A comparison of average daily gain,apparent digestibilities,energy balance,rumen fermentation parameters,and serum metabolites between yaks(Bos grunniens)and Qaidam cattle(Bos taurus)consuming diets differing in energy level

Yaks(Bos grunniens),indigenous to the harsh Qinghai-Tibetan Plateau,are well adapted to the severe conditions,and graze natural pasture without supplements all year round.Qaidam cattle(Bos taurus),introduced to the Qinghai-Tibetan Plateau 1,700 years ago,are raised at a lower altitude than yaks,provided with shelter at night and offered supplements in winter.Based on their different backgrounds,we hypothesized that yaks have lower energy requirements for maintenance than cattle.To test this hypothesis,we measured average daily gain(ADG),apparent digestibilities,energy balance,rumen fermentation parameters,and serum metabolites in growing yaks and cattle offered diets differing in metabolizable energy(ME)levels(6.62,8.02,9.42 and 10.80 MJ/kg),but with the same crude protein concentration.Six castrated yaks(155±5.8 kg)and 6 castrated Qaidam cattle(154±8.0 kg),all 2.5 years old,were used in 2 concurrent 4×4 Latin square designs.Neutral and acid detergent fiber digestibilities were greater(P<0.05)in yaks than in cattle,and decreased linearly(P<0.05)with increasing dietary energy level;whereas,digestibilities of dry matter,organic matter,crude protein and ether extract increased(P<0.05)linearly with increasing energy level.The ADG was greater(P<0.001)in yaks than in cattle,and increased(P<0.05)linearly with increasing energy levels.From the regressions of ADG on ME intake,the estimated ME requirement for maintenance was lower(P<0.05)in yaks than in cattle(0.43 vs.0.57 MJ/kg BW0.75).The ratios of digestible energy(DE):gross energy and ME:DE were higher(P<0.05)in yaks than in cattle,and increased(P<0.05)linearly with increasing dietary energy level.Ruminal pH decreased(P<0.05),whereas concentrations of total volatile fatty acids(VFAs)and ammonia increased(P<0.01)with increasing dietary energy level,and all were greater(P<0.05)in yaks than in cattle.Concentrations of ruminal acetate and iso-VFAs were greater(P<0.05),whereas propionate was lower(P<0.05)in yaks than in cattle;acetate decreased(P<0.001),whereas butyrate and propionate increased(P<0.001)linearly with increasing dietary energy level.Serum concentrations ofβ-hydroxybutyrate were lower(interaction,P<0.001)in yaks than in cattle fed diets of 9.42 and 10.80 MJ/kg,whereas non-esterified fatty acids were greater(interaction,P<0.01)in yaks than in cattle fed diets of 6.62 and 8.02 MJ/kg.Concentrations of serum leptin and growth hormone were greater in yaks than in cattle and serum insulin and growth hormone increased(P<0.01)linearly with increasing dietary energy level.Our hypothesis that yaks have lower energy requirements for maintenance than cattle was supported.This lower requirement confers an advantage to yaks over Qaidam cattle in consuming low energy diets during the long winter on the Qinghai-Tibetan Plateau.

Use of the N-alkanes to Estimate Intake, Apparent Digestibility and Diet Composition in Sheep Grazing on Stipa brevifl ora Desert Steppe

