Effects of diet forage:concentrate ratio and metabolizable energy intake on isolated rumen epithelial cell metabolism in vitro

Crossbred wether lambs were used to assess the effect of altered forage:concentrate ratio and metabolizable energy intake on metabolism of substrates by ruminal epithelium using an isolated cell system. Lambs (n = 28; 20.1 +/- 3 kg BW) were assigned randomly to a factorial arrangement of dietary treatments consisting of either 75% forage or 75% concentrate fed once daily at either .099 or .181 Mcal ME x(kg BW(.75))(-1) x d(-1) for 52 d. After a 52-d feeding period, isolated rumen epithelial cells (IREC) were incubated in the presence of an oxidizable substrate with a single 14C label (acetate, propionate, butyrate, glucose, glutamate, and glutamine) at concentrations ranging from .1 to 50 mM, and substrate oxidation to 14CO2 or metabolism to beta-hydroxybutyrate (beta-HBA), acetoacetate, pyruvate, and lactate was determined. For all substrates, oxidation to CO2 was concentration-dependent and saturable within the physiological range. Differences in substrate oxidation to CO2 by IREC at specific substrate concentrations did not affect Vmax (maximal rate of substrate oxidation, nmol oxidized to CO2 x 1 x 10(6) cells(-1) x 90 min(-1)) and K(ox) (concentration of substrate at which half Vmax oxidation rate is achieved, mmoles/L) estimates for the dietary treatments. Production of beta-HBA from butyrate by IREC from the lambs fed 75% forage was not affected by ME intake; however, production was elevated by high ME intake of the 75% concentrate diet (diet x intake interaction; P < .02). Acetoacetate production from butyrate by IREC from lambs fed at high ME intake was greater (P = .001) than from those fed at low ME intake. Lactate and pyruvate production from glucose, glutamate, and propionate were generally unaffected by dietary treatment; however, rate of glutamine metabolism to lactate and pyruvate by IREC was increased with increased ME intake. The observed changes in metabolite production rates across groups did not affect the predicted Vmax and K(ox) parameter estimates. The estimated K(ox) values corroborate that VFA are the primary oxidizable fuels used by ruminal epithelial cells while illustrating that other substrates such as glucose, glutamate, and glutamine would not be expected to be oxidized extensively in vivo due to the high K(ox) relative to substrate concentrations in vivo. In conclusion, the capacity of isolated ruminal epithelial cells to oxidize substrates was largely unaffected by ME intake or dietary forage:concentrate ratio of the diet.     

Effects of forage:concentrate ratio and forage type on apparent digestibility, ruminal fermentation, and microbial growth in goats

The effects of forage type and forage:concentrate ratio (F:C) on apparent nutrient digestibility, ruminal fermentation, and microbial growth were investigated in goats. A comparison between liquid (LAB) and solid (SAB)-associated bacteria to estimate microbial N flow (MNF) from urinary purine derivative excretion was also examined. Treatments were a 2 x 2 factorial arrangement of forage type (grass hay vs. alfalfa hay) and high vs. low F:C (70:30 and 30:70, respectively). Four ruminally cannulated goats were fed, at maintenance intake, 4 experimental diets according to a 4 x 4 Latin square design. High-concentrate diets resulted in greater (P < 0.001) nutrient digestibility except for ADF. However, CP digestibility increased (P < 0.001) only for the high-concentrate diets including grass hay. Likewise, N retention, ruminal NH(3)-N concentration, and urinary excretion of purine derivatives increased (P < 0.05) with increasing concentrate in animals fed diets based on grass hay (0.23 vs. 0.13 g of retained N/g of digested N, 30.1 vs. 12.9 mg of NH(3)-N/100 mL, and 11.5 vs. 8.40 mmol/d, respectively), but not (P > 0.05) when diets included alfalfa hay. Total protozoa numbers and holotricha proportion were greater and less (P < 0.001), respectively, in high- than in low-concentrate diets. The F:C affected (P < 0.001) ruminal pH but not total VFA concentration (P = 0.12). Ammonia-N concentration was similar (P = 0.13) over time, whereas pH, VFA concentration, and protozoa numbers differed (P < 0.001) among diets. Estimated MNF was strongly influenced by using either the purine bases:N ratio obtained in our experimental conditions or values reported in the literature for small ruminants. There was a F:C effect (P = 0.006) on MNF estimated from LAB but not from SAB. The effect of F:C shifting from 70:30 to 30:70 in goat diets depends on the type of forage used. The MNF measured in goats fed different diets was influenced by the bacterial pellet (LAB or SAB). In addition, the purine bases:N ratio values found were different from those reported in the literature, which underlines the need for these variables to be analyzed directly in pellets isolated from specific animals and experimental conditions.     

