Influence of Protein Percentage and Degradability on Performance of Lactating Cows During Moderate Temperature

Abstract

Sixty high producing Holstein cows (15/treatment) averaging 157 d postpartum were offered the following diets: high protein (18.5%), high rumen degradability (60%); high protein (18.0%), medium degradability (41%); medium protein (15.4%), high degradability (61%); medium protein (15.0%), medium degradability (46%). All diets contained 32% corn silage, 15% alfalfa haylage, and 10% whole cottonseed. Degradabilities were determined by the ficin method and were lowered by replacing soybean meal with meat and bone meal and brewers dried grains. Cows were milked three times daily and the study was conducted from May 11 to June 23 in Provo, UT during ascending day temperatures but cool nights. Milk yields were not different for the respective treatments (36.9, 35.4, 34.8, and 36.7 kg/d), but milk fat was higher at high protein degradability: 3.11, 2.89, 3.04, 2.78%, respectively, resulting in a tendency toward higher FCM. Lower acetate and propionate and acetate:propionate ratios were observed for medium degradability diets and were consistent with lower milk fat. Rumen NH3, butyrate, valerate, isovalerate, 2-methyl butyrate, and blood urea N were higher for cows on high protein diets but were not affected by degradability. Serum glucose and cortisol were not significantly affected by protein treatment, but serum triiodothyronine was lower on high protein; the interaction effect for thyroxine was significant.

Effects of ratios of non-fibre carbohydrates to rumen degradable protein in diets of Holstein cows: 1. Feed intake, digestibility and milk production

“…Also, as the study was conducted in hot ambient temperature (ranging from 28 to 36 ºC) and cows were subjected to moderate to severe heat stress. A reduction of DMI might have been the result of a higher amount of RDP (Higginbotham et al, 1989;Huber et al, 1994). Because of a similar percentage of OM between treatments (Table 1), intake of OM followed the same pattern as DMI.…”

Effect of varying ruminally degradable to ruminally undegradable protein ratio on nutrient intake, digestibility and N metabolism in Nili Ravi buffalo calves (Bubalus bubalis)

“…Similar findings were reported by Chumpawadee et al (2006) and Vongsamphan and Wandapat (2004). Higginbotham et al (1989) found an increase of 2.6 mg/dL in BUN in cows fed isonitrogenous and isocaloric diets by increasing RDP (0.2 kg/d) from 58 to 65% of dietary CP.…”

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

“…Although milk protein concentration was not reported in that trial, in light of the difference of 62% in CP intake between groups, it is very likely that the increase in milk yield was associated with a concomitant reduction in milk protein production efficiency. Higginbotham et al (1989a) investigated the effect of CP level (18% vs. 15%) on milk yield of cows during mid lactation; the cows were maintained under mild heat conditions (daily maximum = 27°C). Milk yield was not affected by percentage of dietary protein, but milk protein efficiency was higher for the low protein diet.…”