The application of n-alkane as markers to estimate herbage intake, apparent digestibility and species composition of diet consumed by grazing sheep was studied. Six local Mongolian sheep were used to determine dry matter （DM） intake, apparent DM digestibility and species composition of diet during summer, autumn and winter. Animals were orally dosed twice daily with n-alkane gelatin capsules containing 60 mg C32-alkane as an external marker. Diet composition was estimated by comparing the odd-chain n-alkanes pattern profile （C27-C31） of the consumed plant species with the n-alkanes fecal concentrations of grazing animals, using a non-negative least squares algorithm called EATWHAT software package. The alkane pair C32：C33 and C33 alkane were used to estimate DM intake and diet apparent DM digestibility, respectively. The results showed that daily dry matter intake of the sheep were 1.77, 1.61 and 1.18 kg d-1 in summer, autumn and winter, respectively. Apparent DM digestibility, crude protein （CP）, metabolizable energy （ME） and neutral detergent fiber （NDF） intake of diet consumed by sheep decreased significantly （P〈0.01） from summer to winter, with no evident changes in ADF and ADL intake. Diet composition indicated Artemisia frigida Willd was the most dominant diet component, contributed 79.68, 68.12 and 86.26% of sheep＇s diets in summer, autumn and winter, respectively. Cleistogenes songorica Ohwi and Convolvulus arnmannii Desr were the important components of the diet. Although Stipa breviflora Griseb is one of the main plant species in the study area, the sheep rarely choosed it. The study indicated that CP and ME in diet consumed by sheep were deficient in winter. Therefore, appropriate supplementation strategies should be indispensable during this period.

Effect of protease supplementation on apparent ileal crude protein and amino acid digestibility of over-processed soybean meals in broilers

Background: Nutritional value of proteins in feed ingredients can be negatively affected by hydrothermal processing, which causes large variation in the bioavailability of amino acids(AA) and negatively affects animal productive performance. Supplementation of exogenous proteases could increase the rate of digestion of damaged proteins, thereby increasing overall AA digestibility and bioavailability. The aim was to determine the effect of exogenous protease supplementation on the apparent ileal digestibility(AID) of crude protein(CP) and AA of soybean meals(SBM) with different degrees of hydrothermal processing in broilers.Methods: The experiment involved a 3 × 2 factorial arrangement, with SBM processing time(commercial SBM or autoclaved for 30 or 60 min at 120 ℃) and protease supplementation(not supplemented and supplemented) as factors. Protease was included at three times the recommended dose(0.06%) and the experimental diets were fed from 15 to 21 d.Results: The interaction between the effects of SBM processing and protease supplementation was significant for the AID of CP(P = 0.01), Trp(P = 0.01), Gly(P = 0.03) and Pro(P = 0.03), and also for the average daily gain(P = 0.01)and feed conversion ratio(P = 0.04). Increasing the processing time of SBM decreased(P < 0.0001) the AID of all amino acids, whilst the effect of protease supplementation was only significant for the AID of Phe(P = 0.02) and Tyr(P = 0.01).Conclusions: Exogenous protease supplementation at three times the commercial dose does not seem to offset the negative effects of hydrothermal processing of SBM on the apparent ileal digestibility of CP and amino acids or performance of broilers. Whilst positive numerical improvements of digestibility and performance(ADG and FCR)were noticed with protease supplementation at relatively mild processing levels, negative results were obtained with the harsh-processed meals.

Effect of Three Feed Antibiotics Substitutes on Growth Performance and Apparent Nutrient Digesti- bility of Guangxi Jinling Partridge

Totally 150 individuals of 1-day-old Guangxi Jinling partridges were randomly divided into five groups, 30 chickens each group. Chickens in control group were fed with basal diet, while chickens in experimental groups were fed with the diet containing antibiotics, Chinese herbal medicine, probiotics and acidifi- er. The entire trial lasted 50 d, and growth performance and apparent nutrient digestibility of tested chickens were observed and measured. Compared with control group, the feed gain ratio in experimental groups significantly decreased （P 〈 0.05 ）, while that in probiotics group was the lowest. The average daily gain in pmbi- otics group was significantly higher than that in control group or other experimental groups （P 〈 0.05）. The apparent digestibility of crude protein, crude fat and energy in probiotics group were significantly higher than that in control group or other experimental groups （P 〈 0.05 ）. The apparent digestibility of phosphorus, crude fat, crude fiber, calcium and crude protein in antibiotics group were significantly higher than that in control group （P 〈 0.05 ）. The apparent digestibility of crude protein, crude fiber and phosphorus in Chinese herbal medicine group were significantly higher than that in control group （P 〈 0.05 ）. The apparent digesti- bility of nutrient in acidifier group were significantly lower than that in control group or other experimental groups （ P 〈 0.05 ）. Therefore, pmbiotics had better effects on growth performance and apparent nutrient digestibility of chickens than antibiotics, while Chinese herbal medicine and acidifier had inferior effect than an- tibiotics.

