Influence of corn supplementation to beef cows during mid- to late-gestation: Supplementation decreases placental microvascular surface density but does not alter uterine blood flow or neonatal performance

Authors: TANNER, A - North Dakota State University; BAUER, M - North Dakota State University; SWANSON, K - North Dakota State University; KENNEDY, V - North Dakota State University; KIRSCH, J - North Dakota State University; GASPERS, J - North Dakota State University; NEGRIN-PEREIRA, N - North Dakota State University; FONTOURA, A - North Dakota State University; PERRY, G - Texas Agrilife Research; STOKKA, G - North Dakota State University; RODAS-GONZALES, A - University Of Manitoba; WARD, A - North Dakota State University; DAHLEN, C - North Dakota State University; Neville, Bryan; BOROWICZ, P - North Dakota State University; REYNOLDS, L - North Dakota State University; OMINSKI, K - University Of Manitoba; VONNAHME, K - North Dakota State University

Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2023
Publication Date: 1/10/2023
Citation: Tanner, A.R., Bauer, M.L., Swanson, K.C., Kennedy, V.C., Kirsch, J.D., Gaspers, J., Negrin-Pereira, N., Fontoura, A.B.P., Perry, G.A., Stokka, G., Rodas-Gonzales, A., Ward, A., Dahlen, C.R., Neville, B., Borowicz, P.P., Reynolds, L.P., Ominski, K.H., Vonnahme, K.A. 2023. Influence of corn supplementation to beef cows during mid- to late-gestation: Supplementation decreases placental microvascular surface density but does not alter uterine blood flow or neonatal performance. Livestock Science. 268. Article 105155. https://doi.org/10.1016/j.livsci.2023.105155.
DOI: https://doi.org/10.1016/j.livsci.2023.105155

Interpretive Summary: Low nutrient status is common in extensively managed beef cows, and can be resolved by improving forage quality, providing supplemental feed, or other alternative feeding strategies. When grazed forage is limited, alternative feeds can be given to cows. Previous research has demonstrated that supplementing cows with distillers grains during late gestation improved uterine blood flow and subsequent birth weight. In the current study, corn supplementation decreased maternal roughage intake and did not have negative effects on birth or weaning weights. While corn supplementation in cows seemed to alter placental capillary microvascularity, the differences in nutrient intake were not great enough to elicit differences in uterine or mammary hemodynamics. When applied properly, corn could be utilized to decrease forage intake of gestating beef cows when costs and availability are economically advantageous to the producer.

Technical Abstract: Gestating cows fed low-quality forage diets are often at risk of nutrient restriction, including energy, protein, or both. Thus, the objective of this study was to evaluate the effects of supplementing corn to gestating beef cows fed low-quality forage by tracking uterine and mammary hemodynamics and neonatal performance. We hypothesized that mid- to late-gestating beef cows receiving corn supplementation would have enhanced uterine and mammary hemodynamics and increased placental microvascularity. At d 100 of gestation, multiparous cows, predominantly of Angus breeding, and carrying male calves were assigned randomly to the following treatments: supplementation (SUP; n = 24) at the level of 0.2% (dry matter basis) of body weight (BW) or basal diet without supplement (CON; n = 23). All cows were fed the same basal diet (60% hay, 30% wheat straw, and 10% concentrated separator by-product). Intake was monitored individually with Insentec feeders from d 100 of gestation through calving. Every 28 days from the beginning of supplementation at d 100 until d 240 of pregnancy, uterine and mammary hemodynamics were monitored using Doppler ultrasonography, and jugular blood samples were obtained to determine hormone concentrations. At birth (CON: 277.6 ± 3.1 days; SUP: 275.5 ± 2.8 days; mean ± stdev), cow and calf BW, colostrum samples, and placental tissues were collected. Representative cotyledons were excised from fetal membranes and histological image analysis of placental vascularity with hematoxylin and eosin staining was conducted. All measurements and data collected were analyzed with the MIXED procedure and means were separated using the LSMEANS statement in SAS. Hemodynamics, placental weight, and colostrum variables were not altered by supplementation (P = 0.13). Placental microvascular surface density was suppressed (P < 0.01) by maternal corn supplementation. The differences in nutrient intake were not great enough to elicit differences in uterine or mammary hemodynamics, even though placental vascular surface density was decreased by corn supplementation in multiparous beef cows. Moreover, the few alterations in the maternal endocrine profiles due to corn supplementation did not translate into negative endocrine or early developmental changes in the offspring. Corn may be a good substitute for hay when costs and availability are economically advantageous to the producer.