Effect of Parity on Milk Yield and Calving Interval of Thrabam Cattle at Nucleus Herd, Tashiyangphu, Bhutan

Abstract

A study was carried out to understand the productive and reproductive performances in local Nublang/Thrabam cattle managed at the nucleus herd, Tashiyangphu, Bhutan. Data on performances were accessed and analyzed from 3794 individual animal records maintained at the farm for 21 years [1997 to 2018]. The record covered 1st to 8th parity for individual animals. The nucleus herd had a fair balance of young and old stock for regular replacement. Overall average daily milk yield of local Thrabam cows [all parity] was 3.54±0.23 kg [n=436] and take-home milk was 2.04±0.23 kg day-1 , excluding 1.5 kg day-1 estimated to be spared to suckling calves. The average daily milk yield increased from 3.11 kg day-1 in first parity to 3.78 kg day-1 in fourth parity. Similarly, the average lactation milk yield increased from 708±215 kg in first parity to 889±190 kg in fourth parity. Lactation yield in fourth parity was significantly higher than yields in all other parity. The average lactation length was 230.9±5.4 days [7.7 months], which had little or no improvement with advancing parity. Notably, calving interval had decreased from 16.1±3.6 months [n=173] in 1st/2nd parity to 12.1±1.1 months in 7th/8th parity [n=165], indicating improvement in reproductive efficiency of the nucleus herd. The study concluded that the highest milk yield [daily and lactation yield] of Thrabam cattle is in fourth parity with no drastic decline till seventh parity, suggesting that cows fit for breeding can be retained in the nucleus herd beyond seventh parity based on their productivity. Further, Thrabam being draught purpose breed with short lactation length and low milk yield, it is unlikely to compete in milk production with recognized dairy breeds even if they are rigorously selected. Hence, apart from improvement in milk production, traits for diseases resistance, adaptability/ foraging ability] need to be given equal weightage while selecting this cattle breed.