Pedro Franklin Barbosa

Estimativas de (Co)Variâncias e Tendências Genéticas para Pesos em um Rebanho Canchim

The objectives of this study were to estimate variances and covariances and to evaluate the genetic trends for body weight at birth (BW), weaning (WW) and twelve months of age (YW) in a Canchim (5/8 Charolais + 3/8 Zebu) herd. Data on 6.517 animals, born from 1953 through 1996, were used to estimate breeding values by the derivative free restricted maximum likelihood method, using a model that included the fixed effects of contemporary group (year-season of birth-sex of calf) and the covariable age of cow at calving (linear and quadratic effects), and the random additive direct, additive maternal and permanent environmental effects. Genetic trends for direct, maternal and total maternal effects were estimated by the weighed regression of the annual (generation) breeding value (direct, maternal and total maternal) means on year (generation) of birth of the animals. The direct heritability estimates were equal to 0.39, 0.48 and 0.63 for BW, WW and YW, respectively, while the maternal heritabilities were, in the same order, equal to 0.03, 0.04 and 0.05, respectively. The annual direct genetic trends were equal to 0.046, 1.336 and 1.619 kg for BW, WW and YW, respectively, corresponding to 0.13, 0.66 and 0.75% of the herd means. By generation, the genetic trends were, in the same order, 0.269, 7.715 and 9.599 kg, respectively. The maternal and total maternal genetic trends were linear and positive. The results showed that the selection criteria used resulted in genetic progress for BW, WW and YW; however, the progress obtained was much smaller than the possible one.

Correlações genéticas entre características produtivas de fêmeas em um rebanho da raça Canchim

The objective of this study was to estimate the genetic correlations of female body weights at weaning (BWW), 12 (W12) and 18 (W18) months of age with age at first calving (AFC), body weight at first calving (WFC), adult body weight (ABW), and the parameters for mature weight (A) and maturation rate (k) obtained using the Von Bertalanffy model, in a Canchim herd. The restricted maximum likelihood method, with two-trait analyses, was used with models that included the fixed effects [...]The objective of this study was to estimate the genetic correlations of female body weights at weaning (BWW), 12 (W12) and 18 (W18) months of age with age at first calving (AFC), body weight at first calving (WFC), adult body weight (ABW), and the parameters for mature weight (A) and maturation rate (k) obtained using the Von Bertalanffy model, in a Canchim herd. The restricted maximum likelihood method, with two-trait analyses, was used with models that included the fixed effects of contemporary group and the random additive direct effect. For BWW the model also included the covariate age of cow at calving (linear and quadratic effects) and the additive maternal and the permanent environmental random effects, and for ABW the model included also the fixed effect of age of cow. The means of the heritability estimates were equal to: 0.37 (BWW), 0.31 (W12), 0.35 (W18), 0.39 (A), 0.29 (k), 0.13 (AFC), 0.39 (WFC), and 0.42 (ABW). The genetic correlations between BWW and the other traits were: 0.46 (A), 0.02 (k), -0.12 (AFC), 0.66 (WFC) and 0.42 (ABW). With W12 they were equal to 0.39 (A), 0.31 (k), -0.32 (AFC), 0.77 (WFC) and 0.66 (ABW), while with W18 they were equal to 0.21 (A), 0.42 (k), -0.29 (AFC), 0.65 (WFC) and 0.60 (ABW) These results indicate that selection to increase BWW, W12, W18, WFC, ABW, and parameters A and k should result in direct genetic responses, and that selection to increase female body weights from weaning to 18 months of age should result in favorable responses in AFC and parameter k, but in unfavorable correlated responses in WFC and ABW.

