Calf ADG Research Articles

Winter-annual pasture as a supplement for beef cows.

In each of two experiments, 120 pregnant beef cows were stratified by body condition score, BW, breed, and age, randomly divided into six groups of 20, and assigned to one of six 5.1-ha bermudagrass (Cynodon dactylon [L.] Pers.) pastures (two replicates/ treatment) in early January to evaluate the use of winter-annual pasture as a supplement. All cows in Exp. 1 and 2 had ad libitum access to bermudagrass/dallisgrass (Paspalum dilatatum Poir.) hay plus three treatments: 1) a concentrate-based supplement fed 3 d/wk, 2) limit grazing on winter-annual pasture 2 d/wk (7 hr/ d; 0.04 ha x cow(-1) x grazing d(-1)), or 3) limit grazing on winter-annual pasture 3 d/wk (7 hr/d; 0.04 ha x cow(-1) x grazing d(-1)) sod-seeded into a portion of the pasture until mid-May. The seeded portion of pastures in Exp. 1 was planted with a mixture of wheat (Triticum aestivum L.) and rye (Secale cereale L.), but annual ryegrass (Lolium multiflorum Lam.) was added to the seed mixture in Exp. 2. In mid-May, cows were blocked by treatment and the previous sorting factors, randomly assigned to six new groups of 20, and placed on the six perennial pastures until calves were weaned. Groups of cows were exposed to a bull for 60 d beginning in mid-May. In Exp. 1 and 2, limit-grazing winter-annual pasture compared to the concentrate-based supplement or limit grazing 2 vs 3 d/wk did not affect (P > 0.15) cow BW. In Exp. 1, cows limit grazed on winter-annual pasture had a lower (P = 0.05) body condition score than cows fed the concentrate-based supplement in the early spring. However, in Exp. 2, cows limit grazed on winter-annual pasture had higher (P < or = 0.07) body condition score than cows fed the concentrate-based supplement. The conception rate of cows in Exp. 1 and 2 did not differ (P > 0.22) between cows fed concentrate-based supplements and cows limit grazed on winter-annual pasture. In Exp. 2, cows limit grazed 2 d/wk tended to have a greater (P = 0.10) conception rate than cows limit grazed 3 d/wk. In Exp. 1 and 2, birth weight, total gain, BW, and ADG of calves were not affected (P > 0.15) by treatment. We conclude that wheat and rye pasture is a marginal supplement for lactating beef cows. However, cows limit grazed 2 d/wk on winter-annual pasture of wheat, rye, and annual ryegrass as a supplement maintained BW and body condition score as well as cows fed the concentrate-based supplement. But, grazing pasture 3 vs 2 d/wk did not seem to affect performance of cows.

Effect of calf age and dam breed on intake, energy expenditure, and excretion of nitrogen, phosphorus, and methane of beef cows with calves1

The effects of calf age and dam breeds of different milk yield potential on turnover of energy and nutrients were followed in 16 Simmental and 16 Angus beef cows with Angus-sired calves. Calf ages investigated were 1, 4, 7, and 10 mo. The forage offered for ad libitum access consisted of hay for the calves and of a constant mixture of grass silage, meadow hay, and straw (1:0.7:0.3 on a DM basis) for the cows. Calves of 10 mo of age received an additional 2.6 kg DM/d of crushed barley. The animals were kept in groups of four cows and four calves except in the respiration chambers, where only one cow (tethered) and her calf (loose) were grouped together. Indicator techniques were applied to obtain individual data on feces and urine volumes during group housing. In the Simmental cows, heavier on average by 22 kg, voluntary DMI was higher than in the Angus cows (14.0 vs 12.3 kg/d). In calves, DMI from supplementary feeds was 1.6, 3.9, and 6.3 kg/d, on average, at 4, 7, and 10 mo of age, respectively. Dam breed had no significant effect on DMI and ADG of calves and on BW changes of cows. System retention of energy, N, and P showed a curvilinear development with calf age. System energy expenditure, which linearly increased with calf age, was higher with Simmental than with Angus dams (11%), even when adjusted for metabolic BW (8%). Energy loss through methane linearly increased with NDF intake and, consequently, with calf age from 18 to 30 MJ/d (446 to 751 L/d) for cows and calves together. Similarly, fecal and urinary N excretion and fecal P excretion steadily increased with calf age. In calves, the easily volatile N percentage of manure N rapidly decreased from very high levels in young calves. The resulting changes in inclination to gaseous N loss during manure storage for 8 wk were more than compensated by alterations in N intake of the calves, resulting in an increased total system N loss with progressing lactation. Overall, the present results indicate a difference between Angus and Simmental in efficiency of nutrient and energy utilization that might be explained by the difference in amount of delivery of nutrients to the calves via milk vs forage. Suggestions are made as to how the emissions of N, P, and methane, which were excessive in relation to productivity, could be reduced by nutritional means.

