Performance,digestibility, microbial protein synthesis,and body composition of Brangus x Zebu steers on tropical pasture receiving supplementation

Tropical Animal Health and Production - The use of additional supplement can affect ruminant performance by increasing the animal weight gain and maximizing profits from the activity. Thus, the...     

Influence of zeranol and breed on growth, composition of gain, and plasma hormone concentrations

Seven Angus and six Brangus steers averaging 225 and 245 kg, respectively, were assigned randomly to zeranol (36 mg) implant (I) and no implant (NI) treatments. Steers had ad libitum access to a corn silage diet plus .68 kg of a soybean meal-based supplement fed daily. Steers were bled via jugular catheters on d 0, 28, 56, and 84 at 15-min intervals for 4 h before and 4 h after feeding. Concentrations of growth hormone (GH), insulin (INS), triiodothyronine (T3), thyroxine (T4), and glucose were determined. Whole-body protein and fat contents were monitored. A breed x I interaction (for d 56 to 84 and d 0 to 84) was observed for ADG (P less than .05 and P less than .07, respectively), feed conversion (P less than .05 and P less than .07, respectively), and protein deposition (for d 0 to 29 and d 0 to 84; P less than .07 and P less than .05, respectively). These interactions were attributed to a greater response to I by Angus than by Brangus steers. A feeding x period interaction (P less than .10) was observed for mean GH concentration, and INS, T4, and T3 concentrations were higher (P less than .05) during the 4-h postfeeding period than during the 4-h prefeeding period. The implant increased (P less than .08) mean GH concentration but did not alter the frequency, duration, or amplitude of plasma GH peaks. Steers that were implanted had lower (P less than .05) plasma T3. Brangus steers had lower (P less than .05) plasma glucose, T3, and T4 concentrations than Angus steers. Results indicate that growth factors beyond those measured are responsible for the anabolic response to zeranol.     

Relationships of metabolic hormones and serum glucose to growth and reproductive development in performance-tested Angus, Brangus, and Brahman bulls

Understanding mechanisms that regulate growth and reproduction are important for improving selection strategies in cattle. In this study, Angus, Brangus, and Brahman bulls (n = 7 per breed) of similar age were selected from a group of 65 weanlings. Bulls were evaluated after weaning (i.e., approximately 6 mo of age) for 112 d for serum concentrations of metabolic hormones and glucose, growth, and reproductive traits. Performance data and blood sera were collected on d 0, 28, 56, 84, and 112. Sera were also collected in periods from d 50 to 59 (56D) and 103 to 112 (112D). Angus bulls were heavier (P < 0.05) throughout the study than Brahman bulls and were heavier than Brangus bulls on d 56, 84, and 112. Initial and final BW for Angus, Brangus, and Brahman bulls were 292.7, 260.6, and 230.4 and 468.3, 435.6, and 350.7 +/- 12 kg, respectively. Conversely, Brahman bulls had greater hip height (P < 0.05) than Brangus, and Brangus were taller (P < 0.05) than Angus. Angus bulls had the greatest (P < 0.05) scrotal circumference (SC) and Brahman bulls the least. Mean SC across days was 31.5, 29.7, and 25.0 +/- 0.6 cm for the three respective breeds. Serum testosterone was greater (P < 0.01) in Angus and Brangus bulls (10.0 and 8.9 +/- 1.4 ng/mL) than in Brahman bulls (4.0 +/- 1.4 ng/mL) throughout the study. After d 112, 100, 86, and 57% of the Angus, Brangus, and Brahman bulls passed a breeding soundness exam (P = 0.51). Serum concentrations of IGF-I and leptin were greater (P < or = 0.06) in Angus bulls on d 56, 84, and 112 than in Brangus and Brahman bulls. Serum concentrations of GH (P < 0.08) and glucose (P < 0.03) were greater in Brangus bulls than in Angus or Brahman bulls throughout the study. Prediction analyses suggested that serum concentrations of leptin could be used to predict (P < or = 0.08) BW and SC (R2 > 0.82) in the 56D and 112D periods among these breeds. Leptin was also useful in predicting (P < or = 0.09) serum concentrations of GH and testosterone in the 112D period (R2 > 0.32). Residual correlation analyses with the effect of breed removed suggested that leptin was correlated (r > or => 0.53, P < 0.05) with both SC and serum testosterone. Angus and Brahman cattle differ in phenotype, level of adiposity, and rate of sexual development. Data herein suggest that these characteristics could be due to varying mechanisms by which metabolic hormones such as leptin, GH, and(or) IGF-I are regulated.     

