Effect of sequential implanting with zeranol on steer lifetime performance

Three trials involving 513 exotic crossbred steers were conducted to determine the effect of zeranol implanting in the suckling and growing phases on subsequent feedlot performance and carcass characteristics. Treatments were 1) unimplanted control, 0000; 2) implanted twice in the finishing phase, 00II; 3) implanted in the growing phase and twice in the finishing phase, 0III; 4) implanted in the suckling phase and twice in the finishing phase, I0II; 5) implanted in the suckling and growing phases with a single implant in the finishing phase, III0; and 6) implanted in the suckling and growing phases and twice in the finishing phase, IIII. Implanting in the suckling period did not significantly affect preweaning gain. Implanting in the growing period produced a treatment x trial interaction (P less than .05), but zeranol increased gains by an average of 8.4% over the three trials. Growing period gain was not influenced by implanting during suckling. Implanting twice during the finishing period increased gain (P less than .05) over unimplanted and III0 steers. Finishing gain was not influenced by previous suckling and(or) growing implant treatment. Lifetime ADG of steers was increased (P less than .05) by all implant treatments compared with unimplanted controls. Zeranol tended (P = .14) to improve feed conversion in the finishing phase. All implant treatments increased hot carcass weight (P less than .05), and all but III0 reduced fat deposition, as indicated by lower quality grade (P less than .05). Other carcass characteristics were not significantly affected by treatment. These trials demonstrated that implanting in the suckling and(or) growing phases of production did not reduce performance in the finishing phase.     

Effect of pre- and postweaning zeranol implant on steer calf performance

One hundred ninety-five steer calves were assigned to five zeranol implant treatment (trial 1). Treatments were no implants (0000), two implants during the finishing period (00XX), three implants during growing and finishing periods (0XXX), one implant at 1 to 2 mo of age during the suckling period and two during the finishing period (X0XX) or four implants (XXXX). The growing period implant was administered at weaning. Weaning weights (211 vs 208 kg) of implanted and nonimplanted suckling calves were not different (P greater than .05). Calves implanted at weaning, before shipment to the feedlot, had greater (P less than .05) weight loss in shipment than nonimplanted calves. In the feedlot, finishing-period daily gains of steers implanted in the growing and finishing period (0XXX) were greater (P less than .05) than gains of steers that had received a suckling period implant (X0XX and XXXX). Nonimplanted steer gains were less (P less than .05) than gains of steers from the other four treatment groups. Postweaning daily gains and final weights were 1.18 and 517 (0000), 1.26 and 533 (00XX), 1.32 and 551 (0XXX), 1.26 and 540 (X0XX) and 1.25 and 533 kg (XXXX), respectively. Gains and final weights of nonimplanted steers were less (P less than .05) than gains of steers implanted only in the feedlot growing and finishing periods (0XXX). In a second trial, 82 steers were assigned either to a 0XXX or XXXX implant scheme. Weaning weights were 11 kg greater (P less than .05) for the implanted steers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. II. Pathogenic and other fecal bacteria

This study assessed the influence of cattle genotype and diet on the carriage and shedding of zoonotic bacterial pathogens and levels of generic Escherichia coli in feces and ruminal contents of beef cattle during the growing and finishing periods. Fifty-one steers of varying proportions of Brahman and MARC III [0 (15), 1/4 (20), 1/2 (7), and 3/4 Brahman (9)] genotypes were divided among 8 pens, such that each breed type was represented in each pen. Four pens each were assigned to 1 of 2 diets [100% chopped bromegrass hay or a diet composed primarily of corn silage (87%)] that were individually fed for a 119-d growing period, at which time the steers were switched to the same high-concentrate, corn-based finishing diet and fed to a target weight of 560 kg. Feces or ruminal fluid were collected and analyzed at alternating intervals of 14 d or less. Generic E. coli concentrations in feces or ruminal fluid did not differ (P > 0.10) by genotype or by growing diet in the growing or finishing periods. However, the concentrations in both feces and ruminal fluid increased in all cattle when switched to the same high-corn diet in the finishing period. There was no effect (P > 0.25) of diet or genotype during either period on E. coli O157 shedding in feces. Forty-one percent of the steers were positive for Campylobacter spp. at least once during the study, and repeated isolations of Campylobacter spp. from the same steer were common. These repeated isolations from the same animals may be responsible for the apparent diet (P = 0.05) and genotype effects (P = 0.02) on Campylobacter in feces in the finishing period. Cells bearing stx genes were detected frequently in both feces (22.5%) and ruminal fluid (19.6%). The number of stx-positive fecal samples was greater (P < 0.05) for 1/2 Brahman steers (42.9%) than for 1/4 Brahman (25.0%) or 3/4 Brahman steers (22.2%), but were not different compared with MARC III steers (38.3%). The greater feed consumption of 1/2 Brahman and MARC III steers may have resulted in greater starch passage into the colon, accompanied by an increase in fecal bacterial populations, which may have further improved the ability to detect stx genes in these cattle. There was no correlation between either ADG or daily DMI and the number of positive samples of E. coli O157, Campylobacter spp., or stx genes, which agrees with our current understanding that these microorganisms occur commonly in, and with no measurable detriment to, healthy cattle.     

Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 1. Feedlot performance, carcass quality, and production costs

Forty Angus-cross steers were used to evaluate 5 beef cattle management regimens for their effect on growth performance, carcass characteristics, and cost of production. A 98-d growing phase was incorporated using grass silage with or without growth promotants (trenbolone acetate + estradiol implants, and monensin in the feed) or soybean meal. Dietary treatments in the finishing phase were developed, with or without addition of the same growth promotants, based on exclusive feeding of forages with minimal supplementation or the feeding of barley-based diets. Overall, ADG for animals treated with growth promotants or fed supplemented diets (soybean meal and barley) was increased (P < 0.01) by 25 and 21%, respectively, compared with steers reared on grass silage alone and not treated with growth promotants. Except for HCW (P < 0.01), the use of growth promotants did not affect carcass measurements. Increasing the proportion of barley in the diet of steers finished on forage produced a heavier HCW (P < 0.01) and a greater (P < 0.01) quality grade. Because of their lower HCW and quality grade, cattle targeted to a forage-fed, nonimplanted beef market would need to garner a 16% premium to be economically competitive with cattle finished conventionally.     

宫内发育迟缓仔猪小肠形态和屏障功能相关基因的表达特征

为了研究宫内发育迟缓(IUGR)仔猪小肠形态和屏障功能相关基因的表达特征,选取24窝"长白×大白"杂交新生仔猪,每窝选取1头IUGR仔猪和1头正常出生体重(NBW)仔猪,分别于7、21和28日龄屠宰8头IUGR仔猪和8头NBW仔猪,采集小肠样品进行分析.结果表明:1)与NBW仔猪相比,IUGR仔猪7日龄时空肠绒毛高度、...     

Production and economic potentials of cattle in pasture-based systems of the western Amazon region of Brazil

Our objectives were to evaluate strategies to improve productivity and economic returns from beef and dual-purpose cattle systems based on data collected on one dual-purpose (Bos taurus x Bos indicus) and two beef (Nellore) cattle farms in the western Amazon region of Brazil. Forage chemical composition and digestion rates of carbohydrate fractions of grazed Brachiaria decumbens and Brachiaria brizantha cv. Marandu grasses and Pueraria phaseoloides (tropical kudzu) legume were measured monthly during a 9-mo period from the end of one dry season to the end of the subsequent rainy season. Measurements of milk and growth responses to grazing these forages were used to predict animal productivity responses to dietary nutrient availability throughout an annual cycle. The ME available for gain in our simulations was always more limiting than metabolizable protein. The predicted ME available for gain was 0.50 kg/d for steers grazing B. brizantha and 0.40 kg/d for finishing steers grazing B. decumbens. Grasses contained more NDF and neutral detergent insoluble protein and less ME (P < 0.05) in the rainiest months than in the less rainy season, which resulted in 20% less predicted weight gain by growing steers (P < 0.05). Supplementation with sorghum grain was required to increase milk production and growth by 25 or 50% per animal, respectively, but this strategy was less profitable than current forage-only diets. Greater productivity of land and labor from higher stocking indicated greater net margins for beef production, but not for milk. This study suggested that more intensive beef production by judicious fertilization of grass-legume pastures and greater stocking density is the preferable strategy for owners of these cattle systems to improve economic returns under current conditions. It also might help decrease the motivation for additional forest clearing.     

