Can activity meters be used as heat detectors for water buffaloes in hot climates?

Sammanfattning: Water buffaloes are very important dairy animals in many developing countries, for example India. One of the greatest problems with buffalo milk production is the poor reproduction efficiency. Silent heat is common among buffaloes, which means that ovulation occurs without any visual heat signs. This makes it hard to detect heat and causes economical losses for the farmers. One method used for heat detection in cattle is measurements of the physical activity. The aim with this study was to document if activity tags (measurements of the physical activity) can be useful in water buffaloes. The milk production and behaviour during heat were followed to see if deviation in those could be used for heat detection as well. Eight Murrah buffaloes were selected for the heat study. Four of them were expected to come in heat during the experimental period and four were induced to heat with hormonal treatment. The heat induced buffaloes were also followed during their next natural heat. Altogether thirteen heats were followed. In addition to this two control groups with five pregnant buffaloes and three pregnant cows were selected. All animals were equipped with activity tags (DeLaval, Sweden) during the entire study time. The animals in the control groups were not exposed to any other observations than the activity measurements. The animals were kept indoors in a lose housing system and were milked twice daily. The activity and milk yield were recorded daily by ALPRO®. The strip yield was measured with a measuring cylinder and milk samples were taken every milking to determine fat content in the strip yield. Milk samples were taken once daily to determine progesterone concentration. The fat was removed before running RIA (radioimmunoassay). Five days before expected heat and until the heat had passed the buffaloes were examined with ultra sound (7.5 Mhz) to see when ovulation occurred. At the same time the external genitalia were checked for heat signs (congestion, relaxation and swelling). The behaviour study started as well five days before expected heat with two 30-minutes observations daily (before milking in the morning and the evening). Three days before expected heat the study increased with two more observations, at 14.30 and 22.30. The ultrasound measurement together with heat signs expression in the external genitalia determined the actual heat dates. Statistical evaluations of the activity data showed that it was only possible to correctly detect one heat in one buffalo. This buffalo had a significant high activity during the heat day. The other buffaloes in the study had too many false alarms and the heat day would not have been possible to distinguish. The progesterone analysis was not useful in this study due to inefficient fat removal. A trend in decreased morning milk yield and increased evening strip yield during heat was observed. The behaviour observations showed that the buffaloes spent more time standing and less time standing eating roughage before morning milking during heat. This might be indications of restlessness and decreased appetite. There were no differences in numbers of social interactions during heat. There were no expressions of the heat signs standing when mounted by herd mates and no attempts to mount herd mates. The conclusion with this study is that the today's activity meter system is not useful for heat detection in buffaloes, but there were indications that activity meters can be useful after adjustments and further improvement.