Abstract
Twenty-seven mares with body condition scores (BCS) of = 4.0 were stratified by expected foaling date and age, and assigned to one of three treatment groups. The control-thin (T) group was fed a conventional diet to maintain its initial BCS. Control-gain (C) mares were fed the same diet to gain 12% of their body weight by 90d postpartum. The FS group was fed to gain at the same rate as C on a l 2% fat-supplemented concentrate. The hypothesis that fat-supplementation would elevate serum LH concentrations and improve reproductive performance was tested. Days to first ovulation (FOV) and cycles per conception (CPC) were not different among groups (P > . 10). Days to conception (DTC) were greater in FS mares as compared to C mares (P < .05). This significance may be due to several BCS factors more so than being a result of diet. Pregnancy rates were different (P < .10), with FS mares having a higher pregnancy rate than both C and T. Areas under the curves (AUC) and LH peak (PK) concentrations for the first (FST) and fertile (FER) postpartum ovulation were not different among treatment groups (P > .10,. P > .15, respectively). A trend was observed towards FS mares having higher FSTPK concentrations as compared to C mares (P =.21). Additionally, FS mares tended to have larger FERAUC's than both C (P = .12) and T (P = . 18) groups, and larger FERPK'S than C mares (P =.11). Several weak trends were seen especially when treatments were separated into the age groups, young (< 10 y) and old (= 10 y). In conclusion, fat supplementation of mares foaling in thin BCS did not appear to produce significant changes in amplitude or magnitude of LH concentrations (P > . 15), d to FOV (P > .35), or CPC (P > .55). Fat-supplemented mares had significantly higher pregnancy rates (P < .10). Days to conception was also greater in FS mares as compared to C mares (P < .05). However, due to several confounding errors in protocol and execution of the treatments these differences can not be attributed solely to effects of fat- supplementation.
Hagstrom, Debra Jean (1999). Luteinizing hormone concentrations in mares foaling in thin body condition and fed a fat-supplemented diet. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -H34.