Anabolic implant and frame size effects on growth regulation, nutrient repartitioning and energetic efficiency of feedlot steers

Rates of growth and partitioning of nutrients among tissues were measured in large (Simmental x [Hereford x Brahman]; n = 34) and very large (Chianina x Angus and Maine Anjou x Angus; n = 37) steers implanted with different anabolic growth regulators. All cattle were fed individually a whole shelled corn (13% crude protein) diet. Implant strategies were: none (n = 13), Ralgro 36 mg (n = 15), Ralgro 72 mg (n = 14), Synovex-S (n = 15) and Ralgro 36-Synovex-S (n = 14) administered at d 0 and 90. Empty body composition of all cattle was measured initially and at 90 d by D2O dilution procedures and at slaughter (average, 182 +/- 4.1 d) by carcass specific gravity. Empty body weight for large and very large cattle averaged 274 and 324 kg (P less than .05) initially and 497 and 603 kg (P less than .05) at slaughter. Empty body protein differed (P less than .05) for large and very large steers and averaged 51 and 61, 67 and 79, and 87 and 103 kg initially, at midpoint and at slaughter, respectively. Percentage empty body fat was lower for very large steers (13.5 vs 15.6%) initially (P less than .05) but was similar for very large and large steers at the midpoint (18.7 vs 18.1%) and at slaughter (23.2 vs 21.9%). Daily rates of empty body gain (DEBG) were greater (P less than .05) for very large vs large steers for both growing and finishing periods and averaged 1.53 vs 1.26 kg/d overall. Daily rates of protein gain (DPG) were similar for very large and large steers for the growing phase (204 vs 202 g/d) but greater (P less than .05) in very large steers for the finishing phase and overall (253 vs 204, and 229 vs 202 g/d). All implant strategies, except R36, increased DEBG and DPG and tended to decrease the percentage of fat in daily gain. In both large and very large cattle, implant growth regulators increased growth rate and partitioned nutrient use away from fat toward protein accretion, with the magnitude of partitioning toward protein increasing with greater rates of growth. These data indicate that anabolic growth regulators are viable strategies to enhance lean beef production in steers, regardless of animal size.     

Influence of genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. III. Odorous compound production

Three beef cattle diets were assessed for their potential to produce odorous compounds from cattle feces excreted during the growing and finishing periods. Eight pens containing 51 steers of varying proportions of Brahman and MARC III genotypes were fed either a chopped bromegrass hay diet or a corn silage diet for a 119-d growing period. After the growing period, all steers were switched to the same high-corn finishing diet (high corn) and fed to a target weight of 560 kg (finishing period). Fecal slurries were prepared from a composite of fresh fecal pats collected in each pen during both periods and incubated anaerobically. In additional flasks, starch, protein, or cellulose was added to the composite fecal subsamples to determine the preferred substrates for fermentation and odorous compound production. The content and composition of the fermentation products varied both initially and during the incubation, depending on the diet fed to the steers. The corn silage and high corn feces had the greater initial content of VFA (381.0 and 524.4 micromol/g of DM, respectively) compared with the bromegrass feces (139.3 micromol/g of DM) and accumulated more VFA than the bromegrass feces during the incubation. l-Lactic acid and VFA accumulation in the high corn and corn silage feces was at the expense of starch, based on starch loss and the production of straight-chain VFA. In the bromegrass feces, accumulation of branched-chain VFA and aromatic compounds and the low starch availability indicated that the protein in the feces was the primary source for odorous compound production. Substrate additions confirmed these conclusions. We conclude that starch availability was the primary factor determining accumulation and composition of malodorous fermentation products, and when starch was unavailable, fecal microorganisms utilized protein.     

