Effects of dried distiller's grains and lasalocid inclusion on feedlot lamb growth, carcass traits, nutrient digestibility, ruminal fluid volatile fatty acid concentrations, and ruminal hydrogen sulfide concentration.

Our hypothesis was that increasing the inclusion level of dried distiller's grains with solubles (DDGS) to feedlot lambs would increase growth and the inclusion of lasalocid (LAS; Bovatec, Alpharma, LLC, Bridgewater, NJ) would increase ADG and G:F, while not affecting digestibility, ruminal VFA concentration, and ruminal pH. Furthermore, we hypothesized that rations containing LAS and higher levels of DDGS would cause increased ruminal hydrogen sulfide gas (HS) concentrations. Two hundred forty crossbred (Suffolk × Rambouillet) lambs (31.9 ± 5.87 kg BW; approximately 90 d of age) were allocated to 6 treatments in a completely randomized design with a 3 × 2 factorial arrangement of treatments. Lambs were placed into 24 feedlot pens (4 pens/treatment; 10 lambs/pen) for a 111 d finishing study. Main effects included concentration of DDGS (0, 15, or 30% DM basis) and inclusion of LAS (0 or 22.05 g/metric ton LAS) resulting in treatments of: 1) 0% DDGS without LAS (0DDGS-NL), 2) 0% DDGS with LAS (0DDGS-L), 3) 15% DDGS without LAS (15DDGS-NL), 4) 15% DDGS with LAS (15DDGS-L), 5) 30% DDGS without LAS (30DDGS-NL), and 6) 30% DDGS with LAS (30DDGS-L). Two-day weights were taken at the beginning and end of the experiment. Two-hundred-eighteen lambs (64.8 ± 7.99 kg BW) were slaughtered on d 112 at a commercial abattoir and carcass data collected. The inclusion of LAS increased ( ≤ 0.02) final BW, ADG, G:F, and HCW. As DDGS in the ration increased to 30%, DMI decreased linearly ( = 0.03) while G:F increased linearly ( = 0.03). A second study was conducted utilizing the same treatments to evaluate N and S balance, ruminal VFA and H2S concentration, and ruminal pH in 24 crossbred wethers (Suffolk × Rambouillet; 41.2 ± 12.23 kg BW). Daily urinary sulfur excretion and ruminal H2S concentration were linearly increased ( < 0.001) as DDGS increased in the ration. Total ruminal VFA concentration linearly decreased ( = 0.002) as DDGS increased in the ration. The inclusion of LAS increased ( = 0.02) ruminal pH. The results confirm our hypothesis that LAS increased overall growth and increasing DDGS increased ruminal HS concentration but did not influence growth. We reject the hypothesis that the combined effects of LAS and DDGS would have no effect on rumen pH and VFA concentrations.

Supplementation of metabolizable protein during late gestation and fetal number impact ewe organ mass, maternal serum hormone and metabolite concentrations, and conceptus measurements.

To examine the effects of maternal metabolizable protein (MP) supplementation during late gestation on serum hormone and metabolites and organ masses, multiparous ewes (n = 45) carrying singletons or twins were allotted randomly (within pregnancy group) to 1 of 3 treatments: 60% (MP60), 80% (MP80), or 100% (MP100) of MP requirements. Blood samples were drawn before the initiation of diets (day 100) and before slaughter (day 130) for chemistry panel analysis and weekly for hormone analysis including progesterone (P4) and estradiol-17ß (E2). At day 130, ewe organ masses were recorded. Despite being fed isocaloric diets, MP60 ewes gained less weight throughout pregnancy compared with MP80 and MP100 ewes which were similar. Although diet did not impact E2 or P4 concentrations, ewes carrying twins had greater (P < 0.05) concentrations of both as gestation advanced. Albumin, aspartate aminotransferase, and total protein were reduced (P < 0.05) in MP60 compared with MP100 ewes near term. There was a diet by fetal number interaction (P = 0.03) for lactate dehydrogenase. Twin-carrying MP80 ewes had greater lactate dehydrogenase compared with all other groups on day 130 of gestation. Ewes that were fed MP80 had greater body weight on day 130 of gestation compared with MP60 ewes. Kidney and heart weights were lighter in MP60 ewes compared with MP80 ewes. There was a maternal diet by fetal number interaction (P = 0.05) on fetal weight per unit empty ewe body weight. In ewes carrying singletons, MP60 ewes supported less fetal weight compared with MP100. In contrast, MP60 ewes supported more fetal mass compared with MP100 ewes when carrying twins. The level of protein, and not just total energy, in the diet appears to impact some aspects of the maternal system. Moreover, it appears some measurements of mobilizing maternal body resources are enhanced in ewes carrying twins.

