20～50 kg川藏黑猪的能量代谢与沉积规律研究

本试验旨在研究20~50 kg川藏黑猪的能量代谢与沉积规律。试验一:选择体重接近[(20.17±3.46)kg]的川藏黑猪配套系商品猪64头,预试7 d后屠宰4头猪测定胴体成分;其余试验猪按公母随机分成5个组,每个组4个重复,每个重复3头,各重复单圈饲养,自由采食消化能(DE)水平分别为13.79、13.37、12.96、12.54和12.12 MJ/kg的饲粮。试验猪体重达50 kg时,结束试验一,测定平均日采食量、平均日增重和料重比,并在各组选择1头猪屠宰测定胴体成分。试验二:选择试验一中15头体重接近[(48.34±4.07)kg]的公猪,随机分成5个组,每个组3个重复,每个重复1头,单独饲养于代谢笼,分别采食上述5种DE水平的饲粮,进行消化代谢试验。预试期3 d,正试期4 d。采用析因法建立能量需要量预测模型。结果表明:饲粮DE水平影响了20~50 kg川藏黑猪的平均日采食量、平均日增重和料重比;饲粮DE转化为代谢能(ME)效率(ME/DE)为97.26%~98.10%,ME用于沉积产品能的效率(DED/ME)平均值为41.71%;此阶段川藏黑猪维持需要ME平均值为0.49 MJ/W~(0.75)或0.85 MJ/W~(0.60)(按DE计为0.50 MJ/W~(0.75)或0.87 MJ/W~(0.60)),增重需要DE和ME平均值分别为18.91和18.47 MJ/kg。由此得出,20~50 kg阶段川藏黑猪能量需要模型为:DE(MJ/d)=0.504 W~(0.75)+18.91ΔW或DE(MJ/d)=0.867 W~(0.60)+18.91ΔW;ME(MJ/d)=0.492 W~(0.75)+18.47ΔW或ME(MJ/d)=     

Genotype and sex effects on the relationship between energy intake and protein deposition in growing pigs

Seventy-two crossbred (Large White X Landrace) pigs were used in a 3 X 7 factorial experiment to investigate the response of two strains of boars (strains A and B) and of castrated male pigs (strain B) to seven levels of intake of a single diet (ranging from 5.3 Mcal digestible energy [DE]/d to ad libitum) between 45 and 90 kg live weight. All aspects of growth performance and body composition were affected to different degrees by both strain and sex. At all levels of energy intake strain A boars grew faster, had a lower feed to gain ratio and contained less fat and more water in the empty body than strain B boars, which in turn exhibited faster live weight gain and more efficient and leaner growth than castrated males. The magnitude of the differences in growth performance between strain A and strain B boars and castrates increased with increased energy intake above 7.88 Mcal DE/d, and these differences were associated with concomitant strain differences in their respective capacity for protein growth and in the relationship between energy intake and protein deposition. For strain A boars the rate of protein deposition increased linearly from 92 to 188 g/d with increased energy intake from 5.3 Mcal DE/d to ad libitum. For strain B boars and castrates the rate of protein deposition increased linearly with increased energy intake up to 7.88 Mcal DE/d, but thereafter it remained constant at 128 and 85 g/d, respectively. For castrates protein deposition was depressed (P less than .01) when the diet was offered ad libitum. Strain A boars had a higher energy requirement for maintenance (3.55 Mcal DE/d) than strain B boars (2.77 Mcal DE/d) or castrates (2.60 Mcal DE/d). Strain A boars also contained less protein and more water in the fat free empty body than the other two pig types.     

