B. W. Neville

Effect of thiamine concentration on animal health, feedlot performance, carcass characteristics, and ruminal hydrogen sulfide concentrations in lambs fed diets based on 60% distillers dried grains plus solubles

Limited data are available regarding the influence of thiamine supplementation on the incidence of polioencephalomalacia (PEM) in lambs fed diets containing increased concentrations of S in the diet (>0.7%). Therefore, our objective was to evaluate the influence of thiamine supplementation on feedlot performance, carcass quality, ruminal hydrogen sulfide gas concentrations, and incidence of PEM in lambs fed a finishing diet containing 60% distillers dried grains with solubles (DDGS; DM basis). Two studies were conducted using completely randomized designs to evaluate the influence of concentration of thiamine supplementation. Study 1 used 240 lambs fed in 16 pens, whereas study 2 used 55 individually fed lambs. Lamb finishing diets contained 60% DDGS, which resulted in a dietary S concentration of 0.73% (DM basis). Treatments diets were based on the amount of supplemental thiamine provided: 1) no supplemental thiamine (CON), 2) 50 mg/animal per day (LO), 3) 100 mg/animal per day (MED), or 4) 150 mg/animal per day (HI). Additionally, in study 2, a fifth treatment was included, which contained 0.87% S (DM basis; increased S provided by addition of dilute sulfuric acid) and provided 150 mg of thiamine/animal per day (HI+S). In study 1, ADG decreased quadratically (P = 0.04), with lambs fed the CON, LO, and MED diets gaining BW at a greater rate than lambs fed the HI diet. In study 1, DMI responded quadratically (P < 0.01), whereas G:F tended to differ linearly (P = 0.08) to concentration of thiamine supplementation, with MED lambs having greater DMI and decreased G:F. No differences (P > or = 0.17) in lamb performance were observed in study 2. In both studies, most carcass characteristics were unaffected, with the exception of a tendency for decreased carcass conformation (study 1; P = 0.09) and greater flank streaking (study 2; P = 0.03). No differences in ruminal hydrogen sulfide concentration (P > 0.05) among treatments were apparent until d 10, at which point lambs fed the LO diet had less hydrogen sulfide concentrations than all other treatments. Lambs fed HI had the greatest concentrations of hydrogen sulfide on d 31 (1.07 g of hydrogen sulfide /m(3); P < 0.009). Ruminal pH did not differ (P = 0.13) and averaged 5.6 +/- 0.06. No clinical cases of PEM were observed during the course of either study. The use of thiamine as a dietary additive to aid in the prevention of PEM in finishing lambs does not appear to be necessary under the conditions of this study.

Influence of advancing season on dietary composition, intake, site of digestion, and microbial efficiency in beef steers grazing a native range in western North Dakota

Four ruminally and duodenally cannulated beef steers (388 +/- 12 kg) were used to evaluate effects of advancing season on forage quality, intake, site of digestion, and microbial efficiency while grazing mixed-grass prairie in western North Dakota. Five 11-d sample collections were conducted from late June to mid-November. Chromic oxide (8 g) was dosed twice daily at 0700 and 1900 h via gelatin capsule from d 2 to 11 of each collection period, and duodenal and fecal collections were performed on d 7 to 11. Masticate samples were collected for each sampling period. Dietary N declined linearly (P = 0.01), from 1.95% in June to 1.15% in November, whereas NDF increased linearly (P = 0.01), 72.4% in June to 85.1% in November. Total OM intake (g/kg of BW) decreased linearly (P <or= 0.01) from June to November, from 26.2 to 11.4 +/- 2.7 g/kg of BW, respectively, and ruminal fill increased linearly (P <or= 0.01) from June to November, from 45.4 to 65.9 +/- 3.3 kg, respectively. True ruminal OM and N digestion declined linearly (P <or= 0.01) with advancing season. Total tract OM, N, and NDF digestion declined linearly (P <or= 0.01). Microbial efficiency (g of microbial N/kg of OM truly fermented) increased linearly (P = 0.02) from late June to late November. Undegradable intake protein (UIP) intake (g/d) declined (P <or= 0.06) linearly and cubically from 374.4 in June to 215.9 g in November. Degradable intake protein (DIP) intake was 735.5 g/d in June and declined linearly (P <or= 0.01) to 99.5 g/d with advancing season. Likewise, microbial CP supply at the duodenum (g/d) declined linearly (P <or= 0.01) as season advanced. As expected, DIP (% of CP) decreased (P <or= 0.01; 66.1 to 31.9 +/- 5.8% for June to November, respectively), whereas percentage of UIP increased (P <or= 0.01; 33.9 to 68.1 +/- 5.8% for June to November, respectively) with advancing season. The portions of DIP and UIP (% of CP) were not different in late August and mid-September. These data imply that mixed-grass range forage consumed by cattle after late September is deficient in N, particularly DIP, and that forage intake may decrease and may be too low to support adequate cow performance. Supplementation could be implemented to overcome these deficiencies; however, additional research is needed to determine supplemental type and frequency needed to optimize nutritional and economic efficiency.