Impacts of supplemental arginine on the reproductive performance of fall lambing ewes.

In sheep, embryonic and fetal death during pregnancy can account for 25% to 50% of the total number of corpora lutea (and thus potential embryos). The objective of this study was to determine the effects of injectable and oral Arg supplementation provided for 14 d postbreeding on the reproductive performance of naturally stimulated fall lambing ewes. Rambouillet ewes ( = 210) were exposed to rams equipped with marking harnesses to induce cyclicity in April 2012. Upon estrus detection (d 0) ewes were randomly assigned, in a completely random design, to 1 of 6 treatments for a 14-d treatment period: injectable saline (CON; = 25), injectable Ala (IVALA; = 20), injectable Arg (IVARG; = 23), oral rumen-protected Arg (RPARG; = 20), oral fish meal (FM; = 24), or oral soybean meal (SBM; = 23). Daily treatments, except CON, IVALA, and SBM, were formulated to provide supplemental Arg at 30 mg·kg BW·d and were provided at 0800 h daily. Ewes receiving injectable treatments were provided 454 g corn/d postinjection, whereas ewes receiving oral supplements were provided a ground ration of their respective treatments with corn individually at 0800 h daily. Plasma and serum samples were collected on d 0, 2, 4, 6, 8, 10, 12, and 14 from 12 ewes per treatment to evaluate plasma progesterone and serum AA concentrations. At lambing, birth weight, birth type, and sex were recorded. Weaning weights were recorded when the average age of lambs was 85 d. No differences ( ≥ 0.39) were detected for pregnancy, prolificacy, and lambing rates or lamb birth weights among treatments. However, litter weaning weight tended to be greater ( = 0.06) and weaning rates were greater ( = 0.05) in Arg-injected ewes (1.09, 0.95, 1.29, 0.72, 1.00, and 0.86, respectively). Plasma progesterone and serum Arg concentrations showed a treatment and day effect ( < 0.001), but no treatment × day interaction ( ≥ 0.99) was observed. In contrast to previous research, supplemental Arg during the first 14 d of pregnancy did not improve pregnancy or lambing rates; however, IVARG did positively impact weaning rates.

Maternal metabolizable protein restriction during late gestation on uterine and umbilical blood flows and maternal and fetal amino acid concentrations near term in sheep.

To examine the effects of maternal metabolizable protein (MP) restriction during late gestation on uterine and umbilical blood flows, conceptus size, and amino acid concentrations in the uterine and umbilical vessels, 11 ewes with singleton pregnancies were assigned to one of three isocaloric diets formulated to provide 60% of MP (MP60), 80% of MP (MP80), or 100% of MP (MP100) requirements from days 100 to 130 of gestation. On day 130 of gestation, intraoperative uterine and umbilical blood flows were obtained as well as serum samples from the uterine artery, uterine vein, umbilical artery, and umbilical vein. Ewes on the MP60 diet had lighter (P=0.04) and smaller (P≤0.05) fetuses, but increased (P=0.02) uterine blood flow relative to fetal weight compared with MP100 ewes, with MP80 being intermediate. Umbilical blood flow was similar (P=0.70) across treatments. Glutamine, glycine, isoleucine, leucine, ornithine, serine, and valine concentrations were impacted (P≤0.02) by maternal treatment. While uterine flux of total serum nitrites was greater (P=0.03) in MP60 and MP80 ewes compared with MP100 ewes, fetal flux did not differ. Decreased maternal protein intake resulted in less (P<0.01) maternal cytochrome P450 1A enzyme activity. There were minimal impacts of maternal diet on steroid concentrations. Maternal dietary protein may alter fetal growth by impacting placental vasculature function and nutrient absorptive capabilities.