Protein and Energy Requirements of Pre-weaned West African Dwarf Goats Fed Soyabean Diet as a Replacement for Milk in a Tropical Environment

Twenty-one early-weaned West African dwarf goats weighing between 1.0 and 1.5 kg at birth were used to assess the protein and energy requirement of pre-weaned West African Dwarf (WAD) goats fed soyabean diet. Three isonitrogenous diets (24%) were prepared such that dried whole-milk protein was replaced by corn starch and soyabean concentrate protein at 0.0%, 25.0% and 50.0% levels such that a 14.5% total solid solution was obtained for each diet. Results indicated that a daily digestible energy (expressed as kcal/day/W0.75 kg) intake of 58.2, 63.7, 98.5 and 114.6 kcal was required for maintenance, while a corresponding value of 7.37, 4.50, 2.18 and 1.91 kcal was required per day per gram live weight gain by the kids at 4, 6, 9 and 13weeks old, respectively. Similarly, a digestible crude protein (DCP) intake of 3.59 g/day/W0.75 kg) appeared to be adequate for maintenance of the kids between 0 and 13 weeks, while 0.34 g/day/W0.75 kg of DCP intake was required per day per gram live weight.     

Protein and amino acid metabolism in the intestinal tract of growing young bulls. 7. Protein estimation and evaluation of protein supply in growing ruminants by the apparently digestible total protein in the duodenum based on rations

The following values were derived from experimental studies of the crude protein (CP) and amino acid (AA) metabolism of growing fattening bulls, the detailed results of which were described in installments 1-6, for the ascertainment of the content of apparently digestible total protein at the duodenum (ADTPD): a) partial method: Degradation quotaCP = NPN + 0.69 X g pure protein/CP; g AD feed PD = g CP (1 -decomposition quotaCP) X 0.72 or g AD feed PD = 0.31 X g pure protein X 0.72; g ADBPDE = 0.149 X g AD org. matter X 0.80 X 0.72 (ADBPDE = apparently digestible pure bacteria protein at the duodenum, dependent on energy release in the reticulo-rumen; g ADBPDN = g CP X (degradation quotaCP) X 0.80 X 0.72 (ADBPDN = apparently digestible pure bacteria protein at the duodenum, dependent on CP supply of rumen microbes); g AD total PD = g AD feed PD + ADBPDE g AD total PD = g AD feed PD + ADBPDN; b) summarizing method: AD total PD = 0.429 + 10.9 X 0.80/CP in % AD org. matter X (CP intake) X 0.72; AD total PD = 0.196 + 16.6 X 0.80/pure protein % AD org. m. X pure pr. intake X 0.72. The requirement of AD total PD was calculated under consideration of the endogenous urine N, skin N and hair N losses as well as protein retention per kg live weight assuming a utilization of 0.70 for this partial performance. The practical application of this balance method is demonstrated in comparison to the digestible CP-system.     

Energy balances of lactating sows in relation to feeding level and stage of lactation

Twelve crossbred sows were used in an energy balance study to estimate energetic efficiency of milk production from feed. Balances were made from 7 to 14 d and from 18 to 25 d of lactation. Two feeding levels were applied (high and low). The low level (L) was meant to supply energy slightly above maintenance, with energy needed for milk to be derived from body reserves. The high level (H) was meant to supply sufficient energy for maintenance and for milk production. The low-level animals received 2.5 to 2.6 kg of feed/d and the high level animals 4.8 to 6 kg/d. The loss of weight of sows during lactation depended more on feeding level than on stage of lactation. A high level of feeding to sows resulted in heavier piglets compared with the low feeding level (significant after 10 d). At 24 d of age piglets with the high-feeding-level sows weighed 7.5 kg and those with the low-level sows, 5.7 kg. At the high level, animals excreted 1,200 to 2,800 kcal more milk energy per day than the low-level animals. Energy for milk from feed was produced with an efficiency of 67 to 69% with a maintenance requirement of 112 to 125 kcal metabolizable energy (ME) X W-.75 X d-1. Efficiency of milk production from feed was calculated as 62% and the maintenance requirement was 68 kcal. In this calculation, milk was corrected toward zero energy balance. Another way of calculating this efficiency after correcting feed toward zero energy balance resulted in estimates of 68% for efficiency and of 88 kcal ME X W-.75 X d-1 for maintenance requirement. From these data it was derived that, for each piglet, the sow needed to receive .5 to .6 kg of extra feed (ME content 3,000 kcal/kg) per day to cover milk production. Level of metabolic rate for nursing piglets was estimated as 97 kcal ME X W-.75 X d-1 for maintenance and, in addition, .195 kcal/kcal extra of milk intake above maintenance.     