Metano entérico de bovinos leiteiros em condições tropicais brasileiras

The objective of this work was to quantify methane (CH4) emission using the sulfur hexafluoride (SF6) tracer technique, by dairy cattle on pasture in Brazilian tropical field conditions. Measurements were performed in the rainy season, with Holstein and Holstein x Zebu crossbred, from lactating and dry cows and heifers grazing fertilized Tobiata grass, and heifers grazing unfertilized Brachiaria grass. Methane and SF6 concentrations were determined by gas chromatograph. Methane emissions by lactating cows varied from 13.8 to 16.8 g/hour, by dry cows from 11.6 to 12.3 g/hour, by heifers grazing fertilized grass was 9.5 g/hour and by heifers grazing unfertilized grass varied from 7.6 to 8.3 g/hour or 66 to 72 kg/head/year. Methane emission per digestive dry matter intake (DMDI) varied from 42 to 69 g/kg DMDI for lactating cows, 46 to 56 g/kg for dry cows, 45 to 58 g/kg for heifers grazing fertilized grass and 58 to 62 g/kg for heifers in unfertilized grass pasture. The CH4 emission measured on dairy cattle feeding tropical grasses was higher than that observed for temperate climate conditions.

Herdabilidades e correlações genéticas de características de machos e fêmeas, em um rebanho bovino da raça Canchim

The objective of this study was to estimate the heritabilities and the genetic correlations of body weight (BW12) and scrotal circumference (SC12) of males at twelve months of age and culling age (DH, days in herd) of females, and number (NW10) and kilograms (KW10) of weaned calves produced by females up to ten years of age, in a Canchim (5/8 Charolais + 3/8 Zebu) beef cattle herd. Data were composed of 1370, 826, 826, 2726 and 1051 observations of DH, NW10, KW10, BW12 and SC12, respectively. The variance and covariance components were obtained by the bayesian method, with a statistical model that included, besides the additive direct and residual random effects, the fixed effects of year of birth for all traits, month of birth for BW12 and SC12, and the covariate age for SC12. The heritability estimates, obtained by the one-trait analyses, were equal to 0.38, 0.52, 0.24, 0.33 and 0.34 for BW12, SC12, DH, NW10 and KW10, respectively, indicating that all traits have enough genetic variability to show response to selection. The genetic correlations of DH (0.33 and 0.33, respectively), NW10 (0.38 and 0.30, respectively) and KW10 (0.61 and 0.41, respectively) with BW12 and SC12, obtained by the two-trait analyses, suggest that selection for increased body weight and scrotal circumference of the males at twelve months of age will not result in decreased days in herd for the females, and decreased number and kilograms of weaned calves produced by the females up to ten years of age.

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

The objectives of this study were to obtain estimates of heritability and genetic, phenotypic and environmental correlations for average daily gains from birth to weaning (DGBW), from weaning to 12 months (DGW12), from 12 to 18 months (DG1218) and from 18 to 24 months (DG1824) of age, and to estimate the principal components for these growth traits in Canchim cattle. The data were analyzed by the least square method. The heritability estimates were 0.39± 0.07 (DGBW), 0.12±0.04 (DGW12), 0.20±0.05 (DG1218) and 0.13±0.05 (DG1824). The genetic correlations between DGBW and DG1218, and DGW12 and DG1218 were moderated and positive, indicating favorable genetic association among these traits. The genetic correlations among body weight gains and adjacent body weights were, in general, high and positive. For body weights, the first principal component explained 74% of total variation, and it is an index of the studied traits, and the importance of each one increased as the animal aged. The second component explained 14% of the variation, and contrasts heavier animals at weaning and at 18 months with heavier animals at 24 months old, characterizing animals with higher or less precocity and precocious and late maturation rate. For body weight gains the first component explained 44% of the total variation, and contrasts animals with higher DGW12 and DG1824 with animals with higher DG1218 or, in other words, contrasts the gains obtained during the less favorable season of the year (from weaning to one year of age and 18 to 24 months of age) with the gains obtained during the most favorable season of the year (from12 to 24 months).

