Effects of sustained cold and heat stress on energy intake, growth and mitochondrial function of broiler chickens

To study the correlation of broiler chickens with energy intake, growth and mitochondrial function which exposed to sustained cold and heat stress and to find out the comfortable temperature, 288 broiler chickens（21-day with（748±26） g, 144 males and 144 females） were divided randomly into six temperature-controlled chambers. Each chamber contained six cages including eight AA broilers per cage, each cage as a repeat. After acclimation for one week（temperature, 21℃; relative humidity, 60%）, the temperature of each chamber was adjusted（finished within 1 h） respectively to 10, 14, 18, 22, 26, or 30℃（RH, 60%） for a 14-day experimental period. After treatment, gross energy intake（GEI）, metabolizable energy intake（MEI）, the ratio of MEI/BW, metabolizability, average daily gain（ADG）, the concentration of liver mitochondria protein and cytochrome c oxidase（CCO） were measured respectively. Our results confirmed that when the temperature over 26℃ for 14 days, GEI, MEI and CCO activities were decreased significantly（P〈0.05）, but the concentration of liver mitochondria protein was increased and metabolizability of broilers was not influenced（P〉0.05）. Compared with treatment for 14 days, the ratio of MEI/body weight（BW） were also decreased when the temperature over 26℃ after temperature stress for 7 days（P〈0.05）, meanwhile mitochondrial protein concentration was increased at 10℃ and CCO activity was not affected（P〉0.05）. Additionally at 22℃, the ADG reached the maximal value. When kept in uncomfortable temperatures for a long time, the ADG and CCO activities of broiler were reduced, which was accompanied by mitochondrial hyperplasia. In summary, our study focused on the performance of broilers during sustained cold and heat environmental temperatures ranging from 10 to 30℃. From the point of view of energy utilization, moreover, 22 to 26℃ is comfortable for 28–42 day s broilers. And these could provide the theoretical basis on the high efficient production.

Nutritional value of a partially defatted and a highly defatted black soldier fly larvae (Hermetia illucens L.) meal for broiler chickens: apparent nutrient digestibility,apparent metabolizable energy and apparent ileal amino acid digestibility

Background: The study aimed to determine the apparent total tract digestibility coefficients(ATTDC) of nutrients, the apparent metabolizable energy(AME and AMEn) and the amino acid(AA) apparent ileal digestibility coefficients(AIDC)of a partially defatted(BSFp) and a highly defatted(BSFh) black soldier fly larvae meal. The experimental diets were: a basal diet and two diets prepared by substituting 250 g/kg(w/w) of the basal diet with BSFp or BSFh, respectively.Results: Significant differences were found between BSFp and BSFh meals for ATTDC of the nutrients: BSFp resulted more digestible than BSFh, except for ATTDC of CP which did not differed between meals, while a statistical trend was observed for ATTDC of DM and EE. The AME and AMEn values were significantly(P < 0.05) different between the two BSF meals, with higher levels for BSFp(16.25 and 14.87 MJ/kg DM, respectively). The AIDC of the AA in BSFp ranged from 0.44 to 0.92, while in BSFh they ranged from 0.45 to 0.99. No significant differences were observed for the AA digestibility(0.77 and 0.80 for BSFp and BSFh, respectively), except for glutamic acid, proline and serine that were more digestible in the BSFh meal(P < 0.05).Conclusions: Defatted BSF meals can be considered as an excellent source of AME and digestible AA for broilers with a better efficient nutrient digestion. These considerations suggested the effective utilization of defatted BSF larvae meal in poultry feed formulation.

Energy Requirements for Maintenance and Growth of German Mutton Merino Crossbred Lambs