Impact of different wheat milling by-products in supplements on the forage use and performance of beef cattle consuming low-quality, tallgrass-prairie forage.

Two experiments were conducted to evaluate the impacts on forage use and beef cattle performance of incorporating divergent wheat milling by-products in a 30% CP supplement. The by-products were wheat bran (high fiber) and second clears (high starch). The by-products were added as 1) 100% wheat bran; 2) 67% wheat bran, 33% second clears; or 3) 33% wheat bran, 67% second clears to constitute approximately 47 to 49% of the supplement. In Exp. 1, 90 Hereford x Angus cows (BW = 554 kg) grazing winter, tallgrass-prairie range were fed the supplement treatments (2.27 kg/cow daily) from early December 1997 until calving (average calving date = 3/11/98). Cumulative BW and condition changes from trial initiation through calving were not significantly different among treatments. Similarly, significant treatment effects on cow pregnancy rates as well as calf birth weights, ADG, and ending weights were not evident. In Exp. 2, 16 ruminally fistulated Hereford x Angus steers (BW = 484 kg) were blocked by weight and assigned to one of the same three supplement treatments or to a negative control (forage only). Steers had ad libitum access to tallgrass-prairie hay (76.4% NDF, 3.1% CP) and were fed supplement at the same rate (relative to BW) as the cows in Exp. 1. Forage OM, NDF, and digestible OM intakes were lower (P < 0.01) for the negative control than for supplemented steers but were not significantly different among the supplemented steers. Digestion of OM was lower (P = 0.03) for the negative control than for supplemented steers, although significant treatment differences were not evident among the supplemented groups. Digestion of NDF was not affected (P = 0.49) by treatment. Within the context of the amount of supplemental protein offered, changes in the combination of wheat milling by-products in the supplement did not affect cow performance or intake and digestion of low-quality forage.

Lactation and calf weight traits of mature crossbred cows fed varying daily levels of metabolizable energy.

Our objective was to evaluate differences in lactation traits and calf weights produced by F1 cows under varying daily metabolizable energy availability. Measures of milk yields and calf weight traits were recorded on mature F1 cows. The cows were produced from matings of Angus or Hereford dams with sires representing Angus/Hereford, Shorthorn, Galloway, Longhorn, Nellore, and Salers breeds. The cows' daily DM intakes of a diet composed of a corn silage or alfalfa silage plus corn silage were recorded from approximately 2 wk postpartum until the calves were weaned at an average age of 170 d. Milk yield measurements were recorded when the calves were approximately 14, 28, 56, 84, 112, 140, and 168 d of age. Sources of variation considered for the traits of interest included sire breed of the cow (SBC) and the covariates weaning age of the calf and daily metabolizable energy intake (DMEI) of the cow for lactation and calf weights. The linear and quadratic effects were evaluated for DMEI. The SBC x DMEI (linear) interaction was significant for total milk yield. Sire breed of cow differences (P < .05) were observed for milk yield at time of peak yield, persistency, preweaning ADG, and weaning weight. Salers- and Shorthorn-sired cows had greater (P < .05) peak yield than Galloway, Longhorn, or Nellore cross-bred cows but were not significantly different from the Hereford/Angus. Increasing DMEI linearly increased peak yield and total yield (P < .05). Preweaning ADG of calves from Nellore-sired cows was greater (P < .05) than all SBC. Preweaning ADG of calves from Galloway-sired cows was less than all SBC (P < .05). The linear effect of DMEI was heterogeneous across SBC for total yield. The pooled quadratic effect of DMEI was significant for all traits except birth weight. The DMEI for expression of maximum weaning weight was estimated to be 29 Mcal. Feed efficiency ratios for the test period were 28, 27, 30, 25, 28, 32, and 30 g calf weight:Mcal DMEI for reference and 1980s Angus/Hereford-, Shorthorn-, Galloway-, Longhorn-, Nellore-, and Salers-sired cows, respectively, at the DMEI level of 29 Mcal.

