Growth Performance Of Heifers Research Articles

Change in growth performance of crossbred (Ankole × Jersey) dairy heifers fed on forage grass diets supplemented with commercial concentrates.

Rearing heifers for dairy cow replacement is a challenge in smallholder dairy farms in the tropics due to feed shortage. The objective of this study was to evaluate Brachiaria hybrid cultivar Mulato II as a forage resource for improving growth performance of dairy heifers under cut-and-carry feeding system in Rwanda. Sixteen crossbred (Ankole × Jersey) heifers (mean weight 203 ± 35 kg) were randomly allocated to two dietary treatments viz: Mulato II with 2 kg/day of commercial concentrates (MCC) and Napier grass (Pennisetum purpureum) with the same supplement (NCC), for a period of 12 weeks. Mineral lick and water were provided ad libitum. Daily feed intake and fortnightly live weight were measured. Average daily gains and feed conversion ratio (FCR) were calculated. Results showed that absolute daily dry matter intake (g DMI/day) and relative intake (g/kg of metabolic body weight--BW(0.75)) were higher in heifers fed on MCC than in heifers fed on NCC (P < 0.001). FCR was lower (P < 0.001) in MCC than NCC diets. Final body weight (FBW) and body weight gain (BWG) did not differ between the two groups of heifers (P > 0.05). Average daily weight gain (ADWG) also not differed significantly (P > 0.05). Based on numerical body weight changes and nutritive values, Mulato II showed potential to be integrated into local cut-and-carry feeding systems for better heifer rearing to facilitate dairy cow replacement.

Performance of Beef Replacement Heifers Supplemented with Dried Distillers Grains or a Mixture of Soybean Meal and Ground Sorghum Grain

The feed, labor, and equipment costs of developing heifers in a confined feeding system are relatively high. High Plains beef producers can reduce input costs by developing heifers on dormant native range; however, heifers are typically unable to consume sufficient crude protein (CP) from the low-quality ( 30% CP). Traditionally, producers have used oilseed meals in this capacity, but with the expansion of the ethanol industry, dried distillers grains with solubles (DDG) have become widely available as an alternative protein source for producers in corn and sorghum-producing regions. Adequate heifer body weight and body condition score at first breeding are essential to minimize age at first calving and to increase lifetime productivity. Therefore, the objective of our study was to evaluate the effects of supplementation of DDG or an approximately isonitrogenous mixture of soybean meal and ground sorghum grain on growth and reproductive performance of replacement heifers grazing low-quality, dormant native range.

Growth performance and sorting characteristics of corn silage-alfalfa haylage diets with or without forage dilution offered to replacement Holstein dairy heifers

Gravid heifers consuming high-quality forage diets are susceptible to excessive weight gains and overconditioning. One approach for controlling this problem is to dilute diets with low-energy forages, such as straw, that reduce the caloric density and dry matter intake (DMI) of that diet by heifers. These diluting agents are often sortable by dairy heifers, but previous visual evidence has suggested that eastern gamagrass haylage may be a nonsortable alternative. Our objectives were (1) to compare the growth performance of dairy heifers offered a high-quality forage diet (control) with diets containing 1 of 3 diluting agents [eastern gamagrass haylage (EGH), chopped wheat straw (WS), or chopped corn fodder (CF)]; and (2) evaluate sorting behaviors of heifers offered these forage diets. Holstein heifers (n=128) were stratified (32 heifers/block) on the basis of initial body weight (heavy, 560±27.7kg; medium-heavy, 481±17.7kg; medium-light, 441±22.0kg; and light, 399±14.4kg), and then assigned to 1 of 16 identical research pens (4 pens/block; 8 heifers/pen), where each of the 4 research diets were assigned to 1 pen within each block. Diets were offered in a 118-d feeding trial with heifers crowded to 133% of capacity at the feed bunk. Inclusion of low-energy forages was effective in reducing both diet energy density and DMI. Concentrations of physically effective fiber (pef) particles did not change during the 24-h period following feeding for either the control or EGH diets; however, this response for pef particles masked the competing (and cancelling) responses for individual large and medium particles, which heifers sorted with discrimination and preference, respectively. Sorting against pef particles was detected for WS, and much more severely for the CF diet. Sorting of forage particles by heifers could not be related to heifer performance. Compared with control (1.16kg/d), average daily gains (ADG) were reduced by dilution in all cases, but were virtually identical between EGH (0.98kg/d) and CF (0.97kg/d), which exhibited no sorting and extensive sorting of pef, respectively. Furthermore, ADG for WS was approximately 0.2kg/d less than EGH or CF, despite exhibiting sorting characteristics intermediate between EGH and CF. Diets diluted with low-energy forages were formulated to be isonitrogenous and isocaloric; within that context, WS was most effective in reducing DMI and maintaining ADG within typical recommendations for Holstein heifers.

