Effect of dietary niacin supplementation on serum constituents of periparturient dairy cattle

A total of 60 multiparous periparturient Holstein cows were used to determine the differences in serum constituents between cows given supplemental niacin in the diet and cows not given supplemental niacin. Serum inorganic phosphorus concentration was consistently higher (P less than 0.10) and serum potassium, total calcium, and sodium concentrations and alkaline phosphatase activities were consistently lower in cows given supplemental niacin than in cows not given supplemental niacin. Serum chloride, creatinine, and albumin values also tended to be lower in niacin-supplemented cows. Serum total protein tended to be slightly higher in niacin-supplemented cows. There was no consistent difference in urea nitrogen between groups of cows.     

包被硒对西门塔尔牛血液指标和抗氧化能力的影响

选用4头装有永久性瘤胃瘘管的西门塔尔阉牛．采用4x4拉丁方设计，研究包被硒（0、0．3、0．6和0．9mgSe／kgDM）对血液指标和抗氧化能力的影响。结果表明：0．6mg／kg组血清TG、GLU、ALB、TP、GFrr、GOT、SOD、GSH—px和GSH含量显著高于对照（P〈0．05）；0．9mg／kg组和0．3mg／kg组血清Se含量显著高于对照（P〈0．05）。兼顾基础日粮含硒量，建议以包被硒为Se源时，日粮Se水平为0．67mgSe／kgDM。     

包被硒对西门塔尔牛瘤胃发酵和尿嘌呤衍生物的影响

选用4头装有永久性瘤胃瘘管的西门塔尔阉牛,采用4×4拉丁方设计,研究日粮中添加包被硒(0、0.3、0.6、0.9mg/kg)对瘤胃发酵和尿嘌呤衍生物的影响。结果表明:添加包被硒瘤胃中pH值、VFA、乙酸/丙酸比值均无显著差异(P>0.05);瘤胃氨态氮浓度显著降低(P<0.05);玉米秸秆DM、OM、ADF和NDF有效降解率提高;0.6mg/kg和0.9mg/kg组豆粕DM、OM和CP有效降解率显著高于对照组(P<0.05);0.6mg/kg组和0.9mg/kg组尿囊素、PD显著高于对照组和0.3mg/kg组(P<0.05)。兼顾基础日粮含硒量以及考虑硒的安全剂量,建议以包被硒为硒源时日粮硒添加水平为0.60mg/kg(以干物质计)。     

Effect of dietary chromium-L-methionine on glucose metabolism of beef steers

Thirty-six crossbred steers (288 +/- 3.7 kg initial BW) were used to determine the effect of Cr, as chromium-L-methionine, on glucose tolerance and insulin sensitivity in beef calves. Calves were fed a control diet or the diet supplemented with 400 or 800 microg Cr/kg of diet as chromium-L-methionine. Calves were kept in drylots (six calves/pen; two pens/dietary treatment). Steers were caught twice a day in locking headgates and individually fed their respective diets for a period of 22, 23, or 24 d prior to the metabolic challenges. Calves received a totally mixed diet containing 54% corn, 38% cottonseed hulls, and 5% soybean meal. On d 21, 22, and 23, four calves/dietary treatment were fitted with an indwelling jugular catheter. Approximately 24 h after catheterization, an intravenous glucose tolerance test (500 mg glucose/kg of BW), followed 5 h later by an intravenous insulin challenge test (0.1 IU insulin/kg of BW), was conducted. There was no effect (P > 0.10) of dietary treatment on ADG or ADFI. During the intravenous glucose tolerance test, serum insulin concentrations were increased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.05). There was a time x treatment interaction (P < 0.05) on plasma glucose concentrations after the glucose infusion. Plasma glucose concentrations of calves fed 400 microg Cr/kg of diet were lower than those of controls and calves supplemented with 800 microg Cr/kg of diet (quadratic effect of Cr, P < 0.05) 5 and 10 min after the glucose infusion. Supplemental chromium-L-methionine increased the glucose clearance rate from 5 to 10 min after the insulin challenge test (linear effect of Cr, P < 0.05). Glucose half-life from 5 to 10 min after the insulin infusion was also decreased by supplemental chromium-L-methionine (linear effect of Cr, P < 0.10). These data indicate that supplemental Cr, as chromium-L-methionine, increased glucose clearance rate after an insulin infusion and increased the insulin response to an intravenous glucose challenge in growing calves with functioning rumens.     

