51 A preliminary study of the effect of dietary cottonseed on the follicular reserve of does artificially infected with Haemonchus contortus.

Abstract

Abstract Numerous studies have reported the negative effect of cottonseed gossypol on the ovarian reserve of the follicles, impairing female fertility. Injuries resulting in the depletion of primordial follicles can lead to permanent infertility. At birth, female mammals possess a fixed number of ovarian primordial follicles, which develop into primary, secondary, and antral follicles in a continuous and irreversible process. In this study, we evaluated the potential effects of dietary cottonseed gossypol in combination with parasitic infection on ovarian follicular reserve in meat goats. A total of 40 Boer x Spanish cross does were randomly subjected to cottonseed (CS) and parasite (P: Haemonchus contortus) in a 2x2 factorial arrangement of does (n = 8) per treatment groups (CS-/P-; CS+/P-; CS-/P+, and CS+/P+). Does were artificially infected with Haemonchus contortus for 2 d, and after 25 d, they began shedding parasite eggs. Thereafter, does were fed a hay diet supplemented with cottonseed (0.5% BW; CS+) or concentrate (CS-), to meet the nutritional requirements. Ten weeks later, animals were slaughtered, and ovaries of each treatment group (n = 4) were fixed with formalin and subjected to a standard procedure of histology staining (Periodic acid–Schiff and Hematoxylin counterstaining). Cuts of one left and one right ovary of two does were placed on microscope slides, and 48 slides were subjected to a microscope visualization (EVOS FL Auto; 20x magnification). Primordial follicles were classified as healthy (stained nucleus), unhealthy (pycnotic), and undetermined. Data were analyzed with ANOVA 1 and expressed as mean ± sem. P < 0.05 indicates a significant difference. A total of 20,562 primordial follicles corresponding to 10,410 (50.6%) healthy; 3,729 (18.1%) unhealthy; and 6,909 (33.6%) undetermined were examined; of which 26%, 20%, 31%, and 23% of total primordial follicles belonged to the CS-/P-, CS-/P+, CS+/P-, and CS+/P+ treatment groups, respectively. A significantly (P < 0.05) greater number of follicles were counted on left vs. right ovary sections (11,584 vs. 8,978) corresponding to 56.3% vs. 43.7% of total follicle counts. Averages of 121 ± 6 vs. 101±6 follicles were calculated per left and right ovary sections. Diets containing cottonseed (CS+/P-) increased the average number of follicles per ovary section, while parasite infections significantly (P < 0.05; CS-/P+ and CS+/P+) decreased these numbers. Regardless of the treatment group, the proportions of healthy follicles remained comparable between treatment groups. We concluded that dietary cottonseed and parasitic infections inversely affect ovarian follicle reserve, while the proportions of healthy follicles were unaffected across treatment groups. Nevertheless, higher microscopic magnification is needed to better characterize the large proportion of undetermined follicles.