Effect of an injectable trace mineral at the initiation of a 14 day CIDR protocol on heifer performance and reproduction

Trace Mineral Supplementation of Beef Cattle in Pasture Environments

The United States Department of Agriculture defines pastureland as "A land cover/use category of land managed primarily for the production of introduced forage plants for livestock grazing." The purpose of this article is to review trace mineral supplementation for beef cattle in this environment. Supplementation of trace minerals in these environments is accomplished with the use of a trace mineralized salt or a complete mineral-vitamin product that contains macrominerals, trace minerals, and vitamins. The form of the supplement may influence uptake and utilization. Supplementation may be augmented with pulse dosing with injectables or oral products.

A Trace Mineral Injection before Joining and Lambing Increases Marking Percentages and Lamb Weights on Diverse Farms in Victoria, Australia

This study was conducted on five commercial farms across Victoria, Australia, between September 2018 and November 2019, where the TM status of ewes was within normal ranges before joining. Mix breed ewes (n = 1484) were randomly allocated to receive either nil treatment (Control) or two injections of an ITM product containing zinc (40 mg/mL), manganese (10 mg/mL), selenium (3 mg/mL), and copper (10 mg/mL); 0.2 mL per 10 kg BW (Multimin® plus Copper for Sheep, Virbac (Australia) Pty Ltd., Milperra, NSW, Australia) 30 days before the start of joining and 30 days before the start of lambing. Approximately 90 days after joining, pregnancy status and conception rate were determined by ultrasound. The marking rate was determined approximately four weeks after the end of lambing, and lamb weights were determined at weaning (12 weeks after the end of lambing). In all farms, ITM treatment did not affect the conception rate. The average conception rate was 156 ± 11.0% (p > 0.05). The marking rate of ITM ewes was 9% higher than control ewes (95% Confidence Interval 3−21%). Lambs born to ITM ewes were 2.31 kg heavier at weaning than lambs born to control ewes (p < 0.001). Although not significant, ewe mortality across farms was 1.3% lower in the ITM group than in the control group. On average, ewes treated with ITM pre-joining and pre-lambing produced more and heavier lambs that represent an extra AU$ 2338 per 100 ewes net benefit for the producer. These results help to understand strategic TM supplementation for animal health, performance and farm profitability beyond the treatment of clinical deficiencies.

Effects of inorganic selenium injection on the performance of beef cows and their subsequent calves

Sixty-seven pregnant Angus cows and their subsequent calves were used in a randomized design to evaluate the effect of inorganic Se injection from 80 d of gestation until weaning on cow reproductive parameters, BW and BCS evolution, milk yield and quality, calf growth and calf hematology parameters. The treatments were as follows: 1) Se+: cows were administered Se as sodium selenite at doses of 0.05 mg/Kg of BW at 80, 140, 200, 260 d of gestation and 30, 90, 150 and 240 d of lactation. Calves from Se + cows were Se as sodium selenite subcutaneously injected with a dose of 0.05 mg/Kg of BW at 70, 104, 144 d of age; 2) Control: cows and calves were administered sterile NaCl solution (9 g/l) at the same volume and intervals as Se + treatment. At the start of the experiment, forage Se concentration was 58.6 ppb ± 7.6 ppb, and cow whole blood Se concentration was similar (P > 0.10) between treatments (Se+, 29.3 ± 0.3 ppb; Control, 28.1 ± 0.5 ppb). After Se injection, cow whole blood Se concentration was increased (P < 0.01) in Se + cows in relation to control cows until the end of the experiment. Calf whole blood Se concentration was increased (P < 0.01) at birth and 30 d of age in calves from Se + cows compared to calves from Control cows. However, calf whole blood Se concentration was not different (P > 0.10) between treatments at d 70 after birth. After the first Se injection (70 d of age), calf whole blood Se concentration was increased (P < 0.01) at 104 and 144 d of age in calves from Se + cows compared to calves from Control cows. Cow BW and BCS did not differ (P > 0.10) between treatments throughout the experiment. Ovarian follicle diameter measured by ultrasound 47 d postpartum was greater (P = 0.03) in Se + cows compared to Control cows. Pregnancy rate to fixed time artificial insemination (FTAI), overall pregnancy rate (P > 0.10) and pregnancy loss (P = 0.19) did not differ between groups. Selenium injection did not affect (P > 0.10) milk yield and composition. Calf morphometric parameters, BW at birth and growth rate during lactation were not affected (P > 0.10) by treatments. No significant effect (P > 0.10) was observed between treatments on hematological results of blood samples from calves at weaning. Results of this study shown that inorganic Se injection was an efficient tool to improve Se-status in cow-calf operation under extensive management. Selenium injection increased follicle diameter in postpartum beef cow, however, did not affect the rest of the variables studied.

