Interpretation of 25-OH-D3, NEFA, and calcium correlations among cow and calf pairs

In the present study, the aim was to determine alteration of NEFA, calcium and vitamin D3 levels in cow and calf pairs at parturition as well as correlation between each parameter levels. For this purpose, a cow-side device employing the enzymatic colorimetric method was used for measurement of NEFA and calcium levels. On the other hand, serum 25(OH)D3 analysis was performed using the fluorescence immunochromatographic method at the laboratory in the Faculty. Blood samples were taken from Vena jugularis of 15 Simmental cow and calf pairs immediately after parturition and placed in serum and heparinized tubes. In cow and calf pairs, concentration of vitamin D3 (15.6-120 and 31.8-120 ng/mL, respectively), NEFA (0.12-1.2 and 0.09-0.8 mmol/L, respectively) and calcium (1.8 ± 0.9 and 2.2 ± 0.6 mmol/L, respectively) were determined. There was no significant correlation between NEFA, Ca, and vitamin D3 in cows and calf pairs. Taking into account several co-factors that influenced test results, which could not easily be excluded, further studies may be warranted with larger cow-calf pair populations. In conclusion, vitamin D3 concentration in calves is not affected by the negative energy balance of dams in the parturition period.

Analysis of the USDA’s 2017 Cow-Calf Management Practices Results: Part 2—Breeding Practices/Reproductive Technologies

This paper discusses the use of breeding practices and reproductive technologies in cow-calf operations, and the ways they affect calf crop. Written by Mario Binelli, João Bittar, and Angela Gonella, and published by the UF/IFAS Department of Animal Sciences, December 2021.

Potential Bull Buyers and Consignors Perceive Increased Value to Their Operations When Purchasing Bulls from the Florida Bull Test: A 20th Anniversary Survey

This publication discusses impacts as well as cow/calf producer perceptions of the Florida Bull Test. Written by Gleise M. Silva and Nicolas DiLorenzo, and published by the UF/IFAS Department of Animal Sciences, November 2021.

Effects of housing beef cow-calf pairs on drylot or pasture in the Midwest on production parameters and calf behavior through feedlot receiving

The objectives were to analyze the effects of housing cow-calf pairs in drylots (DL) or pasture (PAST) on cow performance and reproduction as well as calf performance and behavior through feedlot receiving. Simmental × Angus (2 yr; 108/yr; 81 ± 15.3 d postpartum) spring-calving cows were stratified by age, body weight (BW), body condition score (BCS), and calf sex and allotted to 6 groups/yr. Groups were randomly assigned to 1 of 2 treatments: DL or PAST. Cows in DL were limit-fed at maintenance and calves had ad libitum access to the cow diet in an adjacent pen. Pairs on PAST were rotationally grazed and calves received creep ad libitum three weeks prior to weaning. On d 110 calves were fence-line weaned and behavior was observed on d 111 and 112. On d 116 calves were transported 272 kilometers to a feedlot for a 42-d receiving period. Behavior was evaluated again on d 117 and 118. Data were analyzed using the MIXED procedure of SAS except reproductive data which was analyzed using the GLIMMIX procedure. Cows on DL had greater (P ≤ 0.01) BW and BCS at weaning. There were no differences (P ≥ 0.42) detected in reproductive data. Cows on DL had greater (P = 0.02) milk production. Calves on DL had greater BW (P ≤ 0.01) on d 55 and at weaning and greater preweaning average daily gain (ADG). There were treatment × time effects (P = 0.01) for lying and eating on d 111 and 112. More DL calves were eating in the morning and lying in the evening. More (P < 0.01) PAST calves were walking on d 111. Pasture calves vocalized more (P ≤ 0.01) on d 112. On d 117, more (P ≤ 0.05) pasture calves were lying and eating, and DL vocalized more. On d 118, treatment × time and treatment effects were detected (P ≤ 0.02) for lying and walking. More PAST calves were lying and more DL calves were walking. Drylot calves had greater (P ≤ 0.02) BW at the beginning and end of the receiving phase. Pasture calves had greater (P < 0.01) ADG and tended (P = 0.10) to have greater gain efficiency during feedlot receiving phase. In conclusion, housing cow-calf pairs in drylots improved BW, BCS, and milk production of cows but did not affect reproductive performance. Drylot calves had increased BW and ADG during the preweaning phase. Calf behavior at weaning and receiving was influenced by preweaning housing. Pasture calves had improved receiving phase ADG and feed efficiency but were still lighter than drylot calves after 42 d receiving phase.