A comparative slaughter trial and a metabolism trial were conducted to determine the requirement of net energy （NE） and metabolizable energy （ME） by the crossbreed of German Mutton Merino×Inner Mongolia Merino for fattening from 35 to 50 kg of body weight （BW）. 49 crossbred female lambs （（33.9＋2.3） （SD） kg BW） of German Mutton Merino×lnner Mongolia Merino were used. 34 lambs were randomly chosen for comparative slaughter, which were offered an identical mixture diet （concentrate：roughage=55：45） at 100, 75 or 55% of ad libitum intake, whereas the remainders were used in the metabolism trial to evaluate the ME of the diet after methane production was measured by open-circuit respirometry. As feed intake decreased from 100 to 75 and 55% of ad libitum intake, the apparent digestibility of dry matter （DM） linearly increased （P=-0.010） from 60.8 to 63.6 and 66.9%, respectively, and methane production decreased from 52.1 to 44.3 and 39.9 L d-l, respectively, but the ratio of methane energy to gross energy intake increased linearly （P=0.010） from 8.20 to 8.96 and 10.97%, respectively. Consequently, the ME values of the diet increased from 9.35 to 9.64 and 9.85 MJ kg-~ DM, respectively. The NE requirement for maintenance （NEro） was 255 kJ kg-1 BW0.75, and the ME requirement for maintenance （MEre） was 352 kJ kg-I BW~.75, with a partial energy efficiency for maintenance （km） of 0.72. The NE requirement for growth （NEg） ranged from 1.26 to 4.66 MJ d-1as average daily gains increased from 100 to 300 g d-1, with a partial energy efficiency for growth （ks） of 0.45. These results indicated that the NEg required by crossbred female lambs of German Mutton Merinoxlnner Mongolia Merino was lower than the recommendation of the American or British nutritional system.

New insights into the associations among feed efficiency, metabolizable efficiency traits and related QTL regions in broiler chickens

Background: Improving the feed efficiency would increase profitability for producers while also reducing the environmental footprint of livestock production. This study was conducted to investigate the relationships among feed efficiency traits and metabolizable efficiency traits in 180 male broilers. Significant loci and genes affecting the metabolizable efficiency traits were explored with an imputation-based genome-wide association study. The traits measured or calculated comprised three growth traits, five feed efficiency related traits, and nine metabolizable efficiency traits.Results: The residual feed intake(RFI) showed moderate to high and positive phenotypic correlations with eight other traits measured, including average daily feed intake(ADFI), dry excreta weight(DEW), gross energy excretion(GEE), crude protein excretion(CPE), metabolizable dry matter(MDM), nitrogen corrected apparent metabolizable energy(AMEn), abdominal fat weight(Ab F), and percentage of abdominal fat(Ab P). Greater correlations were observed between growth traits and the feed conversion ratio(FCR) than RFI. In addition, the RFI, FCR, ADFI, DEW,GEE, CPE, MDM, AMEn, Ab F, and Ab P were lower in low-RFI birds than high-RFI birds(P < 0.01 or P < 0.05), whereas the coefficients of MDM and MCP of low-RFI birds were greater than those of high-RFI birds(P < 0.01). Five narrow QTLs for metabolizable efficiency traits were detected, including one 82.46-kb region for DEW and GEE on Gallus gallus chromosome(GGA) 26, one 120.13-kb region for MDM and AMEn on GGA1, one 691.25-kb region for the coefficients of MDM and AMEn on GGA5, one region for the coefficients of MDM and MCP on GGA2(103.45–103.53 Mb), and one 690.50-kb region for the coefficient of MCP on GGA14. Linkage disequilibrium(LD) analysis indicated that the five regions contained high LD blocks, as well as the genes chromosome 26 C6 orf106 homolog(C26 H6 orf106), LOC396098, SH3 and multiple ankyrin repeat domains 2(SHANK2), ETS homologous factor(EHF), and histamine receptor H3-like(HRH3 L), which are known to be involved in the regulation of neurodevelopment, cell proliferation and differentiation, and food intake.Conclusions: Selection for low RFI significantly decreased chicken feed intake, excreta output, and abdominal fat deposition, and increased nutrient digestibility without changing the weight gain. Five novel QTL regions involved in the control of metabolizable efficiency in chickens were identified. These results, combined through nutritional and genetic approaches, should facilitate novel insights into improving feed efficiency in poultry and other species.

Chemical composition,energy and amino acid digestibility in double-low rapeseed meal fed to growing pigs

