Genetics of heifer performance in 'wet' and 'dry' seasons and their relationships with steer performance in two tropical beef genotypes.

The genetics of heifer performance in tropical 'wet' and 'dry' seasons, and relationships with steer performance, were studied in Brahman (BRAH) and Tropical Composite (TCOMP) (50% Bos indicus, African Sanga or other tropically adapted Bos taurus; 50% non-tropically adapted Bos taurus) cattle of northern Australia. Data were from 2159 heifers (1027 BRAH, 1132 TCOMP), representing 54 BRAH and 51 TCOMP sires. Heifers were assessed after post-weaning 'wet' (ENDWET) and 'dry' (ENDDRY) seasons. Steers were assessed post-weaning, at feedlot entry, over a 70-day feed test, and after similar to 120-day finishing. Measures studied in both heifers and steers were liveweight (LWT), scanned rump fat, rib fat and M. longissimus area (SEMA), body condition score (CS), hip height (HH), serum insulin-like growth factor-I concentration (IGF-I), and average daily gains (ADG). Additional steer measures were scanned intra-muscular fat%, flight time, and daily (DFI) and residual feed intake (RFI). Uni- and bivariate analyses were conducted for combined genotypes and for individual genotypes. Genotype means were predicted for a subset of data involving 34 BRAH and 26 TCOMP sires. A meta-analysis of genetic correlation estimates examined how these were related to the difference between measurement environments for specific traits. There were genotype differences at the level of means, variances and genetic correlations. BRAH heifers were significantly (P < 0.05) faster-growing in the 'wet' season, slower-growing in the 'dry' season, lighter at ENDDRY, and taller and fatter with greater CS and IGF-I at both ENDWET and ENDDRY. Heritabilities were generally in the 20 to 60% range for both genotypes. Phenotypic and genetic variances, and genetic correlations, were commonly lower for BRAH. Differences were often explained by the long period of tropical adaptation of B. indicus. Genetic correlations were high between corresponding measures at ENDWET and ENDDRY, positive between fat and muscle measures in TCOMP but negative in BRAH (mean of 13 estimates 0.50 and -0.19, respectively), and approximately zero between steer feedlot ADG and heifer ADG in BRAH. Numerous genetic correlations between heifers and steers differed substantially from unity, especially in BRAH, suggesting there may be scope to select differently in the sexes where that would aid the differing roles of heifers and steers in production. Genetic correlations declined as measurement environments became more different, the rates of decline (environment sensitivity) sometimes differing with genotype. Similar measures (LWT, HH and ADG; IGF-I at ENDWET in TCOMP) were genetically correlated with steer DFI in heifers as in steers. Heifer SEMA was genetically correlated with steer feedlot RFI in BRAH (0.75 +/- 0.27 at ENDWET, 0.66 +/- 0.24 at ENDDRY). Selection to reduce steer RFI would reduce SEMA in BRAH heifers but otherwise have only small effects on heifers before their first joining.

Effets des diètes de remplacement du maïs sur les performances de croissance, le pH ruminal et les paramètres biochimiques sanguins chez les veaux de grains