Effects of cultivar and grazing initiation date on fall-grown oat for replacement dairy heifers

Fall-grown oat has shown promise for extending the grazing season in Wisconsin, but the optimum date for initiating grazing has not been evaluated. Our objectives for this project were (1) to assess the pasture productivity and nutritive value of 2 oat cultivars [Ogle and ForagePlus (OG and FP, respectively)] with late-September (EG) or mid-October (LG) grazing initiation dates; and (2) to evaluate growth performance by heifers grazing these oat forages compared with heifers reared in confinement (CON). A total of 160 gravid Holstein heifers (80 heifers/yr) were assigned to 10 research groups (8 heifers/group). Mean initial body weight was 509±40.5 kg in 2013 and 517±30.2 kg in 2014. Heifer groups were assigned to specific pastures arranged as a 2×2 factorial of oat cultivars and grazing initiation dates. Grazing heifer groups were allowed to strip-graze oat pastures for 6 h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Main effects of oat cultivar and sampling date interacted for forage characteristics in 2013, but not in 2014. During 2013, oat forage mass increased until early November before declining in response to freezing weather conditions, thereby exhibiting linear and quadratic effects of sampling date, regardless of oat cultivar. Similar trends over time were observed in 2014. For 2013, the maximum forage mass was 5,329 and 5,046 kg/ha for FP and OG, respectively, whereas the mean maximum forage mass for 2014 was 4,806 kg/ha. ForagePlus did not reach the boot stage of growth during either year of the trial; OG matured more rapidly, reaching the late-heading stage during 2013, but exhibited only minor maturity differences from FP in 2014. For 2013, average daily gain for CON did not differ from grazing heifer groups (overall mean=0.63 kg/d); however, average daily gain from FP was greater than OG (0.68 vs. 0.57 kg/d), and greater from EG compared with LG (0.82 vs. 0.43 kg/d). For 2013, advantages in average daily gain for heifers grazing FP pastures were likely related to the greater energy density of FP oat throughout the fall that reached a maximum of 68.8% total digestible nutrients on November 27 compared with only 63.7% for OG on October 10. During 2014, average daily gain from CON exceeded all grazing heifer groups (0.81 vs. 0.57 kg/d), and average daily gain from EG again exceeded LG (0.70 vs. 0.44 kg/d). These results suggest that delaying grazing until mid-October will consistently suppress heifer growth performance, particularly if rapidly maturing cultivars are used.

Beef heifer growth and reproductive performance following two levels of pasture allowance during the fall grazing period.

