Recent results from a trial carried out by Agriculture & Agri-Food Canada have shown that application of a fiber pretreatment to dairy total mixed rations (TMRs) before feeding can significantly increase overall milk production efficiency by 11.3%.

The trial was carried out at the Lethbridge Research & Development Center in Alberta and used 60 early-lactation Holsteins fed a silage-based TMR. The cows were split into three groups and fed either the control TMR with no pretreatment or the TMR following application of 0.5 mL or 1.0 mL/kg dry matter of a Trichoderma reesei-derived fungal extract applied before feeding.

“The pretreatment acts to roughen and create pits in the surface of the fiber in the ration and so increase both the rate and extent of bacterial colonization of the fiber once in the rumen,” AB Vista nutritionist Dr. Nicola Walker explained. “This reduces the lag time before fiber digestion in the rumen begins by around one hour and leads to improved overall digestibility of the ration.”

The Table outlines the main results of the trial, with the cows fed the treated TMR maintaining fat-corrected milk (FCM) yield with 2 kg per day less in dry matter intake (DMI). The overall effect was a significant improvement in milk production efficiency from 1.50 to 1.67 kg FCM/kg DMI, plus a trend towards improved milk protein content.

“These changes are what you’d expect if energy supply increased as a result of an improvement in ration digestibility — more production from the same feed, or as in this case, the same production from less feed,” Walker said. “The possible increase in milk protein is also indicative of increased energy supply to the cow. These results back up the findings of other similar trials that have taken place in Europe.”

In a commercial-scale trial carried out on a U.K. dairy farm last year using 50 first-lactation heifers, pretreatment increased the TMR digestibility value (from 63% to 67%), milk yield (1.3 liters more per cow) and milk protein (from 3.58% to 3.70%). Improvements in fertility were also observed, with a higher rate of confirmed pregnancies (84% versus 64%), while a larger-scale trial in Bulgaria using 310 cows fed a corn silage-based TMR saw feed efficiency improvements lift yields by one liter per cow.

“One of the main priorities for U.K. milk producers at the moment is to maximize milk from all feeds, not just forage,” Walker said. “Because fiber typically makes up 45-50% of the dry matter consumed and is the slowest-digesting fraction of the diet in the rumen, any improvement in fiber digestion efficiency has a substantial impact on overall feed efficiency.

“Not only does this potentially increase productive performance, but as the U.K. trial shows, it may also have an impact on fertility, and the impact can be particularly beneficial during early lactation, when energy requirements exceed intake and cows spend the first few weeks post-calving in negative energy balance,” she concluded.