Selection for breed-specific growth hormone and IGF-I alleles in a synthetic beef cattle cross, Canchim

INTRODUCTIONMolecular markers based on unique sequences arewidely used for population structure analysis. The recentdevelopment of saturated microsatellite maps for the bo-vine genome (Bishop et al., 1994; Barendse et al., 1994,1997) now allows population analysis with markers linkedto specific genes or spread over the entire genome.Canchim is a synthetic beef cattle breed, produced bycrosses between Charolais (Bos taurus) and several Bosindicus breeds (hereafter Zebu). With a genetic composi-tion of 5/8 Charolais + 3/8 Zebu, Canchim combinesgrowth ability associated with a Bos taurus breed and tol-erance to tropical environments that is attributed to Zebubreeds. The herd used in this study was formed in 1953and has been maintained on pastures and subjected to phe-notypic selection for yearling weight and fertility. Therewas no introduction of outside animals, and the averageinbreeding coefficient was kept low by avoiding consan-guineous mating (Alencar et al., 1981).This study was developed to evaluate change ingene frequencies over four generations of this herd. Themain objective was to investigate if selection for growthin a tropical environment would favor specific regions ofCharolais and Zebu genomes, based on the premise thatperformance is a combination of the expression of favor-able genes for growth and adaptation.MATERIAL AND METHODSAnimalsThe herd used in this study was developed andmaintained at the Centro de Pesquisa de Pecuaria doSudeste - Embrapa, Sao Carlos, SP, Brazil. Animals weremaintained on pastures formed essentially of Digitariadecumbens, Panicum maximum, Melinis minutiflora andHyparrhenia rufa, (Ness) Stapf. until 1977. Thereafter,pastures were improved by the introduction of Brachiariadecumbens, Panicum maximum c.v. “Makueni” and “Greenpanic” and Pennisetum purpureum.Male selection was based on three criteria: mor-phological parameters according to the breed standards,andrological evaluation and yearling weight. Annual se-lection intensity was close to 10%. From 1953 to 1976 theonly selection applied to females was to cull old or ill cows.After 1976, female selection was based on the followingcriteria: registry in the herd-book, reproductive health andweight of at least 310 kg at the first service, with an an-nual culling of 20%.The generation number of each animal in thisCanchim herd was determined using the following for-mula: (GS + GD + 2)/2, where GS is the generation of thesire and GD is the generation of the dam (Brinks et al.,1961). Foundation animals were considered generation 0.Blood was collected from a sample of 154 animals groupedinto four classes (Table I). Semen or blood was also col-

Estimativas de parâmetros genéticos e de ganhos direto e indireto à seleção para características de crescimento de machos e fêmeas da raça Canchim

The objective of this study was to estimate heritability and genetic correlations for body weight at birth (BW), weaning (WW), twelve (W12) and eighteen (W18) months of age, weight gains from birth to weaning (DGBW) and from birth to eighteen months of age (DGB18), days to 175 kg from birth to weaning (D175 = 175/DGBW), days to 450 kg from birth to slaughter (D450 = 450/DGB18) and female mature body weight (ABW) using data from a herd of Canchim (5/8 Charolais + 3/8 Zebu) cattle. Univariate and bivariate models including the fixed effects of year and month of birth, sex of calf, year and month of calving, age at calving, age of dam as a covariate (linear and quadratic components) and additive, maternal, permanent environmental and residual random effects were fitted by REML. Heritability estimates obtained by univariate analyses were 0.41 (BW), 0.28 (WW), 0.38 (W12), 0.28 (W18), 0.26 (DGBW), 0.30 (DGB18), 0.23 (D175), 0.23 (D450), and 0.48 (ABW). Genetic correlation estimates ranged from 0.28 to 0.97 between body weight traits, from 0.11 to 0.97 between body weight traits and weight gains, from 0.00 to -0.98 between body weight traits and D175 and D450, and from -0.63 to -0.98 between weight gains and D175 and D450. Genetic correlation estimates were 0.69 between DGBW and DGB18, and 0.76 between D175 and D450. Genetic progress for growth in Canchim cattle is possible by direct as well as by indirect selection on any trait evaluated in this study.