烟酸对热应激奶牛营养物质表观消化率及血清生化指标的影响

试验选用3头健康的泌乳后期的中国荷斯坦奶牛,采用3×3拉丁方设计,在基础日粮中分别添加0、8、15g/d烟酸,研究日粮添加不同水平烟酸对热应激奶牛干物质采食量、营养物质表观消化率和部分血液生化指标的影响。试验期为63d。结果表明:(1)添加8、15g/d烟酸分别使奶牛的干物质采食量显著提高12.71%和11.20%(P0.05);(2)添加8g/d烟酸能使奶牛营养物质消化率显著提高(P0.05),添加15g/d烟酸对奶牛营养物质消化率有提高的趋势,但差异不显著(P0.05);(3)日粮添加烟酸能够维持奶牛血清皮质醇水平的基本恒定、降低血清胆固醇、甘油三酯水平的趋势。综合分析试验奶牛的干物质采食量、营养物质表观消化率和血液生化指标变化,夏季给奶牛补饲烟酸有助于缓解热应激,适宜的添加量为8g/d。     

Effect of nitrogen supplementation and zilpaterol-HCl on urea kinetics in steers consuming corn-based diets

We studied effects of zilpaterol-HCl on steers consuming corn-based diets with nitrogen (N) supplementation provided by dried distillers grains with solubles (DDGS) or urea. Two sets of six steers (approximately 350 kg) were used in two replicates of similarly designed trials. Within each replicate, three steers were fed 60 mg/day of zilpaterol-HCl throughout the trial and three steers received no zilpaterol-HCl. Within zilpaterol treatment, three corn-based dietary N treatments were offered in Latin square designs: control (9.6% crude protein), urea (UREA; 12.4% crude protein) or DDGS (13.7% crude protein). Total feed intake was unexpectedly greater (p < 0.01) with zilpaterol feeding but was not affected by dietary N (p = 0.76). Nitrogen intake was greater (p < 0.01) when zilpaterol was fed and was greater (p < 0.05) for DDGS and UREA than for control. Despite greater N intake, zilpaterol did not affect urea entry rate (p = 0.80) or urea-N recycled to the gastrointestinal tract (GER; p = 0.94). As a percentage of N intake, urea entry rate (p = 0.19) tended to be less when zilpaterol was fed (91 vs. 123% of N intake), and GER was numerically (p = 0.34) less (72 vs. 92% of N intake). Microbial N flow was greater (p = 0.02) for zilpaterol than for control but did not differ (p = 0.78) among dietary N treatments. As a percentage of N intake, microbial N flow was unaffected by zilpaterol (p = 0.97), but was greater (p < 0.05) for control than DDGS or UREA. The lack of change in urea entry and GER in response to zilpaterol, despite greater N intake, as well as lower urea entry and GER when expressed as proportions of N intake provide some evidence that the amount of N available for urea production and recycling was reduced by zilpaterol.     

