Sixty Day Adjusted and Re-Adjusted Weights

HHS107 and triplets ranked 11, 12, 13th

As I mentioned, I just finished doing my sixty day weaning weights on all the lambs, and then performing the adjustment calculations. And not surprisingly, I was surprised by the results. 🙂

Sixty Day Adjusted Weights

I used a calculation method provided by the Katahdin breed registry, KHSI, for adjusting the sixty day weights into some thing that allows for fair comparison of the lambs. (Article here explaining the numbers, and Excel spreadsheet here that automates the math.) There are two levels of adjustments that need to be made to the weights to make them useful. The first is simple, and that is to normalize all of the weights to the sixty day mark. It’s inconvenient to weigh each lamb exactly on his sixtieth day “birthday,” so instead you weigh them all in one day. You subtract from that their birth weight, divide by the number of days old the lamb is on the weighing day, and get his average daily gain. Then you multiple that times sixty, and add the birth weight back in. So, now you have a decent comparison of what they all should weigh, or should have weighed, on their sixtieth day.

These Numbers Reflect Grass…

My raw sixty day weights are somewhat lackluster when compared to other Katahdin breeders around the country. At the KHSI sale last year, the sale catalog showed a lot of people’s lambs weighing a good ten or twenty pounds heavier at sixty days. And I think most people shoot for a pound a day of weight gain in those first sixty days.

But, I don’t feel too bad, because probably many, or most of those lambs had the benefit of creep feed to add to their growth. I do give my ewes dry COB late in pregnancy and tail it off in their first couple of weeks of nursing. But it’s gone before the lambs are eating much solid food at all. So, these lambs have gotten little benefit from grain, and I would expect them to show slower growth because of it. But it still gives me something to strive towards, breeding for sheep that can do almost as well on grass as other sheep do on grain.

Adjusted Again for Katahdin Growth Characteristics

HHS 116, small 2-year-old had twin ewelambs ranking 8th and 10th.

The second adjustment to make to the sixty day weights is the more important one. Because you see, it’s not fair to compare a single ram lamb born to a seven year old mother to a twin ewe born to a yearling, or a triplet wether born to a two year old. They are all getting a different amount and quality of milk from the varying level of maturity of their mothers, and how many siblings with which they’re competing. And they are different sexes, which we know grow at different rates. So, comparing the physical appearance of the lambs, or merely their raw sixty day adjusted weights, does not give an accurate picture of which lambs truly had the best growth characteristics, or presumably, genetics.

Since KHSI has been working with the National Sheep Improvement Program (NSIP) for quite a few years, now there is enough data for our breed to account for these differences mathematically. In other words, after collecting thousands of sixty day lamb weights, productivity trends have emerged. For instance, the data tells us that a yearling ewe who gives birth to and raises a single ewe is 1.17 times more productive than a four year old ewe who raises the same thing to the same weight. So you give the lamb from the yearling ewe a better score  for growth genetics by multiplying her sixty day weight by 1.17 when you compare the two. Make sense?

You Won’t Get What You Expect

So as I said, not surprisingly, I was surprised by the results! Genetics and appearance can fool you! Breeders know better, but we do it anyway: we assume that if the parents have a trait, their offspring will get the trait. If I have a nice big ewe, her babies should be big too, right? Well, of course, not always! Just because she expressed the size trait doesn’t mean she’ll always, or even ever, pass it on! And this was definitely true for me this year.

My biggest ewe from Montana, the one with the curvy Marilyn Monroe rear end (ADS0038)? I’ll grant that she gave birth to triplets (one dead) in her first lambing as a two year old, so her genetic potential for litter size appears good. But her lambs showed pretty poor growth! Her ewe lamb ranked #17 out of 31 lambs (at 49.32 lbs), and her ram lamb was 30th (at 31.81 lbs)- barely beating the orphan-reared Kitchen Lamb (at 26.16 lbs). Ow! I went out and neutered that guy immediately.

On the contrary, one of my most petite ewes, HHS0116, whom I had considered selling last year, rendered two extremely growthy ewelambs, ranking 8th (at 53.30 lbs) and 10th  (at 52.70 lbs) of the group. Those ewelambs are already almost as tall as their mother.

I had a bit of serendipity too. I had chosen a ram lamb as a likely keeper, largely because he is the most unrelated to my set of ewes (out of JPS60224). But it turned out he ranked number one (at 66.39 lbs), so that was a lucky pick! His twin sister was in second place, at 64.87 lbs; so wow, that yearling ewe really shined this year! Those two lambs look nice, but about the same as several other lambs, so I wouldn’t have known just by looking at them what standouts they really are.

Yet another surprise to me was the set of Jacob crossbred wether lambs. They were born last, but are already as tall as the oldest lambs, and they feel very heavy to me. I had been thinking, wow, this cross really came out nice, those are big lambs. But, at least for Katahdin data, it turns out they weren’t that great, they’re not as big as I thought they were for their dam age (three). They ranked 16th (at 49.32 lbs) and and 25th (at 45.02 lbs). My eyes definitely fooled me there.

