FL Beef Enhancement Studies - Will nutritional management of pregnant beef cows impact future calf performance?

Table 2. Growth performance of cows offered molasses during Fall/Winter only (November 2017 to April 2018) or year-round supplementation of molasses or range cubes.

Molasses or range cubes supplementation was not sufficient to improve the body condition score change of cows from June to August compared to cows receiving no supplementation (Fall/Winter cows). As shown in Table 1, the amount of molasses and cubes supplement was increased to 1.5 lb of dry matter per cow daily from August to November, which significantly impacted cow performance. Molasses and range cubes supplementation increased cow body condition score in October and at calving (November) compared to cows receiving no supplementation before calving (Table 2). Hence, a relatively small amount of supplementation from August to November (1.5 lb of dry matter of molasses or range cubes per cow daily) improved the nutritional status of cows leading to better body condition score at the time of calving. It is expected that such improvement in body condition score of cows at the time of calving will improve the reproductive performance of cows in the next breeding season and calf development during late gestation, which might increase calf growth after birth. After calving, we will evaluate the health, immunity and growth performance of all calves. Then, steers will be sent to a feedlot for finishing and carcass data collection, and heifers developed until the end of their first breeding season.

STUDY 2 - Evaluating cost-effective supplementation programs for cows during late-gestation

This study will: (1) evaluate if dry distillers grains (DDG) supplementation of Brangus cows during the entire late-gestation (2.25 lb/day for 12 weeks = 189 lb per cow; August to November) will increase cow reproductive success and calf performance after birth to levels higher than the cost of this supplementation strategy, and (2) investigate if concentrating cow DDG supplementation during the period of lowest nutrient demand (first 6 weeks after weaning) will be more cost-effective than cows supplemented during the entire late-gestation. First, we believe that cows supplemented during late-gestation, regardless of length of supplementation, will have greater profitability than non-supplemented cows due to improvements on cow reproduction and calf performance. Second, we believe that supplementing 4.50 lb/day for 6 weeks after weaning (August to October) will reduce feeding costs, have the greatest improvement on cow weight gain and reproduction success, but not cause fetal-programming effects (due to the shorter supplementation period), whereas the supplementation of 2.25 lb/day for 12 weeks will increase feeding costs, provide less improvement on reproduction, but enhance calf development during gestation and performance after birth.

Six weeks after weaning, cows supplemented with 4.5 lb/day of DDG had greater body condition score in October compared to the other treatments (Table 3). Cows receiving 2.25 lb/day of DDG also demonstrated a small improvement on body condition score in October compared to cows receiving no supplementation, but it was not sufficient to achieve statistical differences. From October to mid-November, only cows assigned to a 12-week supplementation period continued to receive DDG supplementation (SUP12 cows). At the time of calving (November), cows that received DDG supplementation for 6 weeks or 12 weeks had similar body condition scores. This response indicates that a 6-week period of supplementation was more cost effective than a 12-week supplementation period, because cows supplemented for 6 weeks achieved the same body condition score at calving and had half of the feeding labor costs compared to cows supplemented for 12 weeks. In addition, cows supplemented for 6 or 12 week had greater body condition score compared to control cows that did not receive supplementation. Hence, we expect that all cows that received supplementation after weaning (6 or 12 weeks after weaning) will have greater reproductive performance during the 2018 breeding season due to the greater body condition score at the time of calving compared to cows that did not receive supplementation. We also believe that the greater nutritional status of cows that received supplementation before calving will cause fetal programming effects and improve the calf performance after birth.

Table 3.  Growth performance of cows that received no supplementation (No SUP), and cows that were supplemented with 4.50 lb/day of dried distillers grains for 6 weeks after weaning (SUP 6 weeks) or with 2.25 lb/day of dried distillers grains for 12 weeks after weaning (SUP 12 weeks).

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