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FL Beef Enhancement Studies - Will nutritional management of pregnant beef cows impact future calf performance?
February, 2018
Dr. Philipe
Moriel,
UF/IFAS RCREC, Ona
In 2016,
The FL Beef Enhancement Board
announced that our nutrition program at Range Cattle REC successfully
obtained funds for 2 multi-year projects. Study #1 was called
Does year-round supplementation of
cows pay off?
and study #2 was called
Evaluating cost-effective
supplementation programs for cows during late-gestation..
Both
studies will address the FL Cattlemen’s Association Priorities #3 (Calf
loss), #7 (Animal herd nutrition – mineral and winter supplementation), and
#8 (Animal health). In this Ona Report, we will provide a summary of the
results currently available for both studies.
STUDY #1 - Does year-round supplementation of cows pay off?
Body condition score
at calving is the most important factor that influences overall pregnancy
rate and calving distribution of beef cows. Most FL cow-calf operations
provide year-round supplementation of trace minerals, but provide protein
and energy supplementation only during early-lactation (winter time).
However, inadequate energy/protein intake before calving lowers reproduction
even if the amount of energy and protein consumed after calving is
sufficient to meet the demand. Also, recent studies showed that poor
nutrition during gestation can alter fetal organ formation and decrease
offspring’s future growth performance and health (a process called
fetal-programming).
Cows supplemented year-round might achieve a greater body condition score at calving without increasing the annual supplement amount. Another advantage is that the trace mineral salt can be mixed into the supplement, reducing annual fluctuations in voluntary intake and waste of free choice trace mineral formulations, improving cow trace mineral status. We believe that year-round supplementation of molasses or range cubes will increase body condition score at calving and trace mineral status of cows throughout the year. In addition, year-round supplementation of molasses and range cubes will improve calf development during pregnancy, and then, improve calf health, survivability, and growth after birth.
Research approach:
In June, mature Brangus cows were allocated bahiagrass pastures (84
pairs/year). Treatments consist of control cows supplemented with molasses
from calving until end of breeding season (only from November 2017 to April
2018), or cows receiving year-round supplementation of molasses or
year-round supplementation of range cubes-based formulations (June 2017 to
May 2018). Total annual amount of supplement will be similar among all
treatments (600 lb of supplement/cow annually; Table 1). Supplements are
being offered twice weekly (Mondays and Thursdays) and were formulated to
provide similar amounts of energy and protein. Trace mineral/vitamin
supplementation is being provided during the entire year in a loose meal
form for control cows, or mixed into the molasses or range cubes for cows
assigned to year-round supplementation.
Table 1. Supplement dry matter intake (lb/cow daily) of cows offered molasses during Fall/Winter only or year-round supplementation of molasses or range cubes.
Treatmentsa | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Jan | Feb | Mar | Apr | May |
lb of dry matter/cow daily | ||||||||||||
Year-round Molasses | 0.5 | 0.5 | 1.5 | 1.5 | 1.5 | 2.5 | 3.0 | 3.0 | 2.5 | 2.5 | 0.5 | 0.5 |
Year-round Cubes | 0.5 | 0.5 | 1.5 | 1.5 | 1.5 | 2.5 | 3.0 | 3.0 | 2.5 | 2.5 | 0.5 | 0.5 |
Fall/Winter Molasses | 0 | 0 | 0 | 0 | 0 | 4.0 | 4.0 | 4.0 | 4.0 | 4.0 | 0 | 0 |
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.
Treatments | |||||
Item | Fall/Winter Only |
Year-round Molasses |
Year-round Range-Cubes |
SEM | P-value |
Cow BCS | <0.01 | ||||
June | 4.70 | 4.60 | 4.40 | 0.076 | |
July | 5.02 | 5.05 | 5.16 | 0.076 | |
August (weaning) | 4.92 | 4.85 | 4.96 | 0.076 | |
October | 5.55a | 5.92b | 6.00b | 0.076 | |
November (calving) | 5.18a | 6.06b | 5.92b | 0.085 | |
Cow BCS change | |||||
June to July | 0.55 | 0.56 | 0.66 | 0.079 | 0.61 |
July to August | -0.12 | -0.20 | -0.18 | 0.069 | 0.66 |
August to October | 0.64a | 1.08b | 1.02b | 0.094 | 0.08 |
October to November | -0.37a | 0.10b | -0.08b | 0.107 | 0.01 |
a-bWithin a row, means without a common superscript differ (P≤0.05) |
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).
Treatment | |||||
Item | No SUP | SUP 6 weeks | SUP 12 weeks | SEM | P-value |
Body conition score of cows | <0.0001 | ||||
August (week 1) | 5.00 | 5.00 | 5.20 | - | |
October (week 6) | 5.61a | 6.15c | 5.81a | 0.087 | |
November (week 12) | 5.29a | 6.36c | 6.18b | 0.090 | |
Body condition score change | |||||
August to October | 0.53a | 1.04c | 0.74a | 0.096 | 0.0001 |
October to November | -0.31a | 0.22b | 0.37a | 0.129 | 0.0001 |
a-bWithin a row, means without a common superscript differ (P ≤0.05). |