Analysis of the USDA’s 2017 Cow-Calf Management Practices Results: Part 1—Calf Crop and Calving Distribution

This publication analyzes the calf-crop and calving distribution data reported on NAHMS Beef 1997 and provides insights and practical recommendations. Written by Angela Gonella, Oscar Alejandro Ojeda-Rojas, João Bittar, and Mario Binelli, and published by the UF/IFAS Department of Animal Sciences, November 2021.

Reproductive Tract Score: A Tool for Evaluating Beef Heifer Reproductive Potential

This publication explains the RTS methodology and suggests how it can be implemented in a cow-calf operation. Written by Mario Binelli, Thiago Martins, Cecilia C. Rocha, Felipe A. C. C. Silva, João Bittar, Philipe Moriel, Angela M. Gonella-Diaza, Lauren Butler, and Cindy Sanders, and published by the UF/IFAS Department of Animal Sciences, October 2021.

PSVII-13 Performance and environmental benefits from biochar supplementation in beef cattle grazing systems

Worldwide, beef production systems represent a significant source of greenhouse gas (GHG), and enteric methane (CH4) emissions are the primary concern. The objective of this experiment was to determine whether biochar (Oregon Biochar Solution, White City, OR) supplementation can reduce CH4 emissions from grazing beef cows. Biochar is a stable form of carbon produced through the pyrolysis of organic matter (typically forestry waste). Sixty-four cows and their calves were blocked by cow body weight and calf age, and randomly allocated to 8 paddocks, each with 8 cow-calf pairs. Using a crossover design, each paddock was assigned to one of two treatments: (1) biochar supplemented at approximately 3% of estimated dry matter intake (DMI) or (2) control (no biochar). Biochar was incorporated into a pellet containing 45% biochar, 42.5% wheat midds, 10% canola oil, and 2.5% dry molasses and fed in a portable trough once daily. Each period consisted of 28 days: 21 days for biochar adaptation and 7 days for data collection. Enteric gas emissions from each paddock were measured using C-Lock GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) with pasture DMI estimated using paddock entry/exit quadrats during each sampling week. Enteric CH4 emissions expressed as g CH4/d were 249 and 260 ± 50.3 g (P ≥ 0.37) for control and biochar, respectively. Similarly, g CH4/kg DM and g CH4/kg BW were not affected (P ≥ 0.44) by biochar supplementation on pasture. Biochar supplementation did not affect estimated DMI or cow/calf body weights (P ≥ 0.15). Results suggest that biochar was ineffective for reducing methane emissions from grazing beef cows; however, measures of animal performance were not affected by biochar consumption. Further work is required to determine if type or higher inclusions of biochar can reduce CH4 emissions from beef cattle.

PSIII-7 Seasonal effects on nutritional value of Oklahoma prairie grass when grazed in extensive or intensive systems

The objectives of this study were to determine the effects of sampling month and grazing system on tallgrass prairie forage nutritive value. Native tallgrass prairie pastures (n = 6) were assigned to either an extensive (EXT) or intensive (INT) grazing system for 5 consecutive years. Extensive system pasture annual stocking rate was 6.1 hectares per cow-calf pair with cows remaining in their respective pastures year-round. Intensive system pasture annual stocking rate was 3.0 hectares per cow-calf pair with cows present in the pastures 160 days per year [mid-May through mid-July (58 ± 6 d) and mid-September through mid-December (102 ± 4 d)]. Forage samples were collected monthly from two to four locations within each pasture. Samples were dried, separated into subsamples of leaf material and whole plant matter, ground, and analyzed using near-infrared spectroscopy. Data were analyzed using a mixed model (SAS 9.4) with grazing system, month, sample type (leaf or whole), and all two-way interactions as fixed effects and year as a random effect. Forage crude protein (CP) was not different between leaf or whole plant samples (P = 0.97) and increased (P < 0.001) in May (10.8% CP), declined in the fall, and stayed low (2 – 4% CP) in both systems. Neutral detergent fiber (NDF) was greater during May to July (P = 0.040) in the EXT than the INT pastures. Acid detergent fiber (ADF) differed by month (P < 0.001) and was lowest between April and May. In vitro true dry matter digestibility (IVTDMD) was greater in INT (63.7%) than EXT (62.3%) pastures regardless of month (P < 0.001), and both systems were greater during May through August (65 – 75%; P < 0.001) than the winter months (56 – 60%). These data indicate that protein supplementation is likely required outside of May and June, especially for lactating cows.