Effect of marine by-product meals on hen egg production parameters, yolk lipid composition and sensory quality.

The effect of including 5% marine by-product meals in feeds of laying hens on egg production, composition and sensory characteristics was tested. Marine by-product meals were prepared using two methods: (i) cooking (100°C/10 min) followed by drying (60°C/24 hr) or (ii) grinding followed by drying. The raw materials used for meal production were scallop or squid viscera, shrimp heads or whole mackerel. A total of 108 laying hens were allocated to nine diet treatments; one control diet (corn and soya bean based) and eight experimental diets, containing 95% of the control feed and 5% of the experimental meal for three weeks. Daily intake was higher in hens fed the dried mackerel and cooked shrimp meals. All the experimental treatments showed significantly higher concentration of n-3 HUFA in yolk reserves and phospholipids compared to the control (0.12-0.13 g per 100 g), especially those with scallop or squid prepared by both methods (0.53-0.95 g per 100 g). Scallop, squid and shrimp meal inclusion in the feed produced eggs with more astaxanthin (0.22 mg per 100 g) while this carotenoid was absent in the control and mackerel treatments. Visual evaluation of raw yolk colour increased with the inclusion of marine by-product meals with higher values in hens fed shrimp heads (13), followed by scallop viscera (11), squid viscera (9), and with similar values for mackerel and control (4). The taste, aroma, texture and colour of cooked eggs from different treatments were not statically different when evaluated by a panel of 60 untrained people. These results suggest that meals from marine by-products are a better alternative for improving egg yolk composition by increasing n-3 HUFA when compared to fishmeal as they also increase astaxanthin and yolk pigmentation without affecting egg sensory characteristics.

Extension model of lactation curves to evaluate the effect of the recombinant bovine somatotropin on milk yield in Holstein cows / Modelo de extensão de curvas de lactação para avaliar o efeito da somatotropina bovina recombinante sobre a produção de leite em vacas Holstein

An extension model of lactation curves was used to determine the effect of recombinant bovine somatotropin (bST-r) on milk yield in Holstein dairy cattle. This model use the fitted values obtained by the Wood model, and was tested on the records of 66 cows. The milk yield predicted with the extension model and the observed yield were compared and no significant differences were observed (P>0.05). Once the extension model was validated, the milk yield tests of 199 cows were used. The cows received bST-r 500mg by subcutaneous injections. The injections were applied after 100 days in milk at 14-day intervals (seven injections). The observed milk yield was compared with the yield expected by the extension model. An increase of 5.3 percent was observed in milk yield in response to the bST-r. This increase is lower than that reported in the literature in response to the growth hormone in dairy cattle. It is concluded that extension model used in the present work is reliable for extending the lactation curve in Holstein cows, and the increase in milk yield in response to the application of bST-r, determined in the same animal using the extension model, was lower than that reported by other authors.

Um modelo de extensão de curvas de lactância foi utilizado para determinar o efeito da somatotropina bovina recombinante (bST-r) sobre a produção de leite em vacas Holstein. Este modelo, que utiliza os valores ajustados obtidos pelo modelo de Wood, foi testato nos registros de 66 vacas. A produção de leite predita com o modelo de extensão e a produção observada foram comparadas e não se observaram diferenças significativas (P>0,05). Uma vez validado o modelo de extensão, utilizaram-se os controles de produção de leite (de cada 15 dias) de 199 vacas. As vacas receberam injeções de 500mg de bST-r via subcutânea. As injeções fora aplicadas a partir dos 100 dias de lactação a intervalos de 14 dias (sete injeções). A produção de leite observada foi comparada com a produção esperada com o modelo de extensão. Observou-se um incremento de 5,3 por cento na produção de leite em resposta à bST-r. Este incremento foi menor que o relatado na literatura em resposta ao hormônio do crescimento em vacas leiteiras. O modelo de extensão usado é confiável para estender a curva de lactação na vaca Holstein, e o aumento do rendimento de leite em resposta à aplicação de bST-r, determinado no mesmo animal usando o modelo de extensão, foi inferior ao observado por outros autores.

Components of (co)variance of the days open in Siboney dairy cows / Componentes de (co)variância dos dias vazios em vacas leiteiras Siboney

The records of 63,406 calvings of Siboney dairy cows (5/8 Holstein 3/8 Cuban Zebu) were used to estimate the components of covariance of the days open (DO). Five models were used: of repeatability; univariate; bivariate; of random regression with Legendre polynomials and the parity number as predicting variable; and a model of random regression with Legendre polynomials and heterogeneity of the residual variance. The heritability obtained with the univariate model was 0.09 in the first calving and decreased to 0.05 in the fifth. A higher estimate of heritability (0.12) was obtained with the repeatability model. When the model of random regression with heterogeneity of the residual variance was used, the heritability was higher than the values estimated with the previous models. The genetic correlations among the DO in different calvings, estimated with the models of random regression with and without heterogeneity of the residual variance, were close to 1.0. It is concluded that the estimates of heritability increased with the use of the random regression models. The genetic correlations among the DO of different calvings indicated that in the first three, the DO are regulated for the most part by the same genes.

Os registros de 63.406 partos de vacas Siboney (5/8 Holstein 3/8 Cebu de Cuba) foram utilizados para estimar os componentes de (co)variância de dias vazios (DV). Utilizaram-se cinco modelos: de repetitividade; univariado; bivariado; de regressão aleatória com polinômios de Legendre e número de partos como variável preditiva; e de regressão aleatória com polinômios de Legendre e heterogeneidade da variância residual. A herdabilidade obtida com o modelo univariado foi de 0,09 no primeiro e diminuiu a 0,05 no quinto parto. Uma estimativa de herdabilidade mais alta (0,12) foi obtida com o modelo de repetitividade. Quando foi usado o modelo de regressão aleatória com heterogeneidade da variância residual a herdabilidade foi superior aos valores estimados com os modelos anteriores. As correlações genéticas entre os DV em distintos partos, estimadas com os modelos de regressão aleatória com e sem heterogeneidade da variância residual, foram próximos a 1,0. Concluiu-se que as estimativas de herdabilidade foram incrementadas com o uso dos modelos de regressão aleatória. As correlações genéticas entre os DV de diferentes partos indicaram que, nos três primeiros, os DV são regulados na sua maior proporção pelos mesmos genes.