World first for low ni­tro­gen cows

Matamata Chronicle - - Out & About - GER­ALD PIDDOCK

Cows bred to pro­duce less ni­tro­gen in their urine are di­vert­ing this nu­tri­ent into the pro­duc­tion of milk pro­tein.

The dis­cov­ery by CRV Am­breed sci­en­tists is thought to be a world first and has shown that breed­ing this trait in cows not only makes the an­i­mal more en­vi­ron­men­tally friendly, but boosts its milk pro­duc­tion ef­fi­ciency.

The dairy herd im­prove­ment com­pany re­cently be­gun mar­ket­ing se­men from ore than 20 bulls bred for their abil­ity to re­duce the con­cen­tra­tion of milk urea ni­tro­gen (MUN) in their daugh­ters un­der its LowN Sires brand.

An anal­y­sis of the LowN sire bulls sug­gested that about 25 per cent of the ni­tro­gen be­ing di­verted away from urine in their daugh­ters would go into milk pro­tein, CRV Am­breed re­search and de­vel­op­ment sci­en­tist Phil Beat­son said.

More milk pro­tein is good news for milk pro­cess­ing com­pa­nies want­ing less wa­ter in the dry­ing process when creating milk pow­ders.

The low-MUN and high per­cent­age pro­tein ge­netic link could also help sci­en­tists un­der­stand how an­i­mals par­ti­tion the ni­tro­gen they are fed, he said.

‘‘An­i­mal nu­tri­tion­ists will be ex­tremely in­ter­ested in our find­ing as there have been decades of re­search into ni­tro­genuse ef­fi­ciency.’’

This lat­est dis­cov­ery strongly in­di­cated that low-MUN cows could ex­crete less ni­tro­gen as urine be­cause the an­i­mals di­vert some ni­tro­gen away from milk urea and into milk pro­tein, he said.

This meant the ge­net­ics can be used for en­vi­ron­men­tal gains as well as in­creas­ing the ef­fi­ciency of cows. This dis­cov­ery could be the tip of the re­search ice­berg, he said.

‘‘A huge ef­fort has been in­vested over the past 70 years try­ing to un­der­stand ni­tro­gen par­ti­tion­ing and that’s pro­duced some in­ter­est­ing trends but noth­ing con­clu­sive.

‘‘Now New Zealand sci­en­tists may tar­get groups of an­i­mals that are known to be di­verse for MUN to in­ves­ti­gate dif­fer­ences in how they par­ti­tion di­etary ni­tro­gen.’’

Breed­ing and feed­ing cows are dif­fer­ent av­enues to re­duce ni­tro­gen ex­creted as urine and to­gether are ex­pected to yield more gains for farm­ing and the en­vi­ron­ment. ’’In other words, ge­netic gains will add to gains from bet­ter feed­ing.’’

The re­search may also have pos­i­tive im­pli­ca­tions for the beef in­dus­try be­cause it was likely that beef cows could also be bred for re­duced MUN.

That could pro­vide a huge mar­ket­ing tool for New Zealand beef. How­ever, that area of re­search still needed a lot more work, said Beat­son.

Cows bred for lower lev­els of MUN are ex­pected to ex­crete less ni­tro­gen in their urine when they are grazed on pas­ture.

‘‘It could po­ten­tially save New Zealand 10 mil­lion kilo­grams in ni­tro­gen leach­ing a year within 10 years, based on the na­tional herd num­ber of 6.5 mil­lion dairy cat­tle.’’

Farm­ers who started a breed­ing pro­gramme for low-MUN added an­other tool to their farm­ing sys­tems to man­age ni­trate leach­ing and could po­ten­tially re­duce their ni­tro­gen leach­ing by 10-12 per cent by 2025.

That was a sav­ing with a min­i­mal or no dis­rup­tion to nor­mal farm man­age­ment.

The next stage of the re­search would see sci­en­tists study groups of an­i­mals ge­net­i­cally dif­fer­ent for MUN to un­der­stand more pre­cisely the re­la­tion­ship be­tween re­duc­ing MUN and re­duc­ing ni­tro­gen in urine.

SUP­PLIED/CRV AM­BREED

CRV Am­breed re­search and de­vel­op­ment man­ager, Phil Beat­son says their dis­cov­ery of cows di­vert­ing ni­tro­gen into milk pro­tein is thought to be a world first.

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