Combinations of alfalfa hay and wet corn gluten feed in limit-fed growing diets for beef cattle

Two experiments were conducted to evaluate the effects of alfalfa hay (AH) and wet corn gluten feed (WCGF) combinations on ADG and gain efficiency of cattle limit-fed growing diets. In Exp. 1, crossbred beef steers (n = 220; initial BW = 262 kg) were limit-fed diets consisting of steam-flaked corn and 40% WCGF (DM basis) with 0, 10, or 20% ground AH (0AH, 10AH, and 20AH, respectively). A fourth diet containing 20% ground AH and steam-flaked corn served as a control. All diets were fed once daily at 1.8% of BW (DM basis). Growing period ADG, gain efficiency, and dietary NE calculated from performance data decreased linearly (P < 0.01) with addition of AH to diets containing WCGF. Rate of DMI increased linearly (P < 0.05) with AH addition to diets containing WCGF. Following the growing period, steers were finished on a common diet offered ad libitum. Gain efficiencies during the finishing period were higher (P < 0.05) for steers fed the 20AH diet than for steers fed the control diet. In Exp. 2, crossbred beef heifers (n = 339; initial BW = 277 kg) were limit-fed diets containing steam-flaked corn with 10, 20, or 30% ground AH and 0, 40, or 68% WCGF in a 3 x 3 factorial arrangement, fed once daily at 1.6% of BW (DM basis). An AH x WCGF interaction occurred (P < 0.05) for growing period ADG and gain efficiency. Increasing AH or WCGF decreased cattle ADG, gain efficiency, and dietary NE with the exception of heifers fed 30AH/40WCGF, which had ADG that did not differ (P > 0.10) from that of heifers fed 20AH/0WCGF or 30AH/0WCGF, and which had greater gain efficiencies (P < 0.05) than heifers fed 30AH/0WCGF. Rate of DMI increased linearly (P < 0.01) with increasing AH and decreased linearly (P < 0.01) with increasing WCGF. Heifers were finished on diets containing 33% WCGF with 0 or 0.5% added urea (DM basis) offered ad libitum. Increasing WCGF in growing diets tended (linear, P < 0.10) to increase finishing ADG and gain efficiency, whereas increasing AH decreased (linear, P < 0.05) kidney, pelvic, and heart fat, and the percentage of carcasses grading USDA Prime. Urea tended to increase ADG (P < 0.10), but decreased (P < 0.04) the percentage of carcasses grading USDA Choice. Results suggest that the value of WCGF relative to steam-flaked corn in limit-fed growing diets might be improved in diets containing 30% AH relative to diets containing 10 or 20% AH.     

Use of soybean hulls as a replacement for dry rolled corn in beef cattle feedlot receiving diets

Consecutive receiving studies were used to evaluate the replacement of starch (dry rolled corn; DRC) with a nonforage fiber source (soybean hulls; SBH) on performance, mineral, and blood metabolite status of newly arrived feedlot steer calves. Steers in yr 1 (Y1; 9 pens/diet, 8 to 10 animals/pen) and yr 2 (Y2; 6 pens/diet, 9 to 10 animals/pen) were blocked by weaning management, and then stratified by BW and randomly assigned to pens. Pens were randomly assigned to an oat silage-based diet containing starch (HS) from DRC or digestible fiber (HF) from SBH. Diets were formulated for 12% CP (DM basis) and to meet or exceed NRC (1996) nutrient requirements for Ca, P, and vitamins A and E. Mineral status was assessed in Y1 only via liver biopsies and serum samples collected on d 3 and 28. Mineral concentrations on d 28 were compared using d 3 concentrations as a covariate. Glucose, NEFA, and plasma urea N status were assessed in Y2 only via blood collections on d 0, 3, 7, 14, 28, and 59. Morbidity (<10%) and mortality rates were not different (P > 0.10) between treatments across years. Daily BW gain was similar (P > 0.10) between treatments both during the receiving period and cumulatively across years. Overall, feed intake was greater (P = 0.007) for steers fed HF compared with steers fed HS in Y1, but was not different in Y2 (P = 0.13). Steers consuming the HS diet tended (P = 0.07) to have better BW gain efficiency in Y1 only. Across years, BW gain efficiency and ADG were similar between treatments (P > 0.10), although DMI was greater for steers fed HF (P = 0.003). Based on 2 yr of performance, the calculated ME content of SBH was estimated at 92.5% of the ME value of DRC (2.74 vs. 2.96 Mcal/kg, respectively). Mineral concentrations on d 28 were similar (P > 0.10) for most minerals assayed. There was a steeper (P = 0.005) decline in hepatic Cu concentrations early in the feeding period for steers fed HF, resulting in decreased (P = 0.001) d 28 hepatic concentrations. Hepatic Mn was greater (P = 0.003) in steers fed HF on d 28 as a result of greater (P = 0.006) Mn accumulation during the initial 28 d on feed. Blood metabolites in Y2 (using d 0 values as a covariate) were similar (P > 0.10) across treatments, except for reduced (P = 0.025) plasma urea N concentrations on d 7 and greater (P = 0.050) NEFA concentrations on d 28 for steers fed HS. These studies indicate that the use of SBH in receiving diets can support BW gain similar to the use of DRC.     