Influence of Rumen-Protected Methionine and Lysine on Growing Cattle Fed Forage and Corn Based Diets

Microbial protein in ruminants may be inadequate to support desirable levels of performance if the diet does not supply sufficient amounts of intestinally absorbable amino acids. Three experiments were conducted to determine the effects of RPM and/or a combination of RPM and RPL on ADG, serum metabolites, and DMI of calves fed diets based on forage or corn (Zea mays, L.). In Exp. 1, 36 steers were fed alfalfa/fescue (Medicago sativa [L.], Festuca spp. [L.]) hay plus one of three supplemental treatments for 28 d: (i) wheat (Triticum aestivum [L.] em. Thell.) middling basal supplement (WM); (ii), WM + 0.07 oz of RPM (RPM2); or (iii) WM + 0.14 oz of RPM (RPM4). Although there were no overall differences (P > 0.05) in ADG among treatments, there was a numerical trend (P 0.05) among treatments, ADG of RPML1 and RPML2 treatments was increased (P < 0.05) by 9 and 8%, respectively, over the control, during the 58-d period. In Exp. 3, 24 Holstein heifers grazed Kentucky 31 tall fescue (Festuca arundinacea Schreb.) pasture and were fed one of four supplements: (i) soyhulls (Glycine max (L.) Merr.) and cracked corn (control); (ii) control + 0.07 oz of RPM (RPMI); (iii) control + 0.07 oz and 0.25 oz of RPM and RPL (RPML); or (iv) control + 3.5 oz of blood meal (BM). Heifers had greater (P = 0.005) ADG and DMI (P = 0.03) for the first 30 d as compared with the second 30 d. Serum methionine was greater (P = 0.01) for RPML than control and BM treatments. These data suggest that lysine and methionine were the first limiting amino acids in corn/corn silage-based diets but not for heifers grazing tall fescue.

Reproductive performance, calf growth, and milk production of first-calf heifers sired by seven breeds and raised on different levels of nutrition.

We evaluated heifers crossbred from seven breeds of sires (Hereford, Angus, Belgian Blue, Piedmontese, Brahman, Boran, and Tuli) and three breeds of dams (Angus, Hereford, and MARC III [four-breed composite]). Heifers were mated to Red Poll sires to calve at 2 yr of age. Heifers were placed in two treatments from weaning to breeding and raised on a high nutrition level (15.8 Mcal ME/d) or on 80% of the high nutrition level (12.6 Mcal ME/d). Breeds differed in the age of the heifers at parturition (P = .03). Birth weights of calves differed by maternal grandsire (P < .001) but not by heifer treatment (P = .91) or maternal grandam (P = .19). Heifers differed in their postpartum interval to estrus by sire breed (P = .001). Calf age at weaning (P = .02), calf ADG (P < .001), and 205-d weight (P < .001) differed between breeds of maternal grandsires. Milk production from 50 to 200 d of lactation was greatest for heifers of Belgian Blue (1,070 +/- 30 kg) and Brahman (1,029 +/- 38 kg) sires. Milk production did not differ with treatment group (P = .84). This study suggests that over a diverse group of breeds, accelerated rates of gain during the postweaning period within the ranges of this study do not result in increased production efficiency of the cows.