Effects of diet type and metabolizable energy intake on tympanic temperature of steers fed during summer and winter seasons

A summer study and a winter study were conducted using an incomplete factorial structure in a complete randomized design. Within season, the factors studied were 1) type of diet, which included 2 levels of ME, classified as either concentrate (3.04 Mcal of ME/kg) or roughage (2.63 Mcal of ME/kg) diets, and 2) daily ME intakes (MEI) of 11, 18, and 25 Mcal of ME/d for the roughage diets and 18, 25, and 32 Mcal of ME/d for the concentrate diets. In Exp. 1 (summer study), 30 steers (5 steers/treatment combination) were used to collect tympanic temperatures (TT). In Exp. 2 (winter study), 24 steers (4 steers/treatment combination) were used to collect TT. Mean TT was 0.3°C greater for summer than winter (38.9 vs. 38.6°C, respectively; P < 0.05). Steers fed diets based on concentrate tended to display greater TT than steers fed diets based on roughage. Season × diet × hour interactions were found for TT (P = 0.01). In the winter, greater TT (P < 0.05) were found from 0900 to 1400 h when an equal amount of MEI was derived from a concentrate-based vs. roughage-based diet. In cattle fed roughage-based diets during the summer, TT = 38.63 + 0.0114?MEI, whereas for cattle fed concentrate-based diets, TT = 38.69 + 0.0114?MEI. During the winter, for cattle fed a roughage-based diet, TT = 37.65 + 0.0856?MEI - 0.0018?MEI(2), whereas for cattle fed a concentrate-based diet, TT = 35.37 + 0.2635?MEI - 0.0051?MEI(2). In summary, results demonstrate that increases in the energy of the diet resulted in increases in TT. However, the response was dependent on season of the year, with a linear response in TT for summer and a quadratic response during winter.     

粗、精料干物质比例的变化对奶牛日粮成本的影响

就特定的泌乳奶牛营养需要量，设计了7种不同饲粮粗料与精料比例(F：C=82：18、70：30、65：35、60：40、55：45、50：50和40：60)的日粮配方，研究饲粮粗料与精料比例对奶牛日粮成本的影响规律。结果表明，日粮中精料用量不是越少越好，随着日粮中精料用量在一定范围内的增加，在大多数情况下，往往会降低日粮成本，但必须是以日粮原料中具有可以替代的廉价原料为基础。只有在综合考虑日粮成本、精料补充料的可加工性，以及粗料饲喂的可执行性等决定最合理的粗料与精料比例。     

能量水平与精粗比对中卫山羊羯羔羊日粮消化性能的影响

选择体重差异不显著(P>0.05)、健康的5月龄中卫山羊羯羔羊12只,随机分为3组,每组4只。以相同蛋白水平、不同能量水平日粮饲喂各组试验羊,第一、二、三组分别喂给相同蛋白水平的低、中、高三种能量水平的日粮。结果表明:试验羊对NDF、ADF和半纤维素的表观消化率以低能量组效果最好,对于干物质的消化率则以高能组最高。而对于能量的采食量和消化代谢率则以高能组最优,中能组次之。由试验结果可知,在本试验条件下所设的3个能量组中以精粗比为57:43的高能组(粗蛋白含量11.41%,能量水平10.41 MJ/kg)的日粮水平比较有利于中卫山羊羯羔羊的生长发育。结合实际情况,中等能量组精粗比48:52消化能9.53 MJ/kg,最有利于对中卫山羊羯羔羊的组织生产。     

Ruminally undegraded intake protein in sheep fed low-quality forage: effect on weight, growth, cell proliferation, and morphology of visceral organs

