ONA REPORT

published in

THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL


November 2017

Florida Beef Enhancement studies – Will nutritional management of pregnant beef cows impact future calf performance?

by Philipe Moriel

Ona Report - Dr. Philipe Moriel


For questions or comments regarding this publication contact: Dr. Philipe Moriel, University of Florida, IFAS

At the end of last year, 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 Evaluating cost-effective supplementation programs for cows during late-gestation. Both studies address the Florida 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 Florida 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 (day 0 of the study), mature Brangus cows were allocated bahiagrass pastures (84 pairs/year). Treatments consisted 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 (2 pastures/treatment; 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.


Treatments a

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

1.5

2.5

2.5

2.5

2.5

2.5

0.5

Year-round cubes

0.5

0.5

1.5

1.5

1.5

1.5

2.5

2.5

2.5

2.5

2.5

0.5

Fall/Winter Molasses

         

3.3

3.3

3.3

3.3

3.3

3.3

 

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

         

   June

4.70

4.60

4.40

 

 

   August

5.04

5.10

5.14

0.054

0.01

   October

5.57a

5.98b

5.96b

0.075

 

Cow BCS change

         

   June to August

0.52

0.57

0.60

0.054

0.65

   August to October

0.64a

1.08b

1.02b

0.093

0.002

Cow BW, lb

         

   June

957

954

907

 

 

   August

942

936

964

15.2

0.42

   October

1194

1202

1216

17.6

 

Cow BW change, lb

         

   June to August

5

0

32

13.8

0.34

   August to October

309

300

320

11.1

0.52

a-b Within a row, means without a common superscript differ (P ≤ 0.05).       

Molasses or range cubes supplementation was not sufficient to improve body weight and body condition score of cows from June to August compared to cows receiving no supplementation. However, range cubes supplementation increased plasma concentrations of IGF-1 and glucose in August compared to cows receiving no supplementation (data not shown). Insulin-like growth factor 1 (IGF-1) and glucose are crucial hormones and metabolites for proper calf development during gestation, indicating that calf growth during gestation was potentially improved. Additional blood samples are being collected from cows to evaluate multiple indicators of energy metabolism of cows during the study, which will assist on improving future decisions regarding the nutritional management of these cows.

As shown in Table 1, molasses and cubes supplement amount was increased to 1.5 lb of dry matter per cow daily from August to October, which significantly impacted cow growth performance. Molasses and range cubes supplementation increased cow body condition score in October by 0.4 unit compared to cows receiving no supplementation (Table 2). Cows will start calving in approximately 2 weeks. Hence, a relatively small amount of supplementation from August to October (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 near 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 (additional collections of body weight and body condition score will make the data stronger). From October to mid-November, only cows assigned to a 12-week supplementation period will continue to receive DDG supplementation (SUP12 cows). Hence, we expect that all cows that received supplementation after weaning (for 6 or 12 weeks after weaning) will achieve better body condition score at the time of calving (mid-October to December). This better nutritional status before calving might potentially improve pregnancy rates of cows during the 2018 breeding season and calf weaning weight in August 2018.

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

Cow Body Weight, lb

         

   August

908

944

935

   

   October

1216

1275

1268

19.1

0.24

Cow Body Weight change

         

   August to October

288a

349b

341b

11.9

0.0003

Cow Body Condition Score

         

   August

5.00

5.00

5.20

   

   October

5.59a

6.10b

5.80a

0.096

0.0001

Cow Body Condition Score change

         

   August to October

0.53a

1.04b

0.74a

0.096

0.0001

a-b Within a row, means without a common superscript differ (P ≤ 0.05).

You are invited to join us by webinar on November 16, at 1:00 p.m., when I will present the information covered in this Ona Report and will be available for questions. To participate this webinar you simply need to register online here: https://register.gotowebinar.com/register/8383625914529478402. If you are nearby, you are welcome to attend the presentation in person. Join us at the Center in the Grazinglands Education Building.

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You are also invited to join us for the Ona Livestock & Forage Economics and Agronomy Program Highlights with Chris Prevatt and Joao Vendramini – Tuesday, Nov. 14, at the Center from 11:00 - 11:40AM. Register for this webinar at: https://register.gotowebinar.com/register/2862380995453009410 
or to attend in person: call 863-735-1314 ext. 204 to register.