Gender Selected/ Sexed Semenby Dr, Josh Odhiambo

Since the transformation ofsexed semen from a wishfulthought to reality. Thanks to aninstrument known as a "flowcytometer" that allows a greaterthan 90% accuracy queries have

been raised about its application.One of only a few repeatabletechniques to sex sort sperm at ahigh level of purity uses thisdevice called a "flow-cytometer"

to detect a 3 to 4% difference inDNA content between male andfemale sperm and sort themwith upwards of 90% purity.The first step in this procedureis to dilute sperm to a very lowconcentration and stain themwith a fluorescent dye. Thesample is then sent through theflow-cytometer at 60 mph under30 to 60 psi of pressure. As spermpass through the internal laserbeam, the fluorescent dye isexcited. Because of the larger Xchromosome, female spermemit slightly more light thanmale sperm, which possess thesmal ler Y c h r o m o s o m e .Detectors measure the amountof fluorescence and assignpositive or negative charges toeach droplet containing a singlesperm. Charged deflector platesthen split the single stream into 3streams: positively chargedparticles containing one sex go

one way, negatively chargedparticles containing the othersex are deflected in the oppositedirection, while uncharged

Mrs. Kinyua - Membley Acres Farm - Nairobi. BILLICK 507AYO0086

droplets containing multiplesperm or unidentified sex passstraight through. Confirmedwith tens of thousands ofoffspring born in worldwideresearch trials, the procedure

separates sperm of the twosexes with ~90% purity.However, that still leaves 10%of the undesired sex availableto compete for fertilization.

Although the 3,000 to 5,000sperm of each sex sorted persecond sounds like a lot, thistranslates into -1.3 hours ofsorting to process enoughsemen for a standard 20million sperm/straw dosage.Thus, due to the slow sortingspeed, commercialization isonly possible with very lowsperm numbers per dose (~2million).

There are several majorlimitations that have stifledimplementation of sex-sortedsemen. Without question,

reduced conception rates havebeen a primary hurdle. Becauseof the low sperm numbers perdose and compromised spermviability, sexed semen isrecommended for use in well-managed, highly-fertile, virginheifers. While many farms haverea l ized very a c c e p t a b l e

conception rates, averagesindicate well-managed herdsthat achieve 60 to 65%conception rates in virgin heiferswith normal semen, can expect45 to 55% conception rates withsexed semen. In Kenya ourexperience is a lot higherconception rates since we arevery strict on the techniciansand the animals used.Despite these limitations,hundreds of heifers haverecently calved or becomepregnant with sexed semen using

Artificial Insemination withlower sperm numbers per dose

than are used conventionally.

Gender Selected/ Sexed Semen cont.Citations of increased heifercarvings, decreased incidencesof calving difficulties as well asaccelerated upgrading processhave been made with the use ofsexed semen. Use of sexedsemen will require a breedinggun designed to accommodatethe smaller diameter Vi ccstraws. Straws are to be thawedand handled identically to theirVi cc counterparts. However,the smaller diameter andcompromised semen qualitywill make them much moresensitive to cold shock anderrors in semen handling. Strictadherence to procedure is key.The return on investment forthe dairy producer depends on acomplex interaction betweenthe initial conception rate withnon-sexed semen, the percentreduction in conception (if any)due to use of sexed semen, the

price differential between sexedand convent ional semen,expected gender ratio for sexedvis a vis conventional, and thevalue differential between bulland heifer calves. Most of thesefactors^will change considerablyfrom herd to herd, which

differentially affects the breakeven value of sexed semen toeach respective producer.However by and large the gainsfavour the use of sexed semen indairy herds and many dairyfarmers who have gone this routehave neverlookedback.

