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Impact of Heat Stress on Milk Yield and Composition in Early Lactation of Holstein FRIesian Crossbred Cattle

T Chanda
Associate Professor
Patuakhali Science and Technology University (PSTU)

G K Debnath*
Professor
Chittagong Veterinary and Animal Sciences University (CVASU)

K I Khan
Professor
Chittagong Veterinary and Animal Sciences University (CVASU)

M M Rahman
Professor
Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh

G C Chanda
Professor
Chittagong Veterinary and Animal Sciences University (CVASU)

Abstract/ Executive Summary:

The aim of the study was to know the effect of heat stress on milk yield and its composition of Holstein Friesian crossbred dairy cows rearing under intensive management system.Heat stress in dairy cows is caused by a combination of environmental factors i.e. temperature, relative humidity, solar radiation and air movement, etc. Grading-up of local cattle by temperate breeds for greater performance results to increase the sensitivity to heat stress. The trial was conducted during hot (May-July) and cool period (December-February) on a total of 12 crossbred dairy cows in early lactation period (first 60 days of lactation). The selected cows were divided into two groups namely as G1 (Holstein-Friesian 50% × Local 50%) and G2 (Holstein-Friesian 75% × Local 25%) and each group containing three cows of 3rd lactation in both periods of trail. Cows of each group were offered same quality and quantity of feed and reared in same management condition in both the trail periods. The mean average temperature humidity index (THI) of the stanchion barn were 70.83± 0.535 and 83.87± 0.375 in cool and hot period, respectively. The differences of THI of cool and hot season was significant (p<0.05). The average rectal temperature (0F) of G1 group was 101.51± 0.027and 102.15±0.049 in cool and hot period, respectively. On the other hand, the average rectal temperature (0F) of G2 group was 101.68± 0.035 and 102.5±0.052 in cool and hot period, respectively. The differences of rectal temperature of both groups between cool and hot season were significant (p<0.05). The average milk yield (Liter/day) of both groups was significantly (p<0.05) higher in cool period (14.92±0.019 and 19.54± 0.116 for G1 and G2 group, respectively) than in hot period (12.84±0.152 and 15±0.137 for G1 and G2 group, respectively). The milk yield of G2 group hampered more compare to G1 group due to higher THI during hot season. The milk fat, protein and lactose of both groups were significantly higher (p<0.05) during lower THI period compare to higher THI period, while the higher values of minerals detected in higher THI period but the differences were not statistically significant (p<0.05). From the result it is evident that the milk yield and composition are greatly affected by the heat stress during early lactation period.

Keywords: Heat, Stress, Milk yield, Composition, Crossbred

Location: Liza Dairy Farm in Chittagong, Bangladesh

Start Date: 00-12-2013

End Date: 00-07-2014

Program Area: Risk Management in Agriculture

Commodity: Milk

Objectives:

The present study was undertaken to know the effect of heat stress on milk yield and gross composition of common Holstein Friesian crossbred cows during early lactation.

Methodology:

The trial was conducted during cool (December/2013- February/2014) and hot period (May/2014-July/2014), at Liza Dairy Farm in Chittagong, Bangladesh on a total of 12 crossbred dairy cows of Holstein-Friesian(H) 50% × Local(L) 50% and H 75% × L 25% in early lactation period (first 60 days of lactation). The genetic composition, number of lactation, milk yield records in previous lactation and month of calving were the main criterion to select dairy cows. The selected cows were divided into two groups as G1 (H 50%× L 50%) and G2 (H 75% × L 25%) and each group containing three cows of 3rd lactation in each period of trail. Cows were milked two times daily by hand milking (morning and evening) and recorded every day in the course of trial period in both seasons. The nutritional compositions of feedstuffs were analyzed in Poultry Research and Training Centre at Chittagong Veterinary and Animal Sciences University (CVASU). A ration was formulated as per ARC (1990) for each group of cows and offered in both period of trail. Cows were fed two times a day with mixed concentrate rations and four times green grass and rice straw manually. Milking was carried out twice (morning and evening) daily throughout the study period. Both groups of cows were kept in a same stanchion barn. The milk samples were taken for chemical analysis two times daily after milking using dipper and plunger for proper mixing, and chemical composition of milk was determined by using Lactostar (Model No.3510, Funke Gerber, Germany) in Dairy Science Laboratory, CVASU. The meteorological data were recorded three times daily (8.00 am, 1.00 pm and 5.00 pm) by (Model PH1000, Zeal, England) and daily average values used for calculating the THI. The digital thermo-hygrometers were placed inside the barn at the altitude equal to animal height. The THI was calculated by applying the following formula of Maderet al. (2006):
THI = 0.8 × ta + RH /100× (ta − 14.3) + 46.3
Where, THI is the temperature humidity index, ta is the ambient temperature in °C and RH is the relative humidity (%). The rectal temperature of each cow in both groups were recorded daily by clinical thermometer in the afternoon. The mean with standard error of each parameter (THI, rectal temperature, milk yield and milk composition) were analyzed by PROC GLM and PROC MIXED of SAS (2000). The general linear model for this analysis was as:
Yijk = µ+ Bi + Sj + eijk
where,
Yijk = Parameter value
µ= Overall mean
Bi = Effect of ith genotype {i=1(G1) and 2 (G2)}
Sj= Effect of jth season {j=1 (hot) and 2 (cool)}
eijk= Error term, distributed as N (0,σ2)

Source of Information: Bang. J. Anim. Sci. 2017. 46 (3): 192-197

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Milk production of cows is influenced by environmental factors, especially high temperature and humidity during summer. The milk composition especially fat and protein are significantly affected in the period of hot environment. Since, high yielding cattle like Holstein-Friesian and Jersey are included in national cattle breeding policy of Bangladesh, the level of crossing with local cattle has been increasing day by day those progeny are very sensitive to heat stress. Only an intensive management can reduce the influence of heat stress on the quantity of milk production and profitability.

Knowledge Management: Journal