To determine the influence of increasing levels of supplemental ruminally undegraded intake protein (UIP) on visceral organ weights, growth, cell proliferation, and morphology, 20 mature ewes of mixed breeding were fed a 6.55% CP grass hay:straw mixture (40:60) and assigned to one of four supplemental treatments. Supplements were control (no supplement) and low, medium, and high levels of UIP. After 42 to 46 d on treatment, ewes were infused i.v. with 5-bromo-2-deoxy-uridine (BrdU, a thymidine analog used to provide an index of the rate of intestinal cell proliferation) and slaughtered 1 h later. Visceral organs were weighed, and subsamples were obtained to evaluate visceral DNA, RNA, and protein contents (frozen samples) as well as intestinal morphology (fixed samples). Final BW; eviscerated BW (EBW); total visceral weight; and liver fresh, dry, and dry fat-free weights were increased (P<.10) in protein-supplemented ewes compared with controls, but were not influenced by increasing levels of UIP. Tissue weights of duodenum, jejunum, ileum, cecum, and colon were not greatly influenced by treatment. There were no differences among treatments in intestinal DNA and protein concentrations and the ratios RNA:DNA and protein:DNA. Jejunal RNA concentration and content was increased (P<.10) in low compared with medium and high treatments. Jejunal RNA content also was decreased (P<.10) in high compared with the medium UIP treatment. Liver RNA and protein contents were increased (P<.10) with protein supplementation. In contrast, contents of RNA, DNA, and protein in duodenum, ileum, cecum, and colon were not influenced by treatment. In addition, neither the rate of intestinal proliferation (BrdU labeling) nor intestinal morphology (crypt depth, villus length, or villus width) were affected by treatment. These data indicate that the influence of protein supplementation on visceral growth involves primarily the liver and not the intestines. These data also indicate that visceral growth, except in jejunum, are not altered by differing levels of UIP supplementation.     

Influence of myristic acid supplementation on energy, fatty acid and calcium metabolism of sheep as affected by dietary calcium and forage : concentrate ratio

In a 6 x 6 Latin square arrangement, sheep of 41 kg body weight were fed myristic acid [C14:0; 50 g/kg dry matter (DM)] supplemented to two basal diets of forage : concentrate ratios of 1 : 1.5 and 1 : 0.5 and adjusted to dietary calcium (Ca) contents of either 4.2 or 9.0 g/kg DM (the latter only together with C14:0 supplementation). Various variables of energy, fatty acid and Ca metabolism were determined in combined digestibility and respiratory chamber measurements. With C14:0 addition the energy loss via the faeces increased (p < 0.05, post hoc test) without affecting energy digestibility of the complete diet. The apparent digestibility of supplemented C14:0 was higher (p < 0.01) with approximately 0.8 in the forage-based diet than in the concentrate-based diet (approximately 0.6). The elevated levels of plasma C14:0 were mainly accompanied by reduced C18:0 and C18:1 levels. The estimated apparent content of metabolizable energy (ME) of added C14:0 was either 24.5 MJ/kg (concentrate-based diet) or 32.1 MJ/kg (forage-based diet). Extra Ca equalized these differences between basal diets and ME contents amounted to 33.0 MJ/kg on average. As expected from corresponding slight shifts in energy metabolizability, the total efficiency of ME utilization increased (p < 0.1) with C14:0. The lower level of dietary Ca was still within the range recommended, but adding C14:0 to the concentrate-based diet reduced Ca retention in the body of the sheep from 0.9 to -0.1 g/day because of an impaired (p < 0.05, post hoc test) net Ca absorption, whereas no effect was found with the forage-based diet. With C14:0 addition, plasma total phosphorus (P) and serum calcitrol levels increased (p < 0.05, post hoc test) while Ca concentrations did not clearly reflect the reduced net Ca absorption. Increasing the dietary Ca content prevented adverse effects on Ca retention in the concentrate-based diet and improved Ca retention in the forage-based diet. In conclusion, the C14:0 supplementation reduced Ca availability in concentrate-based diets while an additional supply of Ca improved Ca and energy retention. Consequently, Ca supply should exceed recommended levels in diet types where dietary lipids are likely to reduce Ca availability and a compromise in basal diet type has to found to be able to profit best from the energetic value and the methane-suppressing properties of C14:0.     

