The aim of this study was to compare the J-Synch and conventional protocols associated with estrus detection in beef heifers and to compare pregnancy rate between non-lactating cows displaying estrus or not during the J-Synch protocol. In Experiment 1, heifers were subjected to timed artificial insemination (AI) in a conventional protocol with ECP (n=147) or J-Synch protocol plus eCG (n=149). The AI occurred 12 hours after estrus expression; or 48 (Conventional protocol) and 72 hours (J-Synch protocol) after device removal for animals not displaying estrus. The J-Synch group received 10 µg of GnRH at AI. In Experiment 2, the J-Synch was performed (n=116 cows), but without eCG injection, and estrus was monitored. Pregnancy rate was not different between protocols in Experiment 1 (Conventional: 50.68%; J-Synch: 60.4%). Heifers that displayed estrus had higher pregnancy rate only in the conventional protocol. In Experiment 2, pregnancy rate was not different between cows that displayed estrus or not. Therefore, performing AI earlier according to estrus expression increases pregnancy rate in conventional protocol, however it does not increase pregnancy rate in the J-Synch protocol.Keywords: early artificial insemination; cattle; estrus behavior; GnRH-based protocol. ResumoOs objetivos desse estudo foram comparar o protocolo J-Synch e o protocolo convencional associados com detecção de estro em novilhas de corte e comparar a taxa de prenhez entre vacas não lactantes que demonstraram ou não estro após o protocolo J-Synch. No experimento 1, as novilhas foram submetidas à inseminação artificial (IA) em tempo fixo em um protocolo convencional com ECP (n=147) ou através do protocolo J-Synch com eCG (n=149). A IA ocorreu 24 horas após o estro; ou 48 (Convencional) e 72 horas (J-Synch) após a remoção do dispositivo naqueles animais que não demonstraram estro. O grupo J-Synch recebeu 10 µg de GnRH no momento da IA. No experimento 2, foi aplicado o protocolo J-Synch (n=116 vacas) sem administração de eCG e o estro foi monitorado. No Experimento 1, a taxa de prenhez não foi diferente entre os protocolos (convencional: 50,68%; J-Synch: 60,4%). Novilhas que demonstraram estro tiveram maior taxa de prenhez apenas no protocolo convencional. No Experimento 2, a taxa de prenhez não foi diferente entre as vacas que demonstraram ou não estro. Assim, antecipar o momento da IA de acordo com o estro aumenta a taxa de prenhez no protocolo convencional, contudo não aumenta a taxa de prenhez no protocolo J-Synch.Palavras-chave: antecipação da inseminação artificial; bovinos; comportamento estral; protocolos baseados em GnRH.

Animal production systems and agribusiness Full-length research article Cow's functional traits and physiological status and their relation with milk yield and milk quality in a compost bedded pack barn system ABSTRACT-We aimed to determine the relationship of milk yield, milk composition, and somatic cell score (SCS) with functional traits (lameness score, udder cleanliness score, udder depth, and teat end hyperkeratosis score) and physiological status (parity and days in milk (DIM) of cows housed in compost bedded pack barn system (CBP) using multivariate analysis. Data were collected in September and October of 2017 and evaluated using factor and cluster analysis. Four factors were formed, with the first factor showing the traits responsible for altering the lactose content in milk, the second factor comprising the effect of DIM, the third factor representing the teat end hyperkeratosis score, and the fourth factor demonstrating the udder cleanliness. The cluster analysis formed three clusters. Clusters 2 and 3 differed for protein and lactose content, SCS, parity, DIM, lameness score, and udder depth. Cluster 1 differed from the others, especially due to the high milk yield. Cow conformation traits and physiological status affected milk yield and composition in CBP. There is an association between udder depth, parity, and SCS with negative impact on lactose content. Parity is also associated with higher milk yield and teat end hyperkeratosis score. Cows with lower lameness score presented dirtier udders due to increased movements on the feed parlor and water troughs areas. Special attention to the improvement of the udder conformation traits, as well as management practices that reduce hyperkeratosis, are necessary to keep high yielding, healthy, and cows with higher longevity. The cleanliness in the feed parlor and water troughs area is very important to preserve milk quality and healthy cows.