Digestible and metabolizable energy concentrations and amino acid digestibility of dried yeast and soybean meal for growing pigs

Energy values and amino acid (AA) digestibility of dried yeast (DY) and soybean meal (SBM) were determined in 2 experiments with growing pigs. Experiment 1 was conducted to determine the digestible energy (DE) and metabolizable energy (ME) in DY and SBM. Thirty barrows with a mean initial body weight (BW) of 20.6 kg (SD = 1.04) were assigned to 5 dietary treatments in a randomized complete block design with period and BW as blocking factors. A reference diet was prepared with corn, canola meal, and soybean oil as energy-contributing ingredients. Four additional diets were prepared by adding 5% and 10% DY or SBM at the expense of energy-contributing ingredients in the reference diet. The ratio of corn, canola meal, and soybean oil was kept consistent across the experimental diets. Each experimental period consisted of 5-d adaptation and 5-d quantitative collection of feces and urine. Test ingredient-associated DE or ME intake (kcal/d) was regressed against test ingredient intake [kg dry matter (DM)/d] to estimate the DE or ME in test ingredients as the slope of linear regression model. The DE in DY was estimated at 3,933 kcal/kg DM, which was not different from the estimated DE in SBM at 4,020 kcal/kg DM. Similarly, there was no difference between DY and SBM in the estimated ME (3,431 and 3,756 kcal/kg DM, respectively). Experiment 2 was conducted to determine the standardized ileal digestibility (SID) of AA in DY and SBM. Twenty-one barrows with a mean initial BW of 20.0 kg (SD = 1.31) were surgically fitted with T-cannulas at the distal ileum and assigned to 3 dietary treatments in a randomized complete block design with BW as a blocking factor. Two semi-purified diets containing DY or SBM as the sole nitrogen source and one nitrogen-free diet (NFD) were prepared. The NFD was used to estimate the basal ileal endogenous losses of CP and AA. Pigs were fed the 3 diets for 5 d as adaptation, followed by 2 d of feeding with ileal digesta collection. The SID of AA, except Gly and Pro, in DY was less (P < 0.05) than in SBM. The SID of indispensable AA in DY ranged from 64.1% for Thr to 85.2% for Arg, and those in SBM ranged from 83.9% for Thr to 91.8% for Arg. In conclusion, energy values of DY are not different from those of SBM, whereas AA in DY is less digestible than in SBM. The estimated DE and ME as well as the SID of AA in DY and SBM can be used in diet formulation for growing pigs using these ingredients.     

Effect of postweaning feeding on the performance and energy balance of female rabbits at different physiological states

