Growth, feed intake, carcass characteristics, and eating behavior of feedlot lambs fed high-concentrate diets containing soybean hulls

The objectives of this experiment were to determine the effects of replacing ground corn with soybean hulls (SH) in high-concentrate diets on the growth (56-d period), carcass characteristics, and eating behavior of feedlot lambs. Sixty-four Santa Inês ram lambs (18.3 ± 2.8 kg of BW and 69 ± 5 d of age) were assigned to a randomized complete block design experiment with 8 blocks and 4 diets. The control diet contained 10% coastcross (Cynodon sp.) hay, 70% corn, and no SH (SH0) in the dietary DM. In the remaining diets, SH replaced corn at the rate of 15 (SH15), 30 (SH30), or 45% (SH45) of the original corn concentration, resulting in 0, 10.5, 21.0, or 31.4% SH in the dietary DM. Dry matter intake increased linearly (P < 0.01) when SH replaced ground corn (1.0, 1.0, 1.1, and 1.1 kg/d for SH0, SH15, SH30, and SH45, respectively). There was no effect on ADG of lambs, with values of 276, 278, 282, and 287 g for SH0, SH15, SH30, and SH45, respectively. Feed efficiency decreased linearly (P < 0.01) with SH inclusion. Carcass measures were not affected by SH as a replacement for ground corn. Eating time, expressed as minutes per day and minutes per gram of NDF, showed a quadratic effect (P < 0.05), whereas no effect was observed when expressed as minutes per gram of DM. Rumination, in minutes per day, was not influenced by dietary SH inclusion, but a linear decrease (P < 0.01) was observed when this variable was expressed as minutes per gram of NDF. Soybean hulls can replace up to 45% of the ground corn (31.4% of SH in the dietary DM) in high-concentrate diets fed to feedlot lambs without negative effects on ADG and carcass measures. The linear decrease in feed efficiency (11.6% reduction from SH0 to SH45) suggests that optimal dietary SH inclusion rates should be dictated by the relative costs of SH and corn.     

Free ferulic acid uptake in ram lambs

The objective of this research was to investigate the fate of free ferulic acid (FA) in sheep. Ferulic acid is normally present in plants, bound to the indigestible cell wall. If the FA present in a ruminant diet is released from the cell wall with feed pretreatment methods, FA may be released into the rumen for digestion or absorption into the bloodstream or both. Eight male Dorset × Finn lambs were randomly assigned to 1 of 4 treatment (trt) concentrations, 0 (control), 3, 6, or 9 g/d free FA as part of a replicated 4 × 4 Latin square design. Lambs were housed individually and consumed chopped alfalfa hay (Medicago sativa; 22.8% CP, 39.3% NDF, 0.73 Mcal/kg NE(g)) ad libitum and 350 g corn grain (Zea mays L.; 9.1% CP, 11.2% NDF, 1.52 Mcal/kg NE(g)) once daily at 0800 h. Basal concentrations of FA in hay, grain, blood, feces, and urine were established following a 14-d adjustment to diet and housing. An oral dose of free FA was administered for 5 d via bolus after each morning feeding, after which hay, grain, blood, feces, and urine were sampled. Body weights were recorded at the beginning and end of each trt, and DMI was measured daily during trt periods. In addition to trt, each lamb ingested a daily average of 3.78 g FA in its bound form via the offered hay (2.67 mg/g FA; 1.0 kg/d DMI) and corn (3.17 mg/g FA; 0.35 kg/d DMI). The FA administered had a quadratic effect on average hay DMI (1.25, 1.41, 1.41, and 1.29 kg/d for 0, 3, 6, or 9 g/d FA trt; P < 0.01; SE = 58.9 g), but lamb BW did not change as a result of FA trt (P = 0.28). The NDF content and amount of FA in refusals were not affected by trt, (P = 0.30; P = 0.82, respectively). Fecal FA did not differ among trt or when compared with basal FA (P = 0.53), while urine FA increased as FA dose increased (P < 0.01), indicating that free FA was absorbed and transferred into urine. No free FA was found in the plasma analyzed, suggesting that disappearance from the blood of absorbed free FA occurred within the 5 h that passed between bolus dosage and blood collection. An in vitro analysis was conducted to assess the degree of inhibition of microbial NDF digestion caused by FA supplementation. In vitro, NDF disappearance was not inhibited as a result of FA treatment (P = 0.80). These data in combination with the results of the lamb study indicate that free FA as 0.24, 0.43, and 0.70% of DMI in lambs is absorbed and excreted in the urine as opposed to the feces with no apparent effects on rumen microbial NDF digestion.     