Background： The nutritional value of rapeseed meal may be variable due to the variation of its chemical composition. And a precise understandin9 of the nutritional value of an ingredient is beneficial for the accurate diet formulation and reduction of feed costs. This study was conducted to determine the chemical composition, dicjestible energy （DE） and metabolizable enercjy （ME） content, and apparent ileal digestibility （AID） and standardized ileal dicjestibility （SID） of amino acids （AA） for growincj pigs. Thirteen solvent-extracted double-low rapeseed meal （DLIRSM） samples were obtained from the main double-low rapeseed producing areas in China. Methods： The DE and ME contents of the 13 DLRSM samples were measured in cjrowin9 pigs （six pigs per DLRSM sample, average initial body weicjht （BW） =48.3 kg）. The AID and SID of AA of 10 DLRSM samples were determined in 12 crossbred barrows （average initial BW = 35.3 kcj） by using two 6 x 6 Latin square designs. Each Latin square comprised one N-flee diet and 5 DLRSM test diets. Results： The chemical composition of DLRSM varied among samples, and the coefficient of variation was greater than ]0 % for ether extract （EE）, neutral detergent fiber （NDF）, acid detergent fiber （ADF）, calcium （Ca）, and total 91ucosinolates. The AA content of DLRSM varied among samples especially for lysine （Lys） and methionine （Met）. On a dry matter （DM） basis, the apparent total tract digestibility （ATFD） of gross energy （GE）, the DE and ME and the ME：DE ratio of DLRSM averaged 62.39 %, 2862 kcal/k9 and 2723 kcal/kcj, and 94.95 %, respectively. The mean value of S1D of Lys was 70.52 % which varied from 66.54-76.54 %. The SID of crude protein （CP）, Met, and threonine （Thr） averaged 72.81%, 82.41%, and 69.76 %, respectively. Conclusions： There was great variability in chemical composition especially in the concentration of EE, NDF and ADF, but no significant differences in energy content of the DLIRSM samples were observed. In addition, the AID and SID of all AA were relatively similar amoncj DLRSM samples except for that of Lys.

Protein requirements of early-weaned Dorper crossbred female lambs

The net protein （NP） and metabolizable protein （MP） requirements of Dorper crossbred female lambs from 20 to 35 kg body weight （BW） were assessed in a comparative slaughter trial. Thirty-five Dorper×thin-tailed Hart crossbred lambs weaned at approximately 50 d of age （（19.1±2.37） kg of BW） were used. Seven randomly selected lambs were slaughtered at the beginning of the trial as baseline group （BL）. An intermediate group of seven randomly selected lambs fed ad libitum （AL） intake was slaughtered when the lambs reached an average BW of 28.6 kg. The remaining 21 lambs were allotted randomly to three levels of dry matter intake： AL or restricted to 70 or 40% of the AL intake. All lambs were slaughtered when the sheep fed AL intake reached 35 kg of BW. Total body N and N retention were determined. The results showed that the maintenance requirements for NP and MP were 1.75 and 3,37 g kg^-1 metabolic shrunk body weight （SBW^0.75）, respectively. The partial efficiency of protein use for maintenance was 0.52. The NP requirements for growth ranged from 10.9 to 42.4 g d^-1 for the lambs gaining 100 to 350 g d^-1 from 20 to 35 kg BW. The partial efficiency of MP for growth was 0.52. In conclusion, the NP and MP requirements for the maintenance and growth of Dorper crossbred female lambs were lower than those reported by AFRC （1993） and NRC （2007） recommendations.

The effect of the ratio of standardized ileal digestible lysine to metabolizable energy on growth performance,blood metabolites and hormones of lactating sows

A total of 335 lactating sows （Landrace x Large White） were used in two experiments to determine the optimum ratio of standardized ileal digestible lysine （SID-Lys） to metabolizable energy （ME） for mixed parity sows during lactation. In Exp. 1, 185 sows （weighing an average of 256.2 ± 6.5 kg and having an average parity of 3.4 ± 0.3） were allocated to one of six experimental diets in a completely randomized block design within parity groups （1, 2, and 3＋）. The experimental diets were formulated to contain 3.06, 3.16, 3.20, 3.25, 3.30 or 3.40 Mcal/kg of ME and each diet was fed to the sows throughout a 28 day lactation. All diets provided a similar SID-lysine level （0.86%）. As a result, the diets provided a SID-Lys：ME ratio of 2.81, 2.72, 2.69, 2.65, 2.61 or 2.53 g/Mcal ME. Sow feed intake was significantly （P 〈 0.01） affected by the energy content of the diet as well as by sow parity. Using regression analysis, feed intake was shown to be maximized at 3.25, 3.21, 3.21 and 3.21 Mcal/kg of ME for parity 1, 2, 3＋ sows and the entire cohort of sows respectively （quadratic; P 〈 0.01）. In addition, the result of feed intake can be expressed as 2.65, 2.69, 2.69 and 2.68 g/Mcal based on analysis of SID-Lys：ME ratio. Litter weight gain was affected by dietary treatment for parity 3＋ sows and the entire cohort （P 〈 0.01）. Based on regression analysis, litter weight gain was maximized at 3.25 and 3.24 Mcal/kg of ME for parity 3＋ （quadratic; P 〈 0.01） and the entire cohort （quadratic; P 〈 0.01）. Similarly, the result of litter weight gain could be expressed as 2.65 and 2.66 g/Mcal of SID- Lys：ME ratio. Therefore, 3.25 Mcal/kg of ME was selected for Exp. 2 in which 150 sows （weighing 254.6 ± 7.3 kg and having an average parity of 3.4 ± 0.4） were allocated to one of five treatments in a completely randomized block design within parity （1, 2, and 3＋）. The experimental diets were formulated to contain 2.1, 2.4, 2.7, 3.0 or 3.3 g/Mcal of SID-Lys：ME ratio with all diets providing 3.25 Mcal/kg of ME. The diets were fed to the sows throughout a 28 day lactation. Sow body weight loss was affected by dietary treatment （parity 3＋ sows, P = 0.02; entire cohort, P 〈 0.01） and by sow parity （P 〈 0.01）. Litter weight at weaning and litter weight gain were affected by dietary treatment for parity 1, 2, 3＋ sows and the entire cohort （P 〈 0.01） as well as by sow parity （P 〈 0.01）. Plasma urea nitrogen （P 〈 0.01）, creatinine （P 〈 0.01） and non-esterifide fatty acids （P = 0.04） were decreased as the SID-Lys：ME ratio of the diet increased. Insulin-like growth factor-1 （P = 0.02）, estradiol （P 〈 0.01） and luteinizing hormone （P = 0.02） were increased as the SID-Lys：ME ratio in diet increased. Based on a broken-line model, the estimated SID-Lys： ME ratio to maximize litter weight gain was estimated to be 3.05 g/Mcal.