Effect of Source and Amount of Zinc, Copper, Manganese, and Cobalt Fed to Stressed Heifers on Feedlot Performance and Immune Function

One hundred and five crossbred heifer calves (208.6kg ± 2.46) were used in two randomized block design studies to evaluate the effect of source and amount of Zn, Mn, Cu, and Co fed following weaning and transport stress on performance and immune response. Cattle were fed a basal diet that was supplemented with either: 1) inorganic trace minerals consisting of 106ppm Zn from ZnO, 58ppm Mn from MnO, 37ppm Cu from CuSO4, and 7ppm Co from CoCO3 (1× amount), or 2) organic element complexes fed isoelemental to inorganic trace element amounts (1×), providing Zn from Zn methionine (ZnMet), Mn from Mn methionine (MnMet), Cu from Cu lysine (CuLys), and Co from Co glucoheptonate (CoGlu), or 3) organic element complexes supplemented at 3× for the first 14 d posttransport; 318ppm Zn from ZnMet, 174ppm Mn from MnMet, 111ppm Cu from CuLys, and 21ppm Co from CoGlu, then reduced to the 1× supplement amount for the remaining period of the 42-d experiment (3×/1×). No differences were observed among treatments in calf DMI, ADG, or FE over the 42 d trial. There were, however, increases (P<0.01) in calf secondary PI-3 antibody titer response at 14 and 28 d postvaccination. Skin swelling response at 21 d posttransport and at 12, 24, and 48h postinjection to intradermal PHA was better with feeding organic trace elements at the 3×/1× concentration than either the organic 1× or the inorganic 1× treatments. Feeding calves 1× organic trace elements improved antibody titer response to IBRV vaccination at 14 (P<0.01) and 28 (P<0.05) d compared to the calves receiving the 1× inorganic treatment. The calves fed organic 3×/1× had a 17.2% reduction (P<0.05) in incidence of respiratory disease when compared to the other treatments. In this trial, the feeding elevated organic minerals showed significant improvements in primary and secondary humoral, and cell-mediated immunity compared to the feeding of inorganic sources.

Performance of Angus and Brangus cow-calf pairs grazing Alicia bermudagrass and common bermudagrass-dallisgrass pastures.

This research was designed to examine genotype x environment interactions in cow-calf growth performance of grazing animals. Angus and Brangus cow-calf pairs (minimum of six per breed) were allowed to rotationally graze (14-d intervals) treatment pastures from approximately May through early October in each of 2 yr. Treatment pastures contained relatively pure stands of Alicia bermudagrass (AP) or a mixed stand of common bermudagrass and dallisgrass (CDP). Forage allowance was equalized, using "put-and-take" cow-calf pairs, among forage and breed types at the initiation of each 14-d grazing interval. Forage samples were obtained in each paddock at the initiation of each grazing interval. Forage CP concentration was greater (P < .05; 13.5 vs 11.6%) and NDF concentration was less (P < .05; 63.8 vs 70.6%) for CDP than for AP. Daily weight loss was similar for Angus and Brangus cows, but it was greater (P < .05) for cows grazing AP than for cows grazing CDP. Calf ADG during the grazing season was 35% greater (P < .05) for CDP than for AP pastures and was 23% greater (P < .01) for Brangus than for Angus calves. Relative performance of Angus and Brangus cow-calf pairs was consistent between forages; no breed x forage interactions were observed.

Effects of suppressing cortisol following castration of bull calves on adrenocorticotropic hormone, in vitro interferon-gamma production, leukocytes, acute-phase proteins, growth, and feed intake.