Effects of increasing dried distillers grains with solubles on performance, carcass characteristics, and digestibility of feedlot lambs

The objectives of this study were to determine the effects of 0, 20, 40, or 60% dietary dried distillers grains with solubles (DDGS) on 1) growing lamb performance, carcass characteristics, and tissue minerals, and 2) nutrient digestibility and retention in growing lambs. In Exp. 1, ninety-six lambs were blocked by sex (ewes, n = 48; wethers, n = 48) and BW, housed in 24 pens (4 lambs per pen), and used in a 92-d feedlot trial (initial BW = 26.4 ± 9.3 kg). Lambs were fed 1 of 4 dietary treatments 1) 0% DDGS, 2) 20% DDGS, 3) 40% DDGS, or 4) 60% DDGS. The DDGS replaced primarily corn, and diets were fed as a complete pellet. There was a quadratic effect of DDGS inclusion on ADG; lambs fed the 20% DDGS diet had the greatest (P = 0.04) gains at 0.358 kg/d. This effect on ADG led to a quadratic (P = 0.03) effect of DDGS on final BW. Increasing dietary DDGS did not affect (P > 0.13) DMI and resulted in a linear (P = 0.02) decrease in G:F. In the liver, S increased linearly (P = 0.05), whereas Cu decreased linearly (P < 0.01) with increasing dietary DDGS; other liver minerals were not affected (P > 0.05). Carcass backfat, yield grade, and marbling score were not affected (P > 0.05) by dietary DDGS. In Exp. 2, twenty-four lambs (initial BW = 43.0 ± 4.4 kg) were used in a metabolism study. Lambs were adapted to the same diets described above for 17 d before a 5-d sampling period during which total feces and urine were collected. Apparent digestibility of dietary DM decreased linearly (P < 0.01) with increasing dietary inclusion of DDGS. Digestibility of fat followed a similar pattern, whereas N, S, and P absorption increased linearly (P < 0.03) with increasing dietary DDGS. The digestibility of NDF was not affected (P > 0.05) by dietary treatment. Apparent retentions (as a percentage of intake) of N, K, Mg, Cu, Fe, and Zn were not affected (P > 0.05) by dietary DDGS inclusion, whereas the retention of S and P decreased (P < 0.04). Daily urine output increased linearly (P < 0.01) and urine pH decreased linearly (P < 0.01) with increasing DDGS (urine pH was 7.46, 5.86, 5.52, and 5.32 for treatments 1 to 4, respectively). These data suggest urine is a major route for excretion of acid when high-S diets containing DDGS are fed. Increases in dietary DDGS resulted in decreased digestion of DM and fat, which may be partially responsible for decreased lamb feedlot performance for 40 and 60% dietary DDGS when compared with 20% DDGS.     

Effect of energy source and ruminally degradable protein addition on performance of lactating beef cows and digestion characteristics of steers

Two trials were conducted to determine the effect of energy source (ENG) and ruminally degradable protein (RDP) on lactating cow performance and intake and digestion in beef steers. In Trial 1, 78 cow-calf pairs were used in a 2 x 2 factorial design to determine the effect of ENG (corn or soyhulls; SH) and RDP (with our without sunflower meal) to a forage diet for lactating beef cows. The basal diet consisted of 75% grass hay (11.5% CP) and 25% wheat straw (7.4% CP). Supplement treatments and predicted RDP balances were corn (-415 g of RDP/d); SH (-260 g of RDP/d); corn plus RDP (0 g of RDP/d); or SH plus RDP (0 g of RDP/d). Data were analyzed as a split-plot in time, with pen as the experimental unit (two pens per treatment). No interaction between ENG and RDP was present (P > 0.08) for any response variable. No differences (P > 0.39) due to ENG or RDP were noted for BW, BCS, or milk yield; however, final calf weight tended to increase with ENG (P = 0.06). In Trial 2, a 5 x 5 Latin square was used to determine effects of ENG and RDP on intake and digestion in steers (686 +/- 51 kg BW). Treatments were arranged as a 2 x 2 plus one factorial and comprised a control (CON; grass hay, 7% CP), grass hay plus 0.4% BW SH, grass hay plus 0.4% BW SH and 0.15% BW sunflower meal, grass hay plus 0.4% BW corn, and grass hay plus 0.4% BW corn and 0.2% BW sunflower meal. Preplanned contrasts included main effects of ENG and RDP, ENG x RDP interaction, and CON vs. supplemented (SUP) treatments. Supplementation increased total DMI compared with CON (P = 0.001), but forage DMI was greater (P = 0.001) for CON than for SUP. An ENG x RDP interaction occurred for forage DMI (P = 0.02); addition of RDP to corn decreased forage intake, whereas addition of RDP to SH had no effect. There was an ENG x RDP interaction (P = 0.001) for ruminal pH; pH tended to increase with RDP addition to SH (P = 0.07), but decreased with RDP addition to corn (P = 0.001). Supplementation increased ruminal ammonia compared with CON (P = 0.001). Likewise, RDP increased ruminal ammonia (P = 0.001). An interaction occurred for OM disappearance (OMD; P = 0.01). The RDP addition to SH numerically decreased OMD (P = 0.23), whereas RDP addition to corn numerically increased OMD (P = 0.14). Intake and digestion seem to respond differently to RDP addition depending on supplemental energy source. Both corn or SH seem to be suitable supplements for the quality of forage used in this trial. Addition of supplemental protein did not improve cow or calf performance.     

