Conceptus secretion of oestrogen on Day 11 of gestation is involved with establishment of pregnancy in the pig. Changes in oestrogen receptor (ER) protein, mRNA and cellular localization in the endometrium were evaluated during the oestrous cycle and early pregnancy of the gilt. In nonpregnant gilts, concentration of nuclear ER in the endometrium increased from Days 0 to 12 followed by a decline on Day 15 of the oestrous cycle. In pregnant gilts, changes in endometrial nuclear ER during Days 10, 12, 15 and 18 were similar to that in cyclic pigs. Analysis of endometrial ER mRNA expression did not detect any difference between cyclic and pregnant pigs between Days 10 and 15 postoestrus. Expression of ER mRNA in endometrium of cyclic and pregnant gilts was greatest on Day 10 followed by a decline on Day 15. Endometrial ER mRNA increased on Day 18 of the oestrous cycle, but remained low during pregnancy. Immunocytochemical localization of ER in the endometria of cyclic and pregnant gilts indicated that there was intense staining for ER in stromal cells and moderate to strong staining in surface and glandular epithelial cells during oestrus (Day 0) and Day 18 of the oestrous cycle. However, stromal ER staining was absent from Days 5 to 15 of the oestrous cycle and continued to be suppressed on Day 18 of pregnancy. Immunocytochemical staining of ER in the surface and glandular epithelium was readily detectable from Days 0 to 12 of the oestrous cycle and during pregnancy. Intensity of staining for ER declined in surface epithelial cells on Day 15 in both cyclic and pregnant pigs whereas positive staining for ER in glandular epithelium was absent. Staining for ER on uterine surface epithelial cells increased during pro-estrus (Day 18) of cyclic gilts but remained similar to Day 15 in pregnant gilts. Changes in endometrial ER protein, mRNA and localization in surface epithelium are consistent with a physiological role for conceptus oestrogen secretion in uterine function and maternal recognition of pregnancy in the pig.

Luteal lifespan is short after first postpartum ovulation in early-weaned beef cows unless cows are pretreated with a progestogen. Regression of the short-lived corpus luteum in the postpartum beef cow is due to a premature release of prostaglandin F2\ g=a\(PGF2\g=a\) from the uterus. The premature release of PGF2\g=a\ may be mediated through lower concentrations of receptors for progesterone, higher concentrations of oxytocin receptors, or both, in the endometrium. Thirty-one beef cows were randomly assigned to four groups at parturition. Calves from cows assigned to the short cycle group (n = 6; control) and the short cycle/ endometrium group (n = 10) were weaned at 30\p=n-\32 days post partum. (González-Padilla et al, 1975) and sheep (Berardinelli et al, 1980) and following the first postpartum ovulation in cattle (Odde et al, 1980). In anoestrous ewes, induced ovulation by treatment with GnRH is followed by subnormal luteal function (Haresign et al, 1975

In Exp. 1, changes in uterine fluid content of protein, calcium and prostaglandin F2 alpha (PGF) were examined between d 30 to 144 of gestation. Volume of uterine fluid (mean +/- SE) in the nongravid uterine horn of unilaterally pregnant ewes increased (P less than .05) between d 30 (8 +/- 1 ml) and d 144 (749 +/- 46 ml) of gestation. Protein concentration and total protein in uterine fluid also increased (P less than .05) between d 30 (2.3 +/- .4 mg/ml; 19 +/- 7 mg) and d 144 (23.5 +/- 3.3 mg/ml; 17.4 +/- 2.0 g). Total recoverable calcium (mg) in secretions increased from .1 mg (d 30) to over 1.4 g (d 144) due to day of gestation effects (P less than .05). Total PGF also increased (P less than .01) from 7 ng on d 30 to 15.7 g on d 144. In Exp. II, ovariectomized (OVX) ewes were treated with either corn oil, estrone (E), progesterone (P) or P+E (PE) for 30 d. Treatment with P or PE increased calcium concentration and content (P less than .01) in secretions, but differences in uterine fluid volumes and concentrations of protein and PGF were not significant. Treatment of OVX ewes with P stimulated (P less than .05) in vitro synthesis of secretory proteins by endometrium, whereas treatment with E enhanced release of unlabeled proteins (P less than .05). The major endometrial secretory proteins were identified in allantoic fluids from d 60 to term and were detected along the mesenchymal border of the chorioallantois using immunohistochemistry. Results from this study indicate that P may be a primary hormone regulating accumulation of fluid, protein, calcium and specific endometrial proteins in the uterine lumen during gestation, and that uterine milk proteins gain access to the fetal-placental unit.

Two studies were conducted to 1) assess the effectiveness of the California mastitis test (CMT) relative to direct microscopic somatic cell count (DMSCC) and(or) somatic cell count (SCC) procedures for detecting subclinical mastitis in ewes, 2) determine the incidence of subclinical mastitis based on repeated or single sample measures and organisms associated with the inflammation, and 3) assess the relationship between milk quality measures and lamb performance. The relationship between DMSCC and SCC scores was significant (P less than .01); 90% of the variation in DMSCC scores was accounted for by SCC scores. In contrast, CMT scores accounted for only 26% of the variation in DMSCC and 30 to 34% of the variation in SCC scores. Incidence of inflammation varied from 17 to 50% of ewes tested, depending on the study and the method of assessment. Staphylococcus species were cultured from 14/41 samples tested, with cultures of Streptococcus species (3/41) and Micrococcus species (1/41) also present. The effect of subclinical mastitis in ewes on lamb performance was minimal when assessed by regressing lamb weights on subclinical mastitis and milk quality scores. In conclusion, growth performance of lambs in a management system where they had access to supplemental feed was not influenced by the quality of milk produced by ewes, or by the degree of subclinical mastitic inflammation present when they suckled.

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