The objective was to determine the effects of reducing the plasma cortisol rise in calves following castration on plasma ACTH concentrations, keyhole limpet hemocyanin (KLH)- and concanavalin A (Con A)-induced in vitro interferon (IFN)-gamma production, white blood cell (WBC) numbers, neutrophil:lymphocyte (N:L) ratio, plasma haptoglobin and fibrinogen concentrations, ADG, and ADFI. Forty 5-mo-old Friesian bull calves (169 +/- 1.7 kg) were assigned to four treatments: 1) control (CON); 2) oral metyrapone administration (MET); 3) surgical castration at 0 h on d 0 (SURG); and 4) oral metyrapone administration and surgical castration (MET+SURG). Cortisol, ACTH, IFN-gamma production, haptoglobin, fibrinogen, ADFI, and ADG were not different between CON and MET animals. The MET+SURG calves had lower (P < .001) peak and mean cortisol during .25 to 1.5 h than SURG animals, but area under the cortisol vs time curve from 0 to 12 h did not differ (P > .39) between SURG and MET+SURG calves. Peak ACTH concentrations and area under the ACTH vs time curve from 0 to 6 h were greater (P < .05) for MET+SURG than for SURG calves. There were no differences between MET+SURG and SURG animals in IFN-gamma production, WBC numbers, and ADFI. On d 1, MET+SURG and SURG animals had lower (P < .01) KLH- and Con A-induced IFN-gamma production and higher (P < .05) neutrophil numbers and N:L ratio compared with CON animals. Plasma haptoglobin on d 1 and 3 and fibrinogen concentrations on d 3 and 7 were elevated (P < .05) for MET+SURG and SURG compared with CON animals, whereas SURG animals had greater (P < .05) haptoglobin and fibrinogen concentrations than MET+SURG animals on d 7. The ADG of SURG calves was lower (P < .05) than that of MET+SURG calves during d 0 to 7. Metyrapone treatment partially suppressed cortisol and increased ACTH in castrated calves but did not alter the castration-induced suppression of IFN-gamma and increases in neutrophil numbers and the N:L ratio.

Effects of time of weaning, supplement, and sire breed of calf during the fall grazing period on cow and calf performance.

A 4-yr experiment was conducted to determine effects of protein supplementation, age at weaning, and calf sire breed on cow and calf performance during fall grazing. Each year 48 pregnant, crossbred cows nursing steer calves (mean calving date = April 8) were assigned to a 2 x 2 x 2 factorial experiment replicated in three native range pastures. Treatment factors were: 1) no supplement (NS) or an individually fed supplement (S, 3 kg of a 34% protein supplement fed to cows every 3rd d); 2) calves weaned at the beginning (W, mid to late September) or at the end (NW, mid to late December) of the trial each year; or 3) calves sired by Hereford or Charolais bulls. Data were adjusted for cow size (initial hip height and initial and final weights and condition scores) by analyses of covariance using principal component coefficients as covariates. Change in cow weight and condition score were increased by S and W (P < .01), but these responses interacted and were not the same each year (yr x S, year x W, and year x S x W, P < .01). Forage intake was decreased (P < .1) by S and W. Total intake (forage+supplement) was not affected by S but was decreased by W (P < .1). Digestibility of OM was decreased by S (P < .01). Some carryover effects of treatments were observed the next spring in cow weight, condition score, and birth weight (NW decreased birth weight by 2 kg, P < .01), but there were no effects by the next fall on weaning weights or pregnancy rates. Milk yield decreased during the experimental period, and S maintained higher milk production in late lactation (P < .01). Calf ADG was increased by S and Charolais sires (P < .01). Efficiency (grams of output/ megacalorie of input) was not affected by sire breed but was enhanced by S (P < .01). Our conclusions are that 1) effects of feeding a 34% protein supplement to cows were to increase calf gains and improve persistency of lactation and efficiency; 2) delaying weaning decreased cow weight and condition score; 3) effects of weaning age and protein supplementation were highly dependent on forage and environmental conditions in any given year; and 4) whatever effects existed in a given year did not carry over to effects on next year's production as measured by pregnancy rates and weaning weights.

The Effects of Slow-Release Copper Boluses on Cow Reproductive Performance and Calf Growth