Soybean hulls as a primary ingredient in forage-free diets for limit-fed growing cattle

In Exp. 1, 300 heifers (260 kg initial BW) were used to compare growth performance of cattle fed forage-free diets containing predominantly soybean hulls with that of cattle receiving roughage- and corn-based diets and to determine whether cattle fed soybean hull-based diets would respond to supplementation with methionine hydroxy analogue (MHA), lipid-coated betaine, or concentrated separator by-product (CSB; a source of betaine). Treatments included 1) a roughage-based diet fed at 2.75% of BW, 2) a corn-based diet fed at 1.5% of BW, 3) a corn-based diet fed at 2.25% of BW, 4) a soybean hull-based diet fed at 1.5% of BW (SH1.5), 5) a soybean hull-based diet fed at 2.25% of BW (SH2.25), 6) SH1.5 top-dressed with 11.4 g/d Alimet (10 g/d MHA), 7) SH2.25 top-dressed with 11.4 g/d Alimet, 8) SH2.25 top-dressed with 7 g/d of a lipid-coated betaine product (4.2 g/d betaine), and 9) SH2.25 top-dressed with 250 g/d CSB (15.5 g/d betaine). Supplemental MHA, betaine, and CSB did not change DMI, ADG, or gain:feed ratio for cattle fed soybean hulls. Heifers fed soybean hull-based diets gained 29% slower (P < 0.05) and had 27% lower gain:feed ratios than heifers fed the corn-based diets. Cattle fed soybean hull-based diets had gains that were lower (P < 0.05) than those of cattle fed the roughage-based diets, but gain:feed ratios were similar because cattle were fed less of the soybean hull-based diets. Roughage-fed cattle had similar gains but 25% lower (P < 0.05) gain:feed ratios than cattle fed the corn-based diets. In Exp. 2, degradation by ruminal microbes of betaine in anhydrous betaine, betaine-HCl, feed-grade betaine, lipid-coated betaine, and CSB was evaluated in vitro using ruminal inocula collected from steers fed a high-grain or high-roughage diet. The roughage diet led to less betaine disappearance than the grain diet. More betaine was degraded from CSB than from other sources, perhaps because sugars provided by CSB stimulated fermentation, but no large differences occurred among the other four sources. Betaine from all sources was extensively degraded, although some betaine may escape ruminal degradation.     

Camelina meal and crude glycerin as feed supplements for developing replacement beef heifers