Effects of Coated Methionine on the Growth Performance, Blood Biochemical Indices and Nutrient Apparent Ileal Digestibility in Broilers

[ Objective] This trial was conducted to study the effects of different coated methionines on the growth performance, blood biochemical indices and apparent ileal digestibility of amino acids in broilers. [ Method ] A total of 3 780 Cobb 500 broilers aged 18 days were randomly arranged into 7 groups with 3 replicates per group and 180 broilers per replicate. Control group （A） received the basal diet supplemented with O. 16% DL-me- thionine, and trial groups received the basal diets supplemented with 0.32% （ B）, 0.29% （ C）, 0.26% （ D）, 0.22% （ E）, 0.19% （F） and 0.16% （G） of coated methionine, and broilers were fed to the age of 42 days. ＂[ Result] The final weight, average daily gain and average daily feed intake of groups B and C were higher than those of the control group （ P〈0.05）, and the mortality of group B was lower than that of the control group （ P 〈0.05）, but there was no significant difference in all above indices between the other groups and the control group （P 〉 0.05）. Plasma GSH-Px activity of trial groups （ except group G） was higher than that of the control group （ P 〈 0.05）, and SOD activity of groups B and C were higher than that of group G （P 〈0.05）, but there were no significant differences in other blood biochemical indices among all groups （P 〉0.05）. There were no significant differences in apparent ileal digestibility of dry matter and crude protein between trial groups and the control group （ P 〉0.05 ）, and the apparent ileal digestibility of amino acids of trial groups was increased （P 〈0.05） or no change expect that the apparent ileal digestibility of many kinds of amino acids of group G was decreased compared with the control group （P〈0.05）. [ Concluslon~ The growth performance and apparent ileal digestibility of amino acids in broilers were increased with the rising supplementation of coated methionine, but the supplementation of 0.19% coated methionine can meet the needs of broilers, namely, coated methionine can be substituted for 60% DL-methionine in the diet, so DL-methio- nine can be saved up to 40%.

Total Tract Apparent Digestibility, Serum Fatty Acid Profile, and Productive Performances of Mid-lactating Dairy Cows Fed with Dietary Betaine

It is hypothesized that betaine supplementation improves production performance in mid-lactation dairy cows.Twenty-one mid-lactation dairy cows were assigned to a 3×3 Latin square design with three periods of 28 d each and fed three treatments of betaine(0,100,and 200 g/d).Milk samples were collected on day 21 and day 28 of each period.During days 21 to 28,cows were fed with chromic oxide(15 g/d per cow).On days 26 to 28,fecal samples were collected to determine apparent total tract nutrient digestion.Blood samples were obtained on days 26 to 28 of each period for fatty acid(FA)analysis.Data were analyzed using the Proc Mixed in SAS.Apparent total tract dry matter(DM)digestibility tended to be greater for cows supplemented with 100 g betaine as compared to no dietary betaine(61 vs.58±1%;p=0.1).In contrast,DM intake(DMI),milk fat percent,milk yield,energy-corrected milk(ECM)yield,and milk FA composition did not differ among treatments.Supplementation of betaine can decrease the serum saturated FA C11,C12,C15 and C17,total monounsaturated FA,and C18:2 all trans-9,12.In addition,total serum n-3 polyunsaturated FA was significantly increased.This result can decrease total serum n-6 to n-3 ratio(6.80,7.07,and 6.50±0.16%,for 0,100,and 200 g betaine,respectively;p=0.04).Overall,even betaine supplementation did not change DMI or production,betaine could affect the DM digestibility and serum FA biosynthesis.