Effect of human growth hormone-releasing factor and(or) thyrotropin-releasing factor on growth, carcass composition, diet digestibility, nutrient balance, and plasma constituents in dairy calves

Sixty male dairy grain-fed calves, raised from 70 to 223 kg BW in individual crates, were used in a 2 X 2 factorial arrangement to determine the effect of administration of human growth hormone-releasing factor (1-29)NH2 (GRF) and(or) thyrotropin-releasing factor (TRF). Calves received twice-daily s.c. injections of .9% NaCl (control), GRF (5 micrograms/kg BW), TRF (1 micrograms/kg BW) or GRF (5 micrograms/kg BW) plus TRF (1 micrograms/kg GTRF). Average daily gain and days on feed were not affected by treatments, but TRF treatment increased (P less than .05) total intake of dry matter (DM) and feed conversion ratio: 3.00, 3.02, 3.08, and 3.22 kg DM/kg weight gain for control, GRF, TRF, and GTRF, respectively. During two 7-d periods, after 66 and 75 d of treatment, feces and urine were collected from 40 calves (5 per treatment per period). Treatment with GRF increased (P less than .05) digestibility of DM, nitrogen (N), and energy and tended (P less than .20) to increase N retention. At slaughter, withers height was increased (P = .05) by GRF and carcass length was increased (P less than .05) by TRF. Pituitary and liver weights were increased (P less than .05) by TRF. The combination of GRF and TRF slightly increased (P less than .10) protein content and decreased (P less than .05) fat content of the 9-10-11th rib section. After d 1, GRF treatment chronically increased (P less than .05) insulin concentrations and also increased (P less than .10) IGF-I concentrations on d 29 and 57. In summary, chronic treatment with GRF and(or) TRF did not improve growth or efficiency, although GRF increased digestibility of DM, N, and energy and the GRF plus TRF combination resulted in slightly leaner carcasses.     

Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers

Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.     

Influence of zeranol implants on growth, behavior and carcass traits in Angus and Limousin bulls and steers

A 2(3) factorial arrangement of treatments was utilized to determine effects of postweaning zeranol implantation, breed (Angus vs Limousin) and castration (bull vs steer) on growth, behavior and carcass traits. An initial slaughter group was used to account for breed differences in composition and to determine fat and lean growth in the 9-10-11th rib section (NTE). The remaining cattle were fed a finishing diet to a fat end point of .76 cm, as determined by a backfat probe. Control bulls outgained (P less than .01) control steers both to the first kill date and over the entire test and did not require significantly more time to reach the fat end point. The implant did not influence gain in bulls but did increase gain in steers. Angus and Limousins were similar in growth rate for the first 126 d before the first slaughter date. Limousins required more (P less than .01) time to reach the fat end point. Bulls and Limousins produced heavier (P less than .01) carcasses and larger rib eyes (P less than .05; bulls; P less than .01; Limousins). Steers and Angus had higher (P less than .01) marbling scores and lower bone maturity. Implanting decreased (P less than .05) marbling and increased carcass maturity. Small but significant shifts in carcass wholesale cut weight distribution were found between breed and sex condition groups. Bulls and Limousins had greater lean growth in the NTE. Bulls and steers were similar in fat growth, but Angus exceeded Limousin in this trait. Zeranol reduced scrotal circumference (P less than .01) and testicle weight at slaughter (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lysocellin effects on growth performance, ruminal fermentation, nutrient digestibility and nitrogen metabolism in steers fed forage diets

Studies were conducted to determine the effects of lysocellin on growth performance and metabolism of steers fed forage-based diets. Treatments in all experiments consisted of 1) control, 2) 100 mg lysocellin/d, 3) 200 mg lysocellin/d and 4) 200 mg monensin/d. In each of two 90-d performance studies, 24 Hereford steers were individually fed greenchop (fungus-free tall fescue and Coastal and Tifton-44 bermudagrass) ad libitum and .91 kg/d of a corn-trace mineral salt supplement. In Exp. 1, tall fescue was fed from d 1 to 45 and bermudagrass from d 46 to 90. Bermudagrass was offered during d 1 to 45 and tall fescue during d 46 to 90 in Exp. 2. Lysocellin improved gain (Exp. 1, P less than .01) and feed conversion (Exp. 1 and 2 combined, P less than .05), decreased total VFA concentrations (P less than .05), increased molar proportions of propionate, isobutyrate and isovalerate (P less than .01), decreased molar proportions of acetate and butyrate (P less than .01) and lowered acetate:propionate (P less than .01). Two metabolism studies involving a total of 16 Hereford steers were conducted. Steers were fed tall fescue greenchop and .91 kg/d supplement for a 34-d adjustment period followed by a 5-d total collection period. Lysocellin increased N digestibility (P less than .01) and N retention (P less than .06) but did not (P greater than .05) affect DM, NDF or ADF digestibility. Data indicate that lysocellin results in major alterations in ruminal fermentation and can increase growth performance and N retention in steers fed forage-based diets.     