L’objectif de cette étude a été d’évaluer l’effet du remplacement total ou partiel du maïs d’une ration alimentaire standard (MS) sur les performances de croissance, le pH ruminal et les paramètres biochimiques sanguins chez les veaux de grain de race Holstein. Quatre groupes de 80 veaux ont été répartisen32 parcs (10 veaux/parc) et ont été assignés au hasard à quatre rations alimentaires. Les rations alimentaires ont été: la ration standard qui est constituée de maïs et un supplément protéique à 43,6% de protéine brute (MS);une ration réduite de maïs, avec tourteau de canola et de drèche de distillerie de maïs avec soluble (MCD); une ration réduite de maïs, avec supplément protéique à 43,6% de protéine brute et de drèche de distillerie de maïs avec soluble (MSD); et finalement une ration d’orge roulé, de tourteau de canola et de drèche de distillerie de maïs avec soluble (OCD). Les rations alimentaires ont été formulées selon une phase de démarrage P1 (j0 à j54), une de croissance P2 (j55 à j85) et une de finition P3 (j86 à j96). Un groupe additionnel de 5 veaux contrôle (CT), a reçu une ration alimentaire non acidogène à base de fourrage et de concentré. Notons qu’avant le début des traitements alimentaires au j0, sauf CT, les veaux ont reçu une ration d’adaptation contenant du maïs et de l’orge (50-50) et un supplément protéique pendant 20j. Les gains moyens quotidiens (GMQ) ont été similaires aux périodes P1 (0j-j27, j28-j54) et P2 (j55-j85), mais à la période P3 (j86-j96), le GMQ de la ration OCD a été plus grand que ceux dans les autres rations (p<0.001). Le rendement carcasse des veaux abattus au poids vifs d’environ 267 kg, de la ration OCD a été plus petit que ceux des rations MS et MSD (p<0.002). La matière sèche ingérée (MSI) a diminué pour le groupe MSD au j96, comparée à celles des groupes MS et BCD (p<0.001). Cependant, les rations alimentaires n’ont pas eu d’effet sur le poids vif des veaux. Les durées moyennes en dessous du pH ruminal de 5.6 (DpH5.6 en h.j.-1) du j68 au j85 (P2) ont été similaires pour les groupes CT et OCD (p=0.09) et plus petites (p<0.001) que celles des groupes du MS, MCD et MSD. Pendant la phase P3, les DpH5.6 des groupes de MS, MCD et MSD, ont été similaires (p>0.83), mais plus grandes que celle du groupe de OCD (p<0.0001). Les DpH5.6 n’ont pas eu d’effet sur les GMQ. Aux j68 et j96, les rations alimentaires n’ont pas eu d’effet sur la L-lactate (p > 0.05), le pH sanguin (p > 0.001; non significatif après l’ajustement de Bonferroni :NSAB) et le trou anionique (p > 0.009; NSAB). La PCO2 des animaux du groupe MS a été plus grande que celle du groupe CT (p = 0.0003). Au j68, HCO3 - du groupe CT a été plus grande que celle du groupe MCD (p = 0.0008). Les traitements alimentaires n’ont pas d’effets sur la lipopolysaccharide binding protein (LBP) aux j0 et j68. Au j96, la LBP du groupe CT a été plus petite que celle du groupe MS et MCD (p=0.001). Les diètes n’ont pas d’effets significatifs sur les épithéliums et les lamina propria du rumen (p0>0.37), ainsi que sur les abcès du foie (p=0.80). Le remplacement total du maïs par l’orge roulé, la drêche de distillerie de maïs avec soluble et le tourteau de canola amélioré le GMQ en phase de finition, a amélioré le pH du rumen, le rapprochant du pH ruminal physiologique, n’a pas modifié les paramètres biochimiques sanguins qui ont été mesurés et a diminué le rendement carcasse moyen de 1,1%.

Intake, growth and meat quality of steers given diets based on varying proportions of maize silage and grass silage

Simmental × Holstein-Friesian steers were offered four forage diets. These comprised grass silage (G); proportionately 0·67 grass silage, proportionately 0·33 maize silage (GGM); 0·33 grass silage, 0·67 maize silage ( MMG); maize silage ( M) from 424 (s.d. = 11·5) kg to slaughter at a minimum weight of 560 kg. Forages were mixed and offered ad libitum. Steers were offered 2 kg of a concentrate daily, the concentrate being formulated such that all steers had similar crude protein intakes across dietary treatments. A sample of steers was slaughtered at the beginning of the experimental period to allow the calculation of the rate of gain of the carcass and its components. Carcass dissection of a sample of steers allowed the development of a prediction equation of carcass composition based on thoracic limb dissection of all carcasses. Forage dry matter intake and live-weight gain increased linearly as maize silage replaced grass silage in the forage mixture, resulting in improvements in food conversion ratio (all P = 0·001). Killing-out proportion increased with maize silage inclusion ( P < 0·001) but fat and conformation scores did not differ significantly between diets. However, increasing maize inclusion in the diet resulted in a greater weight ( P = 0·05) and proportion ( P = 0·008) of fat in the carcass, and significant increases in internal fat deposition. The inclusion of maize led to a progressive increase in the daily gains of carcass ( P < 0·001), and significant increases in the daily gains of both fat ( P < 0·001) and lean tissue ( P < 0·001). Fat colour was more yellow in cattle given diets G and GGM than diets MMG and M ( P < 0·001) and colour intensity was lower on diet M than the other three diets ( P < 0·001). There were no significant differences in any aspects of eating quality between diets. Therefore, maize silage has the potential to reduce the time taken for finishing beef animals to achieve slaughter weight with no apparent detrimental effects on subsequent meat quality.