Predicting corn digestible and metabolizable energy content from its chemical composition in growing pigs

Background： The nutrient composition of corn is variable. To prevent unforeseen reductions in growth performance, grading and analytical methods are used to minimize nutrient variability between calculated and analyzed values. This experiment was carried out to define the sources of variation in the energy content of corn and to develop a practical method to accurately estimate the digestible energy （DE） and metabolisable energy （ME） content of individual corn samples for growing pigs. Twenty samples were taken from each of five provinces in China （Jilin, Hebei, Shandong, Liaoning, and Henan） to obtain a range of quality. Results： The DE and ME contents of the 100 corn samples were measured in 3.5.3 ±1.92 kg growing pigs （six pigs per corn sample）. Sixty corn samples were used to build the prediction model; the remaining forty samples were used to test the suitability of these models. The chemical composition of each corn sample was determined, and the results were used to establish prediction equations for DE or ME content from chemical characteristics. The mean DE and ME content of the 100 samples were 4,053 and 3,923 kcal/kg （dry matter basis）, respectively. The physical characteristics were determined, as well, and the results indicated that the bulk weight and 1,000-kernel weight were not associated with energy content. The DE and ME values could be accurately predicted from chemical characteristics. The best fit equations were as follows： DE, kcal/kg of DM = 1062.68 ＋ （49.72 ×EE） ＋ （0.54 × GE） ＋ （9.1 ] x starch）, with R^2 = 0.62, residual standard deviation （RSD） = 48 kcal/kg, and P 〈 0.01; ME, kcal/kg of dry matter basis （DM） = 671.54 ＋ （0.89 ×DE） - （5.57 × NDF） - （191.39 ×ash）, with R^2 = 0.87, RSD = 18 kcal/kg, and P〈 0.01. Conclusion： This experiment confirms the large variation in the energy content of corn, describes the factors that influence this variation, and presents equations based on chemical measurements that may be used to predict the DE and ME content of individual corn samples.

Overload type and optimization of meadow carrying capacity in Maqin County in the Three-River Source Region,China

Alpine meadows,comprising the main ecosystem of the Three-River Source Region,play an important role in the economic development of western pastoral areas.To determine whether the grazing level was too intense or the nutrient-carrying capacity of the meadows was overloaded,and to offer solutions in Maqin County,Qinghai Province,China,the meadows carrying capacity was determined by combining grass-yield and nutrients data for different seasons across different meadows.The results showed that the levels of crude protein(CP),ether extract(EE),ash,soluble sugars(SS),gas production,and energy value of forage in the summer–autumn grazing meadows were higher than those of the winter–spring meadows.Neutral detergent fiber(NDF)and acid detergent fiber(ADF)of forage in the summer–autumn grazing meadows were lower than those of the winter–spring meadows.We found that no pastures were overloaded with metabolizable energy(ME)for the whole year but digestible crude protein(DCP)was overloaded in winter–spring.And there were differences in the amount carrying capacity(forage yield)of seasonal grazing meadows for the different herds,the overload types were annual overloading(herd A),overloaded in summer–autumn(herd B),overloaded in winter–spring(herd C),and not overloaded(herd D).Compared with the previous grazing mode,theoretical carrying capacity,DCP carrying capacity,and ME carrying capacity of herd A increased by 20,19,and 27 sheep units,respectively,after optimization;herd B:36,31,and 45 sheep units,respectively;herd C:28,23,and 44 sheep units,respectively;and herd D:43,40,and 61 sheep units,respectively.In the Three-River Source Region and similar alpine pastoral areas,the grassland-livestock structure should be optimized to improve grassland vegetation status and increase the theoretical carrying capacity.

