The Bovine Practitioner

Influence of pre-weaning trace mineral exposure on subsequent performance and trace mineral status of beef calves during finishing

2024-01-16T18:42:06+00:00

Objectives of these experiments were to 1) evaluate the accumulation of Co, Cu, Mn and Zn in liver tissue during the finishing period of calves with or without previous mineral supplement exposure; and 2) evaluate the performance of calves provided either organic or inorganic sources of Co, Cu, Mn and Zn. One-hundred twenty steers of unknown mineral history, and 48 steers of known mineral history prior to weaning were comingled in experiment 1. Steers were allocated to pens and assigned to receive either an inorganic or organic trace minerals. For experiment 2, 83 steers with or without exposure to mineral supplements during gestation and the subsequent lactation, were utilized in a 181-d finishing experiment. ADG tended to be greater (P = 0.09) during the first 53 days on feed in calves provided organic trace minerals. Calves with trace mineral access prior to weaning were heavier at the time of feedlot arrival (P = 0.06), but not at slaughter (P = 0.37). Providing access to mineral supplements to cow-calf pairs during grazing increased (P < 0.01) Cu and Co, but did not affect (P ≥ 0.29) Zn or Mn concentrations at feedlot arrival. Liver Cu status improved during backgrounding in steers fed the organic trace minerals. For calves of known mineral history, providing access to mineral supplements during grazing, prior to weaning, had no impacts on subsequent gain or intake during growing and finishing. Providing organic forms of trace minerals tended to improve growth early in the feeding period.

Methods of processing recycled manure solids bedding on Midwest dairy farms II: Relationships between bedding characteristics and bedding bacterial count

2024-01-16T18:57:20+00:00

The first objective of this study was to identify bedding characteristics associated with bedding bacterial count (BBC) in ready-to-use (RTU) recycled manure solids (RMS). The second objective was to explore the association between processing method and bedding characteristics in RTU solids. A third objective was to investigate factors associated with BBC in used solids (after placed in stalls). This observational study recruited 29 premises in Minnesota and Wisconsin. Farms were visited twice, once in August of 2019 and again in January of 2020. At each visit, the herd manager/owner completed a questionnaire describing facilities, bedding and manure management, and mastitis control practices. Additionally, pre-processed RTU and used bedding samples were collected for determination of BBC (coliforms, Klebsiella spp., Streptococcus or Streptococcus-like organisms and Staphylococcus spp.) and bedding characteristics (dry matter [DM]), organic matter [OM], water soluble carbohydrates, total nitrogen, soluble nitrogen and pH). Mixed linear regression showed that increased DM, decreased OM and RMS processing method were all associated with reduced BBC in RTU RMS samples. Processing method for RMS was associated with DM, total nitrogen and soluble nitrogen, but not other characteristics in RTU RMS samples. Low BBC in RTU solids, decreased OM in RTU solids, and use of deep bedding systems were associated with lower BBC in used RMS. Implications for these findings are that producers should strive to put clean and high DM fresh (RTU) bedding into stalls. Monitoring BBC and DM in RTU solids may be of value for producers using RMS bedding.

Predicting immunization status at arrival in Tennessee stocker calves

2024-02-24T17:48:29+00:00

This study aimed to test if externally observed physical characteristics of calves on arrival at a stocker facility could be used to predict calfhood immunization status based on observed antibody titer levels. Knowledge of highly correlated features could allow stocker operators to mitigate the risk of bovine respiratory disease through informed buying practices and targeted management strategies, thus lowering morbidity, mortality and treatment costs. Ear notches, blood and visual attributes were collected for 408 stocker calves at 4 farms in Tennessee. Each animal was tested for bovine viral diarrhea virus-persistently infected status and titer levels for 3 viral agents that are present in most respiratory disease vaccines. Multiple visual characteristics were predictive of likely vaccination for BRD-causing agents, including the presence of a prior ear tag (1.6 times), castrated males (1.26 times), polled cattle (4.8 times), body condition score (1.46 times per full score), and being declared vaccinated or preconditioned (2.2 times).

Additionally, we followed 60 calves through the stocker phase to ascertain how preconditioning affected downstream health events and performance. We found that preconditioned calves had lower BRD incidence, a higher occurrence of multiple detectible viral titers, and gained more weight over 56 days than did naïve cattle. Interestingly, many calves marketed as preconditioned did not have detectible viral titers on arrival. This work identifies informed, practical solutions and management decisions for stocker operations when purchasing calves. It also lays the groundwork for future work identifying ways to deliver precision management to stocker cattle.

Effects of parenteral or intranasal modified-live virus respiratory vaccination and revaccination on day 14 in auction-derived feedlot heifers

2024-02-24T17:56:12+00:00

Auction-derived beef heifers were received in 12 arrival blocks and randomized to 4 treatment groups: 1) parenteral MLV vaccination on d 0 (INJ), 2) intranasal MLV vaccination on d 0 (INT), 3) parenteral MLV vaccination on d 0 and revaccination with intranasal on d 14 (INJ-R), 4) intranasal MLV vaccination on d 0 and revaccination with intranasal on d 14 (INT-R). Pen was experimental unit, with 12 pens/treatment and 65 to 76 heifers/pen in a randomized complete block design. Performance, health, carcass traits and BRSV and H. somni frequency of carriage in the nasopharynx of revaccinated groups on d 0 and 60 was determined. Morbidity (P = 0.95), mortality (P = 0.80), and other health variables (P > 0.74) did not differ. However, an improvement in gain-to-feed (G:F) (P = 0.04), increased ribeye area (REA) (P ≤ 0.01) and percentage of edible livers (P ≤ 0.01) was observed for INJ and INJ-R. The BRSV (P = 0.09) and H. somni (P < 0.01) frequency of carriage in the nasopharynx increased with time but no treatment effect (P ≥ 0.23) nor treatment x day interaction (P ≥ 0.29) existed. Revaccination with an intranasal MLV did not impact health or growth, and arrival intranasal vaccination (INT and INT-R) resulted in less G:F and REA concomitant with increased liver abscessation, compared to parenteral (INJ and INJ-R). Detection of H. somni in the nasopharynx was frequent on d 60, suggesting important prevalence of this bacterial pathogen in the southern U.S. cattle population.