Supplementing metabolizable protein to ewes during late gestation: II. Effects on ewe lamb performance and reproductive efficiency.

The objective of the current study was to determine the effects of maternal MP intake in isocaloric diets during late gestation on female offspring growth from birth to breeding and measure reproductive performance of those offspring in their first breeding season. In yr 1, maternal dietary treatments were applied at d 100 of gestation, were similar in total energy, and contained 60MP1, 60% of MP requirements; 80MP1, 80% of MP requirements; and 100MP1, 100% of the MP requirements on a DM basis during late gestation. In yr 2, maternal dietary treatments were similar in total energy and contained 60MP2, 60% of MP requirements; 100MP2, 100% of the MP requirements; and 140MP2, 140% of MP requirements on a DM basis during late gestation. While there was a quadratic effect ( = 0.003) for ewe lamb birth weight with the ewe lambs from 80MP1 ewes having increased birth weights compared with ewe lambs from 60MP1 and 100MP1 ewes in yr 1, there was no effect ( ≥ 0.22) of maternal diet on growth of ewe lamb offspring thereafter. A quadratic effect ( = 0.02) was observed for the percentage of ewe lambs bred during the first 17 d of the breeding season, with more ewe lambs born to ewes fed 80MP1 bred compared with ewe lambs born to ewes fed 60MP1 and 100MP1. Ewe lambs giving birth within the first 17 d of lambing season increased ( = 0.001) linearly as MP intake increased in the maternal diet. In yr 2, there was no effect ( ≥ 0.07) of maternal MP treatment during late gestation on growth of ewe lambs and reproductive performance except ADG from birth to weaning and lamb birth weight. There was a quadratic effect ( = 0.01) for ADG from birth to weaning of ewe lambs from ewes consuming 100MP2 being increased compared with ewe lambs from ewes fed 60MP2 and 140MP2. There was a linear ( = 0.04) reduction in birth weight of lambs born to ewe lambs as the dam's maternal dietary MP intake increased. The data from the current study suggest that feeding 80% or 100% of MP requirements during late gestation may have the greatest positive impacts on female offspring reproductive performance.

Supplementing metabolizable protein to ewes during late gestation: I. Effects on ewe performance and offspring performance from birth to weaning.

We hypothesized that a maternal diet greater in MP during the last third of gestation would yield improved offspring growth due to enhanced placental or mammary gland function. Our objective was to determine how MP intake during late gestation affected ewe and offspring performance from birth to weaning in ewes fed diets similar in total energy. In yr 1, maternal dietary treatments were applied at d 100 of gestation, were similar in total energy, and contained 60% of MP requirements (60MP1), 80% of MP requirements (80MP1), and 100% of the MP requirements (100MP1) on a DM basis during late gestation. In yr 2, maternal dietary treatments were similar in total energy and contained 60% of MP requirements (60MP2), 100% of the MP requirements (100MP2), and 140% of MP requirements (140MP2) on a DM basis during late gestation. In yr 1, there was no effect (P ≥ 0.30) of maternal MP restriction on gestation length, lamb birth weight, or milk production of the dam. At lambing, ewe BW (P = 0.02) and BCS (P = 0.01) increased linearly as MP in the diet increased. While there were no differences in lamb BW at birth, lamb weaning BW (P = 0.08) and ADG from birth to weaning (P = 0.10) tended to increase linearly as maternal MP intake increased. In yr 2, maternal BW increased with increased dietary MP. However, there were no significant effects (P ≥ 0.45) of maternal dietary treatment on maternal BCS or lamb birth weight. Moreover, lamb weaning weight and ADG were not influenced by maternal MP levels. These results suggest that ewes maintain and gain BW and BCS when consuming diets similar in total energy with increased MP during late gestation, but the increased MP had minimal effects on lamb performance through weaning.

Influence of level of dried distillers grains with solubles on feedlot performance, carcass characteristics, serum testosterone concentrations, and spermatozoa motility and concentration of growing rams.

