| Two experiments were designed in this study to investigate the effects of improving the lactose energy level on performance, digestibilities and metabolizablities of nutrients, protein and energy deposition, protein turnover and heat production in colostrum-derpived piglets during neonatal period. The objective is to investigate lactose nutritional efficiency and partition effects in neonatal piglets.Experiment 1, eighteen Large WhitexMeishan crossbred neonatal pigs (averagely weighed 1.27kg) from 5 litters were used at 0 day and divided into 3 groups to determine: Basic diet (NL), High Lactose (HL) and Suckling (S), each group has 3 repetition, 2 for each repetition, amounts to six. Suckling piglets were nursed by the sow. HL and NL were artificially fed with liquid diet at 3-hr intervals. The composition of NL diet (DM19.46%, CP5.59%, fat 8.01%, Lactose 5.15%, GE5.33MJ/kg), were close to sow milk. And, the lactose level of HL diet was improved to 9.86%, the content of CP and fat were same as NL diet. Animals were placed in individual cages in an environmentally controlled room and had ad libitum access to diets. The experiment ended when the neonatal pigs were 28 day of age to evaluate utilization of ingested nutrients and energy by neonatal piglets and effects of higher level lactose on performance of pigs. Those result indicated that:1. The piglets aritificially reared grow faster than sow-suckled piglets. HL and NL piglets' weight reached 9.43kg and 10.48kg at day of 28 age, respectively, which exceed that sow-suckled littermates by 42.66%-58.37%. Piglet growth can be greatly accelerated by the feeding of liquid diets.2. Average daily gain of piglets were higher than that pigs fed NL diet by 27.04%, 12.7% respectively at 1st week and during whole neonatal period, which resulted in body weight of 28th day age of 10.48kg, improved by11.1%.3. Piglets fed HL diet consumed approximately 23.19%, 11.76%, 9.71% and 18.36%greater GE per day than the piglets fed NL diet on 1st, 2nd, 3rd, 4th week, respectively. Nitrogen and fat conversion efficiency were improved by 12.5%, 18.2% respectively at lsl week.4. Age and lactose energy had no significant effect on the digestibilities of DM, GE, CP, fat, lactose during the neonatal period. The digestibilities of all of the nutrients were not lower than 97%.5. The protein biological value (BV) was improved by higher lactose energy, but not significantly. The relationship between BV and age of week showed that: HL: BV =86.9833+3.1400w-1.3300w2 (R2 =0.9472, P =0.010, n =12) NL: BV =82.3417+5.0150w-1.6250w2 (R2 =0.9633, P=0.084, n =12) Experiment 2 On the condition of equal nitrogen and energy content between the diets, the objectives were to investigate improving lactose energy level on performance, nutrients utilization, body composition, protein turnover and energy metabolism, to further explore the effects of lactose.Twenty-two Large WhitexMeishan crossbred neonatal piglets (averagely weighed 1.5kg) from 5-6 litters were used. 3-4 pigs were removed from each sow immediately after birth, and placed in cage, equipped with a tray for excreta collection in temperature-controlled room (34-28 °C). After birth, four piglets were killed to determine initial body composition. The remaining eighteen piglets were allotted to treatments consisting of bovine colostrums that was formulated to contain high or normal lactose. Each treatment has 9 pigs, and each treatment has 3 experimental periods, including the first week (0-7d), the second week (8-14d) and the third week (15-21d). The content of GE and CP were same as Experiment 1, fat and lactose offer 44.70% and 29.77% of gross energy respectively. Those piglets access ad libitum to diets. The aim of the study is to investigate performance, digestion of nutrients among weeks 3 piglets were used to determine whole body protein-turnover at 6-7, 13-14, 20-21day separately for each group. Afterwards, the piglets were slaughtered to determine the body composition. The results showed as follow:1. Piglets fed with improving energy supply from lactose grow remarkably faster than that of NL piglets at 1st week by 14%.2. The average daily feed intake, DM, GE, and CP intake were not significantly difference between HL and NL group. However, nitrogen, GE and fat conversion efficiency offed HLdiet were notably promoted by 5.82%, 10.96%, 28% respectively.3. The digestibilities of the DM, GE, CP, fat, and lactose were not significantly influenced by age of the piglets and lactose energy level, digestibilities of those nutrients were all up to 98% from 1st -3rd week among group.4. High lactose energy level improved protein biological value (BV), but not significantly. BV of the diets declined with age of week of piglets following as quadratic equations:HLifi: BV=91.4976+4.3813W-2.2035W2 (R2 =0.8532, n=16, P=0.000) NL*&: BV=88.4255+8.5034W-3.6222W2(R2 =0.7584, n=17, P=0.000)5. High lactose energy supply reduce whole body nitrogen flux 24.47%, FSR 9.32%, FBR 9.95%, resulted in promoting FAR16.15%, declining heat production relative to protein deposition 50.48% at 1st week. Thereafter, experiment demonstrates that energy source in diet does not alter FBR, FAR, and heat production among group from 2nd to 3rd week.6. Whole-body protein FSR and FBR declined following a quadratic curvilinear pattern with age.FSR: HL: FSR= 27.3300-8.4517W+1.2983W2 (R2=0.646, n=9, P=0.038)NL: FSR= 46.5933-20.343W+3.2567W2 (R2=0.981, n=9, P=0.000)FBR: HL: FBR= 15.1600-4.3717W+0.6817W2 (R2=1.000, n=9, P=0.102)NL: FBR= 38.6267-21.005W+3.7917W2 (R2=0.959, n=9, P=0.000)FAR: HL: FAR= 12.1733-4.0850W+0.6183W2 (R2=0.871, n=9, P=0.002)NL: FAR= 7.9767 +0.6483W-0.5317W2 (R2=0.946, n=9, P=0.000)The following conclusions can be drawn from all the above results:Lactose showed that protein sparing and energy partition effect at 1st week of piglet life. High lactose energy level decreased whole body FBR mainly, and FSR, resulted in increasing FSR, declined nitrogen flux and reduced heat production relative protein deposition, caused to increasing average daily gain, improving protein deposition and reduced heat production at lsl week life. During neonatal period, the digestibilities of DM, GE. CP, fat, and lactose of diets were not influenced by age, weight, and energy source. We suggest that increasing the lactose content in liquid can improve ADFI and gross energy, and the practice may be an efficient method for improving performance in neonatal piglets, get heavier weaned body weight.
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