"肉牛育肥散"饲喂效果初试

粗放饲养条件下，将20头供试牛随机分为两组、每组10头，每10d为一个试验期，试验进行了3期。在试验期内其结果为：试验组肉牛的日增重较对照组分别高14．3％、10．7％和10．7％，有极显著差异。从经济效益分析，试验组肉牛头日增重1435g，纯收入3．83元，对照组头日均增重1285g，纯收入3．12元，试验组高出对照组0．71元。试验表明，按规定数量加入“肉牛育肥散”于精料中，可使肉牛增重加快，提高饲料利用率，降低增重成本，从而提高经济效益。     

Effects of feeding whole cottonseed and cottonseed products on performance and carcass characteristics of finishing beef cattle

Three experiments were conducted to determine the effects of whole cottonseed or cottonseed products on performance and carcass characteristics of beef cattle. In Exp. 1, 120 beef steers (initial BW = 381 +/- 31.7 kg) were fed steam-flaked corn-based finishing diets with 10% (DM basis) basal roughage, and whole cottonseed or individual cottonseed components (cottonseed hulls, meal, and oil). Over the entire feeding period, ADG did not differ (P = 0.95), but DMI increased (P = 0.07) and G:F decreased (P = 0.06) for steers fed the cottonseed diets compared with the control diet. Dressing percent (P = 0.02) and marbling scores (P = 0.02) of carcasses from steers fed the cottonseed diets were less than for steers fed the control diet. In Exp. 2, 150 beef steers (initial BW = 364 +/- 9.9 kg) were used to determine the effects of whole cottonseed or pelleted cottonseed (PCS) on performance and carcass characteristics. Cattle were fed steam-flaked corn-based finishing diets in which whole cottonseed or PCS replaced all of the dietary roughage, supplemental fat, and supplemental natural protein of the control diet. Over the entire feeding period, steers fed the cottonseed diets had lower (P = 0.04) DMI and greater (P < 0.01) G:F than steers fed the control diet. Carcass characteristics did not differ (P = 0.16 to 0.96) among dietary treatments. In Exp. 3, 150 beef heifers (initial BW = 331 +/- 17.1 kg) were used to determine the effects of PCS or delinted, whole cottonseed (DLCS) on performance and carcass characteristics. Heifers were fed rolled corn-based finishing diets in which cottonseed replaced the dietary roughage, supplemental fat, and all or part of the supplemental natural protein of the control diet. Over the entire feeding period, ADG, DMI, and G:F of heifers fed the control diet did not differ (P = 0.19 to 0.80) from those of the cottonseed diets; however, heifers fed the diets containing PCS had greater ADG (P = 0.03) and G:F (P = 0.09) than heifers fed diets containing DLCS. Carcass characteristics of heifers fed the control diet did not differ (P > or = 0.28) from those fed the cottonseed diets. Heifers fed the diets containing PCS had greater (P < or = 0.03) HCW, dressing percent, and LM area than those fed DLCS. Based on our results, whole cottonseed, or products derived from processing whole cottonseed, can replace feedstuffs commonly used in beef cattle finishing diets with no adverse effects on animal performance or carcass characteristics.     

Optimal decisions in organic beef production from steers — Effects of criterion of optimality and price changes

Organic beef production from steers demands several decisions concerning grazing strategy, feeding level in the winter and aspects as slaughter weight and length of the finishing period. A model has been developed to optimise these strategies. The objective of this study was (1) to find optimal strategies for organic beef production from steers regarding grazing strategy, feeding level in winter, finishing and slaughter in organic beef production from steer concerning economic output per time unit using a multi-level hierarchic Markov process and (2) to analyse the stability of these results by sensitivity analysis. The results showed that in general the optimal strategy only changes slightly depending on the criterion (net returns per steer versus per time unit). An optimization per time unit in some cases favours a more intensive production based on high feeding level in winter and finishing of steers as well as earlier slaughtering compared to an optimization per steer. Finishing of steers seemed not to be an optimal strategy from an economic point of view and price changes in feed, beef and premiums did not favour finishing of steers. Beef prices as well as prices for ryegrass/white clover pasture and low feeding level seemed to be the most important factors that influence net return.     

