Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis

The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 103 cells/mL, were classified as 1 if mxSCC 500, 2 if 500 <mxSCC <1,000, and 3 if mxSCC 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20% higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7% on the logarithmic scale and 11% on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19% of the variation on the logarithmic scale and 27% of the variation on the real scal

Definición del objetivo económico de selección para un sistema de producción porcina en Argentina

Para un sistema de ciclo completo mixto en Argentina se definió la ecuación de beneficios, se estimaron los pesos económicos absolutos y estandarizados de Proporción de Tejidos Magros de Cerdos Vendidos (%MV), Conversión alimenticia entre el destete y el peso de mercado (CA), Número de lechones nacidos vivos por parto (LVP), Peso del mercado en Kilogramos (PM), Peso por lechón al destete en Kilogramos (PD) y Rendimiento de la res (REND) ; y se condujo un análisis de sensibilidad. LVP, CA, REND y porcentaje MV resultaron ser los de mayor importancia económica. Los pesos económicos resultaron robustos frente a cambios en variables económicas, excepto ante variaciones en los precios del Kilogramo de res y de alimento ; la relación entre dichos precios debe considerarse al asignar importancia relativa a LVP y CA. Los pesos económicos obtenidos, combinados con evaluaciones del mérito genético, pueden utilizarse para tomar decisiones de compra y venta de reproductores y como orientación para la definición del objetivo de selección de los núcleos genéticos que los comercializan

Relationship between beta lactoglobulin and subclinical mastitis in Valle del Belice sheep breed

The objective of the following research was to determine the effect of LGB genotypes on subclinical mastitis in Valle del Belice dairy sheep. Ewes were classified as affected or not by subclinical mastitis within a lactation based on i) a positive culture in one of the test-days and ii) more than 750,000 somatic cells. Generalized linear mixed models were fitted to assess the significance of LGB genotypes on MTB and MTC. The LGB genotypes significantly affected MTB (p=0.0387), and showed a tendency on MTC (p=0.1104). Least square means showed that in the analysis for MTB, individuals with genotypes BB and AB had a higher frequency of subclinical mastitis. Moreover, the least square differences showed that the incidence was significantly higher in BB ewes than in AA ewes (p<0.001), and a tendency of a higher incidence among AB ewes than in AA ewes (p=0.0630). In conclusion, the results of this work show that LGB genotype BB seems to be less favourable in terms of mastitis resistance in Valle del Belice sheep breed

Relationship between beta lactoglobulin and subclinical mastitis in Valle del Belice sheep breed

The objective of the following research was to determine the effect of LGB genotypes on subclinical mastitis in Valle del Belice dairy sheep. Ewes were classified as affected or not by subclinical mastitis within a lactation based on i) a positive culture in one of the test-days and ii) more than 750,000 somatic cells. Generalized linear mixed models were fitted to assess the significance of LGB genotypes on MTB and MTC. The LGB genotypes significantly affected MTB (p=0.0387), and showed a tendency on MTC (p=0.1104). Least square means showed that in the analysis for MTB, individuals with genotypes BB and AB had a higher frequency of subclinical mastitis. Moreover, the least square differences showed that the incidence was significantly higher in BB ewes than in AA ewes (