Effects of the standardized ileal digestible lysine to metabolizable energy ratio on performance and carcass characteristics of growing-finishing pigs

A total of 2,121 growing-finishing pigs （Duroc × Landrace ×Large White） were utilized in six experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID-Lys） to metabolizable energy （ME） on the performance and carcass characteristics of growing-finishing pigs. Exps. 1 （30 to 50 kg）, 2 （52 to 70 kg） and 3 （81 to 104 kg） were conducted to find an optimum ME level and then this level was used in Exps. 4 （29 to 47 kg）, 5 （54 to 76 kg） and 6 （84 to 109 kg） to test the response of pigs to different ratios of SID-Lys：ME. In Exps.1 to 3, four treatments were used consisting of diets with a formulated ME content of 3.1, 3.2, 3.3 or 3.4 in Exps. I and 2 while Exp. 3 used 3.05, 3.1 S, 3.25 or 3.35 Mcal/kg. A constant SID-Lys：ME ratio of 2.6, 2.3 or 2.0 g/Mcal was used in Exps. 1, 2 and 3, respectively. Weight gain was significantly increased with increasing energy level in Exp.1 while weight gain was unaltered in Exps. 2 and 3. For all three experiments, feed intake was decreased （P 〈 0.05） and feed efficiency was improved （P 〈 0.05） with increasing energy level. Tenth rib back fat thickness linearly increased （P 〈 0.05） with increasing energy level, in Exps. 4 to 6, five treatments were used consisting of diets with a SID-Lys：ME ratio of 2.4, 2.6, 2.8, 3.0 or 3.2 in Exp. 1, 2.1, 2.3, 2.5, 2.7, 2.9 or 3.2 in Exp. 2 and 1.8, 2.0, 2.2, 2.4, or 2.6 in Exp. 3. A constant ME level 3.2, 3.2 and 3.05 Mcal/kg was used in Exps. 1, 2 and 3, respectively （selected based on the results of weight gain）. For all three experiments, weight gain increased （P 〈 0.05） and feed efficiency improved linearly （P 〈 0.05） as the SID-Lys：ME ratio increased. Tenth rib back fat thickness linearly decreased （P 〈 0.0,5） as the SID-Lys：ME ratio increased. Based on a straight broken-line model, the estimated SID-Lys：ME ratio to maximize weight gain was 3.0, 2.43 and 2.2 for 29 to 47, 54 to76 and 84 to 109 kg of pigs, respectively.

The correlationship between the metabolizable energy content,chemical composition and color score in different sources of corn DDGS

Background： This study was conducted to evaluate the apparent metabolizable energy （AME） and true metabolizable energy （TME） contents in 30 sources of corn distillers dried grains with solubles （DDGS） in adult roosters, and establish the prediction equations to estimate the AME and TME value based on its chemical composition and color score. Methods： Twenty-eight sources of corn DDGS made from several processing plants in 11 provinces of China and others imported from the United States. DDGS were analyzed for their metabolizable energy （ME） contents, measured for color score and chemical composition （crude protein, crude fat, ash, neutral detergent fiber, acid detergent fiber）, to predict the equation of ME in DDGS. A precision-fed rooster assay was used, each DDGS sample was tube fed （50 g） to adult roosters. The experiment was conducted as a randomized incomplete block design with 3 periods. Ninety-five adult roosters were used in each period, with 90 being fed the DDGS samples and 5 being fasted to estimate basal endogenous energy losses. Results： Results showed that the AME ranged from 5.93 to 12.19 MJ/kg, TME ranged from 7.28 to 13.54 MJ/kg. Correlations were found between ME and ash content （-0.64, P 〈 0.0]） and between ME and yellowness score （0.39, P 〈 0.05） of the DDGS samples. Furthermore, the best-fit regression equation for AME content of DDGS based on chemical composition and color score was AME = 6.57111 ＋ 0.5]475 GE - 0.10003 NDF ＋ 0.1 3380 ADF ＋ 0.07057 fat - 0.57029 ash - 0.02437 L （R^2 = 0.70）. The best-fit regression equation for TME content of DDGS was TME = 7.92283 ＋ 0.51475 GE - 0.10003 NDF ＋ 0.13380 ADF ＋ 0.07057 fat - 0.57029 ash - 0.02437 L （R2 = 0.70）. Conclusions： This experiment suggested that measuring the chemical composition and color score of a corn DDGS sample may provide a quality parameter for identifying corn DDGS sources energy digestibility and metabolizable energy content.