The effect of copper, orally administered via slow-releasing boluses, was examined in two Kansas beef herds. In herd 1, 34 cows and calves were divided into a treated (B; n = 18) and a control group (C; n = 16). The cattle in herd 1 were prediagnosed as copper-deficient by liver biopsy analysis. Cows assigned to B received two boluses, and their respective calves received one. Serum samples were collected at d 0 and 64. Liver samples, collected at d 64 and 106, were analyzed for copper and iron. Liver iron levels tended (P=.068) to be lower in group B. Through d 106, cow ADG did not differ between treatments (.29 vs .28 kg/d for B and C, respectively). Calf ADG was determined 42-d posttreatment. Control calves tended (P=.063) to have a higher ADG. In herd 2, dams were divided into a treated (B; n = 276) and control group (C; n = 830). The cattle in herd 2 were not prediagnosed as copper-deficient, however, unexplained reductions in fertility, coupled with the high prevalence of copper deficiency in this region, made this herd a likely candidate for this study. As in herd 1, dams assigned to B received two boluses, and their respective calves received one. Approximately, 1 mo after treatment, reproductive parameters, including AI pregnancy rate, AI first service conception rate, and number of inseminations per female, were evaluated in all dams. Liver (n = 10) and serum (n = 30) samples were collected randomly from dams on d 0, 97, and 154. Additionally, bull and heifer calf weaning weight was examined in herd 2. No treatment differences were detected in serum copper concentration. On d 97 and d 154 of treatment, bolus administration elevated (P<.05) liver copper. No treatment differences were detected in dam reproductive performance. Bull calves in herd 2 were divided into a treated (BB; n = 56) and a control group (BC; n = 43). Weaning weights were heavier (P<.05) (269 d posttreatment) for BC (354 kg) than for BB (340 kg). Heifer calves in herd 2 also were divided into a treated (HB; n = 36) and a control group (HC; n = 37). Weaning weights tended (P=.093) to be heavier (288 posttreatment) for HC (327 kg) than for HB (313 kg). Orally administered copper boluses tended to increase liver copper, decrease liver iron, and adversely affect calf weight gain; a response in reproductive parameters was not noted.

Protein supplementation of ammoniated wheat straw: effect on performance and forage utilization of beef cattle

We studied the effects of supplement CP concentration on performance and forage use of cattle allowed ad libitum access to ammoniated wheat straw. During two consecutive winters, crossbred beef cows in late gestation (n = 87 in 1990-1991, n = 84 in 1991-1992) were used in a randomized complete block design with three pens per treatment. Cows were stratified by weight, body condition score (BCS), age, and breed and randomly assigned within strata to 1) control (C, no supplement), or 2 kg/d of 2) low-protein (LP) supplement (12% CP), 3) moderate-protein (MP) supplement (20.1% CP), or 4) high-protein (HP) supplement (31.7% CP) (DM basis). The feeding period was 84 d in 1990-1991 and 60 d in 1991-1992. Supplementation (C vs LP, MP, or HP) increased (P < .01) cow weight gains (32.7 vs 60.7, 62.8, and 72.4 kg, respectively) and improved (P < .01) BCS. Calf birth weights, weaning weights, and ADG were not affected by treatment (P > or = .20). Average calving date, percentage of cows cycling at the start of the breeding season and percentage pregnant after a 60-d breeding season were also similar (P > .20) among treatments. Sixteen ruminally fistulated steers (482 kg, four steers per treatment) were blocked by weight and assigned to the same four supplements in a 30-d digestion trial. Supplementation increased (P < .01) digestible DMI and forage DMI (P < or = .04) and tended (P = .09) to increase digestible NDF intake but did not alter (P > or = .15) apparent DM or NDF digestibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Preweaning growth of Angus- (Bos taurus), Brahman- (Bos indicus), and Tuli- (Sanga) sired calves and reproductive performance of their Brahman dams.

Calves born to Angus (A), Brahman (B), or Tuli (T) bulls and B cows were evaluated to determine sire breed of calf effects on preweaning calf growth and reproductive performance of their dams. Records from 242 cow-calf pairs over 2 yr were used to assess birth weight, calf ADG, weaning weight, gestation length, and postpartum interval to estrus (PPI). The sire breed x sex of calf interaction was important (P < .05) for birth weight, weaning weight, and gestation length. Birth weights of BB males (32.8 +/- .8 kg) were significantly heavier than for AB and TB males (30.1 +/- .9 and 28.6 +/- .7 kg, respectively) and BB females (29.4 +/- .7 kg). As a main effect, sire breed of calf affected (P < .05) calf ADG, weaning weight, gestation length, and PPI. Calf ADG and weaning weights were greater for AB (.90 +/- .01 kg/d; 220.9 +/- 3.5 kg) than for TB (.81 +/- .01 kg/d; 200.4 +/- 3.0 kg) and BB calves (.78 +/- .01 kg/d; 198.8 +/- 3.5 kg). Gestation lengths differed (P < .01) among all calf genotypes (284, 288, and 294 +/- 1 d for AB, TB, and BB, respectively). Postpartum intervals were shorter (P < .05) for cows nursing BB calves (83 +/- 4 d) than for cows nursing AB (95 +/- 5 d) and TB calves (97 +/- 4 d). Tuli-sired F1 calves were inferior to Angus-sired F1 calves and similar to straightbred Brahman calves in preweaning growth. Crossbred calves had shorter gestations but longer postpartum intervals than purebred calves.