Technical note: A new surgical technique for ovariohysterectomy during early pregnancy in beef heifers1

We hypothesized that a standing flank ovariohysterectomy procedure could be developed in beef heifers that would provide high quality tissues for addressing critical questions during early pregnancy, while concomitantly keeping livestock stewardship a high priority. To test the hypothesis, we: 1) developed a standing flank ovariohysterectomy procedure for use in beef heifers, and 2) implemented this procedure in a cohort of heifers up to d 50 of pregnancy for tissue collections, documentation of post-surgical recovery, and assessment of feedlot finishing performance. Ovariectomy and cesarean section protocols are well established in research and veterinary medicine and were used as starting points for procedural development. Crossbred Angus heifers ( = 46; ∼ 15 mo of age; BW = 362.3 ± 34.7 kg) were used to develop this new surgical tissue collection technique. Heifers were subjected to the 5-d CO-Synch + CIDR estrous synchronization protocol so ovariohysterectomy occurred at d 16, 22, 28, 34, 40, and 50 of gestation. Key aspects of the standing flank ovariohysterectomy technique included 1) use of local anesthetic for a standing flank incision, 2) locate the uterine and ovarian arteries via blind palpation and ligate them through the broad ligament via an improved clinch knot, 3) cut the ovaries and uterus free from the broad ligament, 4) ligate the cervix and uterine branch of the vaginal artery, and 5) cut through the cervix and remove the reproductive tract. Surgical times, from skin incision to placement of the last suture, were influenced ( = 0.04) by stage of gestation. In pregnant heifers, time decreased from d 22 (120.0 ± 12.0 min) of gestation to d 40 (79.5 ± 12.0 min) of gestation; then increased at d 50 (90.5 ± 14.7 min) of gestation. Using this procedure, we obtained uterine, placental, and embryo/fetal tissues that had experienced limited hypoxia, little or no trauma, and thus were excellent quality for scientific study. All heifers recovered from surgery quickly and were moved to a finishing period. During the finishing period, ovariohysterectomized heifers had a DMI of 13.8 kg, gained 1.99 ± 0.35 kg/d, and had a G:F of 0.145 over 132-d. The standing flank ovariohysterectomy technique represents a new and viable model to economically obtain high quality tissues for investigating critical biological mechanisms during early pregnancy in beef heifers.

Interaction of corn processing and distillers dried grains with solubles on health and performance of steers

Feeding increased concentrations of distillers dried grains with solubles (DDGS) to ruminants has been avoided due to risks of S toxicity and concerns about animal performance. The objective of this study was to evaluate the influence of feeding an increasing concentration of DDGS and corn processing method on animal performance, incidence of polioencephalomalacia (PEM), and concentration of H(2)S gas in feedlot steers. Sixty steer calves (336 ± 13.2 kg) were individually fed for an average of 136 d in a completely random design with a 3 × 2 factorial arrangement of treatments. Main effects included concentration of DDGS (20, 40, or 60% DM basis) and corn processing method [high-moisture (HMC; 71.7% DM) vs. dry-rolled corn (DRC; 86.2% DM)] resulting in treatments of 1) 20% DDGS with DRC, 2) 40% DDGS with DRC, 3) 60% DDGS with DRC, 4) 20% DDGS with HMC, 5) 40% DDGS with HMC, and 6) 60% DDGS with HMC. Ruminal H(2)S gas concentrations were measured on d 0, 7, 14, 21, 28, 35, 49, 63, and 91 via rumen puncture. Animal performance and carcass characteristic data were collected. The day × corn processing × DDGS interaction for H(2)S gas concentrations was not significant (P = 0.91). Ruminal H(2)S concentration increased with increasing DDGS concentration (P < 0.001) and day (P < 0.001), but was not influenced by corn processing method (P = 0.94). Carcass-adjusted final BW decreased linearly (P = 0.009), whereas carcass-adjusted ADG decreased quadratically (P = 0.05) with increasing concentration of DDGS in the diet. Carcass-adjusted G:F was not affected (P ≥ 0.28) by increasing concentration of DDGS in the diet. Carcass characteristics reflected the decrease in final BW with decreased HCW (P = 0.009), as well as decreased fat depth (P = 0.005) with increasing concentrations of DDGS. The combination of decreased HCW and backfat thickness resulted in decreased (P = 0.02) yield grade with increasing DDGS inclusion. There were no confirmed cases of PEM. In conclusion, corn processing did not influence animal performance, incidence of PEM, or H(2)S concentrations under the conditions of this study. Feeding 60% DDGS in beef cattle finishing diets is not recommended due to poor animal performance.

