Influência de fatores raciais e manejo nutricional na contagem de células somáticas e nos constituintes do leite de vacas holandesas e mestiças no Norte do Estado do Paraná, Brasil - DOI: 10.4025/actascianimsci.v25i2.2016

474 milking herds from the north region of Paraná State were analyzed in this study. The herds were characterized for average productivity, genetic group, exploration and milking systems. Two milk samples (bulk or brass) were collected monthly from each farm, totalizing 21.957 samples. They were processed to determine fat, protein and somatic cells count (SCC) at Centralized Analyses Laboratory from Milking Herds Analyses Program of Paraná State. The data was submitted to analysis of variance (proc glm), regression analysis (proc reg) and correlation analysis (proc corr) in SAS to determine the influence of environmental and racial factors on SCC and milk composition, as well as SCC influence on protein and fat levels. Except for the milk system (p > 0.05), all other studied effects were highly significant (p 0.05) was the herd average production, on protein level. The effect of SCC on milk protein and fat was statistically relevant (p 0,05). O efeito da CCS sobre os teores de proteína e de gordura láctea foi estatisticamente relevante (p < 0,0001). Com o aumento da CCS, ocorreu diminuição no teor de proteína e aumento no teor de gordura, embora apenas 0,53% e 3,02% da variação desses sólidos, respectivamente, possam ser creditados à CCS

Carcass characteristics, meat quality, feeding behavior of Nelore heifers fed diets containing sunflower pie

The aim was to evaluate the feeding behavior, carcass characteristics and meat quality of Nelore heifers fed sunflower pie replacing cottonseed meal. They were used 30 heifers with average initial weight of 274 kg ± 28 kg and average age of 24 months, confined for 76 days. The design was completely randomized with five treatments (0, 150, 300, 450 and 600 g kg-1 DM) and six replicates per treatment. By completing 24 hours after slaughter, it evaluated muscle conformation and degree of finish made the longissimus dorsi at the 13th rib. A representative sample between the 10th and 12th ribs was collected for evaluation of the physical components of carcasses. As well as the other variables, the hot carcass weight, dressing percentage, carcass length and rib eye area were not influenced by different pie levels in feed. The mean percentage of muscle, bone and fat from the carcass were 53.45; 16.14 and 29.46%, respectively, similar among treatments. Therefore, the use of up to 600 g kg-1 of sunflower pie replacing cottonseed meal as the main protein source, did not affect the carcass characteristics and meat quality of Nelore heifers.

Genetic parameters of age at first calving, weight gain, and visual scores in Nelore heifers

ABSTRACT This study aimed at estimating the heritability of age at first calving and of performance traits included in the selection index and the genetic correlations between age at first calving and these performance traits. Data were extracted from the Conexão Delta G database and only data from herds in which heifers were bred younger than 24 months of age were used, resulting in a file with 331,310 evaluated animals. The following traits were included in the analyses: age at first calving, birth to weaning gain, post-weaning weight gain, visual scores of conformation, precocity, and muscling evaluated at weaning and in yearling heifers. Covariance components were obtained by bi-character analyses between traits. An alternative age at first calving was also taken into account, in which all heifers were used, including those that were mated and did not calve. Covariance components and estimates of the effects included in the model were obtained using the software program DMU. Heritability estimates were 0.11 and 0.13 for age at first calving and alternative age at first calving, 0.38 for birth to weaning gain, and 0.13 for post-weaning weight gain. Visual score estimates ranged between 0.16 and 0.18 at weaning and 0.19 and 0.29 in yearlings. Genetic correlation estimates of the traits were low, but in the desirable direction. Selection for birth to weaning gain and visual scores does not have a negative effect on age at first calving or alternative age at first calving

Genetic trends for mature body weight, visual scores, and growth traits in Nellore cattle