不同精粗比饲粮对青海黑藏羊肌肉营养组成的影响

本试验旨在研究不同精粗比饲粮对育肥黑藏羊背最长肌中常规营养成分、氨基酸(amino?acid,?AA)及脂肪酸(fatty?acid,?FA)含量的影响.采用单因素随机区组设计,选取60只体重相近[(10.45?±?0.96)?kg]且体况健康的2月龄黑藏羊公羊,随机分为3组,每组5个重复,每个重复4只,分别饲喂精粗比...     

日粮精粗比对山羊生长性能和屠宰性能的影响

本试验旨在研究日粮精粗比对山羊生长发育和屠宰性能的影响。18只青年关中奶山羊随机等分为3组;分别饲喂精粗比为31∶69(低)、54∶46(中)和65∶35(高)的3种日粮,各日粮粗蛋白含量相同。结果表明,日增重随精粗比的增加而提高(P<0.05﹚,高精粗比日粮显著提高饲料利用效率(P<0.05﹚,精粗比不影响胃黏膜总重﹑瘤胃和小肠黏膜重量以及胴体重和屠宰率(P>0.05﹚,中等精粗比日粮显著提高皱胃重量(P<0.05﹚。     

日粮不同能量水平对育成鸡营养物质代谢及肌肉品质的影响

本试验从日粮不同能量水平对育成期塞北乌骨鸡营养物质代谢及肌肉品质进行了研究。结果表明,母鸡在代谢能(ME)为11.51MJ/kg时氮表观代谢率最大为56.08%,公鸡在ME为12.34MJ/kg时氮表观代谢率最大为49.31%,从氮平衡来看,均为正平衡。公鸡和母鸡在ME为12.96 MJ/kg时摄入能量最高,代谢能也最高。能量水平的提高可适当提高塞北乌骨鸡公鸡和母鸡的胸肌率及公鸡的腿肌率,对母鸡的腿肌率的影响不明显。     

精料补饲水平对藏羊屠宰性能和器官发育的影响

选用40只初始体重为(30.21 ±1.42)kg的9月龄欧拉型藏羊(Oura-type Tibetan sheep,OTTS)(高原型)羯羊,随机分为4组,每组10只,在放牧的基础上每只羊每天分别补饲0、0.1、0.2和0.3kg精料,预试期15d,正试期195 d,旨在研究精料补饲水平对藏羊屠宰性能和器官发育的影响.结果表明:补饲精料显著提高了OTTS的屠宰性能(P＜0.05);提高了其头、皮+毛、心脏、肝脏、肺脏、肾脏、大肠占体质量的百分比(P＞0.05),降低了胃、小肠、胃肠道及其内容物占体质量的百分比(P＞ 0.05);提高了胃内容物占总胃肠道内容物的百分比及大肠内容物占整个肠道内容物的百分比(P ＞0.05);降低了肠道占体长的倍数;提高了胃的容积(P＞0.05).初步说明,冷季补饲精料可提高OTTS屠宰性能,刺激器官发育,改变胃肠道内容物的分布.本研究为高海拔地区发展藏羊产业、改善藏羊器官发育和调控其胃肠道内容物分布提供理论依据.     

Effects of supplemental protein source and metabolizable energy intake on nutritional status in pregnant ewes.

Two experiments were conducted to evaluate effects of supplemental protein source and ME intake (Exp. 1) on ewe nutritional status during pregnancy. Forty-two mature Targhee ewes were allotted randomly in Exp. 1 to one of six treatments (n = 7) using a 2 x 3 factorial arrangement. Ewes were individually fed chopped barley straw and supplements containing either urea (U), soybean meal (SBM), or blood meal (BM) plus SBM during the 84-d experiment. Straw and supplement intakes were adjusted to meet either 80 or 100% of ME requirements. In Exp. 2, 30 pregnant Targhee ewes that were allotted randomly to one of three groups (n = 10) were individually fed protein supplements similar to those in Exp. 1 and had group access to long-stem barley straw. In Exp. 1, ewes fed BM + SBM gained more (P less than .05) weight, lost less (P less than .05) body condition, and had increased (P less than .05) wool fiber length compared with ewes fed U; SBM ewes were intermediate (P less than .05) in response. Ewes fed BW + SBM had increased (P less than .05) blood urea N and albumin concentrations compared with ewes fed U. Metabolizable energy intake did not affect (P greater than .05) ewe performance or serum metabolite concentrations. Ewes fed BM + SBM in Exp. 2 gained more (P less than .05) weight than ewes fed either SBM or U, and ewes fed SBM lost less weight (P less than .05) than ewes fed U.(ABSTRACT TRUNCATED AT 250 WORDS)     

Level of nutrition and visceral organ protein synthetic capacity and nucleic acid content in sheep.