Effect of dietary boron on immune function in growing beef steers*

Thirty‐six Angus and Angus × Simmental cross steers (initial BW 269.5 ± 22.3 kg) were used to determine the effects of dietary boron (B) on performance and immune function. Steers were fed on one of the three dietary treatments: (i) control (no supplemental B; 7.2 mg B/kg DM), (ii) 5 mg supplemental B/kg DM and (iii) 50 mg supplemental B/kg DM, from sodium borate for 78 days. Supplementation of dietary B had no effect on body weight (BW) gain, feed intake or gain:feed during the study. Jugular blood samples were collected prior to feeding on days 28, 63 and 77 for plasma‐B analysis. Supplementation of dietary B increased (p < 0.001) plasma B‐concentration in a dose‐responsive manner. Furthermore, plasma B‐concentration was correlated (p < 0.001; R² = 0. 95) to daily B‐intake (mg B/day). Jugular blood was also collected, from an equal number of steers from each treatment, on day 42 or 44 for determination of in vitro production of interferon‐γ and tumour necrosis factor‐α from isolated monocytes and assessment of lymphocyte proliferation. Dietary B did not affect T‐ or B‐lymphocyte proliferation or in vitro cytokine production from monocytes. On day 49 of the study, the humoral immune response was assessed by i.m. injection of a 25% pig red blood cell (PRBC) solution for determination of anti‐PRBC IgG and IgM titre responses. Boron‐supplemented steers had greater (p = 0.035) anti‐PRBC IgG titres than controls on day 7 but not on day 14 or 21 post‐injection. Anti‐PRBC IgM titres did not differ throughout the sampling period. Results from this study indicate that supplemental B had minimal effects on immune function and did not affect performance of growing steers.     

Effect of niacin supplementation in long‐distance transported steer calves

Long‐distance transportation has negative impacts on production and health in cattle. Feed and water are routinely deprived from cattle during transportation. We investigated whether niacin supplementation could improve niacin nutrition and mitigate the adverse effect of transportation with feed and water deprivation in steer calves. We also studied the adverse effect of feed and water deprivation in nontransported steer calves. Twelve calves were assigned to feed and water deprivation for 2 days, or full access to feed and water in experiment 1. Ten calves were assigned to 2‐day transportation with feed and water deprivation, or the transportation with feed and water deprivation, but with supplementation of rumen‐protected niacin at 100 g/day per head in experiment 2. Bodyweight was measured and blood was collected for 32 days in each experiment. Feed and water deprivation temporarily decreased serum glucose concentrations and bodyweight gain. Transportation with deprivation of feed and water caused a temporal decrease in bodyweight gain and serum albumin concentration, and a continuous decrease in serum glucose and total cholesterol concentrations, which was suppressed by niacin supplementation. Niacin supplementation increased blood niacin concentration. These results suggest that niacin supplementation mitigates adverse effects of transportation with feed and water deprivation in steer calves.     

Effects of long-term dietary supplementation of monensin or saccharomyces cerevisiae on blood acid-base and productive performance in growing feedlot steers

The aim of this study was to evaluate the effects of two dietary supplements (monensin and a live yeast culture) on acid-base balance in steers maintained in a commercial feedlot system, considering effects over the growing period (14 to 23 weeks of age). A 63-day feedlot study was performed using 42 double-muscled Belgian Blue steers. Steers were allotted randomly to one of the three study groups: (1) control group [no supplementation, C], (2) monensin supplementation [MON] at a concentration of 30 mg/kg (DM basis), and (3) live Saccharomyces cerevisiae strain supplementation [SACC] at a dose of 500 mg/kg (DM basis).Venous blood samples were collected for the measurement of acid-base parameters and L-lactate. Production parameters were also used as a complementary tool for understanding the internal changes associated with supplementation. Our results show that during the study period no statistical differences were observed between supplemented and control steers, although non-supplemented animals tended to gain more efficiently than those fed monensin or yeast. Nevertheless, taking into account blood parameters, these control animals showed a greater risk of acid overload due to a more marked decline in blood buffer levels over time in comparison with supplemented steers although no differences were observed between monensin or yeast supplemented animals. Additionally, significant effect of supplementation was observed in packed cell volume (PCV) values.     

