Effects of calcium salts of soybean oil on factors that influence pregnancy establishment in Bos indicus beef cows

Abstract Text:

This experiment compared fatty acid (FA) concentrations in plasma, reproductive tissues, as well as hormones, and expression of genes associated with pregnancy establishment in beef cows supplemented or not with Ca salts of soybean oil (CSSO) beginning after timed-AI. Ninety non-lactating multiparous Nellore (Bos indicus) cows were inseminated on d 0 of the experiment, and divided into 18 groups of 5 cows/group. Groups were randomly assigned to receive (as-fed basis) 100 g of protein-mineral mix + 100 g of ground corn per cow/d, in addition to: 1) 100 g/cow daily of CSSO (n = 9), or 2) 100 g/cow daily of kaolin (CON; rumen-inert indigestible substance; n = 9). Groups were maintained in a single Brachiaria brizanta pasture with ad libitum access to forage. However, groups were segregated daily and offered treatments individually during the experiment (d 0 to 18). Blood samples were collected and transrectal ultrasonography was performed to verify ovulation and corpus luteum (CL) volume immediately prior to AI (d 0), on d 7, and 18. On d 19, 36 cows (18 cows/treatment, 2 cows/group) diagnosed without the presence of a CL on d 0, but with a CL greater than 0.3 cm³in volume on d 7 and 18, were slaughtered for collection of conceptus, uterine luminal flushing, and tissue samples from the CL and endometrium. Data were analyzed using the MIXED procedure of SAS with group as experimental unit. Cows receiving CSSO had greater (P ≤ 0.08) concentrations of linoleic and other ω-6 FA in plasma, endometrium, CL, and conceptus compared to CON. On d 7, CSSO-supplemented cows had greater plasma progesterone concentrations (P = 0.02) and CL volume (P = 0.01) compared to CON, whereas no treatment effects were detected (P ≥ 0.20) for these parameters on d 18 (treatment × day interaction; P < 0.01). Cows receiving CSSO tended (P = 0.09) to have greater concentrations of IFNt in the uterine flushing media compared with CON. No treatment effects were detected (P ≥ 0.12) for mRNA expression genes associated with pregnancy establishment in endometrial (cyclooxygenase-2 and oxytocin receptor), CL (steroidogenic enzymes), and conceptus (IFNt) samples. In summary, supplementing beef cows with 100 g of CSSO beginning after AI favored incorporation of ω-6 FA into their circulation, reproductive tissues, and conceptus, without impacting expression of genes associated with pregnancy establishment on d 19 of gestation.

Keywords:

Beef cows; Calcium salts of soybean oil; Pregnancy