Influence of post-insemination nutrition on embryonic development in beef heifers.
Previous studies have demonstrated that a decrease in nutrition immediately following AI reduces pregnancy success in beef heifers. The objective of this experiment was to determine if nutrient restriction following AI impacted early embryonic development among non-super ovulated heifers. Beef heifers in eight replications (Rep; Rep 1; n = 14, Rep 2; n = 15, Rep 3; n = 15, Rep 4; n = 14, Rep 5; n = 15, Rep 6; n = 15, Rep 7; n = 25, Rep 8; n = 25) across two locations (UMN, SDSU) were developed in a dry-lot and fed 125% NRC requirements from weaning to timed-AI (d 0). Heifers were timed-AI to a single sire in all replications. Immediately following AI, heifers were assigned, based on age, weight, and estrous response to one of two post-AI nutritional treatments. Half the heifers in each replication continued on the pre-insemination diet, serving as the control treatment (CON) and the remaining heifers were restricted to a sub-maintenance diet (RES). At UMN, heifers in the RES treatment were fed the same diet, but intake was limited to 80% NEm, while at SDSU, DMI remained the same, but diet composition was altered with the addition of straw to reduce NEmto 50% of requirements. On d 6, single embryos were collected nonsurgically and recovered embryos (CON; n = 46, RES; n = 42) were evaluated to determine quality (grade 1-9) and stage (1-4). Embryos were then stained and evaluated to determine the number of dead cells and total blastomeres. In Reps 1 through 6, concentrations of IGF-1 were assessed on d 0 and 6 and progesterone concentrations on d 4 and 6. Data were analyzed using the Mixed procedures of SAS. There were no treatment by Rep or treatment by location interactions for any embryo parameter evaluated, thus all data were pooled. Embryo stage and quality were improved (P < 0.01) in the CON (4.4 ± 0.16, 2.2 ± 0.19, respectively) compared to RES treatment (3.7 ± 0.16, 2.9 ± 0.19, respectively). Embryos in the CON treatment had greater total blastomeres (66.9 ± 5.05; P < 0.01) and tended to have a greater percentage of live cells (P < 0.10; 80.9 ± 4.19%) compared to RES (47.9 ± 5.41; 69.7 ± 4.39%, respectively). Progesterone and IGF-1 concentrations did not differ between treatments. In summary, nutrient restriction for 6 days immediately following AI resulted in poorer quality embryos that were delayed in stage of development, suggesting that immediate changes in nutritional status after insemination can alter early embryonic development.
North Central Research and Outreach Center, University of Minnesota, Grand Rapids, MN 55744, United States.
S G
SG
Kruse
North Central Research and Outreach Center, University of Minnesota, Grand Rapids, MN 55744, United States. Electronic address: gabridges@elanco.com.
G A
GA
Bridges
North Central Research and Outreach Center, University of Minnesota, Grand Rapids, MN 55744, United States.
B J
BJ
Funnell
North Central Research and Outreach Center, University of Minnesota, Grand Rapids, MN 55744, United States.
S L
SL
Bird
Department of Animal Science, University of Wyoming, Laramie, WY 82071, United States.
S L
SL
Lake
Department of Animal Science, University of Wyoming, Laramie, WY 82071, United States.
R P
RP
Arias
Department of Animal Science, South Dakota State University, Brookings, SD 57007, United States.
O L
OL
Amundson
Department of Animal Science, South Dakota State University, Brookings, SD 57007, United States.
E L
EL
Larimore
Division of Animal Sciences, University of Missouri, Columbia, MO 65211, United States.
D H
DH
Keisler
Department of Animal Science, South Dakota State University, Brookings, SD 57007, United States. Electronic address: George.Perry@sdstate.edu.
G A
GA
Perry
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D004622:Embryo, Mammalian / Q000166:cytology; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D039382:Maternal Nutritional Physiological Phenomena; D009752:Nutritional Status; D011247:Pregnancy; D011374:Progesterone / Q000097:blood
D011374:Progesterone; D007334:Insulin-Like Growth Factor I
Beef; Embryo development; Heifer; Nutrition