The objective of this study was to evaluate the effects of dried distillers grains with solubles (DDGS) on ram lamb feedlot performance, carcass characteristics, serum testosterone concentration, and semen quality. One hundred twenty ram lambs (40.4 ± 9.1 kg; Suffolk × western white face) were used in a completely randomized design to determine the effects of DDGS on feedlot performance and carcass characteristics. Rams were allotted into one of three dietary treatments (n = 4 pens/treatment; 10 rams/pen): 1) 0DDGS: 85% corn and 15% commercial market lamb pellet, 2) 15DDGS: 15% DDGS substituted for corn (DM basis), and 3) 30DDGS: 30% DDGS substituted for corn (DM basis). Rams were weighed on consecutive days at the beginning (d 0 and 1) and end (d 96 and 97 and d 116 and 117) of the trial. Scrotal circumference was measured on all rams on d 84, 96, and 116. Semen and blood samples were collected on a subset of 48 rams (4 rams/pen; 16 rams/treatment; n = 4) to evaluate semen quality. Blood samples were collected every 14 d throughout the study. Semen samples were collected on d 84, 98, and 112. Rams were fed to market weight, shipped to a commercial abattoir, and harvested for carcass data collection. Initial BW, final BW, change in scrotal circumference, days on feed, carcass characteristics, serum testosterone concentrations, and spermatozoa motility score were not different (P ≥ 0.23) due to dietary treatment. However, DMI increased linearly (P < 0.001) as DDGS increased in the ration, resulting in a linear increase (P = 0.02) in ADG. Additionally, spermatozoa concentration decreased linearly (P = 0.05) as DDGS concentration increased in the ration. Increasing DDGS in the diet did not have a negative impact on ram feedlot performance or carcass characteristics; however, spermatozoa production may have been negatively affected, necessitating the need for additional research on the impact of DDGS on ram development.

Cattle and sheep develop preference for drinking water containing grape seed tannin.

Ingestion of small amounts of some types of condensed tannins (CTs) by ruminant livestock can provide nutritional, environmental and economic benefits. However, practical methods are needed to make these tannins more available to ruminant livestock. Results from previous trials with crude quebracho and black wattle tannin indicated that cattle and/or sheep would not preferentially drink water containing these tannins. Therefore, we conducted preference trials to determine if cattle and sheep would learn to prefer water containing purified grape seed tannin (GST) that provided up to 2% of their daily dry matter (DM) intake. After gradual exposure to increasing amounts of this tannin in water during a pre-trial period, five adult ewes and five yearling heifers fed lucerne (Medicago sativa) pellets (19% CP) were offered water and several concentrations of GST solutions for either 15 (sheep trial) or 20 days (cattle trial). We measured intake of all liquids daily. Concentrations of blood urea were also measured for heifers when they drank only tannin solutions or water. Both sheep and cattle developed preferences for water with GST in it over water alone (P < 0.01) although this preference appeared earlier in the trial for sheep than for cattle. For the sheep, mean daily intake of water alone and all tannin solutions (in total) was 0.6 and 6.1 l, respectively. For the cattle, mean daily intake of water and all tannin solutions in total was 21.8 and 20.6 l, respectively, in the first half of the trial and 10.8 and 26.1 l, respectively, in the second half of the trial. Compared with the other tannin solutions, both sheep and cattle drank more of the solution with the highest tannin concentration (2% of daily DM intake as GST) than of water on more trial days (P < 0.05). Ingestion of water with the highest concentration of GST reduced blood plasma urea concentration in the cattle by 9% to 14% (P ≤ 0.10) compared with ingestion of water alone. Results from the trials suggest that providing grape seed and perhaps other CTs via drinking water may be a practical way to introduce CTs into sheep and cattle diets.

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

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.

Treatment of flaxseed to reduce biohydrogenation of α-linolenic acid by ruminal microbes in sheep and cattle, and increase n-3 fatty acid concentrations in red meat.

