Abstract
Four early lactating Holstein cows were used to study the effect of live yeast (LY, Actisaf® CNCM I-4407, Lesaffre Feed Additives, Marcq en Baroeul, France) supplementation on diet digestive utilization of dairy cows receiving concentrated corn silage-based diets with two rumen-degradable protein (RDP) levels. For a 33 d period, cows were fed a total mixed ration (TMR) containing an adequate level (AL) of RDP or a low level (LL, 30% below AL) by using soybean meal or tanned soybean meal, respectively: for 21 d with no LY addition followed by 12 d during which LY was added to the diet. The pH and redox potential (Eh) were recorded and ruminal fluid samples were collected over 3 consecutive days. Feces were collected individually over 48 h and individual dry matter intake (DMI) was measured for determining apparent nutrient digestibility. The effective degradability of individual feed ingredients composing both diets was evaluated with nylon bags technique. Structure of the ruminal bacterial community was studied and diversity index was calculated. Digestibility of organic matter (OM) and crude protein (CP) were lower for LL than those for AL. With LY, digestibility of OM and CP was increased: +2.4 and +0.8 points, for AL, and +3.7 and +5.9 points for LL, respectively. Live yeast reduced dietary N ruminal degradation with both AL and LL. Ruminal pH and Eh were lower with AL compared to LL: 5.95 and –167 mV vs. 6.13 and –144 mV. Live yeast increased ruminal total volatile fatty acids (VFA) (+8.6%), C2 (+10%), and C4 (+35%) contents for LL and decreased that of C3 (?9.8%) for AL. Neither the structure of bacterial populations of the rumen nor the diversity index (Shannon) was altered by treatments. Those results suggested a specific interest in using LY in RDP deficient diets for early lactating cows.
Highlights
Lactation high-producing dairy cow nutrition strategies aim at providing adequate energy and rumen undegraded protein (RUP) to support high requirements regarding milk production increase and because, most of the time, cows are in negative energy balance
Ruminal pH, Eh and rH were significantly lower for HL compared to values recorded for LL: on average 5.95, −167 mV and 6.35 vs. 6.13, −144 mV and 7.47, respectively (Table 2)
Our results showed that dry matter intake (DMI) was not significantly affected by the rumen degradable protein (RDP) level
Summary
Lactation high-producing dairy cow nutrition strategies aim at providing adequate energy and rumen undegraded protein (RUP) to support high requirements regarding milk production increase and because, most of the time, cows are in negative energy balance. On one hand, absorbed protein requirements implied that more dietary protein escapes rumen degradation with the risk that ruminal ammonia concentration is insufficient to support rumen microbial crude protein (CP) production. This can cause a depression in fiber degradation, and reduce dry matter intake (DMI) and energy supply to the animal. An imbalance in NSC and rumen degradable protein (RDP) may be responsible for uncoupled fermentation and consequent reduction in ruminal microbial growth and/or activity During this critical period, many alternatives have been evaluated to improve digestive processes in the rumen and increase feed efficiency
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