Cattle adapted to tropical and subtropical environments: social, nutritional, and carcass quality considerations

Beef production needs to increase from 60 million to 130 million tons by 2050 to feed a growing world population, and 70% of this production increase is expected from beef industries located in subtropical and tropical regions of the world. Bos indicus-influenced cattle predominate in these regions but are often managed using practices developed for Bos taurus breeds reared in temperate climates. Hence, a fundamental step to meet the increasing global demand for beef is to develop specific management for B. indicus-influenced cattle in tropical or subtropical environments. Bos taurus and B. indicus are different subspecies, and diverge in social and biological functions due to selection pressure caused by complex evolutionary and domestication processes. Bos indicus cattle display different social responses compared with B. taurus counterparts, which must be taken into account by management planning as these traits directly impact cattle performance and welfare. In tropical and subtropical regions, warm-season perennial C4 grasses are the dominant forages, and their availability has a significant influence on the productivity of beef cattle systems. The resilience of C4 grasses under adverse conditions is one of their most important characteristics, even though these forages have reduced nutritive value compared with forages from temperate climates. Accordingly, nutritional planning in tropical and subtropical conditions must include management to optimize the quantity and quality of C4 forages. Nutritional requirements of cattle raised within these conditions also require special attention, including inherent metabolic compromises to cope with environmental constraints and altered energy requirements due to body composition and heat tolerance. Nutritional interventions to enhance beef production need to be specifically tailored and validated in B. indicus-influenced cattle. As an example, supplementation programs during gestation or early life to elicit fetal programming or metabolic imprinting effects, respectively, yield discrepant outcomes between subspecies. Bos indicus-influenced cattle produce carcasses with less marbling than B. taurus cattle, despite recent genetic and management advances. This outcome is mostly related to reduced intramuscular adipocyte volume in B. indicus breeds, suggesting a lesser need for energy stored intramuscularly as a mechanism to improve thermotolerance in tropical and subtropical climates.

Effects of a single trace mineral injection at beginning of fixed-time AI treatment regimen on reproductive function and antioxidant response of grazing Nellore cows

Two experiments evaluated the effects of injectable trace minerals (ITM) administered 11 d before artificial insemination (AI) on body weight (BW), body condition score (BCS), ovarian structures, pregnancy rate, and antioxidant response of Nellore cows. In Experiment 1, 20 multiparous cows were assigned to one of two treatments: subcutaneous injection (6 mL/cow; 11 d before AI) of saline solution or ITM (60, 10, 5, and 15 mg/mL of Zn, Mn, Se and Cu, respectively) and BW, BCS, ovarian structures and blood were evaluated. In Experiment 2, 1,144 multiparous cows were assigned to same treatments described in Experiment 1 and pregnancy rate on d 30 was evaluated. In Experiment 1, ITM did not affect (P ≥  0.23) BW, dominant follicle size, ovulation rate, and plasma concentrations of haptoglobin, ceruloplasmin and progesterone (P4). The ITM treatment tended to increase (P =  0.06) cow BCS and reduce (P ≤  0.06) corpus luteum (CL) diameter and volume. Furthermore, ITM treatment tended to increase (P =  0.06) plasma concentrations of SOD and increased (P =  0.007) GSH-Px compared with saline injection. In Experiment 2, ITM treatment tended (P =  0.06) to increase pregnancy rate of cows with BCS ≤ 5.0 but not cows with BCS > 5.0 (P =  0.99). The ITM treatment did not alter BW, plasma P4, and acute phase response, but enhanced plasma concentrations of antioxidant enzymes, and tended to enhance BCS and pregnancy rates to AI of cows with BCS ≤ 5.0, even though there was a smaller corpus luteum size.