Effect of dietary vitamin A restriction on marbling and conjugated linoleic acid content in Holstein steers

To determine the effect of duration of dietary vitamin A restriction on site of fat deposition in growing cattle, 60 Holstein steers (BW = 218.4 +/- 6.55 kg) were fed a diet based on high-moisture corn, with 2,200 IU of supplemental vitamin A/kg of DM (control) or no supplemental vitamin A for a long (243 d; LR) or short (131 d; SR) restriction before slaughter at 243 d. The SR steers were fed the control diet for the first 112 d. Steers were penned individually and fed for ad libitum intake. Jugular vein blood samples for serum retinol analysis were collected on d 1, 112, and 243. Carcass samples were collected for composition analysis. Subcutaneous fat samples were collected for fatty acid composition. Fat samples from the i.m. and s.c. depots were collected to measure adipocyte size and density. Feedlot performance (ADG, DMI, and G:F) was not affected (P > 0.05) by vitamin A restriction. On d 243, the i.m. fat content of the LM was 33% greater (P < 0.05) for LR than for SR and control steers (5.6 vs. 3.9 and 4.2% ether extract, respectively). Depth of back-fat and KPH percentage were not affected (P = 0.44 and 0.80, respectively) by vitamin A restriction. Carcass weight, composition of edible carcass, and yield grade were similar among treatments (P > 0.10). Liver retinol (LR = 6.1, SR = 6.5, and control = 44.7 microg/g; P < 0.01) was reduced in LR and SR vs. control steers. On d 243, LR and SR steers had similar serum retinol concentrations, and these were lower (P < 0.01) than those of control steers (LR = 21.2, SR = 25.2, and control = 36.9 microg/dL). Intramuscular adipose cellularity (adipocytes/mm2 and mean adipocyte diameter) on d 112 and 243 was not affected (P > 0.10) by vitamin A restriction. Restricting vitamin A intake for 243 d increased i.m. fat percentage without affecting s.c. or visceral fat deposition, feedlot performance, or carcass weight. Restricting vitamin A intake for 131 d at the end of the finishing period appears to be insufficient to affect the site of fat deposition in Holstein steers.     

Effect of chickpea husk dietary supplementation on blood and cecal parameters in rats

Chickpea husk was functionally evaluated for antioxidant status, blood parameters, cecal fermentation and microbial profiles in rats. Fifteen male rats (5 weeks of age) were divided into three groups; they were individually housed and fed one of the following diets for 3 weeks: purified diet containing 5% cellulose (Cellulose), an identical diet in which cellulose was replaced by corn starch (Starch) or by chickpea husk (Chick). Rats were sacrificed to obtain blood and cecal digesta samples. Chickpea husk contained high polyphenolic content and significant superoxide dismutase and 2,2‐diphenyl‐picrylhydrazyl scavenging activities. In a feeding experiment, Chick showed lowered cholesterol levels and improved antioxidant activity represented by reduced thiobarbituric acid reactive substances in blood. Chick showed increased cecal levels of total short chain fatty acids and butyrate, leading to a lower pH. Chick presented with lowered cecal indole and skatole concentrations, as did Cellulose. Cecal bacterial changes were notable in Chick, evidenced by differences in denaturing gradient gel electrophoresis banding patterns. However, representative bacteria quantified by real‐time PCR assay did not support this bacterial change. These results indicate that chickpea husk feeding can improve the antioxidative status of rats through its polyphenolic components and modulate the hindgut environment by its fibrous components.     