开食料中纤维来源对湖羊羔羊生长性能、营养物质消化的影响

为研究四种不同中性洗涤纤维来源的开食料对湖羊羔羊生产性能、采食量及营养物质消化代谢的影响,试验选用初生重(3.47±0.69)kg,日龄相同,健康状况良好的湖羊公羔60只作为试验动物.羔羊0～3日龄吮食母乳,4日龄与母羊分离开始饲喂乳源性代乳粉至28日龄断奶,在7日龄[(3.77±0.46)kg]开始补饲开食料前,采用...     

Effects of maternal selenium supply and plane of nutrition during gestation on passive transfer of immunity and health in neonatal lambs

To investigate the influence of maternal Se supply and plane of nutrition on lamb morbidity, mortality, and passive transfer of IgG, pregnant ewe lambs were used in 2 experiments with 2 × 3 factorial treatment arrangements. Supplementation of Se began at breeding and was either adequate Se (ASe, 9.5 μg/kg of BW) or high Se (HSe, 81.8 μg/kg of BW) in Exp. 1 or ASe (11.5 μg/kg of BW) or HSe (77.0 μg/kg of BW) in Exp. 2. On d 50 or 40 of gestation for Exp. 1 or 2, respectively, ewes were assigned randomly to 1 of 3 nutritional planes: 60% (RES), 100% (control, CON), or 140% (HI) of NRC requirements. This resulted in the following treatments: ASe-RES, ASe-CON, ASe-HI, HSe-RES, HSe-CON, and HSe-HI. Upon parturition, lambs were separated from their dams and serum samples obtained. Lambs were fed artificial colostrum for the first 20 h and then placed on milk replacer and grain pellets until completion of the study (Exp. 1, 57 d; Exp. 2, 21 d). Twenty-four hours after parturition, lamb serum samples were collected for IgG analysis. All lambs were reared similarly and morbidity and mortality assessed. Main effects were considered significant when P ≤ 0.05. In Exp. 1, there was a Se × plane of nutrition interaction (P ≤ 0.01) for lamb morbidity from birth to weaning and for 24-h IgG concentration. Lambs from ASe-RES and HSe-HI ewes were treated more frequently (P < 0.01) for respiratory and gastrointestinal disease, and lambs from HSe-HI ewes had the smallest (P < 0.01) 24-h serum IgG concentration. In Exp. 1, lambs from HI ewes also had the greatest (P < 0.01) mortality rates from birth to weaning compared with lambs from CON and RES ewes. In Exp. 2, there was an effect (P < 0.01) of maternal plane of nutrition with lambs from RES ewes having increased 24-h IgG compared with lambs from CON and HI ewes. There was no effect of maternal Se supplementation on lamb 24-h IgG in Exp. 2; however, there was a Se × plane of nutrition interaction (P < 0.01) for morbidity. From birth to 21 d of age, lambs from ASe-CON ewes had fewer (P < 0.01) treatment days compared with lambs from any of the other treatment groups. There also tended (P = 0.08) to be an effect of maternal Se supplementation on lamb mortality with increased mortality observed in lambs from HSe ewes. Results from the studies show a restricted maternal plane of nutrition can increase lamb serum IgG concentration. Selenium results were not consistent between the 2 experiments and may be due to differences in maternal Se.     

Intake and digestibility of low-quality meadow hay by cattle receiving various levels of whole shelled corn

Two trials were conducted to evaluate the effects of whole shelled corn supplementation on intake and digestibility of low-quality meadow hay by cattle. In Trial 1, four ruminally cannulated steers (avg BW 418 kg) were used in a latin square design with four treatments (no corn or corn fed at .25%, .50% or .75% of BW). Hay DMI decreased (P = .002) linearly .43 g for each gram of increase in corn intake. In contrast, total diet DMI increased (P = .001) linearly as level of corn supplementation increased. Apparent DM digestibility of the diet increased (P = .026) linearly, whereas hay DM digestibility was not affected (P greater than .05) by supplemental corn, although the DM digestion coefficient for hay alone was 24% higher than for hay fed with corn at .75% of BW. Ruminal ammonia concentration and pH were not affected (P greater than .05) by treatments; however, ratio of acetate:propionate and acetate:butyrate responded (P less than or equal to .097) quadratically to increased corn supplementation. Corn supplementation resulted in a cubic (P less than or equal to .081) decrease in meadow hay NDF disappearance from nylon bags suspended in the rumen at all incubation intervals after 4 h. In Trial 2, 45 crossbred, nonlactating, pregnant cows (avg BW 474 kg) were used in a completely randomized design with three treatments (no corn, .91 and 1.81 kg corn.hd-1.d-1). Cow performance was not altered (P greater than .05) by treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of inclusion of graded amounts of soya bean hulls on feed intake,chewing activity and nutrient digestibility in dairy cows