ABSTRACT: Mature weight (MW) of cows is related to the costs of their production. Usually, cows with moderate MW are more efficient in challenging environments, such as those available in the production systems in Brazil. In the present study, the selection index comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, WM) yearling (YC, YP and YM), scrotal circumference at yearling (SC), days to gain 160kg from birth to weaning (D160) and 240kg after weaning (D240). This are related to birth weight gain at weaning (WG) and from weaning to yearling (YG). The mature (MW) and birth weight (BW) traits were not considered in the selection index. The aim of this study was to estimate the values for the genetic trends (GT) of some important selection (MW) and economic traits (BW). A bi-character analysis of MW and other characteristics was performed to estimate the (co)variance components and genetic parameters. The GT results obtained for MW were null (0.0065% or 0.02718kg per year) in the period 1990-2007. The GT values were determined for BW (-0.0650% or -0.02017kg), WG (0.0758% or 0.0865kg), YG (0.1051% or 0.11377kg), and MW (0.0393% or 0.11276kg) per year. The visual score values (in score units) were also determined for GTat weaning [WC (0.2310%; 0.00707), WP (0.3624%; 0.3623%),aWM (0.01149; 0.01087)] yearling [YC (0.3256%; 0.00990), YP (0.4795%; 0.01496),YM (0.5041%; 0.01457)] per year. Index-based selection was effective to promote genetic progress in WG, WC, WP, WM, YG, YC, YP, and YM characteristics keeping BW and MW constant

Economic feasibility of four grazing intensities of Tanzania grass for beef cattle<br>Viabilidade econômica de quatro intensidades de pastejo do capim Tanzânia na pecuária de corte

Were evaluated the economic effects of four grazing heights (20, 40, 60 and 80 cm) of Tanzânia grass for beef cattle. The total area was 12 acres divided into paddocks of one hectare, with three replications. We used three animals, males, Nelore per paddock, as more animals need additional adjustment to the height you want. The reduction in sward height allowed higher stocking rate, which, even with a reduction in individual performance, there was more beef production per area. The interest rate on capital given the property represented the largest share in the final cost of production. The participation of fixed variables showed a positive linear function of the increase in height from grazing, showing significant reduction of the production scale. A reduction in cost of production per hectare per year with increasing grazing height. No differences were found in certain economic indicators, and the four systems remunerate the capital invested.<p><p>Foram avaliados os efeitos econômicos de quatro alturas de pastejo (20; 40; 60 e 80 cm) do capim Tanzânia para bovinos de corte. A área total foi de 12 hectares divididos em piquetes de um hectare, com três repetições. Foram utilizados três bovinos, machos, Nelore por piquete, mais animais adicionais conforme necessidade de ajuste para as alturas pretendidas. A redução da altura do pasto permitiu maior taxa de lotação, onde, mesmo com redução no desempenho individual, houve maior produção por área. A taxa de juros atribuída sobre o capital do imóvel representou a maior parcela no custo final de produção. A participação das variáveis fixas apresentou comportamento linear positivo em função do aumento na altura dos pastos, se mostrando sensível à redução da escala de produção. Houve redução do custo de produção anual por hectare com aumento da altura de pastejo. Não foram detectadas diferenças nos indicadores econômicos determinados, e os quatro sistemas remuneraram o capital investido

Genetic parameters of age at first calving, weight gain, and visual scores in Nelore heifers

This study aimed at estimating the heritability of age at first calving and of performance traits included in the selection index and the genetic correlations between age at first calving and these performance traits. Data were extracted from the Conexão Delta G database and only data from herds in which heifers were bred younger than 24 months of age were used, resulting in a file with 331,310 evaluated animals. The following traits were included in the analyses: age at first calving, birth to weaning gain, post-weaning weight gain, visual scores of conformation, precocity, and muscling evaluated at weaning and in yearling heifers. Covariance components were obtained by bi-character analyses between traits. An alternative age at first calving was also taken into account, in which all heifers were used, including those that were mated and did not calve. Covariance components and estimates of the effects included in the model were obtained using the software program DMU. Heritability estimates were 0.11 and 0.13 for age at first calving and alternative age at first calving, 0.38 for birth to weaning gain, and 0.13 for post-weaning weight gain. Visual score estimates ranged between 0.16 and 0.18 at weaning and 0.19 and 0.29 in yearlings. Genetic correlation estimates of the traits were low, but in the desirable direction. Selection for birth to weaning gain and visual scores does not have a negative effect on age at first calving or alternative age at first calving