, ADG and F/G of low protein treatment tended to increase9.15%(P<0.05) and8.48%(P<0.05),10.00%(P<0.05) and15.79%(P<0.05),decrease0.02%(P>0.05) and6.80%(P<0.05). Each treatment of feed cost was10.37Yuan/kg,10.47Yuan/kg and11.30Yuan/kg.On the later-finishing period, F/G of middle protein treatment decreased3.60%, which compared with low protein treatment (P>0.05). ADFI and ADG of each treatment were no significant difference. Each treatment of feed cost was15.34Yuan/kg,14.90Yuan/kg and14.75Yuan/kg.2The effects of dietary protein levels on serum biochemical indexes and crude protein digestion in Huai pigsIn each period of experiments, samples of serum, feed and feces were taken.On the growing period, serum urea nitrogen of low protein treatment declined16.25%(P<0.05) compared with middle protein treatment, tended to decrease11.96%which compared with high protein treatment. Serum total protein, globulin, glucose, total choleasterol and trigly ceride of each treatment did no significant diference (P>0.05).On the early-finishing period, serum glucose and serum urea levels of low protein treatment tended to decrease18.77%(P>0.05) and increase4.78%(P>0.05) compared with middle protein treatment, to decrease28.34%(P<0.05) and5.46%(P>0.05) which compared with high protein treatment. Serum total protein, albumin, globulin, trigly ceride and total cholesterol were no significant difference between each treatment (P>0,05).On the later-finishing period, serum total protein, albumin and urea nitrogen of middle protein treatment tended to decrease1.40%(P>0.05) and10.06%(P<0.05) and increase19.61%(P>0.05) that compared with low protein treatment, to increase5.73%(P>0.05) and decrease5.22%(P>0.05) and8.55%(P>0.05) that compared with high protein treatment. There was no significance on each treatment of serum globulin, glucose, trigly ceride, total cholesterol.On the growing period, low protein treatment crude protein digestion decreased significantly which compared with high protein treatment. The highest digestion of crude protein in each period was76.54%,76.45%and73.84%, respectively. 3The effects of dietary protein level on carcase characteristics and meat quality of Huai pigAt the end of feeding experiment of later-finishing Huai pig, four pigs in each treatment were selected and slaughtered. Carcass characteristics, meat quality and the contents of inosinic acid, cholosoterol and fatty acids of longissimus muscle were determined.Compared with low and high protein treatment, crude fat, cholesterol, shear stress and arachidic acid of longissimus muscle of middle protein treatment decreased17.98%(P>0.05) and26.52%(P<0.05), decrease11.02%(P>0.05) and42.98%(P<0.05), increase16.52%(P<0.05) and19.02%(P<0.05), increase8.57%(P>0.05) and40.74%(P<0.05). Linolenic acid in high protein treatment was significantly higher than in low protein treatment. There were no significant differences in other indexes.Collectively, on the growing period, serum urea nitrogen in low protein treatment was significantly lower than in middle protein treatment. On the erarly-finishing and later-finishing period, serum urea nitrogen was no significance between every treatment. On the growing and early-finishing period, crude protein digestion of low protein treatment was higher than other treatments. On the later-finishing period, dressing percentage, lean meat percentage, back fat thickness, subcutaneous fat percentage and carcass length of each treatment were no significant differences. ADG and F/G for reference, the dietary crude protein requirements of three period of growing-finishing Huai pig were14.53%,13.10%and13.04%, respectively.