Effects of grazing on deposition of chemical body components, energy retention and plasma hormones in steers

The objective of this study was to evaluate the effects of grazing on the accretion of energy and chemical components in steers, using the comparative slaughter technique and taking into consideration the growth rate. Twelve Holstein steers aged 6 months and weighing 160 kg were divided into three treatment groups – an initial, grazing and control group. The initial group was slaughtered at the beginning of the experiment. The grazing group was grazed on timothy pastures for 18 weeks. The control group was kept in a stable and offered concentrate and timothy hay in a proportion of 2:1 throughout the 18 weeks. The amount of ration offered to the control group was adjusted in order to obtain a growth rate similar to that of the grazing group. The grazing and control groups were slaughtered at the end of the experiment. The grazing and the control groups had similar growth rates of approximately 0.8 kg/day throughout the experimental period and similar final live weights of approximately 260 kg. The grazing group had lower fat and energy deposition rates than the control group (P < 0.05). Deposition rates of protein, fat, ash, moisture and energy were 130, 32, 30, 374 g/day and 4.4 MJ/day, respectively, in the grazing group and 117, 85, 32, 381 g/day and 6.2 MJ/day, respectively, in the control group. The net energy for growth was lower in the grazing group (7.7 MJ/kg) than in the control group (9.9 MJ/kg, P < 0.05). The grazing group had higher plasma concentrations in growth hormone and lower plasma concentrations in insulin and insulin‐like growth factor 1 than those in the control group (P < 0.05).     

Influence of condensed tannin on intake, digestibility, and efficiency of protein utilization in beef steers fed high concentrate diet

This trial was conducted to evaluate if the effect of condensed tannin (CT) is associated with a true protein source on intake, ruminal and total digestibility, ruminal digestion rate, protein efficiency, and microbial efficiency in beef steers fed high concentrate diet (87% of DM). Four Bos indicus steers (407 ± 12 kg of BW) fitted with rumen cannula were assigned to a 4 × 4 Latin square design, arranged in a 2 × 2 factorial arrangement. Treatments consisted of either inclusion (0.4% of DM) or exclusion of condensed tannin (CT) from quebracho extract (76% of CT) with or without the use of soybean meal (SBM) as source of true protein. The level of inclusion was calculated to provide a daily intake of 1 g/10 kg of BW of CT. Intake of DM and nutrients was not affected (P > 0.10) by CT inclusion. However, there was an effect (P < 0.10) of CT inclusion on ether extract digestibility. An interaction (P < 0.10) was observed between CT and SBM on ruminal digestibility and digestion rate of crude protein (CP): when mixed with soybean meal, CT decreased the ruminal digestibility and, consequently, reduced the digestion rate of CP. Intake of CP increased (P < 0.10) with the inclusion of SBM. No differences in DM passage rate were observed (P > 0.10) among treatments. Effects of the interaction (P < 0.10) between CT and SBM were observed on flux of rumen undegradable protein (RUP), metabolizable protein (MP), and on the ratio MP:CP. In the presence of soybean meal, the addition of CT increased (P < 0.10) the flux of RUP and MP, and improved the ratio MP:CP. The yield of microbial protein on the abomasum and the microbial efficiency did not differ among treatments (P > 0.10). There was no difference (P > 0.10) on the pH, VFA, and ruminal ammonia (N-NH₃) with the addition of condensed tannin. The N-NH₃ increased and the ruminal pH decreased with the inclusion of soybean meal (P < 0.10). The utilization of condensed tannin as an additive in beef cattle diets with high level of concentrate and soybean meal as a source of true protein implies positive effects on crude protein utilization, decreasing digestion rate and ruminal digestibility of crude protein and consequently increasing the levels of metabolizable protein, with no changes in the ruminal fermentation parameters.     