The objective of the study was to determine if flaxseed treated with a formaldehyde-free process could increase n-3 fatty acid (FA) concentrations in lamb and steer muscle. Twenty-four lambs (initial BW 43.8 ± 4.4 kg) were randomly divided into 4 groups for a 90-d trial. One treatment group (FLX) was fed 136 g/d of nontreated ground flaxseed; another treatment group (FLXT1) was fed 136 g/d of flaxseed treated to protect a-linolenic acid (ALA) from microbial hydrogenation; a third treatment group (FLXT2) was fed 136 g/d of a second treated flaxseed; and a fourth treatment group (CNTL) was fed corn and soybean meal with similar CP and DE levels as the other treatments. Intake of treated flaxseed raised plasma triacylglycerol concentrations of ALA more (P < 0.01) than intake of nontreated flaxseed did, but there was no difference (P = 0.65) in ALA increase between FLXT1 and FLXT2. Intake of treated flaxseed increased (P ≤ 0.05) muscle phospholipid ALA and eicosapentaenoic acid concentrations more than nontreated flaxseed did. There were no differences in muscle phospholipid n-3 concentrations between FLXT1 and FLXT2. Ten yearling steers (initial BW 437 ± 18 kg) were randomly divided into 2 groups. One group was fed ground flaxseed (0.05% of steer BW/d; FLX; n = 5) and a second group was fed treated flaxseed at the same rate (FLXT; n = 5). The 175-d trial was divided into 2 periods: high roughage, low concentrate period followed by high concentrate, low roughage period. Steers were fed rations that were formulated to be isonitrogenous, isocaloric, and isolipidic. There was no difference (P = 0.37) in increase of ALA in blood plasma of FLX and FLXT groups by the end of the first period. However, FLXT had 16% greater (P = 0.003) concentration of ALA in their plasma during the second period. Muscle phospholipid n-3 FA were not greater (P ≥ 0.55) for steers in the FLXT group. Intake of treated flaxseed raised n-3 concentrations in blood and muscle of sheep, and in blood of cattle but did not raise n-3 FA concentrations in muscle of steers. Supplementing the diets of forage-fed lambs with flaxseed treated to reduce hydrogenation of ALA by ruminal microbes can increase concentrations of n-3 FA in the muscle of lambs.

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.

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.

Growing rate of gain on subsequent feedlot performance, meat, and carcass quality of beef steers.

Eighty Angus and Angus x Simmental steer calves were used in a completely random design to determine the effect of rate of BW gain during the backgrounding period on subsequent feedlot performance, carcass characteristics, Warner-Bratzler shear force (WBSF), and sensory analysis. Animals were stratified by BW and allotted randomly to 1 of 10 pens (5 pens/treatment). Dietary treatments were formulated for an ADG of 0.91 kg/d [low BW gain (LG), 1.06 Mcal of NE(g)/kg] diets and 1.25 kg/d [high BW gain (HG), 1.19 Mcal of NE(g)/kg]. Steers were fed 70 d during the growing period. The LG diet consisted of 52.5% barley silage, 39.0% whole shell corn, and 8.5% supplement, whereas the HG diet contained 43.9% barley silage, 47.4% whole shell corn, and 8.7% supplement (DM basis). Initial BW (226 kg) was not different (P = 0.70) between treatments. Steers fed the HG diet had increased ADG (1.67 vs. 1.40 kg/d; P < 0.001) compared with steers fed LG diet. Dry matter intake was greater (9.49 vs. 8.35 kg/d; P < 0.001) for steers fed the HG vs. LG diet. Total backgrounding cost ($/animal) was less (P < 0.001) for those steers fed LG diet compared with HG diet ($126.00 vs. $140.35, respectively); however, total cost per kilogram of BW gain was not different (P = 0.24; $0.485/kg of BW gain). After the backgrounding period, steers were fed a common finishing diet for 135 d. During the finishing period, LG steers had similar (P = 0.12; 10.73 vs. 10.35 kg/d) DMI compared with those fed HG diets; however, ADG was not different (1.55 kg; P = 0.72) among treatments. Hot carcass weight, marbling score, 12th-rib fat, LM area, and USDA yield grade were not different (P > 0.12) between treatments and averaged 363 kg, Sm(30), 1.33 cm, 83.8 cm(2), and 2.7, respectively. There were no differences (P = 0.77; 3.63 +/- 0.12 kg) in WBSF tenderness of rib-eye steaks. Percent cooking loss was increased in LG diets (P = 0.017). No differences were observed in consumer sensory analysis of tenderness, juiciness, and flavor intensity (P > or = 0.276; 5.43 +/- 0.12, 5.07 +/- 0.13, and 5.17 +/- 0.05, respectively). These data suggest that feeding steers diets that differ in energy concentration and result in ADG of 1.4 and 1.7 kg/d during the growing period results in minimal changes in subsequent finishing performance and does not affect meat quality.