Use of near-infrared reflectance spectroscopy for the rapid determination of the digestible energy and metabolizable energy content of corn fed to growing pigs

Background： The ability of near-infrared reflectance spectroscopy（NIRS） to determine the digestible energy（DE）and metabolizable energy（ME） content of corn fed to growing pigs was tested. One hundred and seventeen corn samples, comprising different planting regions and varieties were collected from all over China in a three-year period. The samples were randomly split into a calibration set（n = 88） and a validation set（n = 29）. The actual and calculated DE and ME content of the corn samples was determined by digestion-metabolism experiments and the prediction equations of Noblet and Perez（J Anim Sci. 71：3389–98,1993）. The samples were then subjected to NIRS scanning and calibrations were performed by the modified partial least square（MPLS） regression method based on77 different spectral pre-treatments. The NIRS equations based on the actually determined and calculated DE and ME were built separately and then validated using validation samples.Results： The NIRS equations obtained from actually determined DE, the coefficient of determination for calibration（RSQcal）, cross-validation（R^2CV）, and validation（RSQv） were 0.89, 0.87 and 0.86, and these values for determined ME were 0.87, 0.86 and 0.86. For the NIRS equations built from calculated DE, the RSQcal, R^2CV, and RSQvvalues were 0.88, 0.85 and 0.84, and these values for calculated ME were 0.86, 0.84 and 0.82. Except for the equation based on calculated ME（RPD_v= 2.38, 〈 2.50）, the other three equations built from actually determined energy and calculated DE produced good prediction performance（RPD_vranging from 2.53 to 2.69, 〉 2.50） when applied to validation samples.Conclusion： These results indicate that NIRS can be used as a quantitative method for the rapid determination of the available energy in corn fed to growing pigs, and the NIRS equations based on the actually determined energy produced better predictive performance than those built from calculated energy values.

Energy and Protein Requirements for 0-to 4-Week-Age Gushi Chicks

In this experiment, 540 male and female chicks of 1-day-age were selected respectively and reared separately. 3×3 factorial experiment was designed. Gushi chicks were fed with nine diets under different metabolizable energy (ME) and crude protein (CP). Effects of different diets on the performances and carcass ingredients of 0-to 4-week-age Gushi chicks were studied by rearing, comparative slaughter and metabolism experiments. Based on the results of three experiments, ME intake per kilogram metabolic weight was regarded as dependent variable (Y) ,and its corresponding net energy (NE) deposition per kilogram metabolic weight was regarded as independent variable (X) , respectively. Lineal regressive analysis was made according to the mathematic model: Y=a+bX. Maintenance ME( MEm) and the converted coefficient from net energy for gain( NEg) to ME for gain( MEg) were found out, then ME requirement was divided into MEm+ MEg, which is ME=359.14 W0.75+ 10.47△W; CP intake and corresponding metabolic weight were regarded as dependent variable and independent variable respectively, and then regressive analysis was made. The result was CP=0. 57 + 8. 21 W0.7S. Consequently, average daily gain (ADG), average daily feed intake and metabolic weight were put into the regressive equations, and then ME and CP requirements for 0- to 4-week-age Gushi chicks were obtained, 12.38 MJ kg-1 and 20.13%, respectively, the ratio of CP to ME was 16. 26 g MJ-1.