The Effect of Dietary Supplementation with Phytase Transgenic Corn on Growth Performance,Phosphorus Utilization and Excretion in Growing Pigs (Sus scrofa)

Two experiments were conducted to investigate the effect of dietary supplementation with phytase transgenic corn （PTC） on growth performance,phosphorus （P） utilization and excretion in growing pigs.In Exp.1,180 pigs （Large White × Landrace,BW=37.7 kg） were randomly allotted to 4 treatments with 5 replicates of 9 pigs each in order to evaluate the effect of PTC supplementation in low-P diets on growth performance.Four corn soybean meal-based diets consisted of a positive control （PC） diet,a diet containing 500 units （U） of exogenous phytase kg-1 （EP） on the basis of low-P （inorganic P reduced by 0.05% from PC diet） and the low-P＋500 （PTC1） or 750 （PTC2） phytase U of PTC kg-1.In Exp.2,20 barrows （Large White×Landrace,BW=31 kg,4 treatments with 5 replicates of 1 pig each） were randomly selected to evaluate the effect of PTC in low-P diets on serum parameters and nutrient utilization.Diets in Exp.2 were similar to those in Exp.1 except that the EP group was replaced by a low-P diet without exogenous phytase supplementation as a negative control （NC） group.The results from Exp.1 showed that the average daily gain （ADG） in the PTC2 group was significantly higher （P〈0.05） than that in the EP group over all periods.On the other hand,the feed：gain （F：G） ratio of the EP group was significantly higher （P〈0.05） than that of the PTC2 group during 1-21 and 1-42 d,respectively.There were no differences in average daily feed intake （ADFI） among all treatments （P〉0.05）.The results from Exp.2 showed that the concentration of serum Ca in the NC group was the highest （P〈0.05）,while the concentration of serum P in the PTC2 group was the highest （P〈0.05） among all treatments.There was a significant decrease （P〈0.05） in the P apparent digestibility of the NC group compared with the other groups,and that of PTC2 group was the best.Furthermore,fecal P excretion was reduced （P〈0.05） from 1.80 g d-1 in the PC group to 1.28 g d-1 in the PTC2 group.In conclusion,dietary supplementation with PTC could reduce the application of inorganic P,decrease fecal P excretion,and improve the growth performance of growing pigs.

Effect of Different Protein Levels on Nutrient Digestion Metabolism and Serum Biochemical Parameters in Calves

The current study has been performed to examine the effects of different dietary protein levels on the growth, nutrient digestion and absorption, as well as biochemical parameters in calves. Nine healthy newborn calves were selected, randomly divided into 3 groups and fed 3 milk replacers with different protein levels （18, 22, and 26%）, respectively. Five period-digestion-metabolism trials were taken between 12-20, 22-30, 32-40, 42-50, and 52-60 days after birth. All 3 groups showed a similar growth curve during 11 to 61 experimental days, however, the growth rate of the 22% crude protein （CP） group was 8.89% higher than that of the 18% CP group and 19.48% higher than that of the 26% CP group, respectively. The apparent digestibility of dry material （DM） declined gradually with age, whereas, the apparent digestibility of N, extract ether （EE） rose slightly. Compared to the 22% CP and 26% CP group, calves fed with 18% CP apparently had a lower digestibility than DM, EE, and nitrogen （N）. The average apparent digestibilities of N were 69.39, 75.36, and 74.55%, respectively. Both the apparent digestibility and retention of calcium （Ca） and phosphorus （P） were steady throughout the experiment, but the average apparent digestibility of P in the 26% CP group was only 63.83%, which was markedly lower than that of the 18% CP group （70.40%） and 22% CP group （69.73%）. In addition, the serum concentrations of total protein （TP）, albumin （ALB）, and globulin （GLOB） of the 22% CP group were higher than those in the 18% CP and 26% CP groups. The urea N （BUN） content in the 18% CP group, on the other hand, was significantly lower than that of the other two groups. The highest glucose （GLU） concentration was found in the 22% CP group （5.38 mmol L^-1）, at the end of the trials. The protein levels in the milk replacer affected the digestion metabolism of nutrition and the serum biochemical parameters of calves at different physiological phases. Calves fed with 22% CP milk replacer had a better growth performance than the other groups.