Mr. Nyairo - Kalua Farm - Kitale. Assorted daughters of

World Wide Sires Ltd Gender Selected Semen

Genomics- "The latest tool "Kit" in the Genetics Block",

"Genomics" - the mapping ofrelevant traits in cattle based ontheir DNA - is a term that waslittle known as recently as 15months ago. Now, leaders in thecattle genetics business not onlybelieve but know it will be animportant influence in everysegment of the industry/'Thisscientific breakthrough mayliterally be the most impactfulevent in the A.I. industry since

by Dr. Josh Odhaimbo

the introduction of frozens e m e n . " Says D r . Jo shOdhiambo.An animal's genetic evaluation isc o m p o s e d o f s e v e r a lcomponents . An animal 'spedigree, the performance ofthat animal, the performance ofthe progeny of that animal, andnow the DNA makeup of thatanimal all contribute to itsgenomic evaluation. Each of

these components is weighteddifferently within the officialevaluation depending on theamount of available information.To put it simply, genomics addsthe actual DNA makeup of ananimal to the animal's genetice v a l u a t i o n b a s e d o nperformance levels of otheranimals with similar DNAmakeup. The combined geneticevaluation is referred to as agenomic evaluation.

Genomics-"The latest tool "Kit" in the Genetics Block" cont.

Genomics is possible thanks tothe mapping of the bovinegenome and the determinationof which genetic markerscorrelate with specific traits incattle. The animals DNA isobtained fromblood, hair, tissueor semen samples via a processknown as genotyping. A SingleNucleotide Polymorphism(SNP) is a single base differencethat marks a difference in DNAfrom one animal to another.Research advancements havem a d e S N P t e c h n o l o g yaffordable for commercial useallowing the dairy industry todevelop genomic too ls .Chromosomes contain twostrands of DNA that containsequences of four different basepairs (Adenine, Thymine,Guanine, Cytosine). Cattlehave 30 different chromosomepairs containing roughly 3billion of these DNA base pairs.Since it is much too costly toidentify the sequence of all 3billion of these base pairs, asubset of these bases in the formof SNPs are measured. Amicrochip has been developedthat allows testing of 50,000 ofthese SNPs in an effort tocondense these 3 billion basepairs in to an a f fo rdab legenotyping tool. Now, quickand relatively inexpensive testscan look at 50,000 of thoseimportant markers and predictwhich calves - mostly bulls atthis point - will have the best

productive potential.

Before genomics was possible,the industry had approved andselected bulls the same way for40 years - through theevaluation of daughters andtheir milk production recordsotherwise famously known asprogeny testing. But thatsystem is slow, taking at leastfive years to provide solid data.Now with the mapping of thenucleotides that make up thegenetic material of cattle, it'spossible to select for manytraits through their geneticmarkers. And it can be done onbaby calves and in theory atleast, an embryo could begenomically tested before it'seven placed into a recipient."The speed of genomics is thereal advantage," he noted

The genomic testing givescattle breeders a three-yearhead start on the nextgeneration because they don'thave to wait several years for abull to grow up and for hisdaughters to be born andcome into production.Through the use of genomics,29 different genetic traitswithin an animal's summarywill be adjusted. This includesfive yield traits (Milk, Fat,Percent Fat, Protein, PercentProtein), seven fitness traits(Productive Life, Somatic CellScore, Daughter Pregnancy

Rate , Sire Calving Ease,Daughter Calving Ease, SireStillbirths, Daughter Stillbirths),16 conformation traits (PTATand 15 linear type traits), andNet Merit Dollars. Since all thesetraits vary in heritability, we'vealways seen a variation in thereliability of each of these figures.Genomics will affect each trait'sreliability differently, and inactuality the biggest winners willbe the fitness traits as theiraccuracies will see the largestincreases.

Dr. Odhiambo is convinced thatgenomic technology will impactpositively in the dairy industrybecause the predictive powergenomics delivers facilitatesmore logical genetic decisionsmaking earlier in an animal's lifespan. This predictive power isdue to the fact that genomicse m b r a c e s D N A b a s e di n f o r m a t i o n , p e d i g r e einformation and daughterperformance information thusan information reliability surgewill be noted. Genomic testedsires will be available andidentified by using the termGTPI for Genomic TotalPerformance Index.

Let's all take a leap into the arenaof technology and move forwardfaster and with better precisionas we take charge of the 21stCentury.