Climatic conditions, twining and frequency of milking as factors affecting the risk of fetal losses in high-yielding Holstein cows in a hot environment.

An epidemiological study of risk factors for fetal losses was carried out on 62,403 high-yielding Holstein cows in 29 large highly technified dairy herds in northern Mexico (25° N; 23.5 °C mean annual temperature). Multivariate multiple-group response model indicated that fetal losses between 43 and 260 days of pregnancy were 23 %. Heat-stressed cows at conception (temperature-humidity index, THI >82) were 14 times more likely (P < 0.01) to present fetal losses than not heat-stressed cows (27 vs. 18 %). Heat-stressed cows at 60 days of pregnancy (THI >82) were 4.5 times more likely (P < 0.01) to present fetal losses than cows suffering heat stress in early gestation (29.1 vs. 17.7 %). The proportion of cows experiencing fetal loss was lower for multiparous than primiparous cows (odds ratio; OR = 0.7). Cows with twin pregnancies had significantly increased chances of losing their fetuses than cows with a single fetus (33.6 vs. 20.7 %; P < 0.01). Cows with three milkings per day were 30 % more likely (P < 0.01) to lose their fetuses than cows milked twice daily. Cows calving in winter and spring had significantly increased chances of losing their fetuses than cows calving in summer and fall (30-35 vs. 4-5 %; P < 0.01). It was concluded that, in this particular environment, heat stress exert a great influence on fetal losses in high producing Holstein cows.

Viabilidade econômica da terceira ordenha em sistemas de produção de leite com ordenhadeira tipo circuito aberto / Economic viability of the third milking in milk production systems using open circuit type milking mechanics

Objetivou-se analisar a viabilidade econômica da terceira ordenha em sistemas de produção de leite que utilizam ordenhadeira mecânica, do tipo circuito aberto, visando fornecer aos técnicos e pecuaristas informações que os auxiliem no processo de tomada de decisões. Especificamente pretendeu-se ainda: a) estimar o custo de uma ordenha; b) estimar, por meio de simulação, o custo da terceira ordenha; c) desenvolver uma equação matemática que permita estimar a quantidade mínima de leite produzido em duas ordenhas, a partir da qual será viável economicamente a realização da terceira ordenha. Os dados foram coletados em três sistemas de produção de leite, em uma rotina de duas ordenhas diárias, sendo realizadas três coletas de dados em cada um, perfazendo um total de nove. Considerando-se os dados médios, seria viável a realização da terceira ordenha se a produtividade média diária das vacas em lactação em duas ordenhas fosse igual ou superior a 38,13kg de leite. A equação matemática desenvolvida pode auxiliar o técnico e o pecuarista a estimarem a quantidade mínima de leite produzido por uma vaca em duas ordenhas, a partir da qual será viável economicamente a realização da terceira ordenha, com precisão e considerável rapidez.

This study aims to analyze the economic viability of the third milking in milk production systems using open circuit milking mechanics, aiming to provide technicians and farmers with information to help in the decision-making process. Specifically intend to a) estimate the cost of a milking; (b) estimate, by means of simulation, the cost of the third milking; (c) develop a mathematical equation that allows estimating the minimum amount of milk produced in two milkings, from which it will be economically feasible to hold the third milking. The data were collected in three milk production systems, in a routine of two milkings per day, with three collections of data in each, a total of nine collections. Considering the average data, it would be feasible to hold the third milking if the productivity of daily average lactating cows is equal or greater than 38.13 kg of milk. The mathematical equation developed may help the technician and the farmer to estimate the minimum quantity of milk produced by a cow in two milkings, from which it will be economically feasible to hold the third milking with precision and considerable speed.