A Study on the Meat and Bone Meal or Poultry By-product Meal as Protein Substitutes of Fishmeal in Concentrated Diets for Paralichthys olivaceus

A study was conducted to evaluate the effects of meat and bone meal （MBM） and poultry by-product meal （PBM） as the replacement of fishmeal in the diets on the growth performance, survival and apparent digestibility coefficient （ADC） of Japanese flounder （Paralichthys olivaceus）. The experimental diets included 0%, 20%, 40%, 60% and 80% MBM or PBM replacement of total fishmeal respectively. All diets were iso-nitrogenous and isocaloric. The results showed that there are no significant differences （P 〉0.05） in growth performance among the treatments fed with 0% -60% MBM replacement of fishmeal, while the percent weight gain （WG, % ）, body length gain （BLG, % ） and ADC significantly decrease when fishmeal is replaced by 80% MBM. The result showed also that there are no significant differences （P 〉0.05） in growth performance and ADC among all treatments fed with the diets with 0% -80% replacements of fishmeal with PBM.

Effects of Different Energy Levels on Nutrient Utilization and Serum Biochemical Parameters of Early-Weaned Calves

Current study was performed to investigate the effects of different energy levels on nutrient digestion metabolism and serum biochemical parameters of early-weaned calves. Twelve neonatal Holstein calves were selected and assigned randomly to receive 1 of 3 treatments that contained 18.51, 19.66 and 20.80 MJ kg^-1 gross energy, respectively （n=4 per treatment）. Digestion and metabolism trials were carried out in 5 phases （12-20, 22-30, 32-40, 42-50, and 52-60 d of age）. At the same time, blood metabolites were determined at 21, 31, 41, 51, and 61 d of age prior to morning feeding. The results indicated that either dry matter （DM）, organic matter （OM） and gross energy （GE） apparent digestibility or N and P retention tended to increase as age advanced; the average value of DM and OM apparent digestibility and Ca retention in high-energy treatment was significantly lower than that of other groups （P 〈 0.05）; there were no significant differences in the concentration of serum glucose, triglyceride and urea N among treatments, whereas a significant effect of age was found on the level of triglyceride （P 〈 0.05）. To sum up, medium-energy milk replacer seems to be more beneficial for GE digestibility and N utilization, whereas low-energy milk replacer appears to be more rewarding for Ca and P utilization.

A Study on the Meat and Bone Meal and Poultry By-product Meal as Protein Substitutes of Fish Meal in Practical Diets for Litopenaeus vannamei Juveniles

A study was conducted to evaluate the effects of meat and bone meal (MBM) and poultry by-product meal (PBM) as the replacement of fish meal in the diets on the growth performance, survival and apparent digestibility coefficients (ADC) of Litopenaeus vannamei. The basal diets were formulated with 22% fish meal and other ingredients which provided about 40% protein and 9% lipid in the diet. The experimental diets included MBM or PBM to replace 0, 20%, 40%, 60% and 80% of total fish meal respectively. All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were no significant differences (P>0.05) in growth performance and ADC among the treatments fed with the diets in which 0-60% fish meal had been replaced with MBM, while the percent weight gain (WG, %), body length gain (BLG, %) and ADC significantly decreased when the MBM was up to 80% of the fish meal. There were no significant differences (P>0.05) in growth performance and ADC among all the treatments fed with the diets in which 0-80% fish meal had been replaced with PBM.