Net protein and metabolizable protein requirements for maintenance and growth of early-weaned Dorper crossbred male lambs

Background： Dorper is an important breed for meat purpose and widely used in the livestock industry of the world.However, the protein requirement of Dorper crossbred has not been investigated. The current paper reports the net protein（NP） and metabolizable protein（MP） requirements of Dorper crossbred ram lambs from 20 to 35 kg BW.Methods： Thirty-five Dorper × thin-tailed Han crossbred lambs weaned at approximately 50 d of age（20.3 ± 2.15 kg of BW） were used. Seven lambs of 25 kg BW were slaughtered as the baseline animals at the start of the trial. An intermediate group of seven randomly selected lambs fed ad libitum was slaughtered at 28.6 kg BW. The remaining 21 lambs were randomly divided into three levels of dry matter intake： ad libitum or 70% or 40% of ad libitum intake. Those lambs were slaughtered when the lambs fed ad libitum reached 35 kg BW. Total body N and N retention were measured.Results： The daily NP and MP requirements for maintenance were 1.89 and 4.52 g/kg metabolic shrunk BW（SBW0.75）.The partial efficiency of MP utilization for maintenance was 0.42. The NP requirement for growth ranged from 12.1 to 43.5 g/d, for the lambs gaining 100 to 350 g/d, and the partial efficiency of MP utilization for growth was 0.86.Conclusions： The NP and MP requirements for the maintenance and growth of Dorper crossbred male lambs were lower than the recommendations of American and British nutritional systems.

Energy requirements of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation

This experiment was conducted to investigate the energy requirement of Dorper×thin-tailed Han crossbred ewes during non-pregnancy and lactation. Fifteen ewes after parturition were randomly assigned to three treatments： ad libitum（100%） feed intake and 80 or 60% ad libitum intake, and another nine non-pregnant ewes were assigned to a blank control group. Digestibility trials were performed in the non-pregnant ewes and in the lactating ewes on the 20 th, 50 th, and 80 th d of lactation. In parallel with the digestibility trial, a respirometry experiment was conducted to determine the methane and carbon dioxide production with an open-circuit respirometry system that was equipped with respiratory chambers. The net energy（NE） and metabolizable energy（ME） requirements for maintenance and growth were calculated using the carbon and nitrogen balance method. The results revealed that the carbon（C） and nitrogen（N） excretions and energy losses at faeces and urine, as well as the output of methane and CO2, increased significantly with decreasing feed intake（P〈0.01）. The apparent digestibilities of C in th e stages of non-pregnancy and early, middle and late lactation were 55.8–58.3%, 62.5–73.8%, 64.8–71.3%, and 61.7–65.0%, respectively, and the apparent digestibilities of N were 45.2–51.3%, 73.7–82.7%, 72.8–80.5%, and 73.6–76.5%, respectively. The corresponding energy apparent digestibilities were 52.0–56.3%, 60.7–76.6%, 61.0–68.8%, and 61.4–67.7%, respectively. The ME/DE（digestible energy） values were 79.5–85.9%, 79.4–83.5%, 81.0%–85.3% and 78.6–82.9%, respectively. The maintenance requirements of NE, ME, and the efficiencies of ME utilisation for maintenance during the stages of non-pregnancy and early, middle and late lactation were 215.5, 253.1, 247.7, and 244.7 k J kg^（–1） BW0.75 d, and 372.4, 327.1, 320.9, and 362.0 k J kg^（–1） BW0.75 d, and 0.58, 0.77, 0.77, and 0.68, respectively. The ME requirement for the growth of non-pregnant ewes was 31.3 MJ kg^（–1） BW gain.

Effects of the Standardized Ileal Digestible Lysine to Metabolizable Energy Ratio on Performance,Nutrient Digestibility,and Plasma Parameters of 10 to 28 kg Pigs

A total of 480 nursery pigs （Duroc x Landrace x Large White） were utilized in two experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID- Lys） to metabolizable energy （ME） ratio on the performance, nutrient digestibility, plasma urea nitrogen （PUN） ,and plasma free amino acids of 10 to 28 kg pigs. In Exp. 1, 192 pigs （ 10.58 kg） were assigned to one of four treatments. The treatments consisted of diets with a ME content of 3.2, 3.25, 3.3, or 3.35 Mcal/kg with a constant SID-Lys：ME ratio of 3.7 g/Mcal. The experiment lasted 28 days. Pigs which were fed the diets containing 3.3 and 3.35 Mcal/kg ME had lower feed intakes （ P 〈 0.05）than those fed 3.2 Mcal/kg. Feed efficiency was linearly improved with increasing dietary ME （ P 〈0.05）. Increasing the dietary ME level also increased （P 〈0.05 ） dry matter and energy digestibility. Therefore,3.3 Mcal/kg ME was selected for Exp. 2 in which 288 pigs （ 10.60 kg） were assigned to one of six treatments. Treatments consisted of SID-Lys： ME ratios of 3.1,3.3,3.5,3.7,3.9, or 4.1 g/Mcal with all diets providing 3.3 Mcal of ME/kg. Weight gain and feed efficiency were increased （P 〈0.05 ） as the SID-Lys：ME ratio in diet increased. Based on a straight broken-line model ,the estimated SID-Lys：ME ratio to maximize weight gain was 3.74.

