Corn silage in back­ground­ing di­ets

Prairie Post (East Edition) - - FARM NEWS -

By Dr. Reynold Ber­gen

Re­cent col­umns in­di­cated that corn’s po­ten­tial to pro­duce 50% higher silage (and starch) yields than bar­ley may off­set its 30% higher grow­ing costs, pro­vided the right corn hy­brid is se­lected for the lo­cal grow­ing con­di­tions, and pro­vided grow­ing con­di­tions co­op­er­ate. The higher starch con­tent of corn silage also means that feed­lot di­ets may need to be re-ex­am­ined. If corn silage is sup­ply­ing more starch to the diet, per­haps back­ground­ing di­ets can feed less bar­ley grain, or maybe cat­tle can be back­grounded to heav­ier weights with a shorter grain fin­ish­ing pe­riod, pro­vided growth rates, feed con­ver­sion and car­cass grade aren’t ad­versely af­fected.

Karen Beau­chemin of Agri­cul­ture and Agri-Food Canada (Leth­bridge) re­cently pub­lished a Beef Clus­ter study ex­am­in­ing whether re­plac­ing bar­ley grain with corn silage in back­ground­ing di­ets im­pacted an­i­mal per­for­mance and car­cass char­ac­ter­is­tics (Ef­fects of feed­ing corn silage from short-sea­son hy­brids and ex­tend­ing the back­ground­ing pe­riod on pro­duc­tion per­for­mance and car­cass traits of beef cat­tle, doi:10.1093/jas/sky099).

What They Did: Bar­ley and a 2175 corn heat unit (CHU) hy­brid corn were seeded near Leth­bridge in May 2014 (last 8-year av­er­age 2200 CHU). Bar­ley was silaged in July at the soft dough stage. Corn was har­vested be­fore the first frost in Septem­ber. 160 cross­bred steers (644lb) were fed one of four back­ground­ing di­ets in a small pen study (10 head per pen, 4 pens per back­ground­ing diet).

The ex­per­i­men­tal back­ground­ing di­ets con­tained (dry mat­ter ba­sis) 60% bar­ley silage or 60% corn silage (40% bar­ley grain-based con­cen­trate), 75% corn silage (25% con­cen­trate) or 90% corn silage (10% con­cen­trate). The silages had very sim­i­lar par­ti­cle lengths, bar­ley grain was dry-rolled (pro­cess­ing index = 82%) and all di­ets con­tained 13.5% pro­tein. Two pens of each diet were back­grounded to an av­er­age weight of 840lbs, and two pens were back­grounded to an av­er­age weight of 950lbs. Cat­tle were fed once daily, and all di­ets con­tained Ru­mensin but not Ty­lan. Feed left in the bunk was sam­pled pe­ri­od­i­cally to as­sess par­ti­cle size and nu­tri­tional value, and steers were weighed every three weeks. All steers were fin­ished on the same diet (91% bar­ley-based con­cen­trate, 9% corn silage; dry mat­ter ba­sis) to an av­er­age pen weight of 1544lbs. Car­cass data and liver scores were col­lected.

What They Learned: Back­ground­ing per­for­mance: Bar­ley silage-fed steers ate the most and grew the fastest, and steers fed 90% corn silage ate the least and grew the slow­est, but these dif­fer­ences weren’t great enough to sub­stan­tially im­pact feed ef­fi­ciency or the num­ber of days to reach the tar­get back­ground­ing end weight.

The pro­por­tion of left­over feed par­ti­cles longer than 8mm in­creased from 51% to 75% as the level of corn silage in the diet in­creased from 0 to 75%. This sug­gests that steers fed higher lev­els of corn silage were avoid­ing some of the di­etary fiber. In con­trast, the pro­por­tion of fine par­ti­cles (shorter than 8mm) fell from 49% to 25% as the level of corn silage in­creased. This sug­gests that the steers on the bar­ley silage diet were leav­ing be­hind some of the starch.

Fin­ish­ing per­for­mance: Be­cause they weighed more, steers back­grounded to 950lbs had higher daily feed in­takes dur­ing the fin­ish­ing pe­riod than steers back­grounded to 840lbs. Aside from that, back­ground­ing diet (silage type or level) and du­ra­tion (back­grounded to 840 vs. 950lbs) did not af­fect growth rate, feed in­take or feed ef­fi­ciency dur­ing the fin­ish­ing pe­riod. To­tal days to slaugh­ter and to­tal feed con­sump­tion did not dif­fer among back­ground­ing diet or du­ra­tion groups. Car­cass char­ac­ter­is­tics: Steers back­grounded to lighter weights on the 75% corn silage di­ets were fat­ter than the steers from any of the other back­ground­ing diet – weight com­bi­na­tions. This is hard to ex­plain and may have been a chance re­sult. There were no other dif­fer­ences among back­ground­ing di­ets or du­ra­tion in terms of car­cass weight, rib­eye area or qual­ity grade. Liver ab­scess scores were not af­fected by back­ground­ing diet or du­ra­tion.

What it Means: These re­sults were some­what un­ex­pected. The re­searchers had ex­pected bet­ter per­for­mance from the steers fed the corn silage di­ets, be­cause corn silage usu­ally con­tains much more starch than bar­ley silage. But in this case the corn silage con­tained slightly less starch than usual (28% in­stead of 30% or more), and the bar­ley silage con­tained more starch than usual (24% in­stead of 22% or less). This likely clouded the po­ten­tial treat­ment dif­fer­ences.

Con­tin­ued on Page 21

Newspapers in English

Newspapers from Canada

© PressReader. All rights reserved.