Total nutrient digestibility and small intestine starch digestion in Nellore and Angus young bulls fed a whole shelled corn diet

Eighteen Nellore and 18 Angus young bulls with BW of 381 ± 12 kg were randomly assigned into two feeding groups (whole shelled corn [WSC] or ground corn with silage [GC]) to evaluate the interaction of breed and diet on total nutrient digestibility, pancreatic α‐amylase, and maltase activity and SLC5A1expression in the small intestine. Experimental diets (DM basis) included (a) a diet containing 30% corn silage and 70% GC and soya bean meal‐based concentrate and (b) a diet containing 85% WSC and 15% of a soya bean meal‐ and mineral‐based pelleted supplement. The treatments were Nellore fed GC diet; Nellore fed WSC diet; Angus fed GC diet; and Angus fed WSC diet. Total faecal collection for the digestibility trial occurred from day 48 until day 50 of the experimental period. Feeding the WSC diet reduced DM and NDF intake (p < 0.01). Angus had greater DM and nutrient intake in kg/day (p < 0.01). However, there was no breed effect on DM and nutrient intakes based on percentage of BW (p > 0.19). Angus had greater starch digestibility (p = 0.03) than Nellore. Cattle fed the WSC diet had greater DM, NDF and starch digestibility (p < 0.01) compared with those fed the GC diet. The activity of pancreatic α‐amylase (U/g of protein) was greater in Nellore (p < 0.01) and was not affected by diet (p = 0.52). In duodenum, maltase activity (U/g of protein) was greater in bulls fed GC diet (p = 0.02). Expression of the gene SLC5A1was not affected by breed or diet (p > 0.05). In conclusion, Nellore had less capacity to digest starch. However, they did not have less pancreatic α‐amylase and duodenal maltase activity compared to Angus. The use of the WSC diet increases DM and total nutrient digestibility.     

Effects of breed and wintering diet on growth, puberty and plasma concentrations of growth hormone and insulin-like growth factor 1 in heifers

Twenty-five Brangus (BR) and 15 Angus (AN) heifers were used to study the effects of breed and wintering diet on average daily gain (ADG), onset of puberty and plasma concentrations of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Wintering diets (fed for 107 days beginning November 15) consisted of the following: 1) native grass hay (NGH), 2) ammoniated NGH, 3) NGH plus cottonseed meal, 4) Diet 3 plus corn and 5) Diet 4 plus monensin. After wintering, heifers were transferred to ryegrass pasture for 70 days. Mean ADG during the wintering phase were -.20, -.10, .17, .29 and .39 kg for heifers fed Diets 1 through 5, respectively (P less than .01). ADG was greater (P less than .05) for BR than for AN heifers. Plasma concentrations of GH were higher (P less than .05) in heifers fed Diets 1 and 2 than in heifers fed Diets 3, 4 or 5. Plasma concentrations of IGF-1 were lowest in heifers fed Diet 1 and highest in heifers fed Diets 4 and 5. During ryegrass grazing, GH concentrations were similar for all groups. However, concentrations of IGF-1 were higher (P less than .05) in heifers fed Diets 3, 4 and 5 than in heifers fed Diets 1 and 2. Age at puberty (onset of cyclic progesterone concentrations) was greatest in heifers fed Diet 1 and lowest in heifers fed Diet 5. Weight at puberty was not affected (P greater than .10) by wintering diet but was greater (P less than .01) in BR than in AN heifers. Therefore, negative ADG appears to be associated with elevated plasma GH concentrations in heifers, and plasma IGF-1 concentration appears to be a more accurate indication of nutritional status than plasma concentrations of GH.     

Failure of photoperiod to alter body growth and carcass composition in beef steers

