Maternal Nutrition Management in Late Gestating Beef Cattle and Its Impact on Offspring Performance

Abstract

This dissertation aimed to elucidate how different dietary supplements can positively impact dam's productivity and optimize calf performance through maternal nutrition. With that, two trials evaluated nutritional management of late-gestating beef cows to enhance offspring productivity. The goal of trial 1 was to evaluate the effects of rumen-protected omega-3 fatty acids (eicosapentaenoic (EPA) and docosahexaenoic (DHA)) supplementation to first-calf beef heifers during third trimester gestation on performance and physiological responses of the offspring. The goal of trial 2 was to evaluate the effects of three sources of Cu, Zn, and Mn (sulfate, organic, and hydroxychloride) supplementation to beef cows during third trimester on performance and physiological responses of the offspring. In the first trial, forty-four pregnant Angus first-calf heifers were ranked by initial body weight (BW) and body condition score (BCS), and assigned to receive a supplement containing 234 g/ heifer/ feeding of Ca salts of PUFA based on EPA and DHA acids (OMG, Strata; Virtus Nutrition LLC, Corcoran, CA; n= 22), or 2) or 234 g/heifer/ feeding of Ca salts of saturated and monosaturated fatty acids based on palmitic and oleic acids (CON; EnerGII, Virtus Nutrition; n= 22). From day 0 (beginning of the first trimester) until calving, cows were gathered and fed the treatments thrice a week. From day 11 (days of gestation 195 ± 5.1) to calving, cows were allocated to rangeland pasture. First-calf heifer BW and BCS were recorded (days −10 and −9), and blood was collected on day −10, and upon calving. Calves were weaned on day 260, and preconditioned from days 260 to 302, and remained on the feedlot from days 303 to 350. No differences were detected for heifer BW or BCS changes at the beginning of the trial and at calving (P ≥ 0.33 and P ≥ 0.65, respectively). A tendency for greater concentration of colostrum IgG (P = 0.08) was observed in heifers supplemented with OMG vs. CON cohorts. There were no differences (P ≥ 0.31) among treatments at calving for calving rate, birth BW, heart girth, and from OMG heifers had greater (P = 0.04) plasma IgG concentration compared to CON calves. No differences were observed (P ≥ 0.11) for weaning rate and age, birth to weaning average daily gain (ADG), weaning weight, liver enzymes, and serum antibodies against respiratory viruses. During the preconditioning, OMG calves had greater (P ≤ 0.05) final BW and ADG compared with calves born to CON heifers. These differences in performance remained (P ≤ 0.05) throughout the receiving phase. A treatment × day interaction was detected (P = 0.05) for plasma cortisol concentration, which was greater (P < 0.01) for calves born to OMG heifers on days 260 and 263 and lower (P < 0.01) on day 306 compared to CON cohorts. In the second trial, seventy-two nonlactating, pregnant Angus cows were ranked by pregnancy type (artificial insemination or natural service), BW, and BCS and assigned to receive a supplement containing: 1) Cu, Mn, and Zn sulfate source (INR; n = 24); 2) Cu, Mn, and Zn organic-complexed source (ORG; n = 24); or 3) Cu, Mn, and Zn hydroxychloride source (HDX; n = 24) from day 0 (beginning of the first trimester) until calving, cows were gathered and fed the treatments thrice a week. Cow BW and BCS were recorded, and blood was collected on days 10 and 11, upon calving, and at weaning. Liver biopsies were performed in all cows on day 10 and upon calving (cows and calves). Longissimus muscle (LM) biopsies were performed, and blood was collected in all calves upon calving. Calves were weaned on day 260, backgrounded for 99 d, and then sent to a commercial feedyard. Calves blood samples were collected on days 245, 260, 264, 268, 275, 280, and 288. No differences were detected (P ≥ 0.31) for cow BW and BCS changes among treatments during gestation, and mineral sources did not increase (P ≥ 0.16) mineral liver concentrations of Zn, Mn, Se, and Co at parturition. However, there was a tendency (P = 0.07) for HDX to have increased liver Cu concentration vs. ORG and INR cows. Cows fed HDX and ORG had increased (P ≤ 0.03) BCS at weaning, and BCS change (P ≤ 0.03) from parturition to weaning vs. INR cows. No treatment differences were detected (P ≥ 0.21) for calf birth measurements, IgG levels, mRNA expression of hepatic enzymes, or LM genes associated with muscle and adipose tissue development. At weaning and during back¬grounding, no treatment differences were detected (P ≥ 0.21) for offspring performance, health outcomes, blood hormones, or metabolites. However, a tendency for a treatment × day interaction was detected (P = 0.07) for haptoglobin con¬centrations, which was reduced (P < 0.01) in calves from cows supplemented with HDX vs. calves from cows supplemented with ORG and INR 15 d after weaning. No treatment effects were noted (P ≥ 0.35) for final BW, feedyard ADG, and carcass traits between treatment groups. Collectively, these results are suggestive of programming effects on postnatal offspring health and productivity resultant from omega-3 fatty acids, on the other hand, different sources of Cu, Mn, and Zn supplementation during last trimester of gestation had little to no effect on offspring performance. However, the true potential of trace minerals from different sources such as hydroxychloride and omega-3 fatty acids supplementation during late gestation on the offspring performance still needed to be further explored.