Ganhos de peso, taxas de deposição e composição química corporal de tourinhos Santa Gertrudes confinados, recebendo alto concentrado e níveis crescentes de polpa cítrica peletizada

Objetivou-se avaliar a substituição do milho em grão pela polpa cítrica peletizada e seus efeitos sobre os ganhos de peso, as taxas de deposição e a composição química corporal de tourinhos Santa Gertrudes em confinamento. Vinte e oito animais (idade média de nove meses e peso inicial de 277 kg) foram mantidos em baias individuais durante 92 dias, após 21 dias de adaptação. Os animais receberam dietas contendo 20% da MS como silagem de milho que continha 40% de grãos. Foram testados os níveis de 0, 25, 40 e 55% de participação da polpa cítrica peletizada na MS da dieta. A composição química corporal foi estimada a partir de equações desenvolvidas para a mesma raça, utilizando-se a composição química do corte da 9-10-11ª costelas. A participação da polpa cítrica peletizada não afetou significativamente o peso corporal final (449 kg) e os ganhos diários de peso corporal (1,50 kg), de corpo vazio (1,26 kg) e de carcaça (0,78 kg). Não houve diferença entre tratamentos para as taxas diárias de deposição de água (0,374 kg), EE (0,589 kg), proteína (0,253 kg), minerais (0,040 kg) e energia (6,934 Mcal) e, conseqüentemente, a composição química corporal final foi similar entre os animais recebendo diferentes níveis de polpa cítrica na dieta. A substituição do milho em grão por polpa cítrica peletizada, até 55% da MS, em dietas para tourinhos em terminação recebendo altos níveis de concentrado, não altera os ganhos de peso, as taxas de deposição e a composição química corporal desses animais.

Estimativas de parâmetros genéticos e fenotípicos e análise de componentes principais para características de crescimento na raça Canchim

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tendência genética em pesos e ganhos em peso de bovinos da raça Guzerá

The main objective of this study was to estimate genetic and phenotypic trends in weights at birth (BW), 8 (W8) and 12 months (W12) of age; and also in the daily gains from birth to 8 months (G8) and from birth to 12 months (G12) for the ''Guzera'' cattle herd from the ''Fazenda de Ensino e Pesquisa do Campus de Ilha Solteira'', UNESP, at Selviria, MS, in the Central-West region of Brazil. The data were collected between 1979 and 1984 from 842 calves, sired by 22 sires. Genetic trends were estimated by three alternative procedures, two of them were based on the methodology of repeated use of sires and the other procedure on the differences in the average genetic values of sires in the different years. The phenotypic annual changes estimated were -0.232 kg, -8.278 kg, -0.033 kg, -8.498 kg e -0.023 kg, for BW, W8, G8, W12 and G12, respectively. The estimates of genetic trends, obtained by the three procedures were different, but showed that genetic changes for all analised traits were little.