Twelve multiparous Holstein dairy cows were used in a replicated 4 × 4 Latin square changeover design to evaluate the effects of graded inclusion of soya bean hulls (SHs) in replacement of diet forages at 0%, 10%, 20% and 30% of dietary dry matter (DM) basis on peNDF > 8 and peNDF > 1.18 contents of diets and their resulting effects on chewing activity, nutrient digestibility and milk production of dairy cattle. The control diet contained 50% forage, 50% concentrate and no SH. In the other three diets, SH was substituted for alfalfa hay, corn silage and wheat bran to supply 10%, 20% and 30% of the dietary DM. Increasing SH concentration in the diets resulted in decreasing concentrations of forage neutral detergent fibre (NDF), physically effective NDF (peNDF) and mean particle size (p < 0.01). Chewing activity per kilogram of daily dry matter intake (DMI) was not affected by the different diets tested. However, chewing activity significantly decreased for kilogram intake of NDF, but increased for peNDF > 1.18 when SH was included in the diets (p < 0.01). Total tract apparent digestibility of nutrients significantly increased for DM, organic matter (p < 0.05) and NDF (p < 0.01) but decreased for crude protein (p < 0.05) as the proportion of SH was increased in the diets. Rumen pH value of cattle was not influenced by the diets. Including medium and high amounts of SH in the diets decreased DMI of the animals (p < 0.05) without any significant effect on their daily milk or 4% fat‐corrected milk production. In conclusion, the results of this study showed that the NDF from a non‐forage fibre source like SH had a lower potential for stimulating chewing activity than did forage NDF. Despite this, the small size of dietary particles increased not only the chewing activity per kilogram of peNDF intake but also saliva secretion as well as the potential for rumen to neutralize acids. The findings of this study demonstrate the greater differences in peNDF > 8 among the diets and that these differences are better reflected in terms of DMI, chewing activity and nutrient digestibility, but not in rumen pH.     

Relationships of body weight, forage composition, and corn supplementation to feed intake and digestion by Holstein steer calves consuming bermudagrass hay ad libitum

Holstein steer calves (101 to 350 kg BW) consumed bermudagrass hay ad libitum without or with supplemental ground corn up to 1.0% of BW. As BW increased, total DMI increased quadratically (-2.459 + .05448 [BW]-.000073 [BW2] + .540 [corn DMI]; R2 = .83, sy.x = .655). Each kilogram of corn DM decreased bermudagrass DMI by .46 kg. Total digestible OM intake (kg) increased with BW and corn supplementation (.314 + .0127 [BW] + .441 [corn OM intake]; R2 = .79, sy.x = .444). Feed intake level accounted for approximately 2.5 times more variability in total digestible OM intake than digestion did. Corn supplementation decreased digestion of bermudagrass NDF (62.50 - 8.468 [corn DMI, % BW]; R2 = .13, sy.x = 8.121), with a similar decrease across BW. Increasing bermudagrass DMI (% of BW) decreased bermudagrass NDF digestion slightly, but variation accounted for was only 33% of that attributable to corn DMI (% of BW). Concentrations of common fiber fractions (NDF, ADF, cellulose, hemicellulose, and ADL) in bermudagrass explained very little variation in feed intake and digestion, indicating considerable influence of other factors. Bermudagrass intake and digestion were not related, and no substantial interactions were observed among steer BW, corn level, and bermudagrass composition.     

Effect of distillers grains or corn supplementation frequency on forage intake and digestibility

Ten ruminally cannulated heifers (BW = 416 kg; SD = 24) were used to test the effect of the form and frequency of supplemental energy on forage DMI and digestibility. Five treatments were arranged in a replicated, 5 x 4 Latin rectangle (n = 8), and included no supplement (control), dry-rolled corn (DRC) fed daily, DRC fed on alternate days (DRC-A), dried distillers grains plus solubles (DDGS) fed daily, and DDGS fed on alternate days (DDGS-A). Supplements fed daily were fed at 0.40% of BW, whereas alternate day-fed supplements were fed at 0.80% of BW every other day. Chopped grass hay (8.2% CP) was fed to allow ad libitum DMI, and the intake pattern was measured. Control heifers had greater (P < 0.01) hay DMI than supplemented heifers (1.88 vs. 1.66% of BW daily, respectively), although total DMI was lower (P < 0.01) for control. Hay DMI did not differ (P = 0.45) between DRC and DDGS, and tended to be lower (P = 0.08) by heifers on DDGS-A and DRC-A than by heifers supplemented daily. Hay intake was lower (P < 0.01) on supplementation days for DDGS-A and DRC-A than on nonsupplemented days. Heifers in alternate-day treatments had fewer (P < 0.01) and larger (P < 0.01) meals and spent less (P < 0.01) time eating than those supplemented daily. Average rumen pH was greater (P = 0.05) for control than supplemented heifers (6.30 vs. 6.19). Control heifers had greater (P = 0.04) rates and extents of NDF disappearance than supplemented heifers. Rate of hay NDF disappearance was lower (P = 0.02) for DRC than for DDGS. Supplementation decreased hay DMI and changed digestion kinetics. Supplementation frequency affected amount and pattern of DMI. Rate of hay NDF disappearance was greater for DDGS than DRC.     