Aditivos químicos e inoculante bacteriano na ensilagem de cana-de-açúcar: efeitos sobre a fermentação das silagens e o desempenho de garrotes

Os objetivos neste experimento foram avaliar o desempenho de tourinhos alimentados com racoes completas preparadas com silagens de cana-de-acucar tratadas ou nao com aditivos e estudar o efeito dos aditivos sobre a fermentacao das silagens. Trinta tourinhos Canchim com peso medio de 312 kg foram distribuidos em delineamento de blocos casualizados para avaliar tres tipos de racoes isoproteicas e isoenergeticas (relacao volumoso:concentrado de 35:65): racao com silagem sem aditivo (controle); racao com silagem tratada com ureia (5 g/kg de materia verde, MV) + benzoato de sodio (0,5 g/kg de MV); racao com silagem inoculada com Lactobacillus buchneri (5 × 104 ufc/g de MV). As silagens apresentaram pH adequado a conservacao ( 53 g/kg de MS). Na silagem tratada com ureia + benzoato e na silagem inoculada, os teores de etanol foram mais baixos em relacao a silagem sem aditivo (43; 73 e 92 g/kg de MS, respectivamente). A silagem com ureia + benzoato apresentou teores mais elevados de proteina bruta e de nutrientes digestiveis totais em comparacao as outras silagens. O tipo de racao nao afeta o ganho de peso vivo (1,75 kg PV/dia) nem a ingestao de MS (10,5 kg MS/dia), mas a conversao alimentar foi melhor nos animais que receberam a racao controle em relacao aqueles alimentados com a racao com silagem inoculada (5,71 vs 6,45 kg MS/kg GPV).

Efeito do teor protéico do concentrado no consumo de cana-de-açúcar com uréia e ganho de peso de novilhas em crescimento

The effect of different protein supplements on intake of sugar cane with urea by crossbred Holstein-Zebu heifers was evaluated during 12 weeks in the dry season. Eighteen heifers, averaging initial weight of 288 kg and age ranging from 15 to 22 months, were supplemented with soybean meal or concentrate with 28.7% crude protein. The amount of supplement fed was 1.0 kg/ animal·day. Sugar cane with urea was fed ad libitum. The average intake of dry matter and neutral detergent fiber of sugar cane with urea in percent of live weight were 2.33 and 2.43; 1.19 and 1.23 for the animals supplemented with soybean meal or concentrate with 28.7% crude protein, respectively. The protein supplements did not affect intake of dry matter and neutral detergent fiber of sugar cane with urea. The supplements did not affect heifers weight gain. The average daily weight gains were .39+.04 and .36+.04 kg/animal·day for animals supplemented with soybean meal or with concentrate containing 28.7% crude protein, respectively.

Utilização de NaCl no Suplemento como Alternativa para Viabilizar o Sistema de Alimentação de Bezerros em Creep-Feeding

Thirty two Canchim suckling calves, maintained on rotational grazing system of Brachiaria brizantha cv. Marandu, were divided in three groups corresponding to three evaluated treatments: control (without creep-feeding); SAL5 (addition of 5% of NaCl to concentrate fed in creep-feeding); and SAL10 (addition of 10% of NaCl to concentrate fed in creep-feeding). Feeding in a creep-feeding system lasted 90 days, divided in three subperiods of 30 days. The body weight gain was greater in the subperiods 1 and 2 for SAL10 and SAL5 treatments, respectively. There were no differences in the third subperiod and, in the overall period, the SAL10 treatment (0.91 kg.animal-1.day-1) was better than control treatment (0.81 kg.animal-1.day-1). The monthly remuneration provided by the treatments SAL5 e SAL10 related to the control group were -12.5 and 6.0%, respectively. The body weight differentials at weaning, compared to the control group, for creep-feeding provide a monthly net profit of 0, 0.6, 1.2, and 6.0% should be 10.8, 11.0, 11.2, and 12.8 kg.animal-1 for SAL5 and 7.6, 7.7, 7.8, and 9.0 kg.animal-1 for SAL10. It was concluded that the limited supplement intake in creep-feeding was necessary to obtain economic viability.