The feeding of a high-fiber and low-energy diet to young rabbit does from weaning to the first kindling was used to modify their body reserves, stimulate their energy intake, and reduce the energy deficit during the first lactation. Rabbits (53 per group) were given ad libitum access to either a control or high-fiber diet (CP, 17.6 vs 15.8% of DM; crude fiber, 15.5 vs 19.9% of DM; digestible energy, 2,565 vs 2,261 kcal/kg of DM, respectively) from weaning to their first kindling. During lactation, both groups received the same diet, which contained 19.3% CP, 16.5% crude fiber, and 2,634 kcal/kg digestible energy (dry matter basis). Four comparative slaughters were performed to estimate the chemical and energy balance of rabbit does at different physiological states: at the beginning of the trial (12 rabbits, 45 d of age), at mating (10 rabbits per group, 136 d), at kindling (10 rabbits per group, 167 d), and at the end of lactation (12 and 11 rabbits for the control and the high-fiber group, 197 d). Large changes in body weight and composition were observed between slaughters. From 45 d to mating, doe body fat and energy increased 7.93 and 4.64 times the initial content, respectively. During pregnancy, body protein concentration decreased from 203 to 186 g/kg. At the end of lactation, body fat and energy concentration were reduced to values close to those measured at 45 d of age. Dietary treatment affected body chemical and energy balance during pregnancy and lactation but not reproductive and lactational performance. The high-fiber diet stimulated feed intake from weaning to the first kindling but not dietary energy intake. During lactation, the rabbits fed the high-fiber diet ate 10 kcal x d(-1) x kg live weight(-.75) more and lost less body fat (-405 vs -504 g) and body energy (-3,628 vs -4,294 kcal) than the does fed the control diet (P < .001). In the same period, all does showed water and protein retention (185 and 45 g, on average) regardless of dietary treatment. In conclusion, feeding young does a high-fiber diet until their first kindling reduced the chemical and energy body deficit at the end of the first lactation.     

青山羊泌乳期母羊的能量需要量研究

选用24只青山羊泌乳母羊,用饲养试验、消化代谢试验、比较屠宰试验及气体能量代谢试验等手段,研究其能量需要量。结果表明,在本试验条件下,试羊的能量表观消化率和代谢率分别为70.4％和85.0％,甲烷能占总能进食量(GEI)的9.20％。维持代谢能需要为502W~(0.75)KJ/天,每产一千克标准乳(FCM)需5060KJ泌乳代谢能。泌乳母羊的维持效率(K_m)为0.845,泌乳效率(K_1)为0.635,热增耗占GEI的14.34％。青山羊泌乳期母羊的代谢能总需要量(MERKJ/天)可按下式求得MER=502W~(0.75)+5060·FCM或:MER=502W~(0.75)+1.578NEL(式中:W~(0.75):kg;FCM:kg/天;NEL:kJ/天)。     

波尔山羊×隆林杂交羔羊育肥期能量和蛋白质营养需要的研究

试验旨在研究育肥期波本杂肉羊能量和蛋白质营养需要量参数,筛选出一个最佳能量和蛋白质搭配的饲料配方,为科学饲养提供理论依据和生产指导。试验选择16只3月龄断奶波隆杂交F1代公羔,采用4×4拉丁方设计,以NRC（1981）营养需要推荐量为参考设计了低能低氮、高能低氮、低能高氮和高能高氮（NRC）4种能氮比日粮,分别为日粮1、2、3和日粮4。试验结果表明,舍饲波隆杂交羔羊育肥期对象草 玉米型日粮干物质采食量与代谢体重和日增重的关系为：DMI（g/d）=181.3W0.75－0.61ΔW－886.2（r=0.9287）;舍饲波隆杂羔羊育肥期粗蛋白质（CP）、总能（GE）、消化能（DE）需要量的估测模型分别为：CP（g/d）=19.56 W0.75＋0.25ΔW－128.6（r=0.7836）,GE（MJ/d）=2.98 W0.75＋0.023ΔW－18.69（r=0.8257）,DE（MJ/d）=1.26 W0.75－.006ΔW－3.56（r=0.6236）;3~6月龄舍饲育肥期波隆杂羔羊,日粮总能代谢率平均为0.49%,粗蛋白质的消化率平均为0.63%,每增重1 g体沉积蛋白质需要量为0.32 g。     

Calculation of protein and energy requirements in beluga sturgeon (Huso huso) using a factorial approach