Dietary inclusion of a partially defatted black soldier fly(Hermetia illucens)larva meal in low fishmeal-based diets for rainbow trout(Oncorhynchus mykiss)

Background:Recent investigations highlighted that Hermetia illucens(BSF)larva meal can be a valuable alternative protein source for aquafeed production.In this study,in substitution of fishmeal,we used increasing inclusion levels of a partially defatted BSF larva meal in low fishmeal-based diets for rainbow trout(Oncorhynchus mykiss Walbaum)and we evaluated the related implications in terms of growth performance,physical characteristics,proximate and fatty acid(FA)compositions of the fillets,gut and liver histology,and diet digestibility.In a 131-day trial,576 fish(100.1±9.29 g)were randomly allotted to 24 tanks(24 fish/tank,4 replicates/treatment).Six experimental diets were produced to have partial replacement of fishmeal(0,10%,20%,30%,40%and 50%)by increasing levels of BSF meal(0%[BSF0],3%[BSF3],6%[BSF6],9%[BSF9],12%[BSF12]and 15%[BSF15]on as fed basis,respectively).Results:No differences were observed among the treatments for all the considered growth performance parameters.The viscero and hepato-somatic indexes showed significant differences among the treatments,with the highest values observed in the BSF15 group.No differences were recorded in terms of fillet’s physical characteristics,dry matter(DM),crude protein(CP)and ether extract(EE)contents.Total saturated and monounsaturated FA increased,while polyunsaturated FA(particularly n-3 FA)decreased while increasing the HI meal inclusion in the diet.Histopathology of liver and gut was not affected,whereas,in posterior gut,villi were higher in BSF6 and BSF9 compared to BSF3 fish.The apparent digestibility of DM,CP,EE and gross energy did not vary among the treatments.Conclusions:These results suggest that a partially defatted BSF meal could be included up to 15%in low fishmeal-based diets for rainbow trout with no adverse effects on growth performance,fillet’s physical characteristics,gut and liver health,and diet digestibility.On the contrary,the fillet FA composition worsened while increasing the level of BSF meal in the diet.

Comparison of Ileal Digested Production of Parental Rice and Rice Genetically Modified With Cowpeas Trypsin Inhibitor

Objective To compare the ileal digestibility of protein and amino acids in parental rice and rice genetically modified with sck gene. Methods Six experimental swines were surgically fixed with a simple T-cannula at the terminal ileum and fed with parental rice and rice genetically modified with sck gene alternately. The ileum digesta were collected and analyzed for determination of apparent and true digestibility of protein and amino acids. Results The apparent and true digestibility of protein was similar in these two types of rice. Except for the apparent digestibility of lysine, there was no difference in the apparent and true digestibility of the other 17 amino acids. Conclusion The digestibility of protein and amino acids is not changed by the insertion of foreign gene, so it can meet the request of ＂substantial equivalence＂ in digestibility of protein and amino acids.

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.

Effects of Supplementary Acidifiers on Lambs

[ Objective] To provide a reference for understand effects of acidifiers on digestibility of lambs. [Method] Feeding experiment as well as digestion and metabolism experiment was conducted to evaluate effects of supplementing acidifiers on ultra-early weaned lambs. [ Result] Diets of ultra-early weaned lambs supplemented with acidifiers greatly improved their production performance and increased digestibility of feed. However, different acidifier products had certainly various effects on lambs. Acidifier product I increased weight gain, feed conversion ratio and apparent di- gestibility of main nutrients more greatly than acidifier product II did, while the result was contrary in reducing diarrhea incidence. [ Conclusion] Whether the acidifiers can increase digestibility of nutrients or not is still uncertain and needs further studies.

Appropriate Metabolic Energy, Crude Protein, Calciumand Available Phosphorus Levels of Diet for BlackMuscovy Duck at 43-91 Days of Age