Effect of field pea replacement level on intake and digestion in beef steers fed by-product-based medium-concentrate diets

Four ruminally and duodenally cannulated steers (703.4 +/- 41 kg initial BW) were used in a 4 x 4 Latin square to evaluate the effects of field pea inclusion level on intake and site of digestion in beef steers fed medium-concentrate diets. Steers were offered feed ad libitum at 0700 and 1900 daily and were allowed free access to water. Diets consisted of 45% grass hay and 55% by-products based concentrate mixture and were formulated to contain a minimum of 12% CP (DM basis). Treatments consisted of (DM basis) 1) control, no pea; 2) 15% pea; 3) 30% pea; and 4) 45% pea in the total diet, with pea replacing wheat middlings, soybean hulls, and barley malt sprouts in the concentrate mixture. Experimental periods consisted of a 9-d dietary adjustment period followed by a 5-d collection period. Grass hay was incubated in situ, beginning on d 10, for 0, 2, 5, 9, 14, 24, 36, 72, and 98 h; and field pea and soybean hulls for 0, 2, 5, 9, 14, 24, 36, 48, and 72 h. Total DMI (15.0, 13.5, 14.1, 13.5 +/- 0.65 kg/d) and OM intake (13.4, 12.0, 12.6, 12.0 +/- 0.58 kg/d) decreased linearly (P = 0.10) with field pea inclusion. Apparent ruminal (17.5, 12.0, 0.6, 6.5 +/- 4.31%) and true ruminal CP digestibility (53.5, 48.7, 37.8, 46.2 +/- 3.83) decreased linearly (P < 0.10) with increasing field pea. Neutral detergent fiber intake (8.9, 7.9, 7.8, 7.0 +/- 0.3 kg/d) and fecal NDF output (3.1, 2.9, 2.6, 2.3 +/- 0.2 k/d) decreased linearly (P < 0.03) with increasing field pea. No effects were observed for microbial efficiency or total-tract digestibility of OM, CP, NDF, and ADF (P > or = 0.16). In situ DM and NDF disappearance rates of grass hay and soybean hulls decreased linearly (P < 0.05) with increasing field pea. Field pea in situ DM disappearance rate responded quadratically (P < 0.01; 5.9, 8.4, 5.5, and 4.9 +/- 0.52%/h, for 0, 15, 30, and 45% field pea level, respectively). Rate of in situ CP disappearance of grass hay decreased linearly (P < 0.01) with increasing field pea level. Field pea is a suitable ingredient for beef cattle consuming medium-concentrate diets, and the inclusion of up to 45% pea in by-products-based medium-concentrate growing diets decreased DMI, increased dietary UIP, and did not alter OM, NDF, or ADF digestibility.     

Corn oil supplementation to steers grazing endophyte-free tall fescue. I. Effects on in vivo digestibility, performance, and carcass traits

Eighteen Angus steers (438 +/- 4 kg of BW) were supplemented with varying levels of corn oil (0 g/kg of BW, none; 0.75 g/kg of BW, MED; or 1.5 g/kg of BW, HI) on rotationally stocked, endophyte-free tall fescue to determine the effect of supplemental oil level on in vivo digestibility, intake, performance, and carcass traits. Pelleted cottonseed hulls were used as a carrier for the oil supplements, and all supplements were offered to steers using Calan gate feeders for individual intake determination. On d 49, each steer was dosed with a controlled-release capsule containing chromium sesquioxide, and fecal samples were obtained 12 d later over a 7-d period to estimate fecal output that, with forage, supplement, and fecal indigestible NDF concentration, was used to estimate DMI and in vivo total diet digestibility. Steers were slaughtered at the end of the 116-d grazing period, and carcass data were collected at 24 h postmortem. Total fatty acid intake linearly increased with corn oil supplementation, and forage DMI, total DMI, and total DE intake were linearly decreased (P < 0.01). The decrease in total DMI was reflected in forage substitution rates greater (P < or = 0.01) than 1, with a trend (P = 0.09) for a greater substitution rate in HI than in MED. In vivo DM, OM, and NDF digestibility were linearly decreased (P < 0.01) by corn oil supplementation. Average daily gain and final BW tended (P = 0.09) to increase linearly in response to oil level. Oil conversion (0.36 kg of BW gain/kg of corn oil) was greater (P < or = 0.05) than zero and did not differ (P = 0.15) between MED and HI. Dressing percent (P = 0.09), carcass weight (P = 0.01), and carcass backfat thickness (P = 0.01) increased linearly with oil supplementation. No treatment effect was observed for carcass LM area, KPH percentage, marbling score, or yield grade (P > 0.10). Oil supplementation to grazing steers linearly reduced forage DMI intake; however, animal performance was maintained and tended to be greater for oil-supplemented cattle. Oil supplementation increased carcass fat thickness and weight without altering other carcass quality parameters.     