This study tried to determine the protein and energy requirements of growing beluga sturgeon Huso huso using a factorial approach. The experiment was composed of four small‐scale growth trails covering different weight ranges. The fish fed at 0, 20, 40, 60, 80 and 100% of satiation. DWG had a steady increase throughout the experiment following a non‐linear equation as Y = 1.433 (±0.056) × Ln(X) ?2.740 (±0.261); r² = 0.99, p < 0.001, where Y = weight gain (g/day) and X = fish weight (g). The daily requirement of digestible energy (DE) for maintenance amounted to 79.09 kJ × BW (kg)^0.8. The daily requirement of DP for maintenance calculated as 0.93 g × BW (kg)^0.7. The relationship between DE intake (X) and DE gain (Y) expressed as Y = ?0.0004 (±0.000) X² + 0.600 (±0.082) X ?44.95 (± 6.72). Also, the relationship between DP intake (X) and protein gain (Y) was expressed as Y = ?0.019 (±0.006) X² + 0.548 (±0.062) X ? 0.498 (±0.121). The daily requirements of energy and protein were estimated as 79.09 kJ × BW (kg)^0.8 + 2.94 × DE gain and 0.93 g × BW (kg)^0.7 + 2.63 × DP gain. Apparently, beluga sturgeon is inefficient in converting energy and protein into body tissue. Therefore, energy content of the diet should be sufficiently high to satisfy large energy demands in beluga sturgeon and also to reduce the catabolism of protein.     

Maintenance energy requirement of llamas.

Five castrated male llamas (mean body weight, 94 kg) were studied in an energy balance trial to determine maintenance energy requirement of llamas. Llamas were fed a 50% oat hay-50% pelleted concentrate diet (2.43 Mcal of metabolizable energy/kg of diet dry matter) at approximately 1.6% of body weight (BW). An 8-day total collection digestion trial was used to determine fecal and urine energy losses. Heat production and methane emissions were determined via indirect respiration calorimetry measurements on each llama fed at the same level of intake as during the digestion trial and subsequently on days 3 and 4 of a period of nonfeeding. Fecal, urine, and methane energy losses of the llamas fed near-maintenance intake were 32.5, 3.5, and 7.1% of gross energy intake, respectively. The postabsorptive metabolic rate, commonly called nonfed (fasting) heat production, was 59.3 kcal/BW0.75. Using a linear relation between postabsorptive and maintenance energy requirement and efficiency of energy use below maintenance of 0.702, metabolizable energy requirement at maintenance was determined to be 84.5 kcal/BW0.75.     

成年阉牛对饲粮蛋白质的消化及维持需要量的估计

选择 6头安装有瘤胃、十二指肠前端和回肠末端瘘管的阉牛 ,分 3期依次饲喂以玉米、棉籽饼和氨化稻草为原料配合的 3种不同饲养水平的日粮 ,以Cr2 O3为指示剂测定小肠表观可消化N供给量 ,采用全收粪尿法测定氮平衡值。结果显示 ,以代谢体重为基础的氮平衡值 (NB)与进食氮和小肠表观可消化氮供给量之间分别存在如下回归关系 :NB =- 0 .5 0 12 +0 .5 76 8×进食氮　　　　　　　　R =0 .76 6 0NB =- 0 .2 80 4 +0 .6 398×小肠表观可消化氮R =0 .9894据此估计 ,阉牛维持的粗蛋白、小肠表观可消化粗蛋白和净蛋白需要量分别为 5 .4 3、2 .74、1.76g kgW0 .75。对体表氮损失加以考虑后 ,阉牛维持的粗蛋白、小肠表观可消化粗蛋白和净蛋白需要量分别为 5 .6 5、2 .93、1.88g kgW0 .75。小肠表观可消化粗蛋白用于维持和增重的效率为 0 .6 4     

7～10月龄杂交肉牛蛋白质需要量及其代谢规律的研究

选择18头健康、体重(183.58±7.89)kg的6月龄利木赞×鲁西黄牛杂交生长牛,采用饲养试验、消化代谢试验和尼龙袋试验,研究了7~10月龄生长牛的蛋白质需要量及其代谢规律。试验结果表明,本试验日粮的粗蛋白质对7~10月龄生长牛的消化率、沉积率和瘤胃降解率分别为75.93%、35.28%和56.28%。生长牛在7~10月龄时的维持粗蛋白质需要量为6.46 g/kgW0.75.d,增重的粗蛋白质需要量为463.42 g/kg。生长牛在7~10月龄时期,其粗蛋白质需要量(RCP,g/d)、可消化粗蛋白质需要量(RDCP,g/d)和瘤胃降解蛋白质需要量(RDP,g/d)可按下式计算:RCP=6.46W0.75+463.42△W;RDCP=4.91W0.75+351.87△W;RDP=2.76W0.75+198.04△W。     