The objective of this study was to compare heifer growth and reproductive performance following 2 levels of stockpiled fall forage allowance of orchardgrass (30.5%) and tall fescue (14.1%). Spring-born heifers (n = 203 and BW = 246 ± 28.9 kg) of primarily Angus background were allocated to 2 grazing treatments during the fall period (November 12 to December 17 in yr 1, November 7 to January 4 in yr 2, and November 7 to January 14 in yr 3) each replicated 3 times per year for 3 yr. Treatments consisted of daily pasture DM allowance of 3.5% of BW (LO) or daily pasture DM allowance of 7.0% of BW (HI) under strip-grazing management. Throughout the winter feeding period, mixed grass-legume haylage and soybean hulls were fed. Heifers were grazed as 1 group under continuous stocking after the winter period. Heifers in the LO group gained less than heifers in the HI group during the fall grazing period (0.12 vs. 0.40 kg/d; P < 0.0001). For each 1 10 g increase in NDF/kg fall pasture (DM basis), fall ADG decreased 0.14 kg (P = 0.01). During winter feeding, ADG was 0.30 and 0.39 kg/d for LO vs. HI heifers, respectively (P = 0.0008). During the spring grazing period (April 16 to May 24 in yr 1, April 22 to May 26 in yr 2, and April 5 to May 16 in yr 3), LO heifers had numerically greater ADG than HI heifers (1.38 vs. 1.30 kg/d; P = 0.64). Hip height (122.7 vs. 121.4 cm; P = 0.0055), BCS (5.8 vs. 5.6; P = 0.0057), and BW (356 vs. 335 kg; P < 0.0001) at the end of spring grazing was greater for HI than LO heifers. Heifers in the LO group compensated with greater summer ADG than heifers in the HI group (0.74 vs. 0.66 kg/d; P = 0.03). Total ADG from treatment initiation (November) through pregnancy diagnosis (August) was greater for HI than LO heifers (0.61 vs. 0.55 kg/d; P < 0.001) as was BW at pregnancy diagnosis (415 vs. 402 kg; P = 0.0055). Percentage of heifers reaching puberty by the time of AI was 34% for both groups (P = 0.93). Percentage of heifers becoming pregnant to AI tended (P = 0.13) to be greater for HI (44%) than for LO heifers (32%). Fall ADG across treatment groups affected the probability of a heifer becoming pregnant by AI (P = 0.01). Percentage pregnant by natural service (61% for LO vs. 59% for HI; P = 0.80) and final pregnancy rate (74% for LO vs. 77% for HI; P = 0.61) was not different for the 2 groups. These results indicate that altering fall forage allowance may delay the majority of BW gain until late in heifer development without negatively affecting overall pregnancy rates.

Growth performance and meat quality of heifers receiving different forms of soybean oil in the rumen

The objective of this experimental study was to evaluate the effects of different forms of soybean oil (soybean grain, rumen-protected fat and soybean oil) in the rumen on the growth performance, nutrient intake, carcass characteristics, body development and the condition and meat quality of heifers. Twenty-one (¼ Nellore×¼ Santa Gertrudis×½ Braunvieh) heifers received a diet containing 600g/kg of corn silage and 400g/kg concentrate, with a 58.0g/kg fat content. The average daily gain and nutrient intake did not differ between the experimental diets (P>0.05). The carcass characteristics and meat quality were only different between treatments for the cold carcass yield, which was significantly greater (P<0.05) in the treatment with the inclusion of rumen-protected fat. The different forms of oil in the diet did not affect the body composition traits and the live weight at slaughter. The cooking loss, shear force, carcass ultimate pH, and values of lightness (L*), redness (a*) and yellowness (b*) were affected by the forms of soybean oil in the rumen. The fatty acid profile in the longissimus muscle did not differ (P>0.05) with different forms of soybean oil in the diet. Using different forms of soybean oil in the rumen does not change the production or meat quality characteristics of beef heifers.

Effects of calf weaning age and subsequent management system on growth and reproductive performance of beef heifers.