Effects of melengestrol acetate and P.G. 600 on fertility in Rambouillet ewes outside the natural breeding season.

The effects of melengestrol acetate (MGA) and P.G. 600 on ewe fertility outside the natural breeding season were evaluated. Rambouillet ewes were assigned to one of four groups: (1) control (C; n=92); (2) PG600 (n=86); (3) MGA (n=99); and (4) MGA+PG600 (n=92). A pellet with or without MGA (0.3mg/ewe/d) was fed at 0.15kg/ewe/d for 7d. On the last day of pellet feeding, ewes were given either saline or 5mL of P.G. 600 i.m. (400IU equine chorionic gonadotropin (eCG) and 200IU human chorionic gonadotropin (hCG)). Ultrasonography was performed between Days 20 and 25 of gestation for ewes that were mated during the first 6 d of the breeding period from the MGA (n=15) and MGA+PG600 (n=8) groups, and the number of luteal structures and embryos were counted. During the first 6d of the breeding period, MGA increased (P<0.05) the percentage of ewes that mated and conceived when compared to C and PG600 (24.2% vs. 3.3% and 10.5%, respectively). Relative to MGA, the mean (+/-S.E.M.) number of luteal structures per ewe was enhanced (P<0.03) in MGA+PG600 (1.53+/-0.13 vs. 2.38+/-0.42, respectively), however as pregnancy progressed, the number of embryos (1.5+/-0.13 vs. 1.8+/-0.16, respectively) and lambs born (1.3+/-0.15 vs. 1.5+/-0.27, respectively) did not differ. Treatment with MGA reduced (P<0.01) the interval from ram introduction to lambing relative to groups that did not receive MGA (168+/-0.8d vs. 171+/-0.6d, respectively). In conclusion, treatment with MGA increased the percentage of ewes conceiving early in the breeding period. Although P.G. 600 increased the number of luteal structures present per ewe, it did not significantly enhance ewe prolificacy.

Influence of protein supplementation frequency on cows consuming low-quality forage: performance, grazing behavior, and variation in supplement intake.

The objectives of this research were to determine the influence of protein supplementation frequency on cow performance, grazing time, distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, harvest efficiency, percentage of supplementation events frequented, and CV for supplement intake for cows grazing low-quality forage. One hundred twenty pregnant (60 +/- 45 d) Angus x Hereford cows (467 +/- 4 kg BW) were used in a 3 x 3 Latin square design for one 84-d period in each of three consecutive years. Cows were stratified by age, BCS, and BW and assigned randomly to one of three 810-ha pastures. Treatments included an unsupplemented control (CON) and supplementation every day (D; 0.91 kg, DM basis) or once every 6 d (6D; 5.46 kg, DM basis) with cottonseed meal (CSM; 43% CP, DM basis). Four cows from each treatment (each year) were fitted with global positioning system collars to estimate grazing time, distance traveled, maximum distance from water, cow distribution, and percentage of supplementation events frequented. Collared cows were dosed with intraruminal n-alkane controlled-release devices on d 28 for estimation of DMI, DM digestibility, and harvest efficiency. Additionally, Cr2O3 was incorporated into CSM on d 36 at 3% of DM for use as a digesta flow marker to estimate the CV for supplement intake. Cow BW and BCS change were greater (P < or = 0.03) for supplemented treatments compared with CON. No BW or BCS differences (P > or = 0.14) were noted between D and 6D. Grazing time was greater (P = 0.04) for CON compared with supplemented treatments, with no difference (P = 0.26) due to supplementation frequency. Distance traveled, maximum distance from water, cow distribution, DMI, DM digestibility, and harvest efficiency were not affected (P > or = 0.16) by protein supplementation or supplementation frequency. The percentage of supplementation events frequented and the CV for supplement intake were not affected (P > or = 0.58) by supplementation frequency. Results suggest that providing protein daily or once every 6 d to cows grazing low-quality forage increases BW and BCS gain, while decreasing grazing time. Additionally, protein supplementation and supplementation frequency may have little to no effect on cow distribution, DMI, and harvest efficiency in the northern Great Basin.