Feed intake and weight gain of growing goats fed diets of various energy and protein levels

Growing goats, 45 Alpine and 45 Nubian, were used in a 3 x 3 factorial arrangement to quantify the influence of dietary energy and protein levels on daily DM intake and nutrient utilization for growth. Goats had ad libitum access to complete mixed diets containing either 2.46, 2.77 or 3.05 Mcal/kg ME plus 11.2, 12.7 or 15.1% CP for 16 wk. Dry matter intake decreased curvilinearly as dietary ME density increased (P less than .001). Dry matter intake increased linearly (P less than .05) as dietary CP level increased during all growth intervals except wk 25 to 28 of age. Average daily gain was 115, 113 and 99 g/d for goats fed diets containing 2.46, 2.77 and 3.05 Mcal/kg ME, respectively. Average daily gain was 104, 106 and 117 g/d for goats fed diets with 11.2, 12.7 and 15.1% CP, respectively. Dry matter intake was higher (P less than .01) for Alpine than for Nubian goats, whereas ADG was similar between breeds. Intake of ME was 248, 260 and 198 kcal/(kg.75.d) for goats fed the low- medium- and high-energy diets, respectively. Intake of CP was 9.1, 10.7 and 13.2 g/(kg.75.d) for goats fed low-, medium- and high-protein diets, respectively. Average requirements for growth derived from regression analysis of all data points were 4.6 kcal ME and .26 g CP/g ADG. The prediction equation for intake of growing goats of 4 to 8 mo of age was: DMI, g/d = 1,749 - 496 DE, kcal/g + 18 live weight, kg + 3 ADG, g/d; r2 = .73 (Sy.x = 127, P less than .0001, n = 90). The requirement of ME for growth was 33% lower than the value recommended in 1981 by the National Research Council.     

Characterization of energy and performance of swine fed a novel corn-soybean extruded product

Background

A novel extruded product was characterized with a metabolism and lactation trial to establish the product’s energy content, and its effects on lactating sow performance. The product was composed of a 60:40 corn-soybean blend, which was then extruded. This product containing the co-extruded 60:40 corn-soybean blend was commercially developed and is used extensively in swine diets in southwest Minnesota. GE of dietary treatments were determined by isoperibol bomb calorimetry. Twelve barrows (59.9 ± 1.4 kg), were used to determine the digestible and metabolizable energy of the extruded product. DE of treatments was determined by subtracting fecal energy from GE provided to barrows by each respective treatment. ME was determined by subtracting urinary energy from calculated digestible energy. Sixty-three sows were used for the lactation trial. Three dietary treatments were utilized: CONTROL (an industry standard diet); PRODUCT (contained the product, vitamins and minerals); OIL (matched the lysine:ME ratio of PRODUCT by addition of soy oil). Sow weight, backfat thickness at the right and left last ribs, body condition score, number of piglets, and litter weights were recorded on the date of farrowing (d 0), (d 9), and at weaning. Blood and milk samples were obtained at weaning, and blood was analyzed for plasma urea nitrogen (PUN), milk was analyzed for total protein and fat content.

