The Effect of Protein Intake on Performance of Cows in Hot Environmental Temperatures

Abstract

Two trials were conducted with cows in commercial herds during midlactation to evaluate the effect of dietary crude protein (CP) concentration on the production, composition, and efficiency of milk production under hot ambient conditions. Cows were group-fed in trial 1, which was conducted in two herds, and were fed individually in trial 2. The respective average ambient temperature, relative humidity, and temperature-humidity index (THI) were 31 degrees C, 45%, and 78 in trial 1 and 27 degrees C, 70%, and 76 in trial 2. Cows were cooled by forced evaporative means six times daily in trial 1 and three times daily in trial 2. Dietary CP was 15.3 or 17.3% of dry matter (DM) in trial 1 and 15.1 or 16.7% of DM in trial 2. The respective ratios of rumen-degradable organic matter (RDOM) to rumen-degradable protein were 5.3 and 4.8 for the low CP (LP) and high CP (HP) diets. Average DM intake, milk yield, and milk fat and protein concentrations were 22 and 23 kg/d, 34 and 35 kg/d, 3.1 and 3.4%, and 3.2 and 3.1% in trials 1 and 2, respectively, and were similar among diets in both trials. The resultant calculated milk protein efficiency ratio and overall CP efficiency were 0.31 and 0.32 for the LP diets and 0.28 and 0.29 for the HP diets. In cows fed the LP diet, diet rumen ammonia was lower in trial 1, and milk urea N was lower in trial 2. The BW change was higher in trial 1, and tended to be higher in trial 2, with the LP diets. Changes in body condition score in trials 1 and 2 tended to be higher with the LP diets. It was concluded that a dietary CP content of 15.3% is adequate to maintain production in heat-exposed dairy cows producing 35 kg of milk/d, provided that the forced evaporative cooling and the ratio of RDOM to rumen-degradable protein is appropriate

Nutritional Strategies to Alleviate Heat Stress in Dairy Animals - A Review

“…The oversupply of rumen degradable protein will lead to its inefficient use in the rumen which in turn will require the animal to expend energy to convert this wasted protein (as nitrogen) to urea which will largely be excreted in the urine. The negative effect of increased dietary protein agrees with recent recommendations which suggest that addition of dietary crude protein is not helpful during heat stress (Arieli et al, 2006). How heat stress affects dietary protein requirements is not well defined and more research is needed in order to generate more appropriate recommendations.…”

The effects of sprinkler+fan, fish meal or dietary fat on milk yield and milk composition of dairy cows in mid lactation during summer

“…Furthermore, all diets used in the present studies were formulated with higher CP content than the requirements of the cows in mid lactation to alleviate the potential decrease in DMI during heat stress (Hassan and Roussel, 1975). However, Arieli et al (2004) reported that there is no obvious reason to increase the dietary crude protein and rumen undegradable protein concentration under heat stress conditions. The limited and/or no improvement in milk yield and milk nitrogen fractions with FM in the present study might have been resulted from enough supply of essential amino acids by all diets.…”

Effects of feeding different dietary protein and energy levels on the performance of 12–15-month-old buffalo calves

“…Nevertheless, an adequate NSC/RDP ratio increased the efficiency of fermentation in dairy heifers (Casper et al 1994). Arieli et al (2004) investigated the effect of varying levels of protein intake on performance of cows in hot environmental temperatures and reported that CP digestibility was increased from 64.4% to 66.2% when dietary CP level was increased from 15% to 17%. In current study, CP digestibility remained unchanged, but digestible CP intake was significant due to increased CP content of the diets.…”