凉茶渣替代象草对育肥牛空肠组织形态、屏障功能以及菌群结构的影响

本试验旨在研究凉茶渣替代象草对育肥牛空肠组织形态、屏障功能以及菌群结构的影响。选取120头健康且体重相近的西门塔尔杂交肉牛,随机分为2个组,分别为对照组(饲喂基础饲粮)、试验组(50%凉茶渣替代部分象草),每组3个重复,每个重复20头。试验期共67 d,包括7 d的预试期,60 d的正试期。在试验期结束后,采集试验牛血液、空肠组织、空肠内容物,通过苏木精-伊红(HE)染色测量空肠绒毛高度、隐窝深度;通过酶联免疫吸附测定(ELISA)试剂盒检测血清中炎症因子、D-乳酸(D-Lac)以及二胺氧化酶(DAO)浓度;通过荧光定量PCR测定空肠紧密连接蛋白基因闭合小环蛋白-1(ZO-1)、闭锁蛋白(Occludin)、闭合蛋白-1(Claudin-1)的mRNA表达水平;利用16S rDNA高通量测序分析空肠菌群结构。结果表明：1)与对照组相比,试验组育肥牛空肠绒毛高度显著增加(P<0.05),血清中D-Lac浓度显著降低(P<0.05),空肠紧密连接蛋白ZO-1的mRNA表达水平显著上调(P<0.05)。2)在门水平上,对照组和试验组厚壁菌门(Firmicutes)相对丰度分...     

Growth, carcass and palatability traits of intact males and steers implanted with zeranol or estradiol early and throughout life

This study was conducted to assess the impact of implanting intact beef males with protein anabolic agents at varying intervals throughout life. Ninety-six intact males were assigned to three implant treatments: 1) not implanted, 2) implanted at 9 wk of age, weaning and at 56-d intervals thereafter with a 36-mg zeranol implant or 3) estradiol implant at 9 wk of age and 68 d post-weaning. During the 118-d, post-weaning growing period, eight animals per treatment (one replication) were castrated. After a 114-d finishing period, cattle were slaughtered (average age of 13 to 14 mo). Feedlot performance, carcass and palatability data were obtained. Average daily gains and feed efficiency did not differ (P greater than .05) between zeranol and estradiol-implanted intact males. Regardless of implant treatment, steers had lighter carcass weights (P less than .05) and higher (P less than .01) quality grades than intact males. Implanting either intact males or steers with zeranol or estradiol resulted in higher (P less than .05) numerical yield grades. Quality grades were higher in zeranol-implanted cattle than the non-implanted or estradiol-implanted cattle. Intact males implanted with zeranol were similar in carcass fatness to zeranol-implanted steers. No differences (P greater than .05) in tenderness or connective tissue were detected. Implanting intact males early and throughout life with zeranol made them similar to steers in fatness, while estradiol implantation had few effects on carcass and palatability traits of intact males or steers.     

Tolerance of cattle to increased dietary sulfur and effect of dietary cation-anion balance