Forage intake by lactating beef cows differing in potential for milk production

Two feeding trials (early and late lactation) were conducted to measure ad libitum forage intake by beef cows from three breed groups of similar mature weight, but with different milk production potential. Twenty-four cow-calf units, eight from each milk production level (low, medium and high) were grouped (two/pen) based on similarity of cow weight and previous weigh-suckle-weigh and calf weaning weight data. Each pair of cow-calf units was confined to separate pens and allowed ad libitum access to chopped native Sandhills meadow hay. Dry matter intake, cow and calf BW and calf milk consumption were determined. Daily DMI (kg/hd) and milk consumption showed a positive linear response (P less than .05) among low, medium and high milk-producing cows. When cow DMI was expressed as g/unit mean cow BW during the trial, both a positive linear (P less than .05) and a quadratic response (P less than .01) expressed the relationship among production levels during early and late lactation. Calf forage intake, birth weight and adjusted 181- and 205-d weaning weight had no linear or quadratic relationship (P greater than .10) to milk production levels. However, June 1 calf weight, actual calf weaning weight and calf rate of gain (birth to weaning) had a positive linear (P less than .07) relationship. Best fit regression models with DMI as the dependent variable were developed for each trial based on R2 and CV values of the potential models. The best fit model (R2 = .94, SE = .33) for early lactation included production level as a class variable with cow BW.75 and calf birth weight as independent variables. The best fit model (R2 = .92, SE = .53) for late lactation included actual weaning weight in addition to the variables used during early lactation.     

Intake, digestion, and N metabolism in steers fed endophyte-free, ergot alkaloid-producing endophyte-infected, or nonergot alkaloid-producing endophyte-infected fescue hay

A digestion and N balance trial was conducted to compare effects of traditional endophyte-infected (E+), endophyte-free (E-), and nontoxic endophyte infected (NE; MaxQ; Pennington Seed, Inc., Madison, GA) Jesup tall fescue (Festuca arundinacea Schreb.) hay on digestion and N retention in steers. Hay composition (DM basis) was as follows: E+ (10.8% CP, 59.9% NDF, and 29.4% ADF), E- (11.8% CP, 58.5% NDF, and 28.4% ADF), and NE (11.6% CP, 58.6% NDF, and 28.3% ADF). Eight Polled Hereford steers (initial BW 240 +/- 9 kg) were used in a replicated, 3 x 3 Latin square design, with an extra steer allotted to each square. Steers were fed ad libitum for 14 d, followed by a 9-d adaptation to restricted intake (based on the animal with the lowest ad libitum intake for the square) and a 5-d fecal and urine collection. Water intake (20.2 L/d) and urine output (7.40 L/d) did not differ (P > 0.10) during the collection period. Plasma prolactin concentration was less (P < 0.05) for steers on the E+ hay (8.83 ng/mL) than for those on the E- hay (18.03 ng/mL) and intermediate for steers on the NE hay (12.65 ng/mL). Endophyte-infected hay differed (P < 0.05) from E- and NE in ad libitum DMI (5.02 vs. 5.62 and 5.61 kg/d, respectively) and ad libitum DMI as a percentage of BW (1.86 vs. 2.06 and 2.06%, respectively). Restricted DMI during the fecal and urine collection was lower (P < 0.05) for E+ hay than for E- (5.04 vs. 5.24 kg/d), and NE was intermediate (5.19 kg/d). Dry matter digestibility was lower (P < 0.05) for E+ compared with E- and NE (62.3 vs. 67.0 and 65.9%, respectively). Digestibility of ADF was lower (P < 0.05) for E+ than for E-, and was intermediate for NE (61.5, 66.0, and 63.9%, respectively). There were no differences for NDF, cellulose, or hemicellulose digestibilities among hay types. Crude protein digestibility was higher (P < 0.05) for E- and NE than for E+ (54.3 and 52.5 vs. 48.1%, respectively). Nitrogen retention was lower (P < 0.01) for E+ than for E- or NE (15.6 vs. 22.7 or 23.0 g/d, respectively). Hay type did not influence plasma urea N, urine urea N output, or urine urea N as a percentage of urinary N. Results from this study indicate that E+ tall fescue hay was lower in ad libitum DMI, DM digestibility, and N retention than NE or E- hays with similar chemical composition. Hay from NE and E- fescue had nearly identical composition, and did not differ for any variable measured.     

Effects of corn processing and dietary fiber source on feedlot performance, visceral organ weight, diet digestibility, and nitrogen metabolism in lambs

In Exp. 1, early-weaned Targhee and Polypay crossbred lambs (60 ewes and 66 rams; initial BW 24 +/- 1.0 kg) were used in a 2 x 3 factorial experiment to determine the effects of corn processing (whole shelled corn [WSC] or ground and pelleted corn [GC]) in combination with supplemental fiber (none [control]; soybean hulls, SBH [highly digestible]; or peanut hulls, PH [highly indigestible]) on DMI, ADG, feed efficiency, and visceral organ weight. For the total trial, WSC resulted in a 4% increase (P < .01) in ADG vs GC, and supplemental fiber resulted in increased (P < .01) DMI and ADG vs the control diet. Experiment 2 was conducted using 12 Targhee and Polypay crossbred wether lambs (initial BW 25 +/- 7 kg) to determine the effects of corn processing and fiber source in high-concentrate diets on diet digestibility and N retention using the same diets as in Exp. 1. Lambs fed WSC had greater (P < .001) apparent N digestion, true N digestion, and N retention (P < .01) than those fed GC. The apparent digestibilities of DM, OM, and NDF were greater (P < .001) for WSC than for GC diets. Peanut hulls resulted in decreased (P < .01) DM, OM, and NDF apparent digestibilities compared with the control and SBH diets. Starch digestion was not affected (P > .10) by diet. Whole corn resulted in improved DM, OM, NDF, and N digestibility compared with GC. Overall, both the SBH and PH diets resulted in greater DMI and ADG than the control diet, which lacked supplemental fiber.     

