Studies on Reducing Nitrogen Excretion: Ⅰ. Net Energy Requirement of Finishing Pigs Maximizing Performance and Carcass Quality Fed Low Crude Protein Diets Supplemented with Crystalline Amino Acids

Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino acids （CAA）. A total of 216 （Exp. 1） and 360 （Exp. 2 ） barrows （ Yorkshire × Landrace× Duroc ） were allotted to one of six treatments （n =6）. The experimental diets were based on corn and soybean meal, and consisted of a high-CP diet that contained approximately 16% CP and 2.50 Mcal/kg of NE as well as five low-CP diets in which the CP level of the diet was reduced by approximately four percentage units but was supplemented with crystalline lysine, methionine, threonine, and tryptophan. The low CP diets provided 2.64, 2.58, 2.50, 2.42, or 2.36 Mcal/kg in Exp. 1 as well as 2.45, 2.40, 2.35, 2.30, or 2.25 Mcai/kg in Exp.2. In Exp. 1, a linear （P=0.03） increase in weight gain was observed with decreasing NE level while the ratio of gain to feed was unaffect- ed （P 〉 0.05） by NE level. There was a linear in-crease （P = 0.01 ） in the percentage of fat-free lean and a linear decrease （ P = 0.03 ） in the percentage of total fat with decreasing NE levels. In Exp. 2, a sig- nificant quadratic （ P = 0.03 ） effect of NE level was observed for weight gain. The ratio of gain to feed demonstrated a significant （P 〈0.01 ） quadratic effect with pigs fed 2.35 and 2.40 Mcal/kg of NE, Pigs fed the diet containing 2.40 Mcal/kg of NE had the lowest percentage of total fat （36. 95% ） and the highest percentage of fat-free lean （49.36%）. The overall results of these experiments indicate that feed- ing either a surplus or a deficiency of NE is detrimen- tal to both pig performance and carcass composition when low CP diets supplemented with CAA are fed. Our results indicate that when the CP content of the diet is reduced by four percentage units and the diet is properly supplemented with CAA, maximum per- formance and carcass quality will be obtained if the diet provides approximately 2.42 Mcal/kg of NE.

Effects of Fermented Nano Chinese Herbal Medicines Replacing Antibiotics on Production Performance and Carcass Quality of Growing-Finishing Pigs

[Objectives]To study the effects of fermented nano Chinese herbal medicines replacing antibiotics on the production performance and carcass quality of growing-finishing pigs.[Methods]200 healthy and disease-free Duroc-Landrace-Yorkshire(DLY)growing-finishing pigs with similar birth time(45±2 d)and body weight of about 31.5 kg were randomly divided into group A(fed with non-antibiotic basal diet),group B(fed with antibiotic basal diet),group C(fed with non-antibiotic basal diet+0.1%fermented nano Chinese herbal medicine preparation),group D(fed with non-antibiotic basal diet+0.3%fermented nano Chinese herbal medicine preparation)and group E(fed with non-antibiotic basal diet+0.5%fermented nano Chinese herbal medicine preparation).The experiment lasted for 90 d.At the end of the experiment,the production performance and carcass indicators were measured.[Results]Compared with group A,the final weight,average daily gain(ADG)and average daily feed intake(ADFI)of groups B,C,D and E were extremely significantly increased(P<0.01),while the feed-to-gain ratio(F/G)was extremely significantly decreased(P<0.01).Compared with group B,the ADG of group E was significantly increased(P<0.05),while the F/G was significantly decreased(P<0.05).Compared with group A,the slaughter rate and carcass length of pigs in groups B,C,D and E were extremely significantly increased(P<0.01);compared with group B,the slaughter rate of groups D and E was extremely significantly increased(P<0.01).[Conclusions]The fermented nano Chinese herbal medicine preparation has better effects in promoting growth than that of antibiotic additives,and it can significantly improve the carcass quality of growing-finishing pigs.

Effects of Low Protein Diets Supplemented with Ami-no Acids on Production Performance,Carcass Qual-ity and Input-output Ratio of Pigs

[ Objectives ] To study the effects of low-protein diets supplemented with amino acids on the production performance, carcass quality and input-output ratio of fattening pigs and growing-finishing pigs. [ Methods] Two studies were conducted on fattening pigs and growing pigs respectively. Pigs in two experimental groupswere fed with low-protein diets supplemented with amino acids and normal diets respectively, and the initial weight, final weight, feed consumption and car- cass index of the tested pigs were measured. [ Results] The average final weight of fattening pigs in test group was 2.4 kg lower than that in control group, while the difference was not significant （P 〉 0.05 ）. The average daily gain of fattening pigs in test group was 60 g lower than that in control group, indicating that low protein diets had a tendency to decrease the growth rate （P 〉 0.05 ）, and reduction of daily weight gain in low protein diet pigs reached 7.6%. The development of pigs in low protein diet group was poor, however, the difference was not significant. Carcass backfat thickness in low-protein diet group was slightly higher than that in control group, the difference was significant （ P 〈 0.05 ）. There was no significant difference in input-output ratio between low-protein diet group and control group. Finalweight of growing-finishing pigs in low-protein diet group was 3.22 % lower than that in control group, the average daily weight gainwas 6.91% lower than that in control group, feed intake in test group was 5.48% lower than that in control group, and difference between the two treatments was significant （P 〈 0.05 ）. Feed meat ratio in low-protein diet group improved, however, the difference was not significant（P 〉0.05）. [ Conclusions] Production performance of the pigs would be decreasedand the input-output ratio could not be improvedwhen the adding contents of crude protein in diets was reduced 3% -4%. Therefore, it is recommended that the crude protein level should be enough when pigs were fed with low-protein diets.