RAPID COMMUNICATION: Isolation of glucose transporters and in bovine uteroplacental tissues from days 16 to 50 of gestation.

Glucose transporter solute carrier family 2 member 14 () is a duplicon of glucose transporter solute carrier family 2 member 3 () with a 95% shared homology to and has not previously been isolated in ruminant uteroplacental tissues. The transporter has been previously isolated in Holstein heifer uterine epithelium but not in ovine epithelium. We hypothesized that and its duplicon would be found in bovine uteroplacental tissues and that maternal nutrition and day of gestation would impact mRNA expression of and . Crossbred Angus heifers ( = 49) were estrus synchronized, bred via AI, and assigned to nutritional treatment (CON = 100% of requirements to gain 0.45 kg/d; RES = 60% of CON) at breeding. Ovariohysterectomy was performed on d 16, 34, or 50 of gestation ( = 6 to 9/d); nonpregnant (NP) controls were not bred and ovariohysterectomized on d 16 of the synchronized estrous cycle ( = 6). The resulting treatment arrangement was a 2 × 3 factorial + 1. Uteroplacental tissues (caruncle, CAR; intercaruncular endometrium, ICAR; and fetal membrane [chorioallantois], FM) were obtained from the pregnant uterine horn immediately after ovariohysterectomy. For NP controls, only CAR and ICAR were obtained. There were no day × treatment interactions for or gene expression in CAR, ICAR, or FM. Expression of in CAR was greater ( = 0.03) on d 50 compared with d 16. In ICAR, was greatest ( = 0.02) on d 50 compared with d 16 and 34 of gestation. In FM, was greater ( = 0.04) on d 16 compared with d 50. Expression of was greater ( = 0.05) in pregnant compared with nonpregnant heifers. Additionally, expression of was greater ( = 0.01) on d 34 and 50 compared with d 16. Expression of in CAR was greater ( = 0.03) on d 50 compared to d 16 and 34. In CAR, tended ( = 0.07) to be greater on d 34 and 50 than on d 16 and was greater ( = 0.02) on d 50 than on d 34. There was no effect of treatment for either or in CAR, ICAR, or FM. These data demonstrate that glucose transporters and are expressed in beef heifer uteroplacental tissues and that they are expressed differentially by day of gestation in bovine uteroplacental tissues.

RAPID COMMUNICATION: Expression of an endogenous retroviral element, during early gestation in beef heifers.

Endogenous retroviral gene elements have been implicated in development and formation of the feto-maternal interface. A variant of the syncytin endogenous retroviral envelope gene family, , was recently found in ruminants. We hypothesized that mRNA would be differentially expressed in utero-placental tissues and would fluctuate during key time points of early gestation in beef heifers. Commercial Angus crossbred heifers ( = 46; ∼15 mo of age; BW = 362.3 ± 34.7kg) housed in 6-animal pens were fed daily with native grass hay and supplemented with cracked corn to gain 0.3 kg/d. The heifers were estrus synchronized, artificially inseminated, (d of breeding= d 0) and ovariohysterectomized on d 16, 22, 28, 34, 40, and 50 ( = 9, 6, 6, 7, 6, and 5, respectively) of gestation and at d 16 of the estrous cycle for non-bred, non-pregnant controls (NP; = 7). Harvested tissues were separated into maternal caruncle (CAR), intercarunclar endometrium (ICAR), and fetal membranes, (FM; chorioallantois, d 22 and later). All tissues were obtained from the ipsilateral uterine horn to the CL. Statistical analyses were conducted via the GLM procedure of SAS. Maternal CAR expression of was greater ( = 0.003) on d 50 by 81.5-fold compared to NP controls. At d 50 expression of in CAR was 190.3-fold greater than ( < 0.0001) ICAR. Fetal membranes had greater ( < 0.002) expression of from d 22 until d 50 of gestation compared to maternal ICAR (d 16 not analyzed). Expression of in FM was greater ( < 0.004) than in CAR until d 40 of gestation. Therefore, we conclude that is differentially expressed in utero-placental tissues and may be involved in the establishment of pregnancy. The expression of in maternal tissues is completely novel and indicates unique functions of syncytin in ruminant pregnancy.

