Repository logo

Effects of monensin sodium, plant extracts and injectable trace minerals on feedlot performance, fertility and morbidity of beef cattle




Fischer, Mariah, author
Ahola, Jason, advisor
Peel, Kraig, advisor
Seidel, George, committee member
Engle, Terry, committee member

Journal Title

Journal ISSN

Volume Title


Two studies were conducted to evaluate the effects monensin sodium, plant extracts, and injectable trace minerals on heifer and bull fertility, and calf feedlot performance and morbidity. In the first study, Angus heifers (n = 107; 259.3 ± 21.0 d of age), blocked by weaning BW (262.7 ± 29.9 kg; d -19), were randomly assigned to treatments in a 2 x 2 factorial design, where all heifers received the same basal ration consisting of a 30% CP liquid supplement containing 200 mg/0.45 kg monensin sodium. Treatments were applied daily to the basal ration as topdressed supplements and were fed at a rate of 0.32 kg•hd-1•d-1. Treatments were as follows: 1) high level of monensin sodium (MON), where monensin sodium was topdressed at 200 mg•hd-1•d-1, 2) low level of monensin sodium plus the plant extracts cinnamaldehyde, capsicum oleoresin and eugenol (CCE), where plant extracts were topdressed at 11,000 mg•hd-1•d-1, 3) control (CON), low level of monensin sodium without topdressed supplements, or 4) high levels of monensin sodium with plant extracts (COMB), where monensin sodium was topdressed at 200 mg•hd-1•d-1 and plant extracts were topdressed at 11,000 mg•hd-1•d-1. In both studies, heifers were weighed and estrus detection patch status was recorded every 11 d. Age at puberty was determined by patch status and was recorded as the d the patch was first activated. A 14 d CIDR-PG-AI protocol was utilized to inseminate heifers, when heifers were 427.3 ± 21.0 d of age. In the 14 d CIDR-PG-AI, a controlled internal drug release device (CIDR) was inserted 33 d prior to AI and removed 14 d later. Prostaglandin was injected 16 d after CIDR removal, and heifers were inseminated 3 d later. Heifers were placed with bulls for natural service 21 d post AI. Pregnancy was determined 56 d post AI via ultrasound and 178 d post AI via rectal palpation. Calving records were used to validate ultrasound results. In the first study, there were no treatment main effects for initial or final BW (P > 0.05). There were no interactions between the main effects of monensin sodium fed at high concentrations and plant extracts for any feedlot or fertility performance variable (P > 0.05); however, there was a main effect of high levels of monensin sodium for heifer DMI from d 0 to 8 and d 8 to 15, where MON and COMB heifers had reduced DMI compared to CCE and CON heifers (P = 0.05). From d 11 to 22 and d 44 to 66, heifers that received plant extracts (CCE and COMB) had lower ADG than CON and MON heifers (P = 0.05). Feed efficiency tended (P = 0.08) to be improved in heifers fed high levels of monensin sodium (MON and COMB) compared to heifers fed low levels of monensin sodium (CCE and CON); however overall DMI, ADG, age at puberty and pregnancy rate were not affected by the main effects of high levels of monensin sodium or plant extracts (P > 0.05). In the second study, Angus bulls (n = 31, yr 1; n = 35, yr 2), heifers (n = 107) and steers (n = 105) were randomly assigned a treatment at weaning (278.6 ± 35.0 kg; 241.0 ± 19.6 d): 1) control (CON), no injection, or 2) injectable trace minerals (MIN), which included Cu, Zn, Se and Mn. The MIN treatment was administered at weaning (d 0) and again on d 64 (yr 1) and d 110 (yr 2) to bulls, and at weaning (d -19) and on d 135 to heifers. The second injections were 80 (yr 1) or 38 d (yr 2) prior to bull breeding soundness exams and 33 d prior to heifer AI. Steers received only the initial injection at weaning. Injections were administered at 1 mL/45.4 kg of BW at weaning and 1 mL/68.0 kg of BW prior to breeding soundness exams and AI, as per the product label. Bulls in both years exhibited no differences in overall ADG based on treatment (P > 0.05); however, MIN bulls had reduced ADG from d 64 to 113 (P = 0.05) versus CON. Steer and heifer ADG was not different across treatments (P > 0.05). Incidence of morbidity was not different among treatments for any class of cattle (P > 0.05). A licensed veterinarian performed the breeding soundness exams and Computer-Assisted Sperm Analysis was performed to analyze sperm motility, velocity, straightness and linearity objectively. Motility and morphology from breeding soundness exams were not effected by MIN (P > 0.05); however, in yr 2 there was a tendency for sperm from MIN bulls to have a higher percentage of secondary defects (P = 0.08). Sperm beat cross frequency was greater in CON in yr 2 (P < 0.01), and tended to be greater in CON in yr 1 (P = 0.10). Progressive velocity of sperm was greater in CON in yr 2 (P < 0.05). Neither BCS nor age at puberty in heifers was affected by treatment (P > 0.05). These results suggest there is no benefit to newly weaned calf performance or morbidity, or yearling bull or heifer fertility, when supplementing cattle with injectable trace minerals at weaning.


Rights Access


beef cattle
monensin sodium
plant extracts
trace minerals


Associated Publications