Effects of the ratio of unsaturated fatty acid to saturated fatty acid on the growth performance,carcass and meat quality of finishing pigs

The effects on finishing pigs(80-100 kg BW) fed diets supplemented with oil sources containing different ratios of unsaturated to saturated fatty acids(UFA:SFA ratio) were evaluated in 15 barrows and15 gilts(Duroc × Large White × Landrace). Three experimental diets were evaluated using a randomized complete block design, with broken rice, soybean meal and rice bran as the main feedstuffs in the control diet. Diets 2 and 3 consisted of the control diet supplemented with 3% oil, with UFA:SFA ratios of 2.5:1 and 5:1, respectively. Overall, there was no significant difference(P> 0.05) found in the average daily gain(ADG) of the pigs fed the treatment diets; however, the pigs fed the control diet and diet 3 had better(P < 0.05) feed conversion ratios(FCR) than the pigs fed diet 2. The pigs fed diets 2 and 3, which were supplemented with oil at UFA:SFA ratios of 2.5:1 and 5:1, had greater(P < 0.05) average daily feed intakes(ADFI) than the pigs in the control group. Additionally, it was found that the gender of the pigs had an effect(P < 0.05) on the FCR. Interaction effects between the experimental diets and the gender of the pigs(P < 0.05) were found in the ADFI and FCR. There were no significance differences(P > 0.05)among the treatment groups with regard to the carcass quality of the pigs; however, it was found that the gilts had greater(P < 0.01) loin eye areas than the barrows fed diets 2 and 3 and the loin eye area of pig fed diet 2 was the largest(P < 0.05); In the case of the meat quality parameters, it was clearly found that the pigs fed the control diet had a greater(P < 0.05) lightness(L~*) in the meat colour, and the lowest cooking loss was found in the pigs fed the diet supplemented with fat containing the UFA:SFA ratio of 5:1.Overall, the dietary treatment did not significantly affect the drip loss, thawing loss and shear force of the pork. In conclusion, the supplementation of oil with UFA:SFA ratios of 2.5:1 and 5:1 has the potential to improve pork quality.

Optimal Nutritional Levels for New America-Line Landrace Pigs during Fattening Period

[ Objective] To investigate the effects of different nutritional levels on production performance, apparent digestibility of nutrients and car- cass quality, and determine the optimal levels of energy, crude protein, calcium and phosphorus in diet for the Landrace pigs at fattening stage. [ Method] A total of 36 healthy Landrace pigs at the same parity with close weaning age and similar body weight [ （70 ± 1 ） kg ~ were selected. They were divided into nine experimental groups randomly. The experiment was carried out according to the L9 （3^4） orthogonal design. Then the production performance, apparent digestibility of nutrients and carcass quality were determined, respectively. The preliminary trial lasted for 7 d, and the trial lasted for 42 d. [ Result] The levels of crude protein and calcium had significant effects on the average daily gain （ P 〈 0.05）, and the energy level had extremely significant effects on the average daily gain （ P 〈 0.01 ）. The levels of energy, crude protein, calcium and phosphorus had effects on the apparent digestibility of nutrients in various degrees. The crude protein level had significant effects on the backfat P2 （P 〈 0.05） ; the energy level had significant effects on the backfat P2 and backfat P1 （P 〈 0.05） ; and the calcium level had significant effects on backfat P2 and lean meat percentage （P 〈 0.05）. [ Condasion] During the fattening period, the requirement of digestible energy, crude protein, calcium and phosphorus for the new America-line Landrace pills was 13.39 MJ/ka. 16.00%. 1.45% and 0.90%. respectively.

Economic Analysis of the Use of Restrictive Food Management in the Cultivation of Tilapia(Oreochromis niloticus)in a Recirculation System

The development of more adequate food programs regarding the intensity and duration of the restriction can be an effective way to minimize the effects of exaggerated food consumption and its negative consequences for the economy of the business.In this sense,juvenile Nile tilapia(Oreochromis niloticus)(137±3 g)were submitted to different feeding strategies in a recirculation system.Five feeding strategies were tested in subsequent weekly cycles:continuous feeding;skipping one meal a week;suppression of two non-consecutive meals a week;suppression of three non-consecutive meals a week;suppression of four non-consecutive meals a week.Productive performance,feed consumption in the post-restriction period and economic indicators were evaluated through projections and profitability analyses.Compensatory intake occurred in all tested groups,so that the total feed intake(FI)did not differ significantly between them(p>0.05).Moderate food restriction provided a linear increase in the relative gross margin for each treatment with each change in salary level,as well as greater profitability when compared to the respective control group(p<0.05).