The objective of this study was to determine if dietary cation-anion balance (DCAB) affects the concentration of S that can be tolerated by growing and finishing cattle without adversely affecting performance. Angus cross and Bradford steers (n=114; average initial BW=252.8 kg) were blocked by BW and breed, and randomly assigned within a block to treatment. The design was a 3 × 2 factorial arrangement of treatments with S (from NH(4)SO(4)) supplemented at 0, 0.15, or 0.30% of DM, and NaHCO(3) added at 0 or 1.0% of DM. Each treatment consisted of 3 pens containing 5 steers and 1 pen containing 4 steers. Steers were used in an 84-d growing study followed by a finishing study. A corn silage-based diet was fed during the growing study and a corn-based diet was fed during the finishing study. Steers were not randomized between experiments. The analyzed concentrations of S in the growing diets were 0.12, 0.30, and 0.46%, whereas the analyzed concentrations of S in the finishing diets were 0.13, 0.31, and 0.46% for treatments supplemented with 0, 0.15, and 0.30% S, respectively. Increasing DCAB by approximately 15 mEq/100 g of DM, by the addition of NaHCO(3,) did not affect (P > 0.36) performance during the growing or finishing studies. During the growing study DMI was not affected (P=0.29) by dietary S. Steers fed diets containing 0.30% S had greater ADG (P=0.02) and G:F (P=0.01) than those receiving 0.46% S, but similar (P > 0.36) performance to steers fed 0.12% S. During the finishing study, steers fed diets containing 0.46% S had less ADG than steers fed 0.13 (P=0.004) or 0.31% S (P=0.07), whereas ADG did not differ (P=0.18) among steers fed 0.13 and 0.31% S. Steers fed diets containing 0.31 (P=0.01) or 0.46% S (P=0.001) had less DMI than controls, but G:F was not affected (P=0.52) by S during the finishing study. Carcass characteristics did not differ (P > 0.18) among steers fed diets containing 0.13 and 0.31% S. Steers receiving diets containing 0.46% S had decreased HCW (P=0.001), quality (P=0.02), and yield grades (P=0.04) than steers receiving 0.13% S. Plasma Cu concentrations on d 101 of the finishing phase and liver Cu concentrations at slaughter were greater (P ≤ 0.05) in control steers compared with those fed diets containing 0.31 or 0.46% S. This study indicates that steers fed growing diets can tolerate up to 0.46% S with minimum effects on performance. Finishing steers tolerated diets containing 0.31% S without adverse affects on ADG or G:F. However, 0.46% S greatly decreased ADG and DMI, and increasing DCAB did not prevent these depressions.     

Expression of mRNA for proglucagon and glucagon-like peptide-2 (GLP-2) receptor in the ruminant gastrointestinal tract and the influence of energy intake

Glucagon-like peptide-2 (GLP-2) is a potent trophic gut hormone, yet its function in ruminants is relatively unknown. Experiment 1 was conducted as a pilot study to establish the presence of GLP-2 in ruminants and to ascertain whether it was responsive to increased nutrition, as in non-ruminants. Concentrations of intact GLP-2 in the blood and gut epithelial mRNA expression of proglucagon (GCG) and the GLP-2 receptor (GLP2R) were measured in 4 ruminally, duodenally, and ileally cannulated steers. Steers were fed to meet 0.75 × NE_M for 21 d, and then increased to 1.75 × NE_M requirement for another 29 d. Blood samples and ruminal, duodenal, and ileal epithelium biopsies were collected at low intake (Days −6 and −3), acute high intake (Days 1 and 3), and chronic high intake (Days 7 and 29) periods. Experiment 2 investigated the mRNA expression pattern of GCG and GLP2R in epithelial tissue obtained from the forestomachs (rumen, omasum, and abomasum) and intestines (duodenum, jejunum, ileum, and colon) of 18 forage-fed Angus steers (260 kg BW). In Experiments 1 and 2, real-time polymerase chain reaction showed that expression of GCG and GLP2R mRNA was detectable in forestomach tissues, but expression was greater (P < 0.001) in small intestinal and colon tissue. High energy intake tended (P = 0.07) to increase plasma GLP-2 during the acute period and was paralleled by a 78% increase (P = 0.07) in ileal GCG mRNA expression. After this initial adaptation, duodenal GCG mRNA expression increased (P = 0.08) during the chronic high intake period. Duodenal GLP2R mRNA expression was not affected by energy intake, but ileal GLP2R expression was increased after 29 d of high energy intake compared to both the low and acute high intake periods (P = 0.001 and P = 0.01, respectively). These data demonstrate that cattle express GCG and GLP2R mRNA primarily in small intestinal and colon tissues. Increased nutrient intake increases ileal GCG mRNA and plasma GLP-2, suggesting that GLP-2 may play a role in the trophic response of the ruminant gastrointestinal tract to increased feed intake.     

