Index - do you breed for it or not?
It's a question that always haunts breeding decisions, most cows are never going to be bull dams, so how important is it? Sure, its nice to have, but what are the drawbacks to chasing it?
Here in NZ we have the BW system run by L.I.C, and the NZMI system run by CRV Ambreed, you can choose whichever you like, they are somewhat different, and cows that rank well under one, may suffer under the other, so which do you choose?
Personally, I dislike the BW system with great intensity. It penalises my cows for their size( BW has reduced the size of the NZ dairy cow considerably since it was introduced) and their higher volume, and doesn't give them credit for their production of milksolids. It also seems to completely ignore type, which in the past has lead to some really bad bulls making the Premier Sires and Bull of the Day teams, just because they had a good index. Surely a profitable cow is one which survives multiple lactations and produces well into old age, without having to have large amounts of money spent on her for mastitis and reproductive disorders etc? ( in defence of the L.I.C bull selection team, they have made great progress over the last 10 years as regards type, especially udder traits, and each year we usually find a bull we think about using in their catalogue, but that thought is always based on the bull himself, and not on index, it's just a shame the bull doesn't get any index credit for his type ratings.)
I have had many "good"cows over the years, ones with high BW indexes, that have had to be culled because their udders dropped out, they had regular bouts of mastitis or they couldn't walk any more. That lead me to use more overseas genetics, they had better udders, survived longer, produced better and got incalf regularly, the only thing they didn't have was a BW index.
A classic example of this is Stormview Chloe, now 10 years old ( and in calf again, to Pierre!) she is by a bull that nobody other than the Mclean family has ever heard of, Peticote US Nick Max, He has a BW of -165 these days, Crap, in anyones book. He was a United Nick son, from the Rotate Martha cow in the US, good genetics to say the least. Chloe herself rates at -53 BW these days, also crap, most folks would cull her. Now explain this then - she has done over 400kgs of milksolids every year, she gets in calf every year, has not had any walking issues or fertility issues, she has one of the best udders in the herd-still, at 10 years old, after 50,000 litres plus has gone through it, and she is showing no sign of giving up anytime soon. Surely that is the sort of cow people would like to have in their herds? She is definately the sort of cow we want here, she allows us the ability to cull out the weaker cows and low producers, because we can rely on her to put in the effort every year.
So why not move to NZMI I hear you ask? Good idea, we are seriously considering it, after all, we use it more than BW when picking our bulls, but NZMI has its problems too.( just out of interest, Chloe scores 165 for NZMI, the top cows around are in the low 300's). There is also the small issue that the NZ dairy industry works with BW, if you want a new sharemilking job, the question is always asked "what's your herd BW?" very few consultants even consider NZMI.
NZMI gives you credit for type, thats a plus, and it doesn't disadvantage your cows for size, so if you like overseas bulls with high type, you have a chance at having a decent index within this system. The bit where NZMI falls down, is it uses essentially the same figures as BW to assess production. therefore, if you have a high volume herd, you still suffer somewhat.
I understand that our dairy industry wants high component milk, not high volume, but it also requires high protein production. In my opinion, the only way to produce high levels of protein, is with total volume. There doesn't seem to be much you can do about protein percentage within milk, it seems to run constantly between 3% and 4%, so surely the only option is to produce more volume to attain the required kilograms of protein?
So you seem to have a choice, you can either breed the cows you want to milk, with decent type and production, a cow that has space for a 50kg calf AND food, is capable of doing large production figures if fed very well, and move to the NZMI system where they have half a chance, OR chase the BW index and be prepared to have a high genetic turnover( the average high BW cow lasts 3.4 lactations), milk smaller cows with less production ( largely because they cant eat enough), and be happy to cull on type.
Personally, after years of getting REALLY annoyed when my good cows come up on herdtest with crappy BW and PW indexes, I am over it. These days we are using the bulls we want, with the genetics we see as advantageous to our herd, and if they come with an index, great, if not, too bad. It will probably bite us in the bum at a few job interviews in the future, where index is important, but we have to get up and milk these girls day in and day out, and milking ugly uddered, small, low producing cows is no fun at all.
Stormview Chloe at 10 years old - No BW, reasonable NZMI, great cow!!
Interesting note - was at a sale recently, and saw a lovely cow from a great cow family sell, she had a BW of -21 and a PW of -139, was doing close to 500kgs of solids per lactation, and was the highest priced lot of the day! Seems I am not the only one who dislikes index in favour of good cows !!
