A:   I'm not sure what's going on in this situation. The data would say that Fall calving cows of the same breed type using the same bulls will have lighter weight calves compared to these same cows bred to calve in the Spring. That doesn't mean that you could not still have calving problems. We have over-supplemented pregnant spring-calving beef cows protein and energy and only in specific situations have we increased calf birth weight. Seems when the weather conditions are really cold and cows are in later gestation, and over-fed protein and/or energy, calf birth weight can increase.

Fall calving cows grazing irrigated pasture all spring and summer I invision cows that are in extremely good body condition at calving. I'm wondering if the high assist rate was due to over-conditioned cows that were calving in hot weather and just got tired and maybe the calves were slightly heavier leading to greater assist rate.

Usually milk production is good for fall-calving cows because nutrient quality of the grass, especially if there is cool-season grasses, matches nutrient needs during lactation. We typically don't observe reductions in milk production in mature cows even if they are well conditioned. Maybe, in this situation, excess fat deposits in the udder might have effect milk production.