Influence of genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. I. Animal performance

Although Brahman crosses constitute a large portion of US beef cattle, little information is available on their response to diverse feed resources compared with Bos taurus steers. Thus, the objectives were to evaluate genotype and diet effects on steer performance during the growing period and subsequent response to a high grain diet during the finishing period. Fifty-one steers [0 (15), 1/4 (20), 1/2 (7), and 3/4 Brahman (9), with the remaining proportion being MARC III] were allotted to 8 pens. Beginning on December 2, steers were individually fed chopped bromegrass hay (n = 26; DM = 85%, CP = 9.5%, ME = 2.19 Mcal/kg) or a corn silage-based diet (n = 25; DM = 51%, CP = 11.9%, ME = 2.75 Mcal/kg) for 119 d. All steers were then fed a high corn diet (DM = 79%, CP = 11.7%, ME = 3.08 Mcal/kg) to a target BW of 560 kg (176 d). Data were analyzed by ANOVA, with genotype, growing diet, and the 2-way interaction included. The interaction was not significant (P > 0.25). The MARC III and 1/2 Brahman steers weighed more (P < 0.01) than 1/4 or 3/4 Brahman steers initially and at the end of the growing period. Weight of bromegrass-fed (325 kg) steers was less than that of corn silage-fed (384 kg) steers at the end of the growing period. Steer ADG and intake of DM, CP, and ME were less (P = 0.087 to 0.001) for 1/4 and 3/4 Brahman than for 0 or 1/2 Brahman steers during growing, finishing, and total, but efficiency of gain did not differ (P > 0.10). Carcass weight, marbling score, quality grade (P < 0.05), and kidney fat (P = 0.06) differed among genotypes. Daily DMI (6.91 vs. 7.06 kg) was similar, but CP (0.66 vs. 0.84 kg) and ME (15.2 vs. 19.4 Mcal) intake of bromegrass fed was less (P = 0.001) than those of corn silage-fed steers. Values for DMI/gain (22.3 vs. 7.43 kg/kg), CP intake/gain (2.13 vs. 0.88 kg/kg), and ME intake/gain (48.8 vs. 20.4 Mcal/kg) were greater (P < 0.001) in bromegrass-fed than corn silage-fed steers. Over the total study, ADG was lower (0.96 vs. 1.01 kg), and DMI (7.82 vs. 7.19 kg), DMI/gain (8.21 vs. 7.10 kg/kg), and ME intake/gain (22.6 vs. 20.9 Mcal/kg) were greater (P < 0.05) in bromegrass-fed than in corn silage-fed steers. Carcass weight, dressing percent, adjusted backfat, and yield grade (P < 0.05) were greater for corn silage-fed than for bromegrass-fed steers. Feed intake and performance, but not efficiency, differed among these genotypes. Compensatory performance during finishing was insufficient to overcome reduced performance during the growing period.     

Use of dried distillers grains throughout a beef production system: effects on stocker and finishing performance, carcass characteristics, and fatty acid composition of beef

A 2-yr study was conducted using a 3 × 2 factorial arrangement of treatments to evaluate the effects of feeding dried distillers grains throughout a beef production system on performance, carcass characteristics, and fatty acid profile of beef. Factors were wheat pasture supplement [no supplement (CON), dry-rolled corn (DRC), and dried distillers grains (DDG)] fed at 0.5% BW daily and finishing diet [steam-flaked corn based diet containing 0 (SFC) or 35% (35DDG) DDG]. Each year, 60 preconditioned Hereford steers (initial BW = 198 kg ± 3) grazed winter wheat pasture with or without supplement. Body weight gain was 8% greater for steers consuming DDG supplement compared with CON and DRC steers (P < 0.01). After the grazing period, pastures within supplement treatment were randomly assigned to SFC or 35DDG. There was no supplement by finishing diet interaction for any performance or carcass variable of interest (P ≥ 0.41). Previous supplementation on winter wheat affected BW at feedlot entry and adjusted G:F (P ≤ 0.05) but had no effect on finishing ADG or carcass traits (P ≥ 0.12). On a carcass-adjusted basis, steers consuming 35DDG had reduced final BW, ADG, G:F, and total BW gain throughout the system (P ≤ 0.04) compared with SFC. Additionally, steers consuming 35DDG had reduced HCW, dressing percent, and fat thickness (P ≤ 0.03) compared with SFC. There was a supplement by finishing diet interaction (P = 0.02) for 18:0, in which cattle supplemented with DRC and fed the SFC finishing diet had the lowest concentration of 18:0 but DRC supplemented steers fed the 35DDG diet had the greatest concentration. The interaction was not significant (P ≥ 0.18) for other fatty acids. Main effects of supplement and finishing diet affected (P ≤ 0.05) several other fatty acids of interest, particularly 18:2, which is associated with reduced flavor-stability of beef. The use of DDG as a supplement to wheat pasture resulted in greater ADG during wheat grazing and heavier BW at feedlot entry, but final BW was not different from CON or DRC groups. Feeding DDG at 35% DM in steam-flaked corn-based finishing diets reduced ADG, G:F, and HCW, and affected the fatty acid composition of beef.     