Effect of Fenbendazole on Nematode Parasites and on Preweaning Average Daily Gain in Beef Cow Herds

AbstractThe objectives of this study were to determine the effects of fenbendazole treatment on nematode parasite control and on the ADG of suckling beef calves. In Exp. 1, seven pastures containing commercial cows were randomly assigned to one of two treatments groups. Cows and calves in treatment 1 received no treatment and served as controls. Cows in treatment 2 were administered fenbendazole 45 to 60 d prior to calving. The calves in treatment 2 were administered fenbendazole at approximately 90 d of age. Fecal samples were collected and calf weights were recorded. Treatment 2 cows (P<.025) and calves (P<.05) had lower fecal egg counts per gram (EPG) than treatment 1 cows and calves. Differences in preweaning ADG were not significant (P>.10), but gains were 15.3% higher for treatment 2 calves. In Exp. 2, treatments 1 and 2 were repeated as described in Exp. 1 except that treatment 2 cows received fenbendazole in deworming blocks. A treatment 3 was added in which cows and calves were administered the same fenbendazole treatment as treatment 2 except that the cows in treatment 3 were administered a second fenbendazole treatment (in suspension) at the time of calf treatment (90 d postpartum). A treatment x time interaction was detected (P<.08) in the cow EPG counts. Treatment 1 EPG counts started at a relatively low value and increased by weaning whereas treatments 2 and 3 cow fecal egg counts started at a higher value and decreased by weaning. Differences in calf preweaning ADG were not significant (P>.10). In conclusion, calves born to cows that were dewormed before calving had lower EPG counts at approximately 90 d of age than calves born to cows that were not dewormed, no significant improvements in calf preweaning ADG were detected, and fenbendazole deworming blocks were as effective in reducing EPG counts as fenbendazole administered as a suspension.

Supplementation of dormant tallgrass-prairie forage: II. Performance and forage utilization characteristics in grazing beef cattle receiving supplements of different protein concentrations.

Two experiments were conducted to evaluate the influence of supplemental protein concentration on the intake and utilization of dormant range forage by beef cattle. In Exp. 1,97 pregnant Hereford x Angus cows (avg wt = 454 kg) were assigned randomly to three isocaloric treatment supplements: 1) low protein (LP), 13% CP; 2) moderate protein (MP), 25% CP; and 3) high protein (HP), 39% CP. In Exp. 2, 15 ruminally and 12 esophageally cannulated steers (avg wt = 319 and 355 kg, respectively) were assigned randomly to LP, MP and HP treatments and were used in a 22-d winter grazing trial to evaluate forage intake and utilization characteristics. In Exp. 1, cow body condition (BC) and BW changes responded in linear (P less than .01) and quadratic (P less than .01) fashions to increasing protein concentration, with MP and HP displaying the least BC and BW loss from trial initiation (d 1) through d 84. From d 84 to calving (avg calving date = d 120), only the HP supplement continued to be effective in minimizing BC loss (P less than .01). Calf birth weight tended (P = .17) to increase in a linear fashion to increasing supplemental protein concentration, but calf ADG and cow reproductive efficiency were unaffected (P greater than .10). In Exp. 2, forage OM intake responded in a quadratic fashion (P less than .10), with the MP treatment having the highest NDF digestibility and ruminal OM fill. In conclusion, beef cow BC and BW losses during the winter grazing period were minimized with increasing supplemental CP concentration. Intake and utilization of dormant forage by steers were improved with moderate (26%) levels of CP in the supplement.

Biological type effects on gestation length, calving traits and calf growth rate.