Effects of supplemental protein type on intake, nitrogen balance, and site, and extent of digestion in whiteface wethers consuming low-quality grass hay

Two experiments were conducted to determine the effects of supplementing ruminally degradable intake protein (DIP) or ruminally undegradable intake protein (UIP) on N balance (Exp. 1; n = 6 wethers; initial BW = 48.7 +/- 4.6 kg) and site and extent of digestion (Exp. 2; n = 5 wethers; initial BW = 36.9 +/- 3.1 kg) in whiteface wethers consuming (as-fed basis) 69% blue grama and 31% love grass hay (mixture = 7.5% CP, 73.0% NDF, 36.0% ADF [DM basis]). Treatments were 1) no supplement (Control), 2) a supplement (219 g/d, as-fed basis) low in UIP (70 g/d of CP; 24.8 g/d of UIP), and 3) a supplement (219 g/d, as-fed basis) high in UIP (70 g/d of CP; 37.1 g/d of UIP). Both experiments were replicated 3 x 3 Latin square designs, with identical feeding and supplementation. Wethers had ad libitum access to the forage mixture and fresh water, and received supplement once daily. In Exp.1, forage intake (percentage of BW) was greatest (P = 0.04) for control, but total DMI (g/d) was greatest (P = 0.05) for lambs consuming supplement. Apparent total-tract OM digestibility was numerically greater (P = 0.11) for supplemented wethers than for controls, whereas total-tract ADF digestibility tended (P = 0.08) to be greater for control wethers. Lambs fed supplements consumed and retained more (P < or = 0.01) N (% of N intake) compared with controls, but no difference (P = 0.22) was observed between low and high UIP treatments. Similar to Exp. 1, forage intake (percentage of BW) tended (P = 0.06) to be greater for control than for supplemented wethers in Exp. 2. Ruminal NDF digestibility was 16.3% greater (P = 0.02) for supplemented wethers than for controls. Postruminal NDF and N digestibilities were greatest (P < or = 0.03) for controls, but apparent OM digestibility did not differ among treatments at all sites. Duodenal N flow was greatest (P = 0.05) for high UIP and least for control wethers. Nonmicrobial N flow was greater (P = 0.02) for high UIP compared with low UIP or controls. Control wethers had greater (P = 0.05) microbial efficiency. Ruminal ammonia concentration tended (P = 0.08) to be greatest for wethers fed low UIP and least for controls, with high-UIP wethers having intermediate ammonia concentrations. Results from these experiments suggest that in lambs fed low-quality forage there was no difference in apparent total-tract digestion or N balance (percentage of N intake) between lambs fed supplements that had the same CP but differed in the proportion of UIP and DIP; however, supplementing protein (regardless of UIP:DIP ratio) to wethers consuming low-quality forage increased N balance.     

Effect of field pea level on intake, digestion, microbial efficiency, ruminal fermentation, and in situ disappearance in beef steers fed forage-based diets

Four ruminally and duodenally cannulated crossbred beef steers (397+/-55 kg initial BW) were used in a 4 x 4 Latin square to evaluate the effects of increasing level of field pea supplementation on intake, digestion, microbial efficiency, ruminal fermentation, and in situ disappearance in steers fed moderate-quality (8.0% CP, DM basis) grass hay. Basal diets, offered ad libitum twice daily, consisted of chopped (15.2-cm screen) grass hay. Supplements were 0, 0.81, 1.62, and 2.43 kg (DM basis) per steer daily of rolled field pea (23.4% CP, DM basis) offered in equal proportions twice daily. Steers were adapted to diets on d 1 to 9; on d 10 to 14, DMI were measured. Field pea and grass hay were incubated in situ, beginning on d 10, for 0, 2, 4, 8, 12, 16, 24, 36, 48, 72, and 96 h. Ruminal fluid was collected and pH recorded at -2, 0, 2, 4, 6, 8, 10, and 12 h after feeding on d 13. Duodenal samples were taken for three consecutive days beginning on d 10 in a manner that allowed for a collection to take place every other hour over a 24-h period. Linear, quadratic, and cubic contrasts were used to evaluate the effects of increasing field pea level. Total DMI and OMI increased quadratically (P = 0.09), whereas forage DMI decreased quadratically (P = 0.09) with increasing field pea supplementation. There was a cubic effect (P < 0.001) for ruminal pH. Ruminal (P = 0.02) and apparent total-tract (P = 0.09) NDF disappearance decreased linearly with increasing field pea supplementation. Total ruminal VFA concentrations responded cubically (P = 0.008). Bacterial N flow (P = 0.002) and true ruminal N disappearance (P = 0.003) increased linearly, and apparent total-tract N disappearance increased quadratically (P = 0.09) with increasing field pea supplementation. No treatment effects were observed for ruminal DM fill (P = 0.82), true ruminal OM disappearance (P = 0.38), apparent intestinal OM digestion (P = 0.50), ruminal ADF disappearance (P = 0.17), apparent total-tract ADF disappearance (P = 0.35), or in situ DM disappearance of forage (P = 0.33). Because of effects on forage intake and ruminal pH, field peas seem to act like cereal grain supplements when used as supplements for forage-based diets. Supplementing field peas seems to effectively increase OM and N intakes of moderate-quality grass hay diets.     

