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Matching Livestock Systems with Available Resources |
MEKARN Regional Conference 2007 |
This study was implemented to compare protein metabolism of growing pigs fed with a diet of ideal balance among indispensable amino acids and another diet of imbalanced ratios amongst indispensable amino acids. The experiment was divided into two turns. A total of ten male castrated pigs (Yorkshire x Mong Cai) with identical body weight (41,95 kg/pig in average) were randomly alloted into ten metabolism cages. Two diets with identical crude protein (CP) levels were formulated and used in the experiment. Diet 1 (TN) was formulated with ideal amino acid pattern according to Wang and Fuller (1989). Diet 2 (ĐC) was formulated with imbalanced amino acid pattern. Diet TN was formulated based on diet ĐC, however, crystalline amino acids (L-Lysine, L-Threonine and L-Tryptophan) were added to the diet TN to adjust the amino acid pattern to the ideal one. ME and CP% in these two diets were identical (11.63 MJ ME/kg for the both diets, 12.3% CP for diet TN, 11.90%CP for diet ĐC). Feed ingredients were rice bran, corn meal, fish meal, soybean meal, cassava root meal, mineral and vitamin premix. All feed ingredients were bought one time at the beginning of the experiment to make sure that quality and quantity of protein in the ingredients and diets were identical from beginning to the end of the experiment. After the first turn, five pigs of the trial 1 (TN) were used for trial ĐC and vice versa five pigs of the trial ĐC were used for trial TN. Thus, replicates for a trial were ten (n = 10).
The experiment was implemented according to standardized experiment in nitrogen balance studies. It lasted for twelve days in which the first seven days were adaptation period and the last five days were the period for colleting faeces and urine amount and sampling. Faeces and urine were collected and weighed two times/day. 50ml H2SO4 20% were added to bucket for urine collection to keep pH of the urine always < 2 to avoid losses of urine through NH3 volatilisation. 10% of total weight of faeces at each collection were sampled. 5% of total weight of urine at each collection were sampled. After sampling, faeces and urine were stored at -20oC. They were homogenized again before chemical analyses. From raw data, the following criteria were drawn out: feed intake, daily weight gain of pigs during collection period, total nitrogen intake, total nitrogen excretion in faeces, total nitrogen excretion in urine, daily nitrogen (protein) deposition, apparent faecal nitrogen digestibility, ratio of nitrogen deposition to total nitrogen intake (PPV), ratio of total nitrogen excretion to nitrogen intake, ratio of total faecal nitrogen to total nitrogen intake, ratio of total urine nitrogen to total nitrogen intake. The experimental data were statistically analysed with SPSS for windows (version 10.0). T-test was used to separate means with confidence level of 95%. Means were considered as statistical difference if p ≤ 0.05.
Results from this study showed that daily feed intake and body weight gain in the collection period of pigs fed diet of ideal amino acid pattern trended to be higher than those of pigs fed diet of imbalanced one (feed intake: 1522.8 vs. 1433.6 g DM/ pig/day; daily weight gain: 650.0 g/pig/day vs. 530.0 g/pig/day). Daily protein deposition of pigs fed diet TN was higher than this of pigs fed diet ĐC (114.7 g/pig/ day vs. 94.39 g/pig/day, respectively). This difference is statistically significant (p < 0.001). The difference in daily protein deposition of pigs was not caused by increment of total protein digestibility. The balance amongst indispensable amino acids in the diet TN leading to a reduction in nitrogen excretion in urine is the cause of the increment in daily protein deposition of pigs fed TN diet. This was demonstrated by the identical digestibility of total protein but the ratio of urine nitrogen to total nitrogen intake of pigs fed diet TN was significantly lower (p < 0.05) than that of pigs fed ĐC diet (0.27 vs. 0.33, respectively).
It can be concluded that efficiency of converting feed proteins to body protein (PPV) of pigs fed diet of ideal amino acid pattern is significantly higher (10.42% higher) than that of the same pigs fed diet of identical protein but imbalanced amino acid pattern. At the same crude protein level in the diets, when amino acids in diet are adjusted to ideal pattern, daily protein deposition of pigs will be increased whereas total nitrogen excretion will be reduced because of a reduction in daily total urine nitrogen. The ideal amino acid pattern should be used as a tool in diet formulation for pigs to increase productivity, lean meat and reduce nitrogen pollution from pig production.