The effects of room temperature and light intensity before breeding and into early gestation were evaluated on the reproductive performance and well-being of gilts housed individually in crates. In eight replicates, estrus was synchronized in mature gilts (n = 198) and after last feeding of Matrix were randomly assigned to a room temperature of 15°C (COLD), 21°C (NEUTRAL), or 30°C (HOT) and a light intensity of 11 (DIM) or 433 (BRIGHT) lx. Estrous detection was performed daily and gilts inseminated twice. Blood samples were collected before and after breeding for determination of immune measures and cortisol concentrations. Gilt ADFI, BW, and body temperature were measured. On d 30 postbreeding, gilts were slaughtered to recover reproductive tracts to evaluate pregnancy and litter characteristics. There were no temperature × light intensity interactions for any response variable. Reproductive measures of follicle development, expression of estrus, ovulation rate, pregnancy rate (83.2%), litter size (14.3 ± 0.5), and fetal measures were not affected by temperature or lighting (P > 0.10). Gilts in COLD (37.6°C) had a lower (P < 0.05) rectal temperature than those in NEUTRAL (38.2°C) and HOT (38.6 ± 0.04°C). Both BW gain and final BW were greater (P < 0.0001) for gilts kept in HOT than those in NEUTRAL or COLD environments. Cortisol was greater (P < 0.01) for gilts kept in COLD compared with those kept in the HOT room. Gilts housed in the HOT environment made more postural changes (P < 0.05) than did those kept in either COLD or NEUTRAL temperatures. Gilts kept in the HOT temperature spent more total time lying and more time lying ventrally compared with those gilts housed in the NEUTRAL or COLD rooms. Total white blood cells and the percentage of neutrophils as well as neutrophil-to-lymphocyte ratio were all influenced (P < 0.05) by temperature but there was no effect (P > 0.10) of light or interaction with temperature on other immune cells or measures. These results indicate that temperatures in the range of 15 to 30°C or light intensity at 11 to 433 lx do not impact reproduction during the follicular phase and into early gestation for mature gilts housed in gestation crates. However, room temperature does impact physiological, behavioral, and immune responses of mature gilts and should be considered as a potential factor that may influence gilt well-being during the first 30 d postbreeding.

Follicle selection and maturation for determining ovulation rate in the pig appears to occur during much of the follicular phase and up to the time of ovulation. There is evidence to suggest that counts of follicles classified as ovulatory-sized at onset of estrus may not reflect the final corpora lutea counts. Follicle size heterogeneity has been reported at estrus and may be related to increased embryonic asynchrony and mortality (Hunter et al. 1989). It is not dear which follicles ovulate at estrus but reports indicate follicles > 4 mm are LH responsive (Dufour & Mariana 1993; Lucy et al. 2001). Counts and size measures for ovulatory follicles may differ by the follicle size classification system and in response to whether follicles were assessed by physical or ultrasound measurement (Soede et al. 1998; Knox et al. 2002; Bracken et al. 2006). We hypothesized that the numbers of follicles classified as ovulatory at estrus may not reflect expected ovulation rate or litter size. We performed two experiments to characterize the changes in follicle populations from onset of estrus (Experiment 1) and from time of weaning to ovulation (Experiment 2). In experiment 1, our objectives were to measure proportions of weaned sows having large, medium and small follicles on the two days before ovulation. A total of 21 sows that had expressed estrus and ovulated between day 2 and 3 and which had real-time ultrasound digital video recordings for both the left and right ovaries on the first (period 1) and second day (period 2) of estrus were included in this study. The images of the ovaries were obtained transrectally using an Aloka 500V ultrasound with a 7.5 MHz linear transducer. The images were digitally recorded and follicles individually counted and measured using a digital display system that was calibrated to the measures of the ultrasound. The follicles were classified as small (S, <3.5 mm), Medium 1 (M1, 3.5-4.99 mm), Medium 2 (M2, 5.0-6.49 mm), Large 1 (L1, 6.5-7.99 mm), Large 2 (L2, 8.0-9.49 mm), and Large 3 (L3, 9.5-12.0 mm). Data were analyzed using the GLM procedures of SAS for the main effects of sow and period (day 1 and 2 of estrus). The response measures included the proportions of sows having the specified size class, numbers of follicles in class, and the size of the follicles. Period did not affect the percentage (22%), number (<3 follicles), or size of small follicles (3.1 mm). Period during estrus also did not affect the percentage of sows with Mt follicles (90%), or their size (4.4 mm), but numbers were reduced (P < 0.05) in period 2 (6.5 vs. 4.5). Period did not affect the percentage of sows with (100%) or numbers (14.1 follicles) of M2, but size was increased (P< 0.05) in period 2 (5.8 vs. 5.9 mm). Period did not affect the percentage of sows having L1 (100%), but numbers (7.8 vs. 9.1, P-0.01) and size (7.2 vs. 7.3, P<0.05) were both increased in period 2. Period tended (P <0.10) to increase the percentage of sows having L2 in period 2 compared to period 1 (37 vs. 63%) but there was no affect on numbe...

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