Effects of winter stocker growth rate and finishing system on: I. Animal performance and carcass characteristics

Angus-crossbred steers (n = 216) were used in a 3-yr study to assess the effects of winter stocker growth rate and finishing system on finishing performance and carcass characteristics. During winter months (December to April) steers were randomly allotted to 3 stocker growth rates: low (0.23 kg x d(-1)), medium (0.45 kg x d(-1)), or high (0.68 kg x d(-1)). Upon completion of the winter phase, steers were randomly allotted within each stocker treatment to a corn silage-concentrate or pasture finishing system. All steers regardless of finishing treatment were finished to an equal-time endpoint to eliminate confounding of treatments with animal age or seasonal factors. Upon completion of the finishing period, steers were slaughtered in 2 groups (one-half of pasture and one-half of feedlot cattle each time) and carcass data were collected. Winter data were analyzed as a completely randomized design, with winter treatment, pen replicate, year, and the winter x year interaction in the model. Finishing performance and carcass data were analyzed in a split-plot design with finishing system in the whole plot, and winter growth rate and winter x finish in the split-plot. Winter treatment mean within finishing replication was the experimental unit, and year was considered a random effect. Winter stocker phase treatments resulted in differences (P < 0.001) in final BW, ADG, and ultrasound LM area between all treatments for that phase. Pasture-finished cattle had lower (P < 0.001) final BW, ADG, HCW, LM area, fat thickness, KPH, dressing percent, USDA yield grade, and USDA quality grade. Winter stocker treatment influenced (P < 0.05) final BW and HCW, with low and medium being less than high. Steers with low stocker gain had greater (P < 0.05) finishing ADG. Dressing percent was greater (P < 0.001) for high than low, and USDA quality grade was greater (P < 0.05) for high than low and medium. Carcass LM area, fat thickness, KPH, and USDA yield grade were not influenced (P > 0.05) by winter rate of gain. Cattle on low during winter exhibited compensatory gain during finishing but were unable to catch the high group regarding BW or HCW. The USDA quality grade was greater for high than low or medium. Animal performance during the winter stocker period clearly impacts finishing performance, carcass quality and beef production in both pasture- and feedlot-finishing systems, when cattle were finished to an equal-time endpoint.     

Evaluation of intensive vs extensive systems of beef production and the effect of level of beef cow milk production on postweaning performance

Charolais-sired calves from three groups of beef cows, similar in growth potential and mature size but different in genetic potential for milk production (5.6, 7.7, 9.0 kg/d; low, medium, and high, respectively), were allotted to two beef production systems each year for 3 yr. At weaning, calves in an intensive (Int) system went directly into the feedlot for finishing (236 d); calves in an extensive (Ext) system were wintered on corn residues (195 d), grazed pasture (115 d) and then were finished (122 d). Postweaning effects of increased weaning weight due to increased level of milk were small and not affected by growing-finishing system. Only the steer calves from the low milk-producing cows showed evidence (P less than .01) of compensatory growth postweaning in response to reduced levels of milk during the suckling phase. Cattle from the Ext system were heavier (P less than .01) before (388 vs 233 kg) and after (595 vs 531 kg) the finishing phase than Int system cattle. During finishing, cattle from the Ext system made more rapid gains (1.70 vs 1.36 kg/d) and consumed more feed (12.4 vs 8.5 kg/d, 2.52 vs 2.19% of average BW) but were less efficient (.137 vs .160, gain/feed) than cattle from the Int system (P less than .05). Extensive systems of beef production produced more total kilograms of beef per animal but they were 196 d older at slaughter.