半胱胺对肉仔鸡脂肪合成代谢的影响

21日龄艾维茵商品代肉仔鸡96只,随机分成2组,分别为基础日粮组和添加半胱胺(cysm ine,CS)组。研究CS对肉仔鸡血浆中胰岛素、肝脏中苹果酸脱氢酶(MDH)水平的影响。结果表明:在42日龄以前,CS使体内胰岛素和MDH水平高于对照组;在42日龄以后,使体内胰岛素和MDH水平低于对照组。     

Effect of vitamin D3 supplementation level on the postmortem tenderization of beef from steers

The objective of this experiment was to determine the effect of different doses of vitamin D3 (VITD) on beef feedlot performance, plasma and muscle Ca2+, tissue residues, and improvement of Warner-Bratzler shear force (WBS) and panel tenderness. A total of 167 steers were fed one of six levels of VITD. The VITD treatments (28 steers/treatment) were 0, 0.5 x 10(6), 1 x 10(6), 2.5 x 10(6), 5 x 10(6), and 7.5 x 10(6) IU/steer daily of VITD fed nine consecutive days before slaughter. Feedlot performance and plasma Ca2+ were measured during the last 21 days on feed. Warner-Bratzler shear force was measured on strip loin and top round steaks at 7, 10, 14, and 21 d postmortem. The VITD treatments of 5 and 7.5 x 10(6) IU/steer daily decreased (P < 0.05) ADG, and VITD supplementation of 2.5, 5, and 7.5 x 10(6) IU/steer daily decreased average dry matter feed intake (P < 0.05) at the end of the feeding trial. Plasma Ca2+ increased linearly with VITD treatment (P < 0.01). Calpastatin and calpain activity were not influenced by treatment (P > 0.05), but muscle Ca2+ was increased (P < 0.05) by VITD treatments of 1, 2.5, 5, and 7.5 10(6) IU/steer daily. Feeding VITD did not influence (P > 0.05) carcass quality or yield traits. Supplementing VITD at levels of 1, 2.5, 5, and 7.5 10(6) IU/steer daily increased (P < 0.05) VITD concentrations in strip loin and liver samples. Cooking liver decreased VITD concentrations 10 to 28%. Vitamin D3 treatments of 0.5 and 7.5 x 10(6) IU/d reduced strip loin steak WBS at d 7 (P < 0.05), but VITD treatments did not decrease strip loin steak WBS at any other time postmortem. The VITD treatments of 0.5, 1, and 5 x 10(6) IU/steer daily decreased top round steak WBS at 7 d, and all VITD treatments decreased 10-d top round steak WBS (P < 0.05). Supplementing steers with 0.5 x 10(6) IU/steer daily of VITD also decreased (P < 0.05) top round steak WBS at 21 d postmortem compared with controls. Sensory tenderness at 7 d postmortem was increased (P < 0.05) by all VITD treatments in top round steaks, yet strip loin tenderness scores were not affected (P > 0.05) by VITD treatment. Treatment with VITD quadratically decreased (P < 0.05) round WBS. Thus, VITD treatment will effectively improve tenderness when cattle tend to be tough and have no impact on cattle that produce tender beef. Feeding steers 0.5 x 10(6) IU of VITD daily for 9 d improved tenderness in two muscles without negatively affecting feedlot performance or tissue residues.     

Effect of dietary vitamin E supplementation and feeding period on pork quality

Feeding increased levels of dietary vitamin E can inhibit lipid oxidation. The aim of this study was to investigate the effect of levels of dietary alpha-tocopherol acetate (VE) and feeding duration on meat quality and lipid oxidation. Eighty-one pigs were allocated to 1 of 3 diets containing 40, 200, or 400 IU of VE/kg of feed, and each diet group was divided into 3 feeding periods (3, 6, or 9 wk). Carcass characteristics and meat quality were evaluated. Oxidative stability of fresh and cooked pork patties and pork chops was determined after chilled or frozen storage. Increasing dietary concentrations of VE did not affect any growth performance parameter. Drip loss, however, decreased (P < 0.05) with increased dietary VE levels. Moreover, an increased duration of VE feeding improved (P < 0.05) pH and drip loss. Less lipid oxidation (P < 0.05) was detected in fresh ground pork from pigs fed greater concentrations of VE after 4 d of storage. A greater (P < 0.05) resistance to oxidation in cooked ground pork was observed in pigs fed 200 or 400 IU of VE/kg at 2 and 6 d of storage. Fresh and cooked pork patty oxidation decreased (P < 0.05) linearly as feeding duration increased from 3 to 9 wk. After 6 mo of freezer storage, lipid oxidation of pork chops from pigs fed 200 or 400 IU of VE/kg was lower (P < 0.05) than for pigs fed 40 IU of VE/kg. Likewise, lipid oxidation of pork chops of pigs fed VE for an extended period of time (6 wk) was lower (P < 0.05) after 9 mo of storage. Fatty acid profiles of neutral lipid fraction of the LM became more unsaturated (P < 0.05) with added VE to the feed. These results indicate an increased intake of dietary VE concentration, and prolonged feeding of VE can improve drip loss and reduce lipid oxidation in ground pork and pork chops. This study suggests that supplementation with 200 IU of VE/kg of feed for 6 wk before market is beneficial in improving lipid stability and pork quality.     