Influence of repeated trace mineral injections during gestation on beef heifer and subsequent calf performance

Commercial Angus heifers (n = 190; body weight (BW) = 315 ± 49.3 kg) were used to determine the effects of trace mineral injections during gestation on heifer and subsequent calf performance. Heifers received three previous subcutaneous trace mineral (Multimin 90 [MM]; n = 93) or sterilized physiological saline (CON; n = 97) injections approximately 90 d apart. These treatments were maintained and subsequent injections were given 205, 114, and 44 ± 26 d prepartum. Heifers were provided free-choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation (296 ± 26 d prepartum) and 5- to 10-week intervals thereafter. Liver samples were collected at trial initiation, 5 and 176 ± 3 d postpartum from a subset of cows to determine trace mineral status. Milk production was assessed on 80 cow-calf pairs (40/treatment) at 71 ± 15 d postpartum. Cows were artificially inseminated (AI) 82 d postpartum and then exposed to bulls for 38 d. Data were reported from 174 calves (n = 87 calves/treatment). Calf liver samples were collected 5 and 147 ± 3 d postpartum to determine trace mineral status. Calf weaning BW was collected at 159 ± 26 d postpartum. Calf performance including calving date, birth BW, weaning BW, average daily gain (ADG), and health data were collected. Heifer BW and BCS did not differ (P ≥ 0.72) throughout the experiment. Multimin heifers tended (P = 0.08) to have greater initial liver Se and tended to have decreased (P = 0.08) initial liver Zn compared with CON. At calving, MM cows had increased (P ≤ 0.01) liver Cu and Se. There was no difference (P ≥ 0.47) in Julian calving date, calving percent, or unassisted births. Calf birth BW was lesser (P = 0.02) for MM than CON calves, and MM calves had greater (P = 0.03) liver Cu concentrations at birth than CON calves. Despite MM cows having increased (P < 0.01) milk production, calf weaning BW and ADG were not different (P ≥ 0.87). In addition, calf morbidity and mortality were not different (P ≥ 0.43) between treatments. Calf mineral status was not different (P ≥ 0.57) at the time of weaning regardless of treatment; however, MM cows had decreased (P = 0.03) liver Zn. Multimin cows had decreased (P = 0.05) AI pregnancy rates, yet there was no difference (P = 0.34) in overall pregnancy rate. Supplementing an injectable trace mineral during heifer development and gestation increased cow milk production and resulted in decreased AI pregnancy rates; however, there was no effect on overall pregnancy rates or preweaning calf health or performance.

Effect of repeated trace mineral injections on beef heifer development and reproductive performance

To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers (n = 290; 199 ± 34.3 kg; 221 ± 22 d of age) were utilized in a completely randomized design. Heifers were stratified by body weight (BW) and were administered an injectable trace mineral (MM; Multimin 90) or saline (CON) given subcutaneously, post-weaning at 221, 319, 401, and 521 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue, red clover pastures and were supplemented with corn distillers grains (2.7 kg per heifer per day) and given access to free choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation and 4- to 7-wk intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers per treatment) were collected at 269, 310, and 361 ± 22 d of age. Blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers per treatment to determine trace mineral status. At 319, 372, and 421 ± 22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for cyclicity determination. Estrous synchronization was initiated, and reproductive tract scores (RTS) were collected at 421 ± 22 d of age, and heifers were bred via artificial insemination (AI) at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON heifers. Respiratory rates were greater (P = 0.05) for MM than CON heifers at 269 ± 22 d of age but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ (P ≥ 0.54). However, MM heifers had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON, and there was no difference (P = 0.60) in liver Mn. Antral follicle count and ovarian size did not differ (P ≥ 0.51) due to treatment. Throughout development, number of heifers cycling was lesser (P < 0.01) for MM than CON heifers. However, there was no difference (P ≥ 0.19) in RTS, AI pregnancy rates, or overall pregnancy rates. Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or pregnancy rates.