Thirty-two crossbred wether lambs were assigned to a feed intake level of either ad libitum (ADLIB) for maximum rate of growth or restricted to maintain body weight (MAINT) throughout a 21-d period. At 7-d intervals (d 0.7, 14, and 21), four lambs per treatment were slaughtered to obtain measurements of visceral organ protein synthetic capacity and tissue composition. Protein synthetic capacity was assessed by in vitro [14C]valine incorporation and tissue RNA, DNA, and protein contents. Concentrations of protein and RNA were not significantly affected in most tissues measured. However, for liver, duodenal, and jejunal tissue, DNA concentrations in ADLIB lambs were lower (P less than .05) than in MAINT lambs. Ratios of protein:DNA in most organs were higher (P less than .05) in ADLIB than in MAINT lambs. During the 21-d period, liver and small intestinal protein and RNA mass were higher (P less than .10) in ADLIB than in MAINT lambs, and DNA mass was unaffected. Also during the 21-d period, the average total mass of ruminal protein, RNA, and DNA in ADLIB lambs was higher (P less than .05) than in MAINT lambs. Estimates of valine incorporation and ratios of RNA:protein seemed to reflect protein synthetic capacity of the visceral tissues measured; however, the effect of level of feed intake on these measurements was equivocal. These data suggest that the level of feed intake affected visceral organ mass through changes in cellular hypertrophy.     

精料补饲水平对藏羊屠宰性能和器官发育的影响

选用40只初始体重为(30.21 ±1.42)kg的9月龄欧拉型藏羊(Oura-type Tibetan sheep,OTTS)(高原型)羯羊,随机分为4组,每组10只,在放牧的基础上每只羊每天分别补饲0、0.1、0.2和0.3kg精料,预试期15d,正试期195 d,旨在研究精料补饲水平对藏羊屠宰性能和器官发育的影响...     

Effects of supplementation on voluntary forage intake, diet digestibility, and animal performance

A data base was constructed to describe and estimate supplementation effects in nonlactating cattle consuming forage ad libitum. The data base included 66 publications on 126 forages (73 harvested and 53 grazed) and a total of 444 comparisons between a control, unsupplemented treatment and a supplemented treatment. Daily gains were reported for 301 comparisons and voluntary intake for 258. Direct measures of forage digestibility were reported for 202 comparisons, and total diet digestibility for 150. Supplements did not increase gain in all cases. Change in ADG due to supplement was not related closely to intake of supplemental TDN. Lowest increases in ADG were with native forages supplemented with molasses alone or with low intakes of molasses containing high levels of NPN. Greatest increases in gain were with improved forages, supplements with > 60% TDN, and supplemental CP intake > .05% of BW. Supplements decreased voluntary forage intake (VFI) when supplemental TDN intake was > .7% of BW, forage TDN:CP ratio was < 7 (adequate N), or VFI when fed alone was > 1.75% of BW. When supplements increased VFI, forage TDN: CP ratio was > 7 (N deficit), and VFI when fed alone was often low. There was little relationship between change in VFI and sources of supplemental CP and TDN. Supplements caused total diet TDN concentration to deviate from expected values by -10 to +5% of OM. When supplemental TDN intake was > .7% of BW, diet TDN concentration was always less than expected. There was little relationship between deviation from expected total diet TDN and type or composition of forages or supplements. Empirical multiple regression equations were developed to estimate effects of supplements on VFI and total diet TDN concentration. The most acceptable intake equation estimated VFI when fed with supplement (r2 = .84) That equation included VFI when fed alone, supplement intake, CP and TDN concentrations in forage and supplement, and classification codes describing forages and supplemental energy. The most acceptable equation for estimating total diet TDN concentration included only the expected total diet TDN concentration (r2 = .87). These equations may be used in nutritional models to account for associative effects.     