[Objective] The paper was to study the effects of diet formulation with different nutrition levels on growth and slaughter performance ofblack muscovy duck at the age of 43-91 days. [Method] Totally 288 individuals of 43dayold black muscovy duck were randomly divided intonine treatments, four repeats each treatment and eight ducks each repeat. UsingL9 （34） orthogonal experiment design （four factors and three levels）,three metabolic energy levels （12.32, 12.72, 13.12 MJ/kg）, three crude protein levels （14%, 16%, 18%）, three calcium levels （0.6%, 0.8%, 1.0%）and three available phosphorus levels （0.30%, 0.45%, 0.6%） were designed, and a total of nine feeding groups （C1C9） were designed according todifferent nutritional levels. Through combination of feeding test （49 d） and metabolic test （pretest 4 d and formal test 3 d）, the growth performance,meat performance and apparent nutrient digestibility of ducks were determined. [Result] The ducks in experimental group C2 had the highest average daily gain, the lowest feed gain ratio, the largest body oblique length, chest width, chest depth and tibia length, which had significant or extremely significant differences with other groups （P〈0.05 or P〈0.01）. The slaughter rate, semieviscerated rate, eviscerated rate and meat quality ofducks in C2 group were higher （P〈0.05）. The apparent digestibility of crude protein and dietary metabolic energy in C2 group were 88.68% and63.07%, respectively, both were significantly or extremely significantly higher than the other groups（P〈0.05 or P〈0.01）, while the interaction effectof calcium and phosphorus level on apparent digestibility was not obvious. [Conclusion] Under the experimental conditions, the suitable metabolicenergy, crude protein, calcium, available phosphorus and total phosphorus levels of 43 -91 days old black muscovy ducks were 12.32 MJ/kg,16.10%, 0.92%, 0.45% and 0.68%, respectively.

Determination of the standardized ileal digestible calcium requirement of Ross broilers from hatch to day 14 post-hatch

An experiment was conducted to determine the standardized ileal digestible(SID)calcium requirement of fast-growing broilers from hatch to d 14 post-hatch.Ross 308(n=360)male broilers were obtained on day of hatch and allocated to 1 of 5 treatments in battery cages.There were 6 birds per cage and 12 pens per treatment.Four treatments were formulated to contain 0.60%,0.46%,0.32%or 0.18%SID Ca.The final treatment was formulated using total Ca to meet or exceed all nutrient requirements,including 0.90%total Ca and 0.49%non-phytate P(nPP),using the same ingredients.This treatment was the reference diet for comparison and validation of the SID Ca diets.Birds and feed were weighed at placement and on d 14.Tibias and ileal contents were obtained on d 14 and excreta was collected per pen and pooled on d 14.Data were analyzed using JMP Pro and requirements were estimated using 3different non-linear regression models.Increasing the SID Ca content in the diet from 0.18%to 0.60%improved(quadratic,P<0.05)body weight gain and mortality corrected feed conversion ratio(mFCR).The estimated SID Ca requirement to optimize gain or m FCR was between 0.39%and 0.52%.Tibia ash percent and weight increased(quadratic,P<0.05)as SID Ca content in the diet increased and the estimated SID Ca requirement was between 0.32%and 0.58%.Phosphorus utilization was improved in birds fed diets formulated using SID Ca compared with birds fed the reference diet.In conclusion,the SID Ca requirement of fast-growing broilers from hatch to d 14 was estimated between 0.534%and 0.398%when quadratic,straight-broken line,or quadratic-broken line regressions were used.These results agree with previously published data evaluating the SID Ca requirement of fast-growth broilers from hatch to d 10.

Alterations in nutrient digestion and utilization associated with different residual feed intake in Hu sheep

Improving feed efficiency is crucial to the animal industry.Residual feed intake(RFI)is now regarded as an index of feed efficiency evaluation and is independent of growth characteristics.Our study aims to explore the alterations in growth performance and nutrient digestion in Hu sheep with different RFI phenotypes.Sixty-four male Hu sheep(body weight=24.39±1.12 kg;postnatal days=90±7.9)were selected for the study.After an evaluation period of 56 days and power analysis,samples were collected from 14 low RFI(L-RFI group,power=0.95)and 14 high RFI sheep(H-RFI group,power=0.95).The L-RFI sheep yielded a lower(P<0.05)feed conversion ratio and dry matter intake;however,both groups exhibited similar average daily gain(P>0.05).The acid detergent fiber,neutral detergent fiber,organic matter,and crude protein apparent digestibility were higher(P<0.05)in L-RFI sheep.N intake and fecal N output(%of N intake)were lower(P<0.05)and N retention(%of N intake)was higher(P<0.05)in L-RFI sheep,whereas no difference(P>0.05)was found in urine N output(%of N intake)between the 2 groups.Furthermore,L-RFI sheep gave lower(P<0.05)serum glucose concentrations and higher(P<0.05)non-esterified fatty acid concentrations.Meanwhile,a lower ruminal acetate molar proportion(P<0.05)and higher propionate molar proportion(P<0.05)were observed in L-RFI sheep.In summary,these results revealed that despite having lower dry matter intake,L-RFI sheep possess higher nutrient digestibility,N retention,ruminal propionate production and serum glucose utilization,in order to meet energy demands.Selection for low RFI sheep could reduce feed costs,which in turn provides economic benefits to the sheep industry.