Evaluation of perennial ryegrass straw as a forage source for ruminants.

Two experiments were conducted to evaluate perennial ryegrass straw as a forage source for ruminants. Experiment 1 evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231+/-2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (<100 and 1,550 ppb, respectively; DM basis) were used to formulate treatment diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H (DM basis). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration. Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased. Experiment 2 evaluated performance and production by 72 Angus x Hereford cows (539+/-5 kg BW) consuming perennial ryegrass straw containing increasing lolitrem B during the last third of gestation. Cows were blocked by body condition score and randomly assigned to one of three treatments. Cows were provided perennial ryegrass straw ad libitum and supplemented with soybean meal (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B straw (467 and 2,017 ppb, respectively) were used to formulate treatment diets: 100% L, 50% L:50% H, 100% H (DM basis). Thirteen of 24 cows on the 100% H treatment exhibited signs of ryegrass staggers and were removed from the study; nevertheless, lolitrem B concentration did not influence pre- or postcalving weight or body condition score change. These data suggest that feeding perennial ryegrass straw containing up to 1,550 ppb lolitrem B (DM basis) did not adversely affect nutrient digestion or physiological response variables in steers. However, providing straw with a lolitrem B concentration of approximately 2,000 ppb (DM basis) resulted in 54% of cows exhibiting signs of ryegrass staggers. These data suggest that blending straws with a high (>2,000 ppb) and low (<500 ppb) concentration of lolitrem B can be a successful management practice.

Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage: II. Effects on site of digestion and microbial efficiency in steers.

Five steers (491 +/- 21 kg BW) were used in an incomplete 5 x 4 Latin square with four 24-d periods to determine the influence of supplemental non-protein N (NPN) source and supplementation frequency (SF) on nutrient intake and site of digestion in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control and a urea- or biuret-containing supplement placed directly into the rumen daily (D) or every other day (2D) at 0700. The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement. Daily TRT were supplemented CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Therefore, all supplemented TRT received the same quantity of supplemental CP over a 2-d period. Forage OM intake was not affected (P > 0.05) by NPN supplementation, NPN source, or SF; however, total OM and N intake were increased (P < 0.01) with CP supplementation. Duodenal flow of N was greater (P = 0.04) with CP supplementation compared with the control. In addition, duodenal bacterial N flow was increased with CP supplementation (P = 0.04) and for biuret compared with urea (P < 0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater (P = 0.05) for biuret than for urea. Apparent total-tract N digestibility was increased with NPN supplementation (P < 0.01) but not affected by NPN source or SF. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage.

Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage: III. Effects on ruminal fermentation characteristics in steers.

Five ruminally and duodenally cannulated steers (491 +/- 21 kg BW) were used in an incomplete 5 x 4 Latin square with four 24-d periods to determine the influence of supplemental nonprotein N (NPN) source and supplementation frequency (SF) on the dynamics of ruminal fermentation in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control (CON) and a urea or biuret supplement that were placed directly into the rumen at 0700 daily (D) or every other day (2D). The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement; therefore, the urea and biuret treatments received the same amount of supplemental N over a 2-d period. Daily TRT were supplemented with CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Forage was provided at 120% of the previous 5-d average intake in two equal portions at 0715 and 1900. Ruminal fluid was collected 0, 3, 6, 9, 12, and 24 h after supplementation on a day of and a day before supplementation for all TRT. Ruminal NH3-N increased (P < 0.04) with CP supplementation on the day all supplements were provided and on the day on which only daily supplements were provided compared with the CON. However, an NPN source x SF interaction (P = 0.03) on the day all supplements were provided indicated that NH3-N increased at a greater rate for urea as SF decreased compared with biuret. Ruminal NH3-N on the day only daily supplements were provided was greater (P = 0.02) for D compared with 2D. On the day all supplements were provided, D increased (P = 0.05) ruminal indigestible acid detergent fiber passage rate and ruminal fluid volume compared with 2D. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage without adversely affecting ruminal fermentation, even when provided every other day.