Angus × Gelbvieh rotationally crossbred yearling heifers (n = 99, yr 1; n = 105, yr 2) were used in a 2-yr randomized complete block design experiment with repeated measures to determine the effect of feeding camelina biodiesel coproducts (meal and crude glycerin) on serum concentrations of triiodothyronine, thyroxine, insulin, β-hydroxybutyrate, and glucose, as well as on growth and reproductive performance. Heifers were assigned to 1 of 15 pens, and pens were assigned initially to receive 7.03 k·?heifer(-1)·d(-1) of bromegrass hay plus 0.95 kg·heifer(-1)·d(-1) of 1 of 3 supplements for 60 d before breeding: 1) control (50% ground corn and 50% soybean meal, as-fed basis); 2) mechanically extracted camelina meal; or 3) crude glycerin (50% soybean meal, 33% ground corn, 15% crude glycerin, 2% corn gluten meal; as-fed basis). Preprandial blood samples were collected via the jugular vein on d 0, 30, and 60 of the feeding period. A 2-injection PGF(2α) protocol (d 60 and 70 of the study) was used to synchronize estrus. Heifers were artificially inseminated 12 h after estrus was first detected. Heifers not detected in estrus within 66 h received a GnRH injection and were artificially inseminated. Dietary treatment × sampling period interactions were not detected (P = 0.17 to 0.87). Dietary treatment did not affect BW (P = 0.44 to 0.59) or serum concentrations of thyroxine (P = 0.96), β-hydroxybutyrate (P = 0.46), glucose (P = 0.59), or insulin (P = 0.44). Serum concentrations of triiodothyronine were greater (P = 0.05) in heifers fed camelina meal. Additionally, dietary treatment did not affect the percentage of heifers detected in estrus before timed AI (P = 0.83), first-service pregnancy rates of those heifers detected in estrus (P = 0.97), or overall first-service pregnancy rates (P = 0.58). Heifers fed camelina meal, however, had greater (P = 0.05) first-service pregnancy rates to timed AI than did heifers fed the control and crude glycerin supplements. The cost per pregnancy was similar for heifers fed the crude glycerin or the control supplement, whereas the cost per pregnancy was the least for heifers fed camelina meal. We conclude that camelina coproducts can replace conventional corn-soybean meal supplements in the diets of developing replacement beef heifers.     

Genetic and phenotypic parameter estimates for feed intake and other traits in growing beef cattle, and opportunities for selection

Growth, feed intake, and temperament indicator data, collected over 5 yr on a total of 1,141 to 1,183 mixed-breed steers, were used to estimate genetic and phenotypic parameters. All steers had a portion of Hereford, Angus, or both as well as varying percentages of Simmental, Charolais, Limousin, Gelbvieh, Red Angus, and MARC III composite. Because the steers were slaughtered on various dates each year and the animals thus varied in days on feed, BW and feed data were adjusted to a 140-d feeding period basis. Adjustment of measures of feed efficiency [G:F or residual feed intake (RFI), intake adjusted for metabolic body size, and BW gain] for body fatness recorded at slaughter had little effect on the results of analyses. Average daily gain was less heritable (0.26) than was midtest BW (MBW; 0.35). Measures of feed intake had greater estimates of heritability, with 140-d DMI at 0.40 and RFI at 0.52; the heritability estimate for G:F was 0.27. Flight speed (FS), as an indicator of temperament, had an estimated heritability of 0.34 and a repeatability of 0.63. As expected, a strong genetic (0.86) correlation was estimated between ADG and MBW; genetic correlations were less strong between DMI and ADG or MBW (0.56 and 0.71). Residual feed intake and DMI had a genetic correlation of 0.66. Indexes for phenotypic RFI and genotypically restricted RFI (no correlation with BW gain) were compared with simple economic indexes incorporating feed intake and growth to elucidate expected selection responses under different criteria. In general, few breed differences were detected across the various measurements. Heterosis contributed to greater DMI, RFI, and MBW, but it did not significantly affect ADG, G:F, or FS. Balancing output (growth) with input costs (feed) is needed in practicing selection, and FS would not be recommended as an indicator trait for selection to change feed efficiency. An index including BW gain and RFI produced the best economic outcome.     

Genetic associations between feed efficiency measured in a performance test station and performance of growing cattle in commercial beef herds

