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.

The present study was carried out to evaluate the excretion of aflatoxin B1 residues in eggs of young laying hens fed aflatoxin B1-contaminated rations for 8 weeks. To this end, 96 twenty-week-old hens were randomly distributed into four experimental groups (24 birds per group) and given rations containing either 0 (controls), 100 micrograms, 300 micrograms or 500 micrograms aflatoxin B1/kg feed. Egg aflatoxin B1 residues were determined by thin layer chromatography; two samples per treatment per week were used for analysis. Egg production and average egg weights were not affected (p < 0.05) in the groups receiving aflatoxin B1-contaminated rations. Residues of aflatoxin B1 were detected only in the eggs of hens given 500 micrograms/kg feed, at levels that ranged from 0.05 to 0.16 microgram/kg (average: 0.10 microgram/kg). The results indicate that the feed to eggs aflatoxin B1 transmission ratio was approximately 5000:1, emphasizing the importance of controlling aflatoxin levels in rations for laying hens.

-The aim of this work was to evaluate the association between milk flow, teat morphological measurements and subclinical mastitis prevalence in Gir cows. Eighty cows in the 2 nd and 3 rd lactations, with 90 to 200 days of lactation, were divided according to milk flow during milking into fast or slow groups. Teat morphometry was assessed by ultrasound scanning of the right anterior teat and external measurements. Milk samples were collected for somatic cells count (SCC) and microbiological culture. The effect of milk flow during milking was evaluated by analysis of variance of milk yield, SCC, morphometry and external measurements. The association of morphometry and external measurements of the teats with the SCC and microorganisms found in milk were analysed. Milk flow was significantly correlated to milk production. Gir cows with slower milk flow had longer teat canal and greater milk yield, in comparison to cows with fast milk flow. Teat-end to floor distance influenced SCC of Gir cows. Prevalence of subclinical mastitis and the type of mastitis-causing pathogens were not affected by milk flow during milking.Index terms: Gir, lactation, mammary gland, milking, morphology. Fluxo de leite, morfometria de tetos e a prevalência de mastite subclínica em vacas GirResumo -O objetivo deste trabalho foi avaliar a associação entre o fluxo de leite, a morfometria dos tetos e a prevalência de mastite subclínica em vacas Gir. Oitenta vacas em 2 a ou 3 a lactação, com 90 a 200 dias de lactação, foram divididas, de acordo com o fluxo de leite durante a ordenha, nos grupos rápido ou lento. A morfometria de tetos foi avaliada por imagens de ultrassom do teto anterior direito e medidas externas dos tetos. Amostras de leite foram coletadas para a contagem de células somáticas (SCC) e a cultura microbiológica. O efeito do fluxo de leite durante a ordenha foi avaliado pela análise de variância de produção de leite, SCC, morfometria e medidas externas dos tetos. Foi analizada a associação entre a morfometria e medidas externas dos tetos e a SCC e microganismos encontrados no leite. O fluxo de leite foi significativamente correlacionado à produção de leite. As vacas Gir com fluxo de leite mais lento tinham maior comprimento de canal dos tetos e maior produção de leite, em comparação a vacas de fluxo rápido. A distância do teto ao solo influenciou a SCC das vacas Gir. A prevalência de mastite subclínica e o tipo de microrganismo causador de mastite não foram alterados pelo fluxo de leite durante a ordenha.Termos para indexação: Gir, lactação, glândula mamária, ordenha, morfologia.

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The aim of this study was to estimate the concentration of milk true protein (TP) by mid-infrared absorbance method (MIR) in samples from bulk tank of dairy herds, and to determine the correlation between the results ofThe reference methodology for crude protein determination in milk is the Kjeldahl method, which measures the total nitrogen (TN) content in milk. By this method, the nitrogen released from protein and other components is converted to ammonia nitrogen by acid digestion. Once quantified the TN amount, milk concentration of crude protein (CP) is obtained by multiplying TN by 6.38 (TOUFEILI, 2007). Thus, the CP content determined by this method refers to nitrogen arising from TP and other sources of nonprotein N (NPN) in milk. Since about 95-97% of CP is TP, the difference is represented by non-protein components such as ammonia, urea, creatine, creatinine, uric acid, orotic, hippuric, amino acids and other nitrogen compounds (FOX;MCSWEENEY, 2003). The concentration of milk casein comprises about 75-85% of CP and 85-95% of TP, while the whey proteins consist of 10-15% of TP (ROUCH et al., 2006).