Self-limiting supplements fed to cattle grazing native mixed-grass prairie in the northern Great Plains.

Objectives of this research were to compare animal performance with or without supplementation, compare effectiveness of three intake limiters, and to examine seasonal changes in nutritive value of native range in south-central North Dakota. Treatments included 1) control (CONT; no supplement); 2) hand-fed (HF) supplement, with no chemical limiter; 3) 16% salt (NACL); 4) 5.25% ammonium chloride and ammonium sulfate (AS); and 5) 7% calcium hydroxide (CAOH). Supplements were based on wheat middlings, barley malt sprouts, and soybean hulls and were formulated to provide 40% of the CP intake and 32% of the NEm intake of 350-kg steers. Trials 1 and 2 each used 70 yearling steers (370.8 +/- 0.04 and 327.9 +/- 0.76 kg initial BW for Trials 1 and 2, respectively). In each year, four 28-d periods from the latter half of June through mid-October were used. Steers were stratified by weight and allotted randomly to treatments in 1 of 10 16-ha pastures (two pastures per treatment for each trial). In Trial 1, diet sampling began in the first 28-d period, but supplementation did not begin until the second 28-d period. In Trial 2, supplementation and diet collection began in the first 28-d period. Cation-anion differences (DCAD; Na + K - Cl - S) for NACL, AS, CAOH, and HF supplements were 151, -735, 160, and 166 mEq/ kg, respectively. In Trial 1, no treatment, period, or treatment x period effects for supplement intake were detected (P > or = 0.29). In Trial 2, a treatment x period interaction for supplement intake occurred (P = 0.005) because HF steers were offered a constant amount of supplement daily, whereas steers fed AS, CAOH, and NACL were allowed to consume ad libitum quantities of supplement. Average daily gain in Trial 1 was not affected (P = 0.21) by supplementation. In Trial 2, NACL, AS, and HF treatments had higher (P < or = 0.07) ADG than CONT. In Trial 1, final weights were not affected by supplementation (P = 0.23). In Trial 2, final weights of NACL- and HF-fed steers were greater than for CONT and CAOH steers (P < 0.10). In Trial 2, CONT steer final weights were lower than all supplemented treatments (P < 0.10). For yearling steers grazing native range, use of NACL as a limiter resulted in increased weight gains compared with using either CAOH or AS; however, no limiter that was tested restricted supplement intake as effectively as HF. More research is necessary to determine the optimum limiter level and the effect of forage quality on supplement intake.

Influence of rumen protein degradability and supplementation frequency on steers consuming low-quality forage: I. Site of digestion and microbial efficiency.

Seven cannulated (rumen and duodenal) Angus x Hereford steers (264 +/- 8 kg BW) consuming low-quality forage (5% CP; 61% NDF; 31% ADF) were used to determine the influence of CP degradability and supplementation frequency (SF) on DMI and nutrient digestion. Treatments included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP treatments (18% UIP) were calculated to provide 100% of the DIP requirement, while the UIP treatments (60% UIP) were provided on an isonitrogenous basis compared with DIP. Forage DMI was not affected by treatment. Total DM and N intake, duodenal N flow, and intestinal N disappearance increased (P < 0.01) with supplementation. Dry matter intake and duodenal N flow responded quadratically (P < 0.04; greatest values on the every-third-day treatments) as SF decreased. However, no differences in N intake or intestinal N disappearance were observed because of CP degradability or SF. Duodenal bacterial N flow and true bacterial N synthesis (g bacterial N/kg of OM truly digested in the rumen) were increased (P < 0.05) with supplementation. Also, duodenal bacterial N flow was greater (P < 0.05) for DIP compared with UIP. Duodenal nonbacterial N flow was increased (P = 0.02) with CP supplementation and for UIP compared with DIP (P < 0.01). Supplemental CP increased (P < 0.01) total tract DM and N digestibility with no difference due to CP degradability or SF. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by steers consuming low-quality forage without adversely affecting DMI, nutrient digestibility, or bacterial CP synthesis, even when provided as infrequently as once every 6 d.