A survey of Mississippi cow-calf producers regarding factors associated with veterinarians performing bull breeding soundness evaluations and/or pregnancy diagnosis

2024-02-24T18:05:31+00:00

Reproductive efficiency is a major driver of profitability in cow-calf herds, yet many beef producers do not hire veterinarians to perform services intended to improve reproductive efficiency such as bull breeding soundness evaluation (BSE) or pregnancy diagnosis. The objective of this study was to determine reasons Mississippi cow-calf producers do or do not hire veterinarians to perform these services. Anonymous surveys were mailed to 1,500 randomly selected members of the Mississippi Cattlemen’s Association. Multivariable logistic regression was used to test respondent characteristics for association with outcome variables (e.g., respondents hire a veterinarian for BSEs and/or pregnancy diagnosis). Of 414 returned surveys, 397 (96%) qualified for analysis for an overall response rate of 26%. Of respondents that answered the respective questions, 155/386 (40%) hire a veterinarian for BSEs, and 103/392 (26%) hire a veterinarian for pregnancy diagnosis. Of 396 respondents, 229 (58%) indicated they had some form of a defined breeding season. The most common reasons for not hiring a veterinarian were lack of time/help (82/202, 41%) for BSEs and cost (91/248, 37%) for pregnancy diagnosis. On inferential analysis, the factors positively associated with hiring a veterinarian for BSEs were having a defined breeding season (OR = 6.8, 95% C.I. = 4.1-11.1) and raising seedstock cattle (OR = 1.7, 95%C.I. = 1.0-13.3). The only factor positively associated with hiring a veterinarian for pregnancy diagnosis was having a defined breeding season (OR = 4.2, 95%C.I. = 2.5-7.3). Management style and operation type influenced producers hiring a veterinarian for BSEs and pregnancy diagnosis.

A survey of Southeast U.S. beef veterinarians regarding methods for bull breeding soundness evaluation

2024-03-26T17:59:19+00:00

The purpose of this survey was to describe veterinarians’ methods for performing bull breeding soundness evaluations (BSEs). Veterinarians in Mississippi, Louisiana and Arkansas were emailed a survey regarding their experience, demographics, opinions and perceptions of client preferences regarding BSEs. Logistic regression was used to test respondent characteristics for associations with dichotomous outcomes including evaluating semen morphology as part of every BSE and detecting the diadem defect. Of 3,757 veterinarians solicited, 204 (5%) responded and 83 (2%) qualified for analysis. Of these, 10/73 (14%) indicated they do not evaluate morphology during every BSE. When shown an image of the diadem defect, 18/73 (25%) indicated seeing it often or sometimes, and 55/73 (75%) indicated rarely or never. The only factor associated with evaluating morphology as part of every BSE, was indicating belief that morphology was most predictive of bull fertility vs. believing motility was most predictive, or being unsure (OR = 11.2, 95% C.I. = 1.3-94.1). Respondents who always evaluate morphology with bright field microscopy at 1,000X (OR = 4.1, 95% C.I. = 1.2-13.3) or with phase contrast microscopy at ≥ 400X (OR = 5.4, 95% C.I. = 1.1-27.7) had higher odds of indicating they detect the diadem defect sometimes/often. There was an interaction between always using 1000X magnification, or not, and always using 400X, or not, on the reported detection of the diadem defect. Veterinarians’ perceptions of which aspects of the BSE are most predictive of fertility influence their methods for performing BSEs, and influence the frequency of detecting diadem defects.

Case Report: Salvia reflexa-contaminated hay poisoning in cattle

2024-03-26T18:35:02+00:00

Salvia reflexa is an annual forb that has recently (2021) been reported to contaminate hay and cause fatal hepatotoxicity in cattle. It is possible that prior poisoning cases may have gone unrecognized due to the lack of information on fatal hepatotoxicity caused by S. reflexa. Two cases are reported. Case 1 occurred in December 2001 in Montana, in which 30 cows died out of 105. Case 2 occurred in 2023 in Wyoming, in which 111 cows out of 155 died. Poisoned cows in both cases had elevated aspartate aminotransferase and alkaline phosphatase activities with microscopic severe acute centrilobular necrosis with hemorrhage. These lesions were similar to those described previously in clinical and experimental S. reflexa trials. Hepatotoxic diterpenes of S. reflexa, salviarin and rhyacophiline, were detected in hay samples in both cases and in rumen contents from animals in Case 2. Plant specimens of S. reflexa were collected from 2 herbaria, representing collections from 12 states, and screened for salviarin and rhyacophiline. The S. reflexa toxins were found in herbarium samples suggesting if S. reflexa is present, it is potentially toxic to cattle.