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The objective was to determine the effects of a decreased interval of progesterone on the ovulatory follicle prior to fixed-timed artificial insemination (FTAI) in a 7 & 7 Synch estrous synchronization protocol using estrus expression (EE), FTAI pregnancy rates (AIPR) on 37±2d, and overall pregnancy rates (OPR) after a 60d bull exposure 90±2d determined via ultrasound. Using conventional Angus semen, multiparous Angus-cross cows (n=201) from two locations were randomized by age and days post-partum into two treatments. Both treatments used a controlled internal drug releasing device (Eazi-breedTM CIDR; 1.38g progesterone) inserted intravaginally -14d of the protocol simultaneous to administration of prostaglandin F2a (PGF; 500µg cloprostenol sodium; Estrumate®). In the first treatment (7&7), gonadotropin-releasing hormone (GnRH; 86µg gonadorelin; Fertagyl®) was administered on -7d. In the second treatment (8&6), GnRH was administered on -6d. Both treatments were then administered PGF simultaneous to CIDR removal on 0d, 66±2h prior to FTAI and administration of GnRH. EE was determined at the time of artificial insemination using an EstrotectTM patch (Rockway Inc., Spring Valley, WI). EE was signified as a patch with 50% or more of the color rubbed off or missing. Subsequently, a patch with less than 50% of the color rubbed off, was not. AIPR, OPR and EE were analyzed by treatment using the GLIMMIX procedure on SAS 9.4 (SAS Institute Inc., Cary, NC.). There was a significant effect on EE (P=0.01), a tendency on PR (P=0.08), and no effect on OPR (P=0.53) by treatment. EE, AIPR, and OPR for 7&7 were 95±2.1%, 82±3.7% and 96.7±1.7% and for 8&6 were 86±4.0%, 91±3.1% and 98±1.5%, respectively. In conclusion, the altered timeframe of GnRH administration affected EE and tended to affect PR in multiparous beef cows, suggesting that GnRH administration may improve PR when administered 6d, instead of 7d, prior to CIDR removal. [ABSTRACT FROM AUTHOR]

• Holstein steers consumed 22 % more DM (kg 100 kg of BW), on average, than Angus steers when fed for ad libitum intakes. • Holstein had greater mean ruminal pH and similar diet digestibility when compared to Angus, regardless of corn processing. • Feeding dry-processed corn grain, as either dry rolled or finely ground corn, decreased ruminal pH. • Compared to feeding WSC, starch digestibility improved by 5% when processed corn grain was fed. Objectives were to evaluate the effects of cattle breed, Holstein or Angus, and corn processing methods on total tract digestibility, and ruminal pH and volatile fatty acid concentrations (VFA). Six Holstein (BW = 548 ± 6.3 kg) and 6 Angus steers (BW = 596 ± 7.6 kg) previously fitted with rumen cannulae, were assigned to a 2 × 3 factorial arrangement of treatments. Factors included breed, Holstein or Angus, and corn processing method, whole shelled corn (WSC), dry rolled corn (DRC), or finely ground corn (FGC). Steers were fed diets containing 815 g/kg corn grain, 100 g/kg grass hay, 65 g/kg soybean, and 20 g/kg supplement. Steers were fed in a replicated 3 × 3 Latin square split-plot design. Each period consisted of 14 d diet adaptation followed by 7 d of sample collection. On d 1, rumen contents were collected. Ruminal pH was recorded at 0, 3, 6, 12, and 18 h after feeding and a portion of the strained ruminal fluid was subsampled at 0 and 3 h for VFA analysis. From d 2–7, feces, feed, and refusals samples were collected and analyzed for DM, NDF, and starch. Data were analyzed using the MIXED procedures in SAS (v9.4 SAS Inst. Inc., Cary, NC). Repeated measures were used to analyze changes in ruminal pH and VFA over time. There was no interaction of breed × diet (P ≥ 0.16) on diet intake and digestibility. Holstein steers had a greater (P ≤ 0.05) intake than Angus steers, regardless of diet. There was no effect (P ≥ 0.81) of breed on diet digestibility. Digestibility of DM, OM, and starch were reduced (P ≤ 0.03) when corn grain was fed whole, regardless of breed. There was an interaction of breed × diet (P = 0.02) on ruminal pH. Angus steers fed FGC had the most acidic ruminal pH, while ruminal pH in Holstein steers fed FGC was similar to ruminal pH Holstein steers fed WSC or DRC. There was no interaction of breed × diet (P = 0.28), nor were there main effects of breed (P = 0.21) or diet (P = 0.92), on total VFA concentrations. Although Holstein steers ate 22 % more DM than Angus steers, they were able to sustain a greater (P = 0.04) ruminal pH. Compared to feeding WSC, starch digestibility improved by 5% when processed corn grain was fed, regardless processing method. [ABSTRACT FROM AUTHOR]

The objectives of this study were to compare ruminal total tract digestibility, bacterial communities, and eating and rumination activity between Holstein and Angus steers fed grain- or forage-based diets. Six Holstein steers (average body weight [ BW ] = 483 ± 23 kg) and six Angus steers (average BW = 507 ± 29 kg), previously fitted with rumen cannulae, were fed in a crossover design with a 2 × 2 factorial arrangement of four treatments: 1) Holsteins fed a grain-based diet, 2) Holsteins fed a forage-based diet, 3) Angus fed a grain-based diet, and 4) Angus fed a forage-based diet. Each period was 35 d with 26 d of diet adaptation and 9 d of sample collection. On days 1 and 2 of collection, feeding activity was recorded for 48 h. On day 3, rumen contents were sampled to measure ruminal pH at 0, 3, 6, 12, and 18 h after feeding. A portion of the strained ruminal fluid was subsampled at 0, 3, and 6 h for volatile fatty acids (VFA) analysis. Rumen contents were subsampled at 3 h for analysis of bacterial communities. From day 4 to 8, total fecal excretion, feed, and refusals samples were collected and analyzed for dry matter (DM), neutral detergent fiber (NDF), and starch. On days 8 and 9 (0 and 3 h post-feeding, respectively), total reticulorumen evacuation was conducted and contents were weighed. Data were analyzed using the MIXED procedures in SAS (v9.4 SAS Inst. Inc., Cary, NC). Repeated measures were used to analyze changes in ruminal pH and VFA over time. There were no interactions of diet × breed (P ≥ 0.07). While the main effects of diet were expected, unique to these data is the fact that bacterial diversity and richness were reduced (P < 0.01) in cattle fed grain-based diets. There was no main effect (P > 0.34) of breed on total tract DM, organic matter, and starch digestibility, but Angus cattle had greater (P = 0.01) NDF digestibility than Holsteins. The increased NDF digestibility may be associated with a numerical (P = 0.08) increased numbers of bacterial species in Angus steers compared with Holstein steers. Holstein steers also spent more time (P ≤ 0.05) ruminating than Angus steers. There was no effect (P > 0.80) of breed on reticulorumen content at feeding time; however, Holstein steers had greater (P = 0.04) reticulorumen content on a wet basis 3 h post-feeding. Although Holstein steers spent more time ruminating, Angus steers were better able to digest NDF when compared with Holsteins, regardless of basal diet, and this improvement may be related to changes in bacterial communities in the rumen or to rumination activity. [ABSTRACT FROM AUTHOR]