In each of two experiments, 70 crossbred steers were blocked by BW and assigned to initial slaughter groups or to treatments in a 2 x 2 design. In Exp. 1, treatments were 168 d of photoperiod (8 h of light [L]:16 h of dark [D] or 16L:8D) and plane of nutrition (high energy [HPN] or low energy [LPN]). On d -22, 67 and 155, blood was sampled every 20 min for 8 h. Relative to LPN, HPN increased (P less than .01) ADG by 28%, carcass weight by 26% and accretion of carcass fat by 109% and carcass protein by 20%. On d 155, compared with LPN, HPN increased (P less than .01) serum insulin (INS; 1.09 vs .64 ng/ml) and lowered (P less than .05) growth hormone (GH; 2.14 vs 3.70 ng/ml), but prolactin was not affected. Photoperiod did not affect BW gains, carcass composition or serum hormones. In Exp. 2, treatments were 113 d of photoperiod (8L:16D or 16L:8D) and Synovex-S implant (presence [IMP] or absence [NONIMP]). On d 93, blood was sampled every 30 min for 10 h. Relative to NONIMP, IMP increased (P less than .01) ADG by 12% and accretion of carcass protein by 16%. Implants did not affect carcass weight or accretion of fat. Compared with NONIMP, IMP increased (P less than .05) GH (3.16 vs 2.39 ng/ml) and INS (.68 vs .46 ng/ml) but did not affect PRL. Photoperiod did not affect BW gain, carcass composition or serum hormones. We conclude that photoperiod fails to influence growth and carcass composition of steers.     

粗纤维水平对断奶新西兰兔营养物质消化率的影响

为了探讨断乳兔日粮适宜的粗纤维水平,选择36只30日龄体重差异不显著的断奶新西兰幼免,设3个水平,分别饲喂粗纤维含量为8%、10%、12%的日粮.每个水平3个重复,每个重复4只.结果表明:粗纤维含量为10%的试验兔日增重(28.59 g)最高,而12%组最低,但各组间差异不显著(P＞0.05).随粗纤维含量的增加,采食量呈上升趋势,3个组的日平均采食量分别为85.01、85.72、89.86 g/d.12%组中料肉比显著高于8%、10%组(P＜0.05).不同粗纤维饲粮的粗蛋白质、能量、总磷消化率差异均不显著(P＞0.05);10%水平组,粗纤维、粗脂肪消化率极显著高于12%(P＜0.01).而钙消化率显著高于12%(P＜0.05);粗脂肪、无氮浸出物显著高于8%(P＜0.05).本试验条件下.断乳免日粮适宜的粗纤维水平为10%.     

喷雾干燥血浆蛋白粉对仔猪生长性能和养分表观消化率的影响

本试验旨在研究喷雾干燥血浆蛋白粉对仔猪生长性能和养分表观消化率的影响。选择160头31日龄仔猪,随机分为对照组和试验组,对照组饲喂基础日粮,试验组添加3%喷雾干燥血浆蛋白粉,试验期14d。结果表明:日粮添加3%喷雾干燥血浆蛋白粉显著提高了仔猪的日增重(P0.05),降低了仔猪腹泻率(P0.05);显著提高了仔猪对饲料干物质的表观消化率(P0.05),对钙、磷、粗蛋白质的表观消化率有提高的趋势,但差异不显著(P0.05)。喷雾干燥血浆蛋白粉适合仔猪的营养需要,可以应用于生产。     

Effect of medium-chain triglycerides on growth performance,nutrient digestibility,plasma metabolites and antioxidant capacity in weanling pigs

The aim of this study was to investigate the effect of medium-chain triglycerides(MCTs) on growth performance, nutrient digestibility, plasma metabolites and antioxidant capacity in weanling pigs. A total of 160 weanling(Duroc × Landrace x Yorkshire) pigs(age: 21 ± 1 d; body weight: 7.50 ± 0.28 kg) were randomly allotted to 4 treatments, receiving the following diets for 28 d: control diet [containing 3.5%soybean oil(SO)], MCT1 diet(containing 0.7% MCTs and 2.8% SO), MCT2 diet(containing 1.4% MCTs and2.1% SO) and MCT3 diet(containing 2.1% MCTs and 1.4% SO). Dietary inclusion of MCTs improved the average daily gain and feed efficiency(FE) of pigs compared with the control during the first 2 weeks post-weaning(P 0.05). A similar positive effect was also observed for the overall FE in MCT2 group(P 0.05). Compared with the control, apparent total tract digestibility(ATTD) of ether extract was improved by MCT2 and MCT3 treatment from day 12-14 post-weaning(P 0.05). In addition, MCT2 treatment also exerted a beneficial effect on the ATTD of dry matter(P 0.05). The increased total protein concentration and decreased urea nitrogen and malondialdehyde levels of plasma were observed in both MCT2 and MCT3 groups on day 14 post-weaning(P 0.05). In conclusion, MCTs could improve growth performance, nutrients utilization, and antioxidant ability of weanling piglets.