Influence of mass of ruminal contents on voluntary intake and digesta passage in steers fed a forage and a concentrate diet

To evaluate the influence of mass of ruminal contents on voluntary intake and ruminal function, five ruminally cannulated steers (550 kg) were fed an orchard grass hay diet ad libitum in a 5 x 5 Latin square experiment. The mass of ruminal contents was altered by adding varying weights of modified tennis balls to the rumen before the initiation of each 15-d experimental period. Treatments consisted of 50 balls with a specific gravity of 1.0, 1.1, 1.2, 1.3, or 1.4; the total weight of the balls was 7.45, 8.50, 9.25, 10.55, and 11.55 kg, respectively. Increasing the specific gravity of the balls added to the rumen decreased DMI and particle passage rate (P < 0.05) in a linear manner. A second experiment was conducted to evaluate the influence of mass of ruminal contents on voluntary intake and ruminal function of both forage and concentrate diets. Five ruminally cannulated steers (580 kg) were fed a 70% concentrate (DM basis) or an orchardgrass hay diet ad libitum in a 5 x 5 Latin square experiment. The mass of ruminal contents was altered as in the first experiment. Treatments consisted of 0 balls added to the rumen of steers fed concentrate diet (control), 75 balls with a specific gravity of 1.1 given to steers fed a concentrate diet, 75 balls with a specific gravity of 1.4 given to steers fed a concentrate diet, 75 balls with a specific gravity of 1.1 given to steers fed a hay diet, and 75 balls with a specific gravity of 1.4 given to steers fed hay diet. The addition of balls to the rumen of steers fed the concentrate diet decreased DMI (P < 0.05) compared with the 0-ball treatment, and increasing specific gravity of balls also decreased DMI (P < 0.01) for both concentrate and hay diets. Adding balls to the rumen of steers fed the concentrate diet decreased particle passage rate (P < 0.05), whereas increasing specific gravity of balls decreased particle passage rate for both concentrate and hay diet. The results of this study suggest that the density of ruminal digesta can have an influence on voluntary intake of both forage and concentrate diets.     

日粮精粗比对育肥藏羊瘤胃组织形态及微生物菌群的影响

本试验旨在研究日粮精粗比对育肥藏羊瘤胃组织形态及微生物菌群的影响.选择210只早期断奶藏羔羊,随机分成7组,每组30只,分别对其饲喂精粗比为20:80(A)、30:70(B)、40:60(C)、50:50(D)、60:40(E)、70:30(F)和80:20(G)的基础日粮,预饲期10 d,试验期90 d.试验结束后,...     

Effect of dietary energy concentration and apparent ileal digestible lysine:metabolizable energy ratio on nitrogen balance and growth performance of young pigs

