Management protocol for averting drop of milk production in dairy cattle during summer

Abstract

A study was conducted to assess the effect of feeding management on milk production and metabolic profile of crossbred cows in mid lactation. Twelve healthy crossbred cows having a peak yield of minimum eight litres in the previous lactation, were selected as the experimental animals. The animals were divided into two groups of six each as uniformly as possible with regard to age, milk yield and parity and were randomly allotted to two dietary treatments, T1 consisting of basal concentrate mixture and green grass as roughages and T2 consisting basal concentrate mixture, green grass as roughage of which 1/3rd of the concentrate and roughage is fed during the day time and rest in the evening and early morning with water availability at all times. Daily maximum temperature, minimum temperature and relative humidity were recorded inside the shed using maximum and minimum thermometer to quantify the microenvironment prevalent around the animals in both the treatment groups. Physiological parameters like respiration rate and rectal temperature were measured to give an immediate response to the climatic stress and consequently the level of comfort to the animal. Individual records of daily intakes of concentrate and roughage, daily milk production and fortnightly body weight were maintained through out the experiment. Milk samples were collected at fortnightly intervals and were analysed for milk fat, total solids and solids not fat. Blood was collected at fortnight intervals for estimating haemoglobin, erythrocyte sedimentation rate, packed cell volume, plasma glucose and cortisol.

The ambient temperature prevailed during the study period was higher than what was reported as comfortable or ideal temperature for better livestock production and the excess humidity and temperature levels recorded in the present study at Mannuthy could be classified as humid and hot.

The average rectal temperature during morning and afternoon between T1 and T2 did not differ significantly. The mean values clearly indicated that high ambient temperature increased the respiratory rate in the afternoon. The respiration rate for morning and afternoon recording was not found to be differed between T1 and T2. Average body weight of animals revealed no significant difference for the both groups during all the fortnight studied. The average daily dry matter intake linearly increased as the lactation progressed in both the groups. Dry matter intake by the animals of T2 was comparatively better than the animals of T1 with a significant increase (P<0.05) during the fourth and seventh fortnight. Scrutiny of the data on milk production during first 120 days of lactation further revealed that comparatively higher milk yield and better persistency was observed in T2. There was no significant difference in any of the milk composition parameters between the treatments. The haematological parameters such as haemoglobin, packed cell volume, erythrocyte sedimentation rate and plasma glucose estimated at the fortnight intervals were not significantly affected by the two dietary treatments. On statistical analysis a significant difference (P< 0.05) in plasma cortisol was obtained between the two groups during the first and second fortnights. The overall average plasma cortisol level was significantly higher in the T1 in comparison to T2.

From the overall results obtained in the present study it could be concluded that the night time feeding of the animals during summer season has improved total milk production and helped to maintain the higher milk yield as well as persistency of milk production in lactating crossbred cows and found that there was some long-term effect on performance of evening fed cows.