Efeito do tipo de dieta e do sistema de alimentação na fase inicial sobre o desempenho de leitões

In this experiment, 96 piglets (Large White x Landrace) were fed simple (SD) or semi-complex (SCD) diets during the initial phase (SP), using a controlled (C) or ad libitum (AL) schedules during the first 14 days of the SP and ad libitum for the rest of SP. By the end of SP one male and one female from each pen were transferred to growing finishing pens where they were fed ad libitum diets specific to each phase. The experimental design consisted of randomized complete blocks with six replicates by treatment. Higher average daily feed intakes (ADFI) were observed during the first 14 days of the SP by pigs fed SCD. Pigs fed AL showed higher ADFI and average daily gains (ADG). No treatment differences were observed between the treatments in feed conversion (FC) or in incidence and severity of diarrhea. Considering SP as a whole, there was no effect of treatments on the variables studied. Treatments used in SF did not affect ADFI and ADG during the growing-finishing phases (GFP), although pigs fed SD showed better FC. The ADG was nor affected by treatments when the total period (SP+GFP) was considered. It can be concluded that a similar performance was obtained when SD or SCD were feci during the initial phase. independently of the feeding system.

Composição corporal e exigências nutricionais de energia e proteína de tourinhos Santa Gertrudes confinados, recebendo alto concentrado e subproduto da produção de lisina

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Silagens de milho consorciado com forrageira tropical e leguminosa em dietas para terminação de cordeiros

Pós-graduação em Ciência e Tecnologia Animal - FEIS

RB30-252 Sex and Age as Factors in Cattle Feeding

Varying economic conditions and changes in the demands of the meat consuming public have been responsible for the turns that have taken place in the beef industry during recent years. Both feeder and producer must recognize and conform to these changes if they are to continue in business. Among the most important of these changes have been the turn toward the marketing of lighter cattle and the gradual disappearance from feed lots of two- and three-year-old animals. Furthermore, the cattle population of the United States is fast reaching stabilization with the resulting effect that more heifers are being marketed, since only one-fourth of the heifer crop is needed to replace worn-out breeding animals. Realizing the increasing importance of the heifer problem from the standpoint of the producer, feeder, and consumer, the Nebraska Experiment Station undertook to compare steers and heifers in a series of trials both in the feedlot and in the beef. It was hoped that these experiments would yield results which would bring out existing differences, if any, between steers and heifers both in quality and quantity of beef produced and thus provide or disprove many of the complaints against heifers. The results of these trials are summarized in this bulletin. Age as well as the sex factor has been considered, since two-year-olds, yearlings, and calves were included in these trials.

Forage-Based Beef Production Research at the Armstrong Outlying Research Farm

Fifty-five yearling crossbred steers and 3C cow-calf pairs were used in a forage-based beef production system demonstration project at the Armstrong Outlying Research Farm. From May 11 to June 13, steers rotationally grazed a 41-acre grass pasture that was divided into eight paddocks. From June 13 to August 24, steers were placed in a drylot and fed berseem clover/oat soilage from a strip-intercropping system. Beginning June 5, 36 cow-calf pairs were allowed to rotationally graze the 41-acre pasture until September 18. Calf weight gains for the 110 days were 1.57 pounds per day, and total production from the pasture was 151 pounds per acre. No cow weight change or condition score change was measured. Total steer production was 29 and 580 pounds per acre or average daily gains were .67 and 2.23 pounds while grazing pasture and being fed in a drylot.

Evaluation of Hay-Type and Grazing Tolerant Alfalfa Hybrids in Season-Long or Complementary Rotational Stocking Systems for Beef Cows