Effects of Dietary Metabolizable Energy and Crude Protein Levels on Reproductive Performance of Magang Geese

[ Objective] To investigate the effects of different levels of metabolizable energy and crude protein on egg laying performance and hatch- ing efficiency in Magang geese. [Method] The healthy Magang geese at 2 years old were randomly assigned into four groups, group Ⅰ, group Ⅱ, group Ⅲ and control group. They were fed with diets at different levels of metabolizable energy and crude protein, and then their eggs were collect- ed and hatched. During the test, their health was observed, and the egg weight, egg yield and hatching rate were recorded. [ Result] The average egg laying rates and average egg weight were significantly higher in the group Ⅰ, group Ⅱ and group Ⅲ than in the control group. The hatchable egg rates and egg fertilization rates of the group Ⅰ, group Ⅱ and group Ⅲ were also increased, and significance was found between the group Ⅲ and the other group （P 〈 0.05）. The feed costs of the three test groups were lower than that of the control group, and the feed cost was higher in the group Ⅲ than that in the group Ⅰ and Ⅱ. [ Conclusion] The levels of metabolizable energy and crude protein in diet have significant effects on laying performance and hatching efficiency in Magang geese.

Evaluation of Pomegranate Pomace Using in Situ and Gas Production Techniques

This study was carried out to determine nutritive value of pomegranate pomace using in situ and gas production techniques. In this study, two fistulated wethers （38 ± 1.5 kg） were used in situ method. The gas production was measured at 2, 4, 6, 8, 12, 16, 24, 36 and 48 h and ruminal DM （dry matter） and CP （crude protein） disappearances were measured at 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h. DM degradabilities of treated pomegranate pomace at 8 h to 96 h were larger than untreated pomegranate pomacewhich showed significant differences （p 〈 0.05）. CP degradabilities of treated pomegranate pomace at 96 h was 62.38% that showed significant differences （p 〈 0.05）. The metabolizable proteins of treated and untreated pomegranate pomace were 73 and 64.27 g/kg respectively that showed significant differences （p 〈 0.05）. The gas productions of treated and untreated pomegranate pomace at 48 h were 79.91 and 128.75 mL/g DM respectively that showed significant differences （p 〈 0.05）. It was concluded that the pomegranate pomace can be used largely as ruminant feeds.

Energy Value and Amino Acid Bioavailability of Faba Bean Seeds in Broilers Diets

The aim of this study was to determine the apparent （AME） and true metabolizable energy （TMEn） as well as the crude protein （CP） and amino acid （AA） total tract （by excreta collection） digestibility （bioavailability） of faba bean seeds （FBS） of the Greek cultivar ＂Polikarpi＂. Forty eight broilers were placed in individual cages and randomly allocated into 4 dietary treatments. Birds consumed 80 g d1 of either a typical commercial diet or the same diet in which 100, 200 or 300 g kg^-1 had been substituted by ground FBS. The experiment lasted 15 d. Apparent and true CP bioavailability of FBS were significantly decreased （P 〈 0.05） only at the inclusion rate of 300 g kg-1. AA bioavailability remained at high levels （-0.80） with the exception of cystine and was similar to CP mean. The mean AME and TMEn values of FBS were estimated equal to 11.1 and 11.4 MJ ME kg^-1, respectively.

Metabolizable Energy and Amino Acid Bioavailability of Field Pea Seeds in Broilers Diets

The aim of this study was to determine the apparent （AME） ＆ true （TMEn） metabolizable energy as well as the crude protein （CP） ＆ amino acid （AA） total tract （by excreta collection） digestibility （bioavailability） of field pea seeds （FPS） of the Greek cultivar ＂Olympos＂. Forty eight broilers were placed in individual cages and randomly allocated into 4 dietary treatments. Birds consumed 80 g/d of either a typical commercial diet or the same diet in which 100, 200 or 300 g/kg had been substituted by ground FPS. The experiment lasted 15 d. Apparent and true CP bioavailability of FPS were significantly decreased （P 〈 0.05） only at the inclusion rate of 300 g/kg. AA bioavailability remained at high levels （-0.80）, with the exception of methionine and valine and was similar to CP mean. The mean AME and TMEn values of FPS were estimated equal to 10.8 and 11.0 MJ ME/kg, respectively.