Effect of Varying Dietary Rumen Undegraded Protein on Nutrient Intake, Nutrient Digestibility and Production Performance in Early Lactating Crossbred Cows

Abstract

The rumen bypass protein has extensively been used in ruminant's diets to enhance their productivity. The objective of this study was to determine the effect of varying levels of dietary rumen undegraded protein (RUP) on nutrient intake and digestibility, milk yield and composition in early lactating crossbred cows. Twenty four early lactating crossbred cows of same parity and similar milk production were divided into 4 groups (6 cows per group). Four iso-caloric and iso-nitrogenous diets were formulated using NRC standards for energy and protein. The rations were formulated to contain 30, 40, 50 and 60% RUP levels. Data regarding nutrient intake, nutrient digestibility, N balance, blood chemistry, milk yield and its composition were collected. The dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) intakes increased (p<0.05) at higher dietary RUP; however, crude protein (CP) intake remained similar. The DM, CP, NDF and ADF digestibility did not alter at lower RUP level (30 and 40%) but at higher dietary RUP level (50 and 60%) digestibility numerically decreased (p>0.05). The nitrogen balance was negative in cows fed RUP30 and RUP40 diets but it was positive in cows fed RUP50 and RUP60 diets. The blood pH and blood glucose and differential leukocyte count resulted in similar (p>0.05) values across all dietary treatments. The blood urea nitrogen, milk urea nitrogen and blood creatinine decreased (p<0.05) at higher dietary RUP level. The milk yield increased (p<0.05) as the level of dietary RUP increased. Milk composition (milk protein, milk lactose, solid not fat and totals solids) remained similar across all dietary treatments. However, milk fat content increased (p>0.05) with increasing level of dietary RUP. In conclusion, the nutrient intake, milk production and milk fat increased by increasing the dietary RUP level. But nutrient digestibility decreased at higher rumen un-degradability of protein.

Effects of rumen-degradable-to-undegradable protein ratio in ruminant diet on in vitro digestibility, rumen fermentation, and microbial protein synthesis

“…Microbial protein synthesis occurs due to the synchronization of protein feed sources and energy sources [21], which must be easily degradable. An increase in RDP can maximize microbial protein synthesis, but an increase in the dietary RUP level reduces microbial protein synthesis, which results in decreased digestibility [19,20]. In this study, increased proteins and RDP levels increased microbial protein synthesis, because of the availability of nitrogen from NH 3 and C from total VFA.…”

“…The previous studies have also reported that feed with high RUP levels decrease NH3 and reduces digestibility [7,20].…”

The Influence of Hempseed Cake on Production Traits, Metabolic Profile and Antioxidant Status of Merinolandschaf Lambs

“…The research by Mustafa et al (1999) showed that hempseed meal was an excellent natural source of rumen undegraded crude protein (774.2 g/kg of crude protein). The research by Akhtar et al (2017) showed the effect of varying levels of RUP in diet of early lactating cows and determined decreased (p<0.05) blood urea nitrogen at higher dietary RUP level. Hempseed cake in lambs´ diets did not influence activity of the enzymes, like AST, ALT, ALP, GGT and CK, as well as SOD and GPx enzymes, thus not affecting the antioxidant status of lambs´ blood, in comparison with SB group.…”

Nutrient digestibility, characteristics of rumen fermentation, and microbial protein synthesis from Pesisir cattle diet containing non-fiber carbohydrate to rumen degradable protein ratio and sulfur supplement

“…High rumen microbial activity increases nutrient digestibility due to increased RDP [20]. Increasing RUP content can reduce rumen microbial activity due to the low N supply for rumen MPS, thereby reducing digestibility [13,21,22]. Proteins degraded in the rumen (RDP) are converted into NH 3 , which is later used for MPS.…”