SUMMARY In dairy farm animals, one the most important goal of the selection is the improvement of milk yield and composition. Several studies have demonstrated that the candidate genes of the kappa-casein (CSN3) and β - lactoglobulin (β-LG) are associated with milk yield, milk quality and health traits in dairy animals. Therefore the aim of this study was to detect polymorphisms in CSN3 and β-LG genes and its association with milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY in Girolando cattle. Totally, 138 bulls and 729 cows (n=867) were sampled. The genotypes of both genes were obtained by the PCR-RFLP method using HinfI and HaeIII enzymes for CSN3 and β-LG genes, respectively. Statistical results revealed two alleles A and B for both genes. The genotypes and alleles more frequents for CSN3 and β-LG genes were respectively: AA (0.7324) and A (0.8558), and AB (0.4827) and A (0.5017). The x2 test revealed that the two loci were at Hardy-Weinberg equilibrium (p<0.001). The allele substitution effects for the variants were not significant on 305MY and PTA for 305MY (p>0.05). The allele variants of β-LG and CSN3 might be more investigated before include them into future breeding schemes designed for Girolando dairy cattle with objective of improving milk traits as milk yield in up to 305 days (305MY) and predicted transmission capacity (PTA) for 305MY..

RESUMONa produção animal, é de fundamental importância o uso racional da água de boa qualidade. A água deve ser considerada como um nutriente essencial e quando a qualidade utilizada na dessedentação animal for duvidosa, esta pode interferir nos índices zootécnicos e na disseminação de enfermidades, acarretando graves prejuízos econômicos. Objetivou-se com esta pesquisa diagnosticar a qualidade da água que é ofertada para dessedentação dos bovinos de leite da Fazenda-escola do IFRN, campus Ipanguaçu. As coletas e análises foram realizadas quinzenalmente nos bebedouros dos bovinos (no total, seis bebedouros) durante os meses de Junho à Setembro de 2015. Os parâmetros analisados foram: temperatura, pH, condutividade, oxigênio dissolvido e sólidos totais dissolvidos; utilizando uma sonda multiparamétrica de qualidade de água. Os dados obtidos revelaram que os parâmetros, exceto sólidos totais dissolvidos, encontraram-se nos limites aceitáveis pela resolução CONAMA 357/2005, com alguns bebedouros apresentando resultados não aceitáveis. Contudo, é preciso ainda um manejo adequado da água (com renovação constante) e bebedouros que estejam dispostos não apenas em locais de fácil acesso aos animais, mas que também possam estar em locais cobertos ou arejados por copa de árvores. PALAVRAS-CHAVE:Nutrição animal, produção animal, índices zootécnicos. WATERING WATER QUALITY BOVINE IN SCHOOL-FARM AT IFRN-IPANGUAÇU ABSTRACTIn animal production, it is of fundamental importance the rational use of good quality water. Water should be considered as an essential nutrient and when the quality used in animal consumption is doubtful, this can interfere with the performance parameters and the spread of diseases, causing serious economic losses. The objective of this research to diagnose the quality of water that is supplied to the watering water quality bovine in schoolfarm at IFRN-Ipanguaçu. Sampling and analyzes were carried out fortnightly in the water drinker of bovine (a total of six drinking fountains) during the months of June to September 2015. The parameters analyzed were: temperature, pH, conductivity, dissolved oxygen and total dissolved solids; using a multi-parameter explorer water quality. The data revealed that the parameters except total dissolved solids, met the limits acceptable by Resolution CONAMA 357/2005, with occasional drinkers presenting unacceptable results. However, it is also necessary to a proper water management (with constant renewal) and drinkers who are willing not only in readily accessible to animals, but they can also be in local or airy covered by tree canopy.