Nutrient transporters in bovine uteroplacental tissues on days sixteen to fifty of gestation1

During early gestation, nutrients are transported to the developing embryo via transporters in the uterine endometrium and chorioallantois. In the present study, we examined glucose transporters and and the cationic AA transporters , , and to test the hypotheses that 1) relative mRNA expression of transporters would be different among uteroplacental tissue type as gestation progresses and 2) concentrations of glucose and cationic AA would be different among target sites (placental compartments, serum, and histotrophic) and days of gestation. To test these hypotheses, crossbred Angus heifers ( = 46) were synchronized, bred via AI, and then ovariohysterectomized on d 16, 22, 28, 34, 40, or 50 of gestation (5 to 9/d) or not bred and ovariohysterectomized on d 16 of the synchronized estrous cycle ( = 7) to serve as nonpregnant (NP) controls. Uteroplacental tissues (maternal caruncle [CAR], intercaruncular endometrium [ICAR], and fetal membranes [FM; chorioallantois, d 22 and later]) were collected from the uterine horn ipsilateral to the corpus luteum immediately following ovariohysterectomy. Relative mRNA expression of the glucose transporters and cationic AA transporters was determined for each tissue from d 16 to 50 of gestation and from NP controls. Chorioallantoic, amniotic, and plasma fluids were collected from heifers on d 40 and 50 of gestation to determine concentrations of glucose and cationic AA. Expression of and showed a tendency ( < 0.10) toward being greater in d 16 ICAR and d 34 ICAR, respectively. Day × tissue interactions ( < 0.05) were present for , , and . Expression of was greater in d 50 CAR, expression of was greater on d 34 in ICAR, and expression of was greater in CAR tissue on d 34 compared with all other tissues and days of gestation. Glucose concentrations tended ( = 0.10) to be impacted by a day × fluid interaction. A day × fluid interaction ( = 0.01) for arginine concentration was observed, with greater concentrations in allantoic fluid on d 40 compared with all other days and fluid types. These data support our hypothesis that glucose and cationic AA transporters differ in their level of mRNA expression due to day of gestation and uteroplacental tissue type. In addition, concentrations of nutrients were differentially impacted by day, target site, and/or their respective interaction.

Effects of increasing dosages of zeranol implants on lamb growth, carcass characteristics, blood hormones, and nitrogen metabolism1

The objective of this research was to compare the growth performance, incidence of prolapse and mortality, carcass characteristics, blood hormone concentration, and N balance of lambs implanted with increasing dosages of zeranol. One hundred forty-four crossbred lambs (29.6 ± 4.9 kg) were used in a completely random design and placed into 16 feedlot pens (4 pens/treatment) for a 116 d finishing study. Lambs were fed an 84.7% corn and 15.3% market lamb pellet (DM basis) diet ad libitum. Treatments were 0, 12, 24, and 36 mg zeranol (Ralgro; Schering-Plough), and lambs were implanted in the ear according to treatment on d 0. Lambs were weighed. Thirty lambs (67.6 ± 3.4 kg) and 96 lambs (65.8 ± 5.1 kg) were harvested on d 84 and d 118, respectively. Carcass data were collected 24 h after chill. Blood samples were collected on d 0, 28, 56, 70, 82, 99, and 116 from 64 lambs (29.6 ± 2.1 kg) in the feedlot study (subsample of 4 lambs per pen) and analyzed for thyroxine, triiodothyronine, and IGF-I. A second study was conducted to compare effects of 0, 12, 24, or 36 mg zeranol on N balance in 16 crossbred lambs (34.8 ± 2.1 kg). There were no differences among treatments for BW, ADG, DMI, and G:F (P > 0.05) in the feedlot study. However, there was a linear increase for incidence of prolapse (P = 0.006; 2.78, 5.55, 24.98, and 27.75%, respectively) and mortality (P = 0.005; 0.00, 5.55, 11.10, and 13.88%, respectively) as zeranol dosage increased. Carcass characteristics, blood hormone concentrations, and N balance were not affected by treatment (P > 0.05). These results indicate zeranol increases incidence of prolapse and mortality without increasing growth performance.