Undegradable intake protein supplementation of compensating spring-born steers and summer-born steers during summer grazing

Three trials were conducted to determine the effects of previous winter gain (Trials 1 and 3) and age of calf (Trials 1 and 2) on response to undegradable intake protein (UIP) supplementation during summer grazing. In Trial 1, 48 spring-born steers (243 kg) were used in a 4 x 2 factorial arrangement. Steers were wintered at four rates of gain: 0.65 (FAST), 0.24 (SLOW), 0.38 (S/F), and 0.38 (F/S) kg/d. The intermediate rates of gain (S/F and F/S) were created by switching steers from slow to fast or fast to slow midway through the wintering period. Following winter treatments, steers were assigned to one of two summer treatments: supplemented (S) or nonsupplemented (NS). In Trial 2, 32 summer-born steers were wintered at an ADG of 0.25 kg/d and allotted to the same summer treatments as Trial 1. The supplement was formulated to supply 200 g/d of UIP. Steers from both trials grazed upland Sandhills range from May to September 1998. In Trial 3, 49 spring-born steers (228 kg) were used in a 2 x 7 factorial arrangement of treatments. Steers were wintered at two rates of gain, 0.71 (FAST) and 0.24 kg/d (SLOW) and then assigned randomly to one of six levels of UIP supplementation or an energy control. Protein supplements were formulated to deliver 75, 112.5, 150, 187.5, 225, or 262.5 g/d of UIP. Sources of UIP for all trials were treated soybean meal and feather meal. In Trial 1, there were no (P > 0.05) winter by summer treatment interactions, and UIP supplementation increased (P = 0.0001) pasture gains over NS steers. In Trial 2, supplementation increased (P = 0.001) pasture ADG of summer-born steers by 0.15 kg/d compared with NS steers. In Trial 3, a winter gain by UIP supplementation interaction was observed (P = 0.09). Gain of FAST steers responded quadratically (P = 0.09) across UIP levels, with the maximum gain occurring at the 150 g/d UIP level. The SLOW steers responded linearly (P = 0.02) to increasing UIP levels; however, the response was negative. Levels of UIP above 150 g/d reduced steers gains; therefore, the data were reanalyzed excluding these levels. These new analyses showed that FAST steers responded linearly (P = 0.08; 0.2 kg/d) to increasing UIP, whereas the SLOW steers had no response to UIP. In Trials 1 and 3, SLOW steers experienced compensatory gain and had higher gains overall. We concluded that previous winter gain affected the response to UIP supplementation with the FAST winter gain group having a greater response.     

畜禽采食量的调节

采食量是影响畜禽生产性能的主要因素;动物根据食物提示因子决定是否采食,根据采食后的消化生理反应决定采食多少;影响采食量的因素是多方面的,包括日粮营养、饲养管理、环境等;瘦素、NPY、增食欲素、生长素等是近年来在人的肥胖领域研究较多的食欲调节肽物质,能否或如何应用于畜牧生产尚需摸索.