Results

On a dry-matter basis, the test diet provided 3,908 kcal/kg DE and 3,833 kcal/kg ME, which was significantly greater than the basal diet, which provided 3,633 kcal/kg DE and 3,567 kcal/kg ME (P < 0.0001). These data were used to establish the DE and ME of the product, which were 3,882 kcal/kg and 3,798 kcal/kg, respectively, on an as-fed basis. No effect of diet was observed for changes in sow backfat (RBF P = 0.24; LBF P = 0.07) or body condition score (P = 0.12) during lactation. Milk total protein (P = 0.69), fat (P = 0.66), PUN, average piglet gain (P = 0.55) and piglet mortality (P = 0.70) did not differ between treatments.

Conclusions

While the novel extruded product was higher in energy content than traditional feedstuffs, it resulted in the same lactational sow performance. Thus, the co-extruded corn-soybean product is a reasonable inclusion in sow lactation diets.     

Estimation of net energy requirements (NEm and NE delta) of lactating beef cows.

Spring-calving Angus cows (n = 24) in moderate body condition were assigned to either a high (H), maintenance-high (MH) to support superior milk, maintenance-low (ML) to support average milk, or low (L) energy diet at 12 d (SD = 4) postpartum. Energy balance for individual cows was determined by body condition change, weight change, and weigh-suckle-weigh milk production estimates. High energy intake increased (P < .05) BW, body condition score (BCS), and megacalories of body energy (BE) by 94 d postpartum. Neither dietary nor BCS accounted for significant (P > .30) variation in days to first ovulation or conception. Fasting heat production was estimated to be 72.5 kcal/BW.75 from the regression of log daily heat production/BW.75 on daily ME intake/BW.75. Rate of daily BW change did not affect concentration of energy in the weight change. Body condition score change was highly correlated (r = .98) to BW change, with each unit of BCS (1 to 5 scale) change associated with 68 kg of BW change. Two methods were used to determine NE for weight change (NE delta) based on empty body weight (EBW) change. Method 1 used the equation: BCS change = -.404 + .0147 (BW change) and Method 2 used only the regression coefficient of this equation to predict daily BCS change. Methods 1 and 2 resulted in similar regression equations: NE delta (Mcal/kg EBW change) = 1.590 + 1.251 (BCS) and NE delta (Mcal/kg EBW change) = 1.317 + 1.251 (BCS). Ranges of estimated protein and lipid in the EBW change, respectively, were 10.0 to 13.7% and 17.1 to 77.2%.     

Energy and protein supply for event horses during training: comparison between intake and requirements

In horses that exercise intensively (for example, event horses in training) the intake and energy requirements were compared on the basis of a diet record and estimates of energy required for exercise. Daily net energy intake over a 7 days period was on average 30% (n = 15) higher than the net energy requirement. Since the horses had a constant body weight, and thus were in energy balance, the energy intake was overestimated and/or the energy requirement was underestimated. The intake of digestible protein was 92% higher than the protein requirement. This study illustrates the problems concerning ration assessment and evaluation in practice.     

Response of nonpregnant versus pregnant gilts and their fetuses to severe feed restriction

Crossbred (Chester White X Landrace X Large White X Yorkshire) primiparous gilts were fed a standard gestation diet at 6,000 or 2,000 kcal calculated digestible energy (DE; 1.8 or .6 kg feed) daily for 84 or 108 (106 to 112) d after mating. Nonpregnant littermates were matched by body weight and assigned to the same diet treatments. Body weight and ultrasonic backfat measurements were made at 3-wk intervals. At 77 and 100 d, eight pregnant gilts (four control and four restricted) were fitted with indwelling jugular cannulas for frequent blood sampling (33 times over an 8-h period) to determine plasma glucose and growth hormone concentrations. At 84 and 108 d all gilts (eight pregnant and eight nonpregnant at d 84 and nine pregnant and nine nonpregnant at d 108 for each diet) were slaughtered and internal organs and reproductive tracts were removed and weighed. Fetal body and organ weights were recorded and an umbilical artery blood sample was removed from fetuses for plasma glucose, growth hormone, total protein and albumin measurements. The results demonstrated the ability of the primiparous gilt to maintain pregnancy through 106 to 112 d of gestation while consuming one-third (2,000 kcal DE daily) of recommended daily feed. Fetal weight at 84 and 108 d was reduced by about 13% without affecting litter size in gilts fed severely restricted intakes. Absolute and relative weights of maternal organs were affected by severe feed restriction, and backfat was reduced but there was no evidence of "pregnancy anabolism" in either adequately fed or restricted gilts. Fetal liver, kidney and gastrointestinal tract weights were reduced by maternal feed restriction; relative kidney weights were reduced while relative brain cortex weight was increased by maternal restriction. Maternal plasma glucose was unchanged by pregnancy or feed intake while plasma growth hormone peak amplitude, but not mean concentration or number of peaks, was increased by feed restriction. Fetal plasma glucose increased with time and in response to severe maternal feed restriction while plasma total protein and albumin decreased. Plasma growth hormone declined with time and was negatively correlated with fetal body weight.     