Comparing to Raw Sixty Day Adjusted Weights

The winners: JPS60224 and twin lambs ranked #1 and #2.

So how do these results compare to just the “raw” numbers? Well, for one, the adjusted calcs spread the data out a little more, so it doesn’t feel like you’re splitting hairs so much in comparing animals. The raw weights spanned form 21.80 to 49.72 lbs; the adjusted weights spanned from 26.16 to 66.39 lbs.

The raw weights identify a different top ram (a twin out of a three year old versus a twin from a yearling). They rank the Jacob lambs higher (4th and 15th), because they are fairly heavy (but their mother is also three).

The extra adjustments help out triplets more, accounting better for the fact that their mother is feeding three.  I had two sets of triplets that were mother-raised. JJK010 (age two) had triplet rams, and their positions didn’t change much either way, but who was before and after then did. HHS107 also had triplets, which ranked 11, 19, 20 in raw weights, versus 11, 12 and 13 post-adjustment. But KRK33, who had three but raised two, and is seven years old, had her babies drop a little in the list, because she should be able to do better at that age. Had she opted to raise all three, it might have been different… 😛

Reflections on Breeding Stock

Not only does this information help to choose replacement ewes and breeding rams, it gives you some information about the breeding stock they came from, too. And your breeding choices! My petite ewe who had two big lams this year out of KMC0900, our young ram, had two small ewes out of Hershey (BLM417) last year. So I know to whom I’m breeding her this year! And the Montana ewes didn’t appear to be a good pairing with Hershey, only one lamb out of their five was in the top 50%.

JJK010 with the "band of brothers", triplet boys ranking 3rd, 6th and 7th. The tiny chocolate one pulled ahead of the Big Red by 60 days, ranking 6th.

But Hershey threw a lot of really good babies, too, and #900 threw some disappointments. I mostly used #900 on small yearling ewes, so it’s too soon to say how he’s doing, I think. Ultimately, it’s all in the combinations… For the ewes that disappointed me this year, I’ll pair them differently in the fall, to give them another chance before making decisions on culling them.

Better Yet: NSIP Data

I’m still waiting for news on the NSIP and its change over to the new administrator. NSIP takes all of the above calculations one step further, in that it correlates data from related animals all over the world to give you even more information on the genetic potential of your breeding stock.

This really takes breeding to a whole new level, from the days of just eyeballing animals at shows, to doing crude weight comparisons, to mathematically ranking all your sheep against each other, and finally ranking against all of their worldwide relatives. Pretty cool! I love spreadsheets, after all…

Below is a snapshot of the results, showing how they ranked with raw weight, and how it changed with the final calculations.

Final Rank	Raw Rank	Lamb #	60 day	Adj Wt	Dam	Sire
1	2	KMC0024	48.82	66.39	JPS60224	BLM417
2	5	KMC0023	43.54	64.87	JPS60224	BLM417
3	3	KMC0003	46.54	61.43	JJK0010	BLM417
4	13	KMC0021	40.84	60.86	ADS0061	BLM417
5	12	KMC0017	40.93	58.53	KMC0904	KMC0900
6	6	KMC0002	43.48	57.39	JJK0010	BLM417
7	8	KMC0004	42.14	55 .63	JJK0010	BLM417
8	9	KMC0026	41.97	53.30	HHS 0116	KMC0 900
9	1	KMC0013	49.72	52.71	HHS0121	BLM417
10	10	KMC0025	41.50	52.70	HHS 0116	KMC0900
11	19	KMC0009	37.55	51.81	HHS107	BLM417
12	11	KMC0010	41.00	51.65	HHS107	BLM417
13	20	KMC0011	37.09	51.19	HHS107	BLM417
14	7	KMC0012	42.85	50.14	HHS0121	BLM417
15	23	KMC0015	34.94	49.96	KMC0908	??
16	4	KMC0030	44.03	49.32	803 (Jacob)	BLM417
17	22	KMC0006	36.95	48.04	ADS0038	BLM417
18	14	KMC0007	40.50	47.39	KMC0910	KMC0900
19	26	KMC0016	31.68	47.20	KMC0904	KMC0900
20	25	KMC0022	34.64	47.10	ADS0061	BLM417
21	16	KMC0018	39.30	45.98	KMC0905	??
22	18	KMC0029	38.06	45.67	KRK33	KMC0900
23	24	KMC0001	34.83	45.57	KMC0903	KMC0900
24	17	KMC0008	38.65	45.22	ADS0065	BLM417
25	15	KMC0031	40.19	45.02	803 (Jacob)	BLM417
26	27	KMC0014	31.25	44.69	KMC0908	??
27	21	KMC0028	37.06	44.47	KRK33	KMC0900
28	28	KMC0019	29.48	43.92	KMC0906	KMC0900
29	29	KMC0020	28.90	43.06	KMC0906	KMC0900
30	30	KMC0005	26.96	31.81	ADS0038	BLM417
31	31	KMC0027	21.80	26.16	KRK33	KMC0900