Gestation length, birth weight calving difficulty, calf mortality rate at birth, calf mortality rate from birth to weaning, preweaning calf growth rate and calf 200-d weight were evaluated in a biological type study in which four sire breeds were bred by AI to Hereford dams. Angus and Red Poll sires represented breeds of medium size, and Pinzgauer and Simmental sires represented large breeds. Angus and Pinzgauer represented breeds with medium milk production, and Red Poll and Simmental represented breeds with high milk production. Dams mated to large sire breeds had longer (P less than .01) gestation lengths (.95 d) and higher calving difficulty scores than dams mated to medium-sized sire breeds. Calves from large sire breeds had heavier birth weight (P less than .01) and 200-d wt (6.1 kg; P less than .01) than calves from medium-sized sire breeds. Calf death loss and ADG to weaning were similar (P greater than .10) for all breeds of sire. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but did not (P greater than .10) in other traits. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but not (P greater than .10) in other traits. Interaction between size and milk production of sire breed existed for gestation length, birth weight, ADG from birth to weaning and 200-d calf weight (P less than .01). In general, mature size of sire breed was a good indication of expected performance traits not easily influenced by environment. Not all differences, however, could be explained by size and milk production of the size breed.

Relative calving date of first-calf heifers as related to production efficiency and subsequent reproductive performance.

Relative date of first calving of beef heifers was studied in relation to production efficiency and subsequent reproductive performance. Crossbred heifers were managed in a drylot environment for 1 yr with feed intake measured through weaning of the first calf. Mean heifer age at entry into drylot was 572 d. Production traits were evaluated by calving group (CG), where CG1 included records of heifers calving (and calves born) in the first 21 d of the calving season for a particular year, CG2 included those calving from 22 through 42 d and CG3 included those calving after 42 d. Calving groups did not differ significantly for preweaning calf ADG, but weaning age differences resulted in heavier weaning weights for CG1 compared with CG2 and CG3. An earlier relative calving date was associated with increased cumulative feed energy intake of heifers and their calves during the 1-yr test period. In terms of production efficiency, the weaning weight advantage of earlier calving was offset only partly by the increased feed energy intake of the dam-calf unit, resulting in 6.3 Mcal (12.4%) less ME per kg calf weaning weight for CG1 vs CG3 for the 1-yr period. Within a limited calving season, earlier calving dams tended to be biologically and economically more efficient because a greater proportion of their annual production cycle was in a productive (lactating) mode, diluting maintenance costs as a fraction of all costs. Heifers in CG1 also tended to calve earlier than CG3 heifers for the second calf. Calving interval was a biased measure under the management conditions of a limited breeding season and culling of open cows.

Non-genetic influences on performance testing of beef cattle

Substantial ( P⩽0.001) location, year and sex effects were identified for post-weaning growth traits recorded for two genetically similar populations born during a 7-year period (1972–1978) at two locations, Brandon (B), Manitoba ( n=2236) and Manyberries, Alberta ( n=2044). Calves weaned at Manyberries were fed and evaluated at Lacombe (L), Alberta. Age-of-dam effects were non-significant for average daily gain during the test period. None of the interactions involving breed cross of dam were significant but there were substantial interactions ( P⩽0.001) involving location X year and sex X year for most of the traits recorded. Location and sex differences in growth patterns during consecutive 28-day periods in the feedlot were attributed to differences in management and feeding practices before and during the test period. A gradual increase in daily energy intake throughout the feeding period (Lacombe) inflated variation in the growth patterns and reduced the reliability of growth prediction procedures compared with feeding an all grain diet. At Lacombe, the maximum deviations observed (actual minus predicted) were −11.57 kg (males) and −5.35 kg (females) when the calf's ADG was used for prediction. Corresponding values at Brandon for males and females were −2.13 kg and −3.00 kg, respectively. Slightly lower variability at both locations was observed when prediction was based on the regression model. However, the Lacombe feeding procedure resulted in more rapid growth L > B by 4.2% and thus appeared to be more appropriate for purposes of challenging the genetic potential for growth rate. The relevance of the results to animal comparison within and among contemporary test populations is discussed.