Interest in selection for improved feed efficiency is increasing, but before any steps are taken toward selecting for feed efficiency, correlations with other economically important traits must first be quantified. The objective of this study was to quantify the genetic associations between feed efficiency measured during performance testing and linear type traits, BW, live animal value, and carcass traits recorded in commercial herds. Feed efficiency data were available on 2,605 bulls from 1 performance test station. There were between 10,384 and 93,442 performance records on type traits, BW, animal value, or carcass traits from 17,225 commercial herds. (Co)variance components were estimated using linear mixed animal models. Genetic correlations between the muscular type traits in commercial animals and feed conversion ratio (-0.33 to -0.25), residual feed intake (RFI; -0.33 to -0.22), and residual BW gain (RG; 0.24 to 0.27) suggest that selection for improved feed efficiency should increase muscling. This is further evidenced by the genetic correlations between carcass conformation of commercial animals and feed conversion ratio (-0.46), RFI (-0.37), and residual BW gain (0.35) measured in performance-tested animals. Furthermore, the genetic correlations between RFI and both ultrasonic fat depth and carcass fat score (0.39 and 0.33, respectively) indicated that selection for improved RFI will result in leaner animals. It can be concluded from the genetic correlations estimated in this study that selection for feed efficiency will have no unfavorable effects on the performance traits measured in this study and will actually lead to an improvement in performance for some traits, such as muscularity, animal price, and carcass conformation. Conversely, this suggests that genetic selection for traits such as carcass quality, muscling traits, and animal value might also be indirectly selecting for more efficient animals.     

Potential of hazelnut husks as a broiler litter material

1. Hazelnut husks and some other litter materials were compared for litter properties and their effects on broiler performance. 2. A total of 750 1-d-old broiler chicks were weighed and assigned at random to 1 of 5 treatments, with each treatment replicated 3 times. 3. The treatments were wood shavings (control), wheat stalks, rice hulls, hazelnut husks, and a mixture of 50% rice hulls and 50% hazelnut husks. 4. Although hazelnut husks were associated with lower body weights at 49 d of age, food efficiency mortality, carcase yield, breast blisters and production index were similar to birds on wood shavings. Hazelnut husks had the highest litter moisture. 5. The results show that hazelnut husks alone and when mixed with rice hulls are a potential alternative litter material for broiler production.     

Nutritive characteristics of pearl millet grain in beef cattle diets

Two trials were conducted to compare pearl millet grain with corn and grain sorghum in cattle diets. Grain portions of diets in metabolism and feedlot experiments contained 73% corn and 6% soybean meal (C); 76.2% grain sorghum and 2.8% soybean meal (GS); and 79% pearl millet (PM). In the metabolism trial (replicated 3 x 3 latin squares; six steers), apparent digestibilities of DM and OM were higher (P less than .05) for C than for GS or PM diets. Ether extract and CP digestibilities were higher (P less than .05) for C and PM than GS. Dietary TDN was higher (P less than .05) for C compared with GS or PM diets. Fecal N was higher (P less than .05) for GS than for C or PM, urinary N was higher (P less than .05) for PM than C or GS, but retained N was similar (P greater than .05) for C, GS and PM diets. In a 90-d feedlot trial (18 individually fed heifers), a trend was observed for higher (P less than .20) ADG on C compared with PM; however, feed/gain was similar for C, GS and PM diets (8.2, 9.1 and 8.5 kg feed/kg gain, respectively). Ruminal fluid acetate:propionate ratios were lower (P less than .05) at 3.5 and 7 h postfeeding for PM compared with C or GS diets on d 83. Pearl millet grain may be used as a feed grain for beef cattle, but diets should be formulated to efficiently utilize the high quantity of protein (about 14% of DM) in this grain as a substitute for supplemental protein.     

Branched-chain amino acids for growing cattle limit-fed soybean hull-based diets.

Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain AA supplementation on N retention and plasma AA concentrations of steers. Steers were limit-fed (3.0 kg/d of DM) twice daily diets low in ruminally undegradable protein (72% soybean hulls, 19% alfalfa, 5% molasses, and 4% vitamins and minerals). Acetate (400 g/d) was continuously infused into the rumen. Treatments were continuous abomasal infusions of 1) 115 g/d of a mixture of 10 essential AA designed to exceed the steers' requirements (10AA), 2) 10AA with Leu removed, 3) 10AA with Ile removed, 4) 10AA with Val removed, and 5) 10AA with all three branched-chain AA removed. Experimental periods were 7 d, with 3 d for adaptation to treatments and 4 d for total fecal and urinary collections for N balance. Blood samples were collected 5 h after feeding on d 7. Retained N decreased in response to removal of Leu (P < 0.06), Val (P < 0.05), or all three branched-chain AA (P < 0.05). Plasma Leu concentrations decreased (P < 0.05) in response to removal of Leu and all three branched-chain AA. Plasma Ile concentrations decreased (P < 0.05) in response to removal of Ile and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Plasma Val concentrations decreased (P < 0.05) in response to removal of Val and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Responses in N balance and plasma AA concentrations of growing cattle limit-fed soybean hull-based diets demonstrate limitations in the basal supply of Leu and Val but not Ile provided that supplies of all other essential AA are met.     

