Effect of somatic cell count and mastitis pathogens on milk composition in Gyr cows

Abstract

BackgroundGyr cows are well adapted to tropical conditions, resistant to some tropical diseases and have satisfactory milk production. However, Gyr dairy herds have a high prevalence of subclinical mastitis, which negatively affects their milk yield and composition. The objectives of this study were (i) to evaluate the effects of seasonality, mammary quarter location (rear x front), mastitis-causing pathogen species, and somatic cell count (SCC) on milk composition in Gyr cows with mammary quarters as the experimental units and (ii) to evaluate the effects of seasonality and somatic cell count (SCC) on milk composition in Gyr cows with cows as the experimental units. A total of 221 lactating Gyr cows from three commercial dairy farms were selected for this study. Individual foremilk quarter samples and composite milk samples were collected once a month over one year from all lactating cows for analysis of SCC, milk composition, and bacteriological culture.ResultsSubclinical mastitis reduced lactose, nonfat solids and total solids content, but no difference was found in the protein and fat content between infected and uninfected quarters. Seasonality influenced milk composition both in mammary quarters and composite milk samples. Nevertheless, there was no effect of mammary quarter position on milk composition. Mastitis-causing pathogens affected protein, lactose, nonfat solids, and total solids content, but not milk fat content. Somatic cell count levels affected milk composition in both mammary quarters and composite samples of milk.ConclusionsIntramammary infections in Gyr cows alter milk composition; however, the degree of change depends on the mastitis-causing pathogen. Somatic cell count is negatively associated with reduced lactose and nonfat solids content in milk. Seasonality significantly affects milk composition, in which the concentration of lactose, fat, protein, nonfat solids and total solids differs between dry and wet seasons in Gyr cows.

Receiver operating characteristic analysis of milk lactosefor identification of mastitis in buffaloes

“…Lower milk lactose observed during mastitis is in agreement with previous studies in dairy buffaloes (Bansal et al, 2007;Sharif Tripaldi et al, 2010;Hussain et al, 2012). Lower lactose content may be due to impairment of synthetic activity of mammary tissues or decomposition by leucocytes or mastitis causing pathogens or leakage from milk into blood (Hussain et al, 2012;Reis et al, 2013). Hence, lactose could be used as an indicator due to consistent change during intramammary infections (Tripaldi et al, 2010;Reis et al, 2013).…”

“…Further, fat is considered as the most variable milk component, followed by protein and lactose is the least variable (Ravikala et al, 2014). On the other hand, during mastitis, alteration of milk lactose occurs markedly compared to other traits (Bansal et al, 2007;Sharif et al, 2007;Tripaldi et al, 2010;Hussain et al, 2012;Reis et al, 2013). Hortet and Seegers (1998) reviewed the alteration of milk fat and protein during mastitis and observed that the alterations were contradictory to several authors.…”

“…Hortet and Seegers (1998) reviewed the alteration of milk fat and protein during mastitis and observed that the alterations were contradictory to several authors. Recently, Reis et al (2013) also reported contradictory alteration of milk fat and protein during mastitis. Moreover, milk lactose showed little variation within lactation as well as from one lactation to the next, and consistently decreased during udder inflammation (Pyorala, 2003).…”

“…The ROC analysis is considered as a simple statistical tool used to characterize a diagnostic variable in terms of area under a ROC curve (AUC) and further provides range of potential threshold values along with their corresponding Sensitivity (Se), Specificity (Sp) and positive likelihood ratio (LR+) values (Patbandha et al, 2012(Patbandha et al, , 2013. Milk constitutes major components such as fat, protein and lactose which are most important to the dairy farmers, producers and consumers (Reis et al, 2013). However, these traits are affected by environmental and nutritional factors as well as physiological and pathological condition of animals.…”

Revisión de los aspectos para la evaluación de la nutrición y alimentación en programas de salud de hato de ganado lechero I: evaluación del hato

“…La interpretación de esta variable debe tomar en cuenta otros factores que pueden influir, como el efecto de la genética (Demeter et al 2010), la etapa de lactancia (Stoop et al 2009), la duración del período seco (van KVan Knegsel et al 2014), la salud de la ubre (Malek dos Reis et al 2013), y el número de partos (Nayak et al 2012), por lo cual no debe considerarse el efecto aislado de cada uno en forma individual. Esto deja ver que la composición de la leche no es un indicador específico del estado nutricional, el cual debe ser analizado junto con otras variables que influyen significativamente en ella.…”