Pastures containing hay-type and grazing tolerant alfalfa hybrids were grazed in a season-long or complimentary rotational stocking system with Nfertilized smooth bromegrass. The pastures were stocked at a seasonal density of .8 cow-calf pairs per acre for 120 days. Pastures were intensively managed by daily strip-stocking with the assumptions that 50% of live forage was available and daily live dry matter consumption of each cow-calf pair was 3.5% of the cow’s body weight. First-cutting forage was harvested as hay from 40% of pasture acres to remove excess forage growth early in the grazing season. Forage was grazed from the remaining 60% of each pasture for the first 44 days of the experiment and then from the entire pasture thereafter. Live forage yields, estimated by monthly clippings, were greater in May and September on the season-long alfalfa pastures compared with the complementary pastures and on the alfalfa pastures compared with the N-fertilized smooth bromegrass pastures. The proportions of legumes in the live dry matter in pastures with grazing tolerant and hay-type alfalfas in the season-long grazing systems declined by 70% and 50%, respectively, in the 120 day trial. The proportions of legumes in the live dry matter in pastures with grazing tolerant and the hay-type alfalfas in the complementary grazing system declined 60% and 42%, respectively, in the 120 day trial. Cows grazing either alfalfa hybrid by either management system had greater weight gains during the breeding and grazing seasons and greater increases in body condition score prebreeding and during the breeding season than the cows that grazed N-fertilized smooth bromegrass for the entire season. Also, cows grazing either alfalfa in the season-long system had greater breeding season increases in body condition score than cows grazing alfalfa in the complementary system with N-fertilized smooth bromegrass. Daily gains and seasonal gains of calves from cows grazing the alfalfa pastures tended to be greater than those grazing N-fertilized smooth bromegrass. Within alfalfa treatments, calves of cows grazing alfalfa pastures in the season-long system tended to produce more pounds per acre than those of cows grazing alfalfa in the complementary systems.

Long Versus Short Feeding Period for Steer Calves of Three Frame Sizes Fed High Energy Finishing Diets

An experiment was conducted using Angus cross steer calves of three frame sizes (small, medium, and large) to compare performance of two different grow/finish feeding programs. Half of the cattle in each frame size group were fed a high energy ration through the growing period, similar to calves going directly into the feedlot. The other half was fed a low energy ration, similar to a backgrounding diet, for a period prior to the finishing phase. All cattle were fed a high energy ration through the finishing period. The data showed the cattle fed the low energy growing diet experienced some compensatory gains as shown by ultrasound backfat and average daily gains coupled with intakes greater than the increases seen in the high energy treatment. Carcass data and overall performance data showed no ill effects due to the low energy growing ration.

Integration of Pasturing Systems for Cattle Finishing Programs—A Progress Report

This progress report is an introduction to a study to evaluate the incorporation of rotational pasturing systems into cattle finishing programs. Because the first year is still in progress and the first trial is not complete, few data are available. However, there is a suggestion that feeding an ionophore to young calves on pasture may result in improved daily gains.

Integration of Pasturing Systems for Cattle Finishing Programs

A 3-year study, using 84 fall-born and 28 spring-born calves of similar genotypes, was conducted to integrate pasturing systems with drylot feeding systems. Calves were started on test following weaning in May and October. Seven treatments were imposed: 1) fall-born calves directly into feedlot; 2 and 3) fall-born calves put on pasture with or without ionophore and moved to the feedlot at the end of July; 4 and 5) fall-born calves put on pasture with or without ionophore and moved to the feedlot at the end of October; 6 and 7) spring-born calves put on pasture with or without ionophore and moved to the feedlot at the end of October. A bromegrass pasture consisting of 16 paddocks, each 1.7 acre in size, was available. Each treatment group had access to 1 paddock at a time and was rotated at approximately 3-day intervals. In the feedlot, steers were provided an 82% concentrate diet containing whole-shelled corn, ground alfalfa hay, and a protein, vitamin and mineral supplement containing ionophore and molasses. As pens of cattle reached about 1150 lb. average live weight, they were processed and carcass traits were evaluated. Pasture daily gains were highest for cattle on pasture for the longest duration (P < .03), and overall daily gains were highest for drylot cattle (P < .01) and decreased with increased time spent on pasture. Although differences among treatments existed in numerical scores for yield and quality grades (P < .05 and P < .03, respectively), all treatments provided average yield grade scores of 2 and quality grades of low Choice or higher. Use of four production costs and pricing scenarios revealed that fall-born calves placed on pasture for varying lengths of time were the most profitable (P < .04) among the treatments. Furthermore, employing a 5% price sensitivity analysis, indicated that fed-cattle selling price had great impact on profit potential and was followed in importance by feeder purchase price and corn grain price. Overall, these findings should provide significant production alternatives for some segments of the cattle feeding industry and also lend substantial credence to the concept of sustainable agriculture.