Effects of roughage source and concentration on intake and performance by finishing heifers

Three experiments were conducted to evaluate the effects of roughage source and concentration on intake and performance by finishing heifers. In Exp. 1, 12 medium-framed beef heifers (average BW = 389 kg) were used in three simultaneous 4 x 4 Latin square intake trials to evaluate the effects of dietary NDF supply from alfalfa hay, sudan hay, wheat straw, or cottonseed hulls fed in each Latin square at 5, 10, or 15% of dietary DM. Within each roughage concentration, roughage NDF accounted for the majority of variation in NEg intake/kg of BW0.75 among the roughage sources. Averaged across roughage concentrations, NEg intake/kg of BW0.75 tended to be greater (P < 0.10) when heifers were fed cottonseed hulls, sudan hay, or wheat straw than when they were fed alfalfa. In Exp. 2, six medium-framed beef heifers (average BW = 273 kg) were used in a 3 x 3 Latin square design to determine whether diets containing 10% (DM basis) alfalfa, cottonseed hulls, or sudan silage differed in eating rate. Average DM eating rates did not differ (P > 0.10) among roughage sources, which we interpreted to suggest that 90% concentrate diets containing alfalfa, cottonseed hulls, and sudan silage do not differ in the amount of chewing required during eating. In Exp. 3, 105 medium-framed beef heifers (average BW = 275 kg) were used in a 140-d finishing trial to evaluate three methods of dietary roughage exchange. Alfalfa at 12.5% of the dietary DM (ALF12.5) was used as a standard, and cottonseed hulls and sudan silage were each fed at three different levels: exchanged with ALF12.5 on an equal percentage DM basis, an equal NDF basis, or an equal NDF basis, where only NDF from particles larger than 2.36 mm (retained NDF) were considered to contribute to the NDF. No differences (P > 0.10) in ADG, DMI, gain:feed ratio, or NEg intake/kg of BW0.75 were detected between alfalfa and cottonseed hulls exchanged on an equal NDF basis. For sudan silage, exchanging with ALF12.5 on an equal retained NDF basis resulted in no differences (P > 0.10) in ADG, DMI, or NEg intake/kg of BW0.75. These data provide a preliminary indication that depending on the roughage sources evaluated, roughage NDF content and(or) roughage NDF from particles larger than 2.36 mm might provide a useful index of roughage value in high-concentrate finishing diets.     

Digestibility and dry matter intake of diets containing alfalfa and kenaf

Two experiments were conducted to determine the dietary value of pellets containing kenaf (Hibiscus cannabinus cv. 'Everglade 41') hay. Averaged across both experiments, kenaf pellets contained 82.6% kenaf hay, 16.6% liquid molasses, and 0.8% mineral oil. The chemical composition of the kenaf pellet was 12.6% crude protein (CP), 41.2% neutral detergent fiber (NDF), and 14.4% acid detergent fiber (ADF). In Exp. 1 (digestion and N balance trial), 18 lambs (body weight [BW] = 36.4 kg) were blocked by BW. Lambs were randomly assigned within a block to Diet 1 (59.5% corn and 40.5% alfalfa pellet), Diet 2 (59.7% corn, 28.4% alfalfa pellets, and 11.9% kenaf pellets), or Diet 3 (59.6% corn, 16.5% alfalfa pellets, and 23.9% kenaf pellets). Diets were formulated so that CP was the first-limiting nutrient. Each diet was limit-fed at 2.4% of BW. Replacing alfalfa pellets with kenaf pellets tended to decrease (P = 0.10) CP and ADF intakes, but increased (P = 0.01) DM digestibility. Diet had no effect (P = 0.33) on N balance. In Exp. 2 (dry matter [DM] intake trial), 32 lambs (BW = 30.4 kg) were blocked by gender and BW. Within a block, lambs were randomly assigned to one of four diets in a 2 x 2 factorial arrangement. Main effects were hay (bermudagrass or fescue) and supplemental protein source (kenaf or alfalfa pellets). Lambs were housed in individual pens with ad libitum access to the assigned hay. Supplemental protein was fed (185 g of DM) once daily. Hay intake was measured weekly for 8 wk. Lambs consumed more (P = 0.002) fescue than bermudagrass hay (743 vs 621 g/ d). Lambs fed fescue hay gained weight more rapidly (P = 0.001) than lambs fed bermudagrass hay (120 vs 72 g/d). Hay intake and ADG were similar (P = 0.90) for lambs fed alfalfa or kenaf pellets. Kenaf hay mixed with molasses and mineral oil can be formed into a pellet. In the diets used in this experiments, kenaf pellets can replace alfalfa pellets in diets fed to lambs without altering forage intake, gain, or N retention.     

Effects of supplementing with calcium salts of palm oil fatty acids or hydrogenated tallow on ewe milk production and twin lamb growth

Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.