Brahman × British crossbred heifers (n = 40 and 38 heifers in yr 1 and 2, respectively) were used to evaluate the effects of calf weaning age and subsequent management system on growth and reproductive performance. On d 0, heifers were ranked by BW (89 ± 16 kg) and age (72 ± 13 d) and randomly assigned to a conventional management group that was normally weaned on d 180 (NW; n = 10 heifers annually) or early weaned (EW) on d 0 and 1) limit fed a high-concentrate diet at 3.5% of BW (as fed) in drylot until d 180 (EW180; n = 10 heifers annually), 2) limit fed a high-concentrate diet at 3.5% of BW (as fed) in drylot until d 90, then grazed on Bahiagrass pastures until d 180 (EW90; n = 10 heifers annually), or 3) grazed on annual ryegrass pastures until d 60 (yr 1; n = 10 heifers) or 90 (yr 2; n = 8 heifers), then on Bahiagrass pastures until d 180 (EWRG). On d 180, all heifers were grouped by treatment and rotated on Bahiagrass pastures until d 390. Grazing heifers were supplemented at 1.0% BW until d 180 and at 1.5% BW from d 180 to 390. From d 0 to 90, EW180 and EW90 heifers were heavier (P ≤ 0.02) than NW and EWRG heifers, whereas NW heifers tended (P = 0.09) to be heavier on d 90 than EWRG heifers. In yr 1 and 2, EW180 heifers were heaviest (P < 0.0001) on d 180. In yr 1, EWRG heifers were lightest (P < 0.0001), whereas EW90 and NW heifers had similar BW (P = 0.58). Conversely, EW90, EWRG, and NW heifers achieved similar BW on d 180 of yr 2 (P ≥ 0.18). Positive correlations were detected (P ≤ 0.05) between liver IGF-1 mRNA abundance on d 90 and ADG from d 0 to 90 and between liver IGF-1 mRNA abundance on d 180 and ADG from d 90 to 180. The EW180 heifers were youngest (P ≤ 0.01) at puberty. From d 260 to 340, the percentage of pubertal heifers was greater (P ≤ 0.03) for EW90 vs. NW heifers but did not differ (P ≥ 0.15) between EWRG and NW heifers. The ADG from d 0 to 90 and the plasma IGF-1 on d 90 and 180 explained approximately 34% of the variability in age at puberty. In summary, the EW90 and EW180 heifer management systems evaluated in this study altered the BW at the time of NW and were good alternatives for anticipating puberty achievement compared to NW heifers.

Comparison of methionine hydroxy analogue chelated versus sulfate forms of copper, zinc, and manganese on growth performance and pregnancy rates in yearling beef replacement heifers

Our objectives were to compare growth performance and pregnancy rates of heifers supplemented with Cu, Zn, and Mn as either methionine hydroxy analog chelate (provided as MINTREX) or in the SO4 form. The experiment used 3 ranches, each having 2 replicate pens per treatment. Performance data were analyzed by ANOVA as a randomized complete block design using pen as the experimental unit. Pregnancy diagnosis data were analyzed using Chi-squared analysis. Heifers (n = 2,480) were fed diets for 181 d (ranch A), 149 d (ranch B), and 151 d (ranch C) before breeding. Heifers were weighed (shrunk) at trial initiation, end of feeding, breeding, and at pregnancy diagnosis. Ranch A heifers were bred by AI followed by natural service (45-d breeding), ranch B heifers were bred by natural service (50-d breeding), and ranch C heifers were bred by AI once at estrus detection only. No ranch × treatment interactions were detected for any measurements, and no differences were detected between treatments for gain, ADG, and G:F. Ranch effects were significant for gain, ADG, G:F, and overall pregnancy rate but not for conception in the first 21 d of breeding. Pregnancies conceived during the first 21 d of breeding did not differ between treatments. Overall pregnancy rate was increased by 2% for heifers supplemented with methionine hydroxy analog chelate versus SO4 form. Under the conditions of this experiment, methionine hydroxy analog chelate contributed to increased pregnancy rates compared with a readily available inorganic form of trace mineral.

The effect of supplemental concentrate feed on live weight gain of yearling heifers over grazing season in subirrigated rangelands of East Anatolia

Animal performance declines considerably after summer dormancy during the grazing season in the steppe rangelands of East Anatolia. The aim of this study was to determine the growth performance of Holstein heifers grazed on rangeland and supported with concentrate. Forage amount, crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents of forage were sampled biweekly during the grazing season. In the experiment, heifers (250 ± 10 kg) were allocated to 1 of 3 feeding trials: 1) control, 2) grazing plus concentrate supplement fed at 1% of bodyweight once daily, and 3)grazing plus concentrate supplement fed at 1.5% of bodyweight once daily. The forage allowance increased from the beginning to the middle of July and thereafter continuously declined until the end of the season. CP content of forage declined from the beginning to the middle of July and thereafter it slightly increased until the end of the season. Both NDF and ADF content of forage increased from the beginning of August and thereafter declined. Bodyweight increased throughout the season, and the increases were considerably higher in the supplemented groups than in the control. Total live weight gain at the end of the grazing season was higher in the supplemented groups than in the control; however, there were no significant differences between the supplemented groups. According to the study results, concentrate supplement fed at 1% bodyweight after the start of summer dormancy can improve animal performance in the rangelands in this region.

