Check­ing a bull’s breed­ing ca­pac­ity

Central and North Burnett Times - - LIFE - Monto Vet­eri­nary Ser­vices Phone Monto Vet Ser­vices on 4166 1285 for more in­for­ma­tion.

RE­PRO­DUC­TIVE per­for­mance is a key driver to prof­itabil­ity in all beef breed­ing en­ter­prises.

The cur­rent strong cat­tle mar­ket is pro­vid­ing the per­fect op­por­tu­nity to as­sess and fine tune the fer­til­ity of your herd.

Pro­duc­ers can of­ten spend a lot of ef­fort in se­lect­ing re­place­ment fe­males and fre­quently be­come so fo­cused on the en­vi­ron­ment of their pro­duc­tion sys­tem they fail to place the nec­es­sary em­pha­sis on ge­netic se­lec­tion of herd sires.

The herd sires set the di­rec­tion of prof­itabil­ity for many years to come, so care­ful se­lec­tions need to be made to achieve sig­nif­i­cant ge­netic progress.

The Aus­tralian As­so­ci­a­tion of Cat­tle Vet­eri­nar­i­ans has deter­mined that fer­til­ity is the abil­ity of a bull to achieve, by nat­u­ral ser­vice, a preg­nancy rate of 60% and 90% in 50 nor­mally cy­cling fe­males within three and nine weeks of mat­ing re­spec­tively.

The Vet­eri­nary Bull Breed­ing Sound­ness Exam (bet­ter known as BULLCHECK) was de­vel­oped by the ACV to stan­dard­ise bull fer­til­ity test­ing and to pro­vide a con­sis­tent de­scrip­tor of bull fer­til­ity along with ap­pro­pri­ate cer­ti­fi­ca­tion.

Cat­tle vet­eri­nar­i­ans must be­come ac­cred­ited to be able to per­form this.

BULLCHECK pro­vides a stan­dard of as­sess­ment for vet­eri­nary eval­u­a­tion of the var­i­ous re­pro­duc­tive traits im­por­tant to beef pro­duc­ers and in­di­cates whether a bull has a high prob­a­bil­ity of be­ing fer­tile.

This eval­u­a­tion is con­ducted prior to sale and de­tails the iden­ti­fi­ca­tion of the sire, date and lo­ca­tion where the eval­u­a­tion was con­ducted, the as­sess­ments made and rel­e­vant disease in­for­ma­tion.

It is purely an eval­u­a­tion of a range of mea­sures on that date on which it was done and does not pro­vide any guar­an­tee or im­ply the num­ber of calves the bull will sire in ei­ther sin­gle or mul­ti­ple sire mat­ings.

The five com­po­nents as­sessed dur­ing BULLCHECK in­clude:

■ Scro­tal cir­cum­fer­ence (cm) and tone or re­silience.

■ A gen­eral phys­i­cal ex­am­i­na­tion in­clud­ing head, legs, joints, feet, sheath, up­per re­pro­duc­tive tract and pe­nis.

■ Col­lec­tion and as­sess­ment of a se­men sam­ple for motil­ity.

■ Lab­o­ra­tory ex­am­i­na­tion of sperm mor­phol­ogy.

■ A serv­ing as­sess­ment to eval­u­ate li­bido and mat­ing abil­ity.

This BULLCHECK data is then trans­ferred into the Bull Re­porter soft­ware, where in­di­vid­ual or group cer­tifi­cates can be pro­duced.

The re­sul­tant cer­tifi­cates should be sought out by bull buy­ers when choos­ing be­tween bulls as they also pro­vide de­tails of as­pects of the eval­u­a­tion that can­not be seen in the live an­i­mal, for ex­am­ple per­cent­age nor­mal sper­ma­to­zoa and con­for­ma­tional de­tail.

Can we ex­am­ine and cat­e­gorise the se­men pro­duced by a bull?

Yes. Many breed­ers will be aware that upon the col­lec­tion of se­men ei­ther by elec­tro-ejac­u­la­tion or rec­tal mas­sage, se­men is ex­am­ined crush-side for colour (no blood or urine stain­ing al­lowed) and den­sity of sper­ma­to­zoa, which is ranked on a one (clear to cloudy) to five (thick creamy colour) ba­sis.

In ad­di­tion, when us­ing low-power mag­ni­fi­ca­tion, the amount of swirl or vig­or­ous swim­ming mo­tion of all the sper­ma­to­zoa is scored on a one (no swirl, gen­er­alised flick­er­ing of in­di­vid­ual sperm only) to five (fast dis­tinct swirl with con­tin­u­ous dark waves) ba­sis.

Once com­pleted, the per­cent­age of in­di­vid­ual sperm that are swim­ming for­ward freely and in­de­pen­dently is recorded.

This as­sess­ment is a com­pul­sory mea­sure of fer­til­ity to meet BULLCHECK stan­dards.

Based on ex­ten­sive re­search, the ACV has deter­mined that a thresh­old of 30% pro­gres­sively motile sperm is a pass on a BULLCHECK for a bull used in a multi-sire herd and 60% pro­gres­sively motile sperm in a sin­gle-sire herd.

Un­der­stand­ing the mor­phol­ogy and why it is im­por­tant

The fi­nal eval­u­a­tion of the se­men is the per­cent­age of in­di­vid­ual sper­ma­to­zoa that are struc­turally nor­mal – the mor­phol­ogy.

Mor­phol­ogy is fre­quently just as im­por­tant, if not more im­por­tant, as far as af­fect­ing a bull’s fer­til­ity.

To test for mor­phol­ogy, a sam­ple of the se­men col­lec­tion is placed in a small tube with a spe­cial dilu­ent and sent to an ac­cred­ited mor­phol­o­gist.

The mor­phol­o­gist will ex­am­ine 100 in­di­vid­ual sper­ma­to­zoa and re­port the per­cent­age of nor­mal sperm and the per­cent­age of ab­nor­mal­i­ties.

Un­like the fe­male that has her quota of eggs at the start of life, the bull is con­tin­u­ously pro­duc­ing se­men within the tubules in the tes­ti­cles.

The tes­ti­cles are about two de­grees cooler than body tem­per­a­ture.

Be­tween the head, body and tail of the epi­didymis there is a long tube for stor­age and mat­u­ra­tion of the sper­ma­to­zoa pro­duced.

This pro­duc­tion pipe­line takes six to eight weeks from the start of pro­duc­tion to when the se­men is ready for ejac­u­la­tion, there­fore se­men re­sults can fluc­tu­ate over time.

PHOTO: JAMIE BROWN

NO BULL: Re­pro­duc­tive per­for­mance should be a key con­sid­er­a­tion.

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