Effect of THI on Milk Production in Dairy Animals
Vasantha S.K.I1
1Assistant Professor, Department of Veterinary Physiology, NTR College of Veterinary Science, Gannavaram, A.P
Abstract :
Thermal stress is of concern for all livestock production systems and its effects have been studied because of the negative impact on production, health and even mortality. Exposure to high ambient temperature is the major constraint on productivity in hot climatic areas. This article focuses on the effect of temperature and humidity on milk productivity and relates how animal stress affects the productivity of dairy animals. By regularly monitoring the temperature and humidity of the farm particularly during summer season, the farmer can himself make necessary microclimatic alterations depending on the THI range and thereby protect the animals from the adverse effects of heat stress and maintain optimum productivity without incurring any economic loss.
Key words: Thermal stress, season, temperature, Humidity, microclimatic, productivity.
Introduction:
It has been documented that India loses 3.2 million tonnes of milk production at present due to climatic stresses. Buffalo population in India comprises of 109 million which significantly contribute to Indian GDP with 49% of India’s milk production. Although buffaloes have not been considered as seasonal breeders but they do show seasonality in breeding and calving, which reduced milk production ultimately in summer (Himadri, 2007). Milk production is affected by a number of factors like genetic potentiality, age, number of previous lactations, pregnancy, season of calving, calving interval and nutrition status (Bernabucci et al., 2002). Among all the factors, the season of calving is said to have marked effect on total production (Pawar et al., 2012). The increase in environmental temperature decreases the milk production in Murrah buffaloes during summer (Vasantha et al., 2021). High heat load in lactating buffaloes reduced milk production and has shortened duration of lactation periods (Upadhyay et al., 2007).
Temperature humidity Index (THI) a proven marker of heat stress:
Heat load and intensity of heat stress can be measured by simple indices such as THI. Temperature is not the only factor of environment that markedly affects the intensity of heat stress. The temperature humidity index (THI) measures the combined effects of ambient temperature (AT) and relative humidity (RH) to ascertain the intensity of heat load. The THI is considered to be the best, simplest and most practical index to measure the intensity of heat stress in dairy animals (Grewal et al., 2019). THI not only measures heat stress but also determines the impact of heat stress on animal productivity. THI is negatively correlated with milk production and reproductive traits in animals. Milk production was not affected when THI values are between 35 and 72, while a rise in THI from 72 to 76 resulted in sharp decline in milk production (Johnson, 1963).
Mechanism of THI effect on milk production:
In a work done by Vasantha et al., (2021) the increase in environmental temperature during summer significantly reduced the milk production in Murrah buffaloes of hot and humid tropics of Andhra Pradesh. Decline in milk yield as a direct result of effect of high environmental temperatures was also reported by Marai et al., (2009). Lactating buffaloes under heat stress have increased reliance on glucose as a fuel source. Heat-stressed buffaloes seem to change their metabolism to preserve glucose for extra-mammary tissues, at the expense of milk lactose synthesis. Despite having much greater energy content, oxidizing fatty acids generates more metabolic heat (~2 kcal/g or 13 % on an energetic basis) compared to glucose. Heat stressed animal become hypersensitive to insulin, and will reduce or block adipose mobilisation and increase glucose ‘burning’ in an attempt to minimise metabolic heat production. This diverts glucose from mammary tissue to other body tissues and reduces glucose supply to the mammary gland for lactose production leading to reduced milk yield. This may be the primary mechanism for reduction in milk yield during summer (Baumgard et al., 2006).
Conclusion:
The effect of environment on the health and productivity of the animals is well evidenced in different species of animals. The mean THI was recorded >80 units that significantly affected the milk production of buffaloes in the reports of Vasantha et al., (2021). It is therefore advisable for the farmers to monitor the temperature and humidity of the farm during summer both in the morning and afternoon by installing a hygrometer. Accordingly necessary microclimatic alterations to mitigate the effects of the higher THI for optimum production and reproduction can be undertaken. Hence, nutritional and summer managemental strategies as published in (https://www.pashudhanpraharee.com/impact-of-heat-stress-on-buffaloes-health-and-production-management-strategies-and-tips-for-farmers-to-optimize-milk-production/) need to be adopted to ameliorate additive effects of summer stress for optimum production and well being of dairy animals.
References :
- Johnson, H. D., Ragsdale, A. C., Berry, I. L., and Shanklin, M. D. 1963. Temperature-humidity effects including influence of acclimation in feed and water consumption of Holstein cattle. Univ. of Missouri Res. Bull (846).
- Himadri, P. 2007. Heat shock protein (s) and lymphocyte response in heat stressed buffaloes Ph.D. Thesis, ICAR-National Dairy Research Institute, Karnal, Haryana.
- Upadhyay, R. C., Singh, S. V., Kumar, A., Gupta,S.K., and Ashutosh. 2007. Impact of climate change on milk production of Murrah buffaloes. Italian Journal of Animal Science 6(2): 1329-1332.
- Vasantha, S. K. I., Ch. Srinivasa Prasad, B. Rambabu Naik, K. Aswani Kumar, Ch. Venkata Seshaiah and Nikhil Kumar Tej, J. 2021. Effect of season on milk production in Murrah Buffaloes: THI a proven marker. J.Curr.Microbiol.App.Sci. 10(04): 252-256.
doi: https://doi.org/10.20546/ijcmas.2021.1004.025
- Grewal, S., Aggarwal, A., and Alhussien, M. N. 2019. Seasonal alterations in the expression of inflammatory cytokines and cortisol concentrations in periparturient Sahiwal cows. Biological Rhythm Research 1-11. DOI: 10.1080/09291016.2019.1670971.
- Marai, I,, Daader, A., Soliman, A., and El-Menshawy, S. 2009. Non-genetic factors affecting growth and reproduction traits of buffaloes under dry management housing (in sub- tropical environment) in Egypt Livestock Research and Rural Development 4(4): 6.
- Pawar, H. N., Kumar, G. R., and Narang, R. 2012. Effect of year, season and parity on milk production traits in Murrah buffaloes. Journal of Buffalo Science 1(1): 122-125.
- Bernabucci, U., Ronchi, B., Lacetera, N., and Nardone. A. 2002. Markers of oxidative status in plasma and erythrocytes of transition dairy cows during hot season. Journal of Dairy Science 85(9): 2173-2179.
- Baumgard, L. H., Wheelock, B., Shwartz, G., Brien, M. O., Van Baale, M. J., Collier, R. J., Rhoads, M. L., and Rhoads, R. P. 2006. Effects of Heat Stress on Nutritional Requirements of Lactating Dairy Cattle. Proceedings of the 5th Annual Arizona Dairy Production Conference: 8-17.