Total amino acid level affects the results of standardized ileal digestibility assays for feed ingredients for swine

It has been demonstrated that the fiber content of oilseed meals and total amino acids(AA)in distillers'grains products affects standardized ileal digestibility(SID)values from swine assays and that total protein concentration affects the AA digestibility in assays using chickens.This analysis was conducted to test the hypothesis that the total AA content of test samples affects the SID assay results.Databases containing total AA profiles and SID values of 20 feedstuffs commonly fed to pigs from 2 sources,AMINODat 5.0(Evonik Industries,2015)and the Nutrient Requirements of Swine,12th edition(NRC,2012)were used to compare AA concentration effects on standardized ileal digestibility coefficients.Databases were compared with AA and SID available in both data sets.The total AA values were similar for the 2 databases with an R2 of 0.979(P<0.001).The linear relationship between digestibility co-efficients from the 2 databases was highly significant,an R2 of 0.810(P<0.001).Both databases had increased SID values with increasing AA contents within and across feed ingredients.The SID=f(AA concentration)relationship was confirmed with an individual paper.Since SID,as typically measured,is a function of both digestion and absorption,both processes following MichaeliseMenten kinetics,SID=f(AA concentration)may simply be a natural phenomenon.Other reasons for the relationship were explored.Methods of estimating endogenous AA losses and misapplication statistical procedures may contribute to variation in results and at least partially explain why SID=f(AA concentration).

Effects of raw material extrusion and steam conditioning on feed pellet quality and nutrient digestibility of growing meat rabbits

This study was conducted to investigate the effects of raw material extrusion and steam conditioning on feed pellet quality and nutrient digestibility of growing meat rabbits, in order to determine appropriate rabbit feed processing methods and processing parameters. In Exp. 1, an orthogonal design was adopted.Barrel temperature, material moisture content and feed rate were selected as test factors, and acid detergent fiber(ADF) content was selected as an evaluation index to research the optimum extrusion parameters. In Exp. 2. a two-factor design was adopted. Four kinds of rabbit feeds were processed and raw material extrusion adopted optimum extrusion parameters of Exp. 1. A total of 40 healthy and 42-day-old rabbits with similar weight were used in a randomized design, which consisted of 4 groups and 10 replicates in each group(1 rabbits in each replicate). The adaptation period lasted for 7 d, and the digestion trial lasted for 4 d. The results showed as follows: 1) ADF was significantly affected by barrel temperature(P < 0.05); the optimum extrusion parameters were barrel temperature 125℃, moisture content 16% and feed rate 9 Hz. 2) Raw material extrusion and steam conditioning both significantly decreased powder percentage, pulverization ratio and protein solubility(P < 0.05), significantly improved hardness and starch gelatinization degree of rabbit feed(P < 0.05). They both had significant interaction effects on the processing quality of rabbit feed(P < 0.05). 3) Extrusion significantly improved the apparent digestibility of dry matter and total energy(P < 0.05). Extrusion and steam conditioning both significantly improved the apparent digestibility of crude fiber(CF), ADF and NDF(P < 0.05), but they had no interaction effects on the apparent digestibility of rabbit feed. Thus, using extrusion and steam conditioning technology at the same time in the weaning rabbits feed processing can improve the pellet quality and nutrient apparent digestibility of rabbit feed.