育成期崂山奶山羊能量需要量

本试验旨在研究饲粮能量水平对育成期崂山奶山羊能量利用率的影响。选择体重为(18.43±0.76)kg的崂山奶山羊育成母羊30只,采用单因素随机分组设计分成3组,每组10个重复,每重复1只羊。分别饲喂粗蛋白质、钙及磷水平基本一致,消化能水平分别为10.40、11.47及12.51 MJ/kg的3种全混合日粮。预试期10 d,正试期90 d。结果表明:1)试验后期3组试羊随着饲粮能量水平的提高,总能消化率依次提高,12.51 MJ/kg组试羊的总能消化率、总能代谢率及消化能代谢率显著高于10.40 MJ/kg组(P0.05);3组试羊的总能、粪能及尿能间呈显著差异(P0.05),10.40 MJ/kg组11.47 MJ/kg组12.51 MJ/kg组;10.40 MJ/kg组试羊的甲烷能显著低于11.47及12.51 MJ/kg组(P0.05)。2)10.40 MJ/kg组试羊末重及平均日增重显著低于11.47及12.51 MJ/kg组(P0.05),但11.47 MJ/kg组与12.51 MJ/kg组间无显著差异(P0.05)。3)育成期崂山奶山羊消化能和代谢能需要量与代谢体重和平均日增重关系的回归公式:DE=0.675W~(0.75)+0.110ADG(P=0.006,R~2=0.982);ME=0.526W~(0.75)+0.076ADG(P=0.027,R~2=0.873)[式中DE为消化能(M J/d),ME为代谢能(M J/d),W~(0.75)为代谢体重(kg),ADG为平均日增重(g)]。综合得出,育成期崂山奶山羊母羊饲粮中消化能以11.47~12.51 MJ/kg(干物质基础)较为适宜。     

空怀期陕北白绒山羊的能量需要量

本试验旨在研究空怀期陕北白绒山羊母羊对能量的适宜需要量。选择1.5岁陕北白绒山羊母羊24只,随机分为4组,每组6个重复,每个重复1只羊。控制各组试羊粗蛋白质摄入量一致(实测值为74.0 g/d),测得各组消化能摄入量分别为7.6、8.3、8.9和9.6 MJ/d,进行为期40 d的饲养试验(前10天为预试期);饲养试验结束后,每组选择3只羊进行为期7 d的消化代谢试验。结果表明:空怀母羊对4种饲粮总能的消化率和代谢率分别为(65.3±3.23)%和(54.7±3.16)%。空怀期母羊平均日增重随能量摄入量增加呈线性增长。空怀母羊消化能和代谢能需要量分别为DE(MJ/d)=0.507 0W0.75+0.026 3 ADG和ME(MJ/d)=0.413 0W0.75+0.024 5 ADG(式中DE为消化能,W0.75为代谢体重,ADG为平均日增重,ME为代谢能)。综合得出,空怀期陕北白绒山羊饲粮中消化能和代谢能分别以9.17～10.14 MJ/kg和7.70～8.60 MJ/kg(风干基础)较为适宜。