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Forskningsartikel2011Vetenskapligt granskad

Differences of Periods of Calving on Days Open of Dairy Cows in Different Regions and Months of Thailand

Kaewlamun, Winai; Chayaratanasin, Rut; Virakul, Prachin; Ponter, Andrew A.; Humblot, Patrice; Suadsong, Siriwat; Tummaruk, Padet; Techakumphu, Mongkol


The objectives of this study were to analyze the potential impact of heat stress on reproduction in different regions of Thailand, to determine the monthly distribution of calving throughout the year and to investigate environmental sources of variation of days-open (DO) in first lactation dairy cows. Data including 13,548 lactation records were collected during 2004 to 2006. Climate data were obtained from the provincial meteorological stations and the corresponding temperature-humidity indexes were calculated. The difference between regions in THI was determined. The geographical regions studied were: Central, Eastern, Northeastern, and Northern. The distribution of calving by month was determined in the 1st to 5th lactation. The effect of month of calving (MOC) on DO was determined only in first lactation dairy cows. The fixed effects in the model included MOC, region and MOC x region. The lowest mean THI was observed in December (72) and the highest mean THI in April (80). THI differed significantly between regions (p<0.0001), and months (p<0.0001). Significant interactions between region and month (p<0.0001) were found for THI. In all regions, minimum THI values were observed in December and January and this effect was more pronounced in the Northeastern and Northern regions. The highest frequency of calving for the first lactation was observed in June (9.96%) and the lowest in February (6.63%). The highest frequencies of calving for the 2(nd) (13.1%), 3(rd) (14.1%), and 4(th) (14.66%) lactation cows were observed in September while for the 5th lactation cows was in October (14.91%). The lowest proportion of calving for 2(nd) (5.02%) and 4(th) (4.14%) lactation cows was in February, and in March for the 3(rd) (4.35%) and 5(th) (4.85%) lactation cows. The average DO in first lactation cows was 152 days. Significant effects of MOC (p<0.0001.) and region (p<0.0001.) were found on DO. February calving cows had the longest DO (219 +/- 11 days) while cows calving in October and November had a significantly shorter mean DO (133 +/- 7 days). The study indicates that the high proportion of cows calving in October and November corresponds to breeding success in the previous months of December and January, which are the coolest Months of the year. Cows which calved during hot months had a prolonged DO period of several months.


dairy cow; days open; month of calving; region; Thailand

Publicerad i

Thai Journal Of Veterinary Medicine
2011, Volym: 41, nummer: 3, sidor: 315-320