Effects of feeding corn modified wet distillers grain plus solubles co-ensiled with chopped whole plant corn on heifer growth performance and diet digestibility in beef cattle1

Two experiments were conducted to evaluate the effect of feeding corn modified wet distillers grain plus solubles (MWDGS; 48% DM) co-ensiled with chopped whole plant corn (WC) on growth performance, dietary intake, and nutrient digestibility of beef cattle. In Exp. 1, 96 Angus-crossed heifers (2 yr old; 522 ± 49.1 kg BW; 5.3 ± 0.1 BCS) were stratified and blocked according to BW and stratified by BCS in each block in a randomized complete block design (24 pens; 4 heifers/pen; 6 treatment replications). Groups were assigned to 1 of 4 dietary treatments for a 62 d trial. Treatments were 1) corn silage (CS) and soybean meal (CON), 2) MWDGS co-ensiled with chopped whole plant corn (WC; CO-EN), 3) CS mixed with MWDGS at feeding (CS+WDG), and 4) CS mixed with dry distillers grain plus solubles (DDGS) at feeding (CS+DDG). In Exp. 2, 4 crossbred beef steers (initial BW = 278 ± 18 kg) fitted with permanent ruminal cannulas were used in a balanced 4 × 4 Latin square to test the effects of feeding MWDGS co-ensiled with WC on DM intake, ruminal fermentation characteristics, and total tract digestibility. There were four 14-d periods, with 10 d for diet adaptation and 4 d for samples collection. Orthogonal contrasts were used and compared CON vs. diets containing distillers grains (DGD), CO-EN vs. diets where distillers grains were mixed at feeding (MIX), and CS+WDG vs. CS+DDG. In Exp. 1, the CON fed heifers resulted in greater G:F (P = 0.04) compared with those fed DGD. However, ADG (P = 0.03), final BW (P = 0.04), and BW gain (P = 0.03) were greatest for DGD diets compared with CON and greatest (P = 0.04) for CO-EN when compared with MIX. Apart from a slightly greater acetate concentration (P = 0.05), which resulted in a greater acetate to propionate ratio (P = 0.03) for the CON diet compared with DGD, no important differences were observed on intake, diet digestibility, or fermentation characteristics when comparing the CON treatment with DGD or when comparing CS+WDG with CS+DDG. However, the CO-EN diet resulted in decreased DMI (P = 0.05) and consequently decreased OM (P = 0.05), N (P = 0.04), and NDF (P = 0.02) intakes compared with MIX. Data from these studies suggest that MWDGS co-ensiled with WC can successfully replace traditional corn-based diets supplemented with soybean meal and corn silage diets supplemented with distillers grains without compromising digestibility and growth performance in pregnant heifers.

Performance by Heifers Grazing Sod-Seeded Cool-Season Annuals Seeded on Different Dates Using Two Tillage Intensities

A total of 120 Gelbvieh × Angus crossbred heifers (552 ± 2.5 lb initial BW) grazed pastures of common bermudagrass [Cynodon dactylon (L.) Pers.] overseeded with wheat (Triticum aestivum L.) and annual ryegrass (Lolium multiflorum Lam.) for a 3-year study to compare the effect of seeding dates and tillage intensities on heifer growth performance. Half of the pastures were seeded in early September (Early) and half in mid October (Late). Within seeding date, half of the pastures were disked once (1×) and half were disked twice (2×) before seeding. Grazing began when forage mass reached approximately 2000 lb/acre and continued through 11 May 2002 (year 1), 25 April 2003 (year 2), and 10 May 2004 (year 3). Forage mass was greater from Early than from Late seeded pastures for 2 of the first 3 months of grazing resulting in 17-day earlier grazing initiation and approximately 165 lb less hay fed per heifer. Total body weight gain, or gain while grazing cool-season annuals did not differ between seeding dates or tillage intensities. Producers in the Mid South region with bermudagrass pastures may have considerable flexibility in their decisions as to when to seed annual forages and to what intensity they till their sod depending upon how soon they