Two experiments were conducted to determine the optimal apparent ileal digestible lysine:ME (Lys:ME) ratio and the effects of lysine and ME levels on N balance (Exp. 1) and growth performance (Exp. 2) in growing pigs. Diets were designed to contain Lys:ME ratios of 0.6, 0.7, 0.8, and 0.9 g/MJ at 13.5 and 14.5 MJ of ME/kg of diet in a 4 x 2 factorial arrangement. In Exp. 1, conventional N balances were determined on 48 crossbred barrows (synthetic line 990, initial BW = 13.1 +/- 0.7 kg) at approximately 15, 20, and 25 kg of BW with six pigs per diet. At 15 kg of BW, an energy density x Lys:ME ratio interaction on daily N retention was observed (P < 0.05). At each BW, N retention improved with an increase in N intake associated with increasing ME concentration. In 15-kg BW pigs, increasing the Lys:ME ratio increased daily N retention at the 13.5 (linear, P < 0.001) and 14.5 MJ of ME level (linear, P < 0.01; quadratic, P < 0.05). In 20-kg BW pigs, N retention (g/d) increased (linear, P < 0.001; quadratic, P < 0.01) and N retention (percentage) increased (linear, P < 0.001) as the Lys:ME ratio increased. At 25 kg of BW, N retention (g/d) increased quadratically (P < 0.05) with an increase in Lys:ME ratio. The Lys:ME ratios that maximized daily N retention at 15 kg of BW were 0.88 and 0.85 g/MJ at the 13.5 and 14.5 MJ of ME levels, respectively and 0.81 and 0.77 g/MJ (for both ME levels) at 20 and 25 kg of BW, respectively. Over the 28-d trial, an energy density x Lys:ME ratio interaction on ADG was observed (P < 0.05). Increasing energy density increased growth performance, whereas increasing the Lys:ME ratio in high-energy diets increased ADG (linear, P < 0.05; quadratic, P < 0.01) and gain:feed ratio (G/F) quadratically (P < 0.01). Average daily gain and G/F ratio were greatest in pigs fed the 14.5 MJ of ME diet and the Lys:ME ratio of 0.82 g/MJ. In Exp. 2, 128 individually housed crossbred barrows and gilts (initial BW = 12.8 +/- 1.6 kg) were used to determine the effect of diets used in Exp. 1 on growth performance in a 4 x 2 x 2 factorial arrangement. The ME level increased ADG and G/F from d 0 to 14 and from d 0 to 28. Increasing the Lys:ME ratio increased ADG from d 0 to 14, whereas growth performance was maximized in pigs fed Lys:ME ratio of 0.82 g/MJ. These results suggest that pigs from 13 to 20 and from 20 to 30 kg of BW fed diets containing 14.5 MJ of ME/kg had maximum N retention and ADG at 0.85 and 0.77 g of apparent ileal digestible lysine/MJ of ME, respectively.     

羔羊日粮精粗比对其肉及脂肪组织中脂肪酸组成的影响

为了研究不同精粗比日粮对广河羊羔肉品质的影响,在广河县羔羊肉生产区,选择不同精粗比饲喂的6月龄健康陶寒杂交(陶赛特羊♂×小尾寒羊♀)断奶去势公羔各3只进行屠宰,取股二头肌、背最长肌、肱二头肌3个部位肌肉和肾周脂肪、皮下脂肪、尾部脂肪3个部位脂肪,用气象色谱法分析其脂肪酸的种类及含量。结果表明,在所有组织中均检测出38种脂肪酸,其中饱和脂肪酸17种,不饱和脂肪酸21种。脂肪组织中饲喂低精粗比日粮的亚油酸(C18∶2n6c)、α-亚麻酸(C18∶3n3)、饱和脂肪酸(SFA)、多不饱和脂肪酸(PUFA)及其与饱和脂肪酸比值(P/S)、n3系多不饱和脂肪酸和n6系多不饱和脂肪酸均显著高于饲喂高精粗比日粮(P<0.05);饲喂低精粗比日粮的所有组织中花生四烯酸(C20∶4)的含量显著高于饲喂高精粗比日粮(P<0.05);与饲喂高精粗比日粮的羊羔肉相比,饲喂低精粗比日粮既节省了生产成本又明显改善和提高了羊羔肉中脂肪酸的营养价值。     

TMR不同精粗比例对中产奶牛碳水化合物消化的影响

以40头中等产奶量的荷斯坦奶牛为研究对象,应用随机分组试验设计将试验动物分为Ⅰ、Ⅱ、Ⅲ和Ⅳ组,日粮精粗比例依次为50%:50%,40%:60%,35%:65%,30%:70%。研究TMR不同精粗比例对奶牛碳水化合物消化的影响,结果表明:随着粗饲料比例增加,CF、NFE、NDF和ADF表观消化率均呈先增加后降低趋势;其中试验Ⅱ组CF表观消化率显著(P<0.05)高于试验Ⅰ组,试验Ⅲ组极显著(P<0.01)高于试验Ⅰ组和Ⅳ组;试验Ⅲ组NDF表观消化率最高,并显著(P<0.05)高于试验Ⅳ组;试验Ⅱ的ADF表观消化率组较高,但各组间均差异不显著(P>0.05)。通过比较发现,当TMR日粮中粗饲料比例在60%~65%时各试验组CF、NDF、ADF和NFE表观消化率均较高,即碳水化合物消化利用最充分。因此,TMR的精粗比例为(40%:60%)~(35%:65%)是中产奶牛TMR较适宜的比例。