The effects of feed additives in cattle fed forage-based diets

Open in a separate window

Ionophores fed to cattle alter the rumen microbiome causing a metabolic shift that underlies improved animal performance. While a majority of the research into mechanisms of action were performed in cattle fed a high-concentrate diet (Thompson et al., 2016), limited information exists detailing their impact in cattle maintained on a high-forage diet. Improved animal performance is especially important in tropical and subtropical regions that are more reliant on forage-based production systems (Cooke et al., 2020). A recent study compared the effects of 3 different feed additives fed to bos indicus bulls receiving a haylage diet (Limede et al., 2021). Results provide new insight into the interplay between ionophore, breed and diet on animal performance.     

Type and mixtures of high-moisture corn in beef cattle finishing diets

In three experiments consisting of three finishing trials each, five corn storage and(or) feeding treatments were evaluated: 1) dry whole (DWC); 2) whole high-moisture (WHMC); 3) mixture (MHMC) of ground (GHMC) or rolled (RHMC) high-moisture corn with WHMC; 4) GHMC stored in a bunker silo; and 5) RHMC, corn stored whole but fed in rolled form. In Exp. 1, gains and feed intakes of steers fed whole corn (DWC vs WHMC) were similar. Steers fed GHMC and RHMC had lower (P less than .05) gains and intakes than steers fed whole corn. However, feed to gain ratios were 9% better (P less than .10) for steers fed RHMC than for steers fed GHMC. In Exp. 1 and 2, gains of steers fed MHMC were intermediate to gains of steers fed whole (DWC and WHMC) or processed corn (GHMC and RHMC). Feed to gain ratios of steers fed whole or processed corn were similar to feed to gain ratios of steers fed MHMC. In Exp. 3, steers fed 28.6% moisture GHMC had lower (P less than .05) intakes and feed to gain ratios than steers fed 22.5% moisture GHMC. Intakes and feed to gain ratios decreased 1.2 and 1.4%, respectively, for each 1% increase in corn moisture. Data are interpreted to mean that the relative effect of corn moisture content on cattle performance depends on form of corn fed; positive associative effects of MHMC are negligible, but RHMC has a greater feed value than GHMC.     

Accuracy of genomic breeding values for residual feed intake in crossbred beef cattle

The benefit of using genomic breeding values (GEBV) in predicting ADG, DMI, and residual feed intake for an admixed population was investigated. Phenotypic data consisting of individual daily feed intake measurements for 721 beef cattle steers tested over 5 yr was available for analysis. The animals used were an admixed population of spring-born steers, progeny of a cross between 3 sire breeds and a composite dam line. Training and validation data sets were defined by randomly splitting the data into training and testing data sets based on sire family so that there was no overlap of sires in the 2 sets. The random split was replicated to obtain 5 separate data sets. Two methods (BayesB and random regression BLUP) were used to estimate marker effects and to define marker panels and ultimately the GEBV. The accuracy of prediction (the correlation between the phenotypes and GEBV) was compared between SNP panels. Accuracy for all traits was low, ranging from 0.223 to 0.479 for marker panels with 200 SNP, and 0.114 to 0.246 for marker panels with 37,959 SNP, depending on the genomic selection method used. This was less than accuracies observed for polygenic EBV accuracies, which ranged from 0.504 to 0.602. The results obtained from this study demonstrate that the utility of genetic markers for genomic prediction of residual feed intake in beef cattle may be suboptimal. Differences in accuracy were observed between sire breeds when the random regression BLUP method was used, which may imply that the correlations obtained by this method were confounded by the ability of the selected SNP to trace breed differences. This may also suggest that prediction equations derived from such an admixed population may be useful only in populations of similar composition. Given the sample size used in this study, there is a need for increased feed intake testing if substantially greater accuracies are to be achieved.     

