Barb Lee
Mon, 14 Jan 2008 15:53:18 -0800
> Barb, what adjustment, if any, have you made to your nutritional > formulas to account for the weight-at-age factor? That is a tough one Carol, the charts don't specify age, but rather weights, and also type of lamb (replacement ram, ewe, and a sort of general market lamb type category). They have classifications for "early weaned lambs" that start in at around 44 pounds, and there are classifications for "moderate growth expected" and "rapid growth expected" (blackbelly lambs do not approach the "moderate growth expected" figures and there is no classification for "slow growth expected). There are percentages of body weight dry matter intake numbers. I started crunching numbers when the lambs were averaging 45 pounds, and the chart starts at 44 pounds, and there are also expected rates of gain on the NRC charts. Our own sheep are only performing at an average of .35 lb adg this year (not so hot), and there are also calculations in the chart for expected rate of gain. I would like to see a minimum of .40 lb ADG and think that for whatever reason, our lambs should have done better this year. Lots of environmental reasons to blame it on. At any rate, the .35 lb adg makes it easy to adjust the lambs feed, because it works out to about 10 pounds per month gain. Chart weights for ewes generally start in at around 110 lb and most of my ewes qualify. All the NRC rates are adjusted for stage of life/production. There does not seem to be a level of life/production where my sheep can handle the dry matter amounts on the charts. (Calculations also take into account the amount of moisture in the feed) Interestingly, their dry matter intake is more in line with goats - however it seems (without a lot of study) that the goats also have lower overall nutrition requirements than sheep. The NRC charts define the percentage of body weight the animals are expected to ingest in dry matter. It varies quite a bit for different classes of animals. For instance, a heavily pregnant ewe doesn't have the capacity of a ewe nursing twins or triplets (DM intake can increase by something like 150% I think, but don't quote me.) and her energy requirements are high. When she's dry, her energy requirements are low but her capacity for DM is high. I am inclined to believe that our sheep maintain a sheep-like nutrition requirement but have more of a goat-like capacity. So what I am trying to do is build some records based on what a "balanced ration" for each classification of animals is expected to be and what my actual experience is in feeding them. I am trying to adjust feed quantities upward or downward according to how much they'll eat and how much they are growing, and figure the percentages of nutrients in the ration so they will approximate proportions (protein/energy/calcium/phosphorus) listed in the charts. I sure don't have anything definitive, but it is food for though so to speak, about what makes our sheep different from other breeds, and where we might look to adapt them to market trends without industrializing them. Truly, I think that focusing on capacity for fresh forage may actually be a step away from industrializing and back to the farm. One wonders just how much to expect the sheep to adapt their natural ways to our (actually my) expectations. I guess all things we select for as shepherds require the critters to adapt or change somewhat from what nature originally equipped them for. Nothing scientific here, it's fun to toss out a speculation and fire up a conversation. Barb _______________________________________________ This message is from the Blackbelly mailing list Visit the list's homepage at %http://www.blackbellysheep.info