The expression of four major steroidogenic enzymes in porcine theca and granulosa cell layers of preovulatory follicles was related to the levels of steroids in follicular fluid and gonadotropin concentrations in peripheral serum at slaughter. Ovaries were collected during proestrus, early estrus, and late estrus as evidenced by behavioral signs. Follicles were dissected from the ovaries, and theca, granulosa, and follicular fluids were pooled for each of 24 sows. Cytochromes P450 17 alpha-hydroxylase/17-20 lyase (P450c17), aromatase (P450arom) and side-chain cleavage (P450scc), as well as 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), were subjected to Northern and Western immunoblot analyses. The concentrations of estradiol-17 beta, testosterone, androstenedione, and progesterone were determined in follicular fluid, and peripheral serum was assayed for estradiol-17 beta, LH, and FSH. Stages of preovulatory development were verified by plasma levels of LH, FSH, and estradiol-17 beta. Thecca expressed P450c17, P450arom, P450scc, and 3 beta HSD whereas granulosa expressed only P450arom and low levels of P450scc. Thecal P450c17, thecal P450arom, and granulosa P450arom expression decreased coincidentally as serum estradiol-17 beta and follicular fluid estradiol-17 beta, testosterone, and androstenedione levels declined after the presumed gonadotropin surge. Unlike P450c17 and P450arom P450scc and 3 beta HSD remained relatively constant in theca and granulosa. From these data, we suggest that the theca interna may be the primary steroidogenic compartment of the porcine follicle during its final stages of preovulatory development. Moreover, preovulatory estrogen secretion appears to be controlled by the coordinated expression of a triad of enzymes in the porcine follicle that includes theca P450c17, theca P450arom and granulosa P450arom.

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Multiple linear regression equations were developed for predicting the percentage of fat content of beef and pork. The predictor variables were bioelectrical resistance, temperature, and weight of product. Equations were developed for trim and product ground through a .95- or a .32-cm plate. The trim, .95-cm, and .32-cm grinds had 64, 108, and 96 observations, respectively, for beef product and 56, 101, and 92 observations, respectively, for pork product. Each of these observations was the average of bioelectrical impedance measurements taken in triplicate. The fat percentage ranges were 4 to 50% for beef and 7.5 to 50% for pork. The prediction equation applied to beef trim provided the following values: R2 = .80, Mallows's C(P) = 5.1, and root mean square error = 6.64. The R2 for equations predicting fat percentage in .95- and .32-cm ground beef were .84 and .95, respectively. The prediction equation applied to pork trim provided the following values: R2 = .77, Mallow's C(P) = 5.0, and root mean square error = 6.2. The R2 for equations predicting fat percentage in .95- and .32-cm ground pork were .87 and .96, respectively. The analyses were repeated with data sets of observations with less than 35% fat. The sample sizes and R2 for the trim, .95-, and .32-cm ground beef were 48, .36; 76, .60; and 65, .86; respectively. The sample sizes and R2 for the trim, .95-, and .32-cm ground pork were 42, .64; 62, .66; and 58, .92; respectively. Resistance, temperature, and weight remained as predictor variables for ground product with less than 35% fat. The smaller the grind, the more accurate the prediction. These results are positive for developing inexpensive, on-line systems for efficiently mixing ground product to a specific fat percentage.

A 2-yr study was conducted to determine the first limiting nutrient for gain in nursing calves grazing native range in southeastern North Dakota. Thirty-two calves (20 steers, 12 heifers) in Trial 1 (169 +/- 5 kg initial BW) and 31 (16 steers, 15 heifers) in Trial 2 (214 +/- 5 kg initial BW) grazed common pastures. Calves were blocked by sex and stratified by weight. Calves were stratified by age of dam in Trial 1 and by pretrial milk intake (MI) in Trial 2. Treatments were nonsupplemented control (CON); energy supplement (ENERGY; 100% soyhulls); degradable intake protein supplement (DIP; 68% soyhulls, 32% SBM); and degradable with undegradable intake protein supplement (DIP+UIP; 80% sulfite-liquor treated SBM, 16% feather meal, 4% blood meal). In Trial 2, 5% molasses was added to all supplements with the ratios of other ingredients held constant. Supplements were formulated to be similar in NE. The DIP and DIP+UIP supplements supplied equal amounts of degradable protein. Supplemented calves were fed individually, with similar supplement DMI. Weight and MI were measured in July, August, and September. Forage intake (FI) was measured in July, August, and September of Trial 1 and July and August of Trial 2. Gain data were analyzed as a randomized complete block and MI and FI as a split-plot in time. Orthogonal contrasts were used to separate means and included CON vs supplemented, ENERGY vs protein, and DIP vs DIP+UIP. No trial effect or trial x treatment interactions (minimum P-value = 0.30) were detected for ADG. Supplemented calves gained faster than CON (P = 0.06). No other contrast differences were observed (minimum P-value = 0.50). Treatment did not affect FI (P > or = 0.55). Forage intake was lower (P < 0.001) in Trial 1 than in Trial 2. A linear increase (P = 0.0001) in FI (kg OM/d and percentage BW) occurred over time. Calves in Trial 2 consumed more (P = 0.004) fluid milk than calves in Trial 1, though no difference (P = 0.28) was observed relative to BW. No treatment or period differences were detected for fluid MI (minimum P-value = 0.23). Relative to BW, MI declined linearly (P = 0.0001) with successive periods. Energy may be limiting weight gain of nursing calves grazing native range in southeastern North Dakota.

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