On the relationships between glucocorticoids and feed efficiency in beef cattle

Improvement in the utilization of feed in livestock is an important target of breeding and nutritional programs. Recent evidence indicates a potential association between feed efficiency and fecal cortisol metabolites, which could eventually be used as an indirect assessment of this trait. This evidence is more comprehensively evaluated in here with samples for plasma cortisol (PC; ng/ml) and fecal cortisol metabolites (FCM; ng/ml) collected more often during the entire finishing phase in beef steers. Individual daily feed intake of 112 steers fed a high-moisture corn-based and haylage diet was measured over 168 d. Body weight, blood and fecal samples were collected every 14 d and ultrasound measures of backfat thickness and longissimus muscle area were taken every 28 d. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F:G) and residual feed intake (RFI). At the end of the feedlot phase, steers were ranked according to RFI and samples were analyzed for PC and FCM from the 32 steers with greatest and 32 steers with lowest feed efficiency. In addition, a sub-group of 12 steers from each of these two groups with divergent feed efficiency were subjected to hourly blood sampling for 24 h. Less efficient steers had greater DMI, F:G and consumed 1.5 kg/d more DMI (P<0.05) than steers with improved feed efficiency. No differences (P>0.10) in PC over the 12 biweekly sampling periods between steers with divergent feed efficiency were observed. However, a trend toward significance between 19:00 and 02:00 h over the hourly sampling evaluation was noticed, with the sub-group of more feed efficient steers presenting higher levels of PC in this period of the day (P=0.08). On the other hand, FCM levels displayed a distinct pattern between RFI groups over the biweekly sampling period, with more efficient cattle presenting greater levels of these metabolites (P<0.05). This study reinforces the positive association between improved feed efficiency and FCM levels over the finishing phase; and the lack of association between feed efficiency and PC when single samples are collected every two weeks through a single jugular venipuncture performed after handling the cattle for sampling. Further studies to develop sampling protocols for assessing FCM as an indicator trait for feed efficiency are warranted, as well as, studies to understand the role of endogenous glucocorticoids in the performance of the bovine.     

Simplified calculation of the NRC estimates for net energy for maintenance in beef cattle diets

Calculation of dietary intake for beef cattle using the equation outlined by the NRC (1984) is confounded by the need to know the net energy for maintenance content of the diet (NEmkg). Intake cannot be calculated until NEmkg is specified, but intake must be indicated before performance can be predicted. To calculate NEmkg, dietary intake must be known or estimated, or it can be calculated using a complicated quartic equation. This quartic equation, when solved, gives the percentages of selected feedstuffs necessary to balance a diet. Placing the resulting percentages of feedstuffs necessary back into the generalized net energy equation solves for NEmkg. The quartic equation may be simplified by inserting imaginary nutrient values that optimize the equation for simplicity. It remains a quartic equation, but the coefficients for the first three factors of the equation are fixed, with only the unary X term and the coefficient containing variables. A modified version of Newton's method of approximating roots of equations estimates the percentage of feed necessary and when incorporated into the generalized net energy equation solves for NEmkg. The final reduced form results in simplified equations for NEmkg for each of the classes of beef cattle that are easily solved by the hand-held calculator.     

Test duration for growth, feed intake, and feed efficiency in beef cattle using the GrowSafe System

This study was conducted to determine the optimum test duration and the effect of missing data on accuracy of measuring feed efficiency and its 4 related traits ADG, DMI, feed conversion ratio, and residual feed intake in beef cattle using data from 456 steers with 5,397 weekly averaged feed intakes and BW repeated measurements taken over 91 d. Data were collected using the GrowSafe System at the University of Alberta Kinsella Research Station. The changes and relative changes in phenotypic residual variances and correlations (Pearson and Spearman) among data from shortened test durations (7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, or 84 d) and a 91-d test were used to determine the optimum test duration for the 4 traits. The traits were fitted to a mixed model with repeated measures using SAS. Test durations for ADG, DMI, feed conversion ratio, and residual feed intake could be shortened to 63, 35, 42, and 63 d, respectively, without significantly reducing the accuracy of the tests when BW was measured weekly. The accuracy of the test was not compromised when up to 30% of the records were randomly removed after the first 35 d on test. These results have valuable and practical implications for performance and feed efficiency testing in beef cattle.