Influence of advancing season on dietary composition, intake, site of digestion, and microbial efficiency in beef steers grazing season-long or twice-over rotation native range pastures in western North Dakota

Eight ruminally and duodenally cannulated beef steers (374 +/- 11 kg) were used to evaluate effects of advancing season and grazing treatment (season-long; SL or twice-over rotation; TOR) on dietary composition (Exp. 1 and 2), intake, site and extent of digestion, and microbial efficiency (Exp. 2) of native range. In Exp. 1, six 11-d sample collections were conducted from early June to mid-November 2000 and 2001. In vitro OM disappearance decreased (P < or = 0.04) for both years and both treatments with advancing season. Dietary N declined (P < or = 0.07), whereas fiber content increased (P < or = 0.05) during both years in both treatments, with the exception of NDF (P = 0.55) during yr 2 (YR2) on the TOR, as season advanced. In Exp. 2, three 11-d sample collections were conducted from late July to mid-September 2000 on SL and TOR. Organic matter intake (g/kg of BW) was not altered (P = 0.28) by grazing treatments or advancing season. Total tract OM and apparent ruminal OM digestion were not different (P > or = 0.12) between treatment and decreased (P < or = 0.04) with advancing season. Grazing treatment x season interactions (P = 0.06) were present for true ruminal OM digestibility with TOR being greater (P < or = 0.10) than SL in late August and mid-September but not late July. Microbial efficiency was greater (P = 0.07; 15.1 vs. 10.8 +/- 1.6 g of microbial N/kg of OM truly fermented) in SL than TOR, respectively. Degradable intake protein (g/d) was less (P = 0.05) in TOR than SL during late July to early August and not affected by treatment in late August or mid-September. However, undegradable intake protein was unchanged (P > or = 0.54) between treatment and across season. These data suggest that mixed-grass range forage consumed by cattle after late September is deficient in N, particularly degradable intake protein, and that forage intake may be insufficient to support adequate performance in lactating cows independent of grazing management strategies evaluated. Knowledge of diet quality and forage intake should aid producers in meeting the nutritional needs of livestock grazing these forages.

Evaluation of implant strategies in Angus-sired steers with high or low genetic potential for marbling and gain

Sixty-nine Angus-sired steer calves (332.3 kg initial BW) were used to determine the effects of single or double implant strategies on steers of high or low genetic potential (GP) determined by the GeneMax (Zoetis, Florham Park, NJ) genetic profiling test. Steers were assigned to treatments in a 2 × 2 factorial design with factors of 1) composite GP score (high, mean GP score of 86.5 [HI]; low, mean GP score of 25.3[LO]) and 2) implant strategy (single, steers implanted on d 70 [1X], or double, steers implanted d 0 and 70 [2X]). All steers were given the same implant (Revalor-S; Merck Animal Health, Summit, NJ), with the 2X group implanted on d 0 and 70 and the 1X group implanted only on d 70. A diet containing 1.38 Mcal NEg/kg DM was fed ad libitum, once daily. Ultrasound was used to measure body composition characteristics on d 0 and 70. Steers were harvested after 140 d on feed. At both the d-0 and d-70 ultrasound, HI steers had greater ( < 0.001) percent intramuscular fat (IMF) than LO steers, but no differences ( ≥ 0.24) were observed in LM area (LMA), rib fat thickness (RF), or rump fat thickness (RMFT). Steers in the 2X group had larger ( = 0.02) LMA and less ( = 0.03) IMF on d 70 than 1X steers and no differences ( ≥ 0.50) in RF or RMFT were observed. From d 0 to 70, HI steers had ADG, DMI, and G:F ( ≥ 0.60) similar to LO steers; however, 2X steers had greater ( < 0.001) ADG and were more ( < 0.001) feed efficient compared with 1X steers during the same interval. Over the entire 140-d feeding period, there were no differences ( ≥ 0.6) in BW, ADG, DMI, or G:F between GP groups; however, 2X steers had greater ( = 0.03) ADG compared with 1X steers and still had similar ( ≥ 0.12) DMI and G:F. Upon slaughter, marbling score tended to be impacted by a GP × implant interaction (499.9 ± 18.5, 545.6 ± 18.5, 487.1 ± 18.5, and 469.8 ± 18.5 for HI and 2X, HI and 1X, LO and 2X, and LO and 1X, respectively; = 0.06). No differences ( ≥ 0.7) were observed between GP groups for HCW, LMA, RF, KPH, or yield grade (YG). Steers in the 1X group had less ( = 0.003) RF than 2X steers but similar ( ≥ 0.14) HCW, marbling, LMA, KPH, and YG. A greater proportion ( = 0.03) of HI steers had choice carcasses (100 ± 0.0%) compared with LO steers (87.8 ± 3.9%). Results of this study indicate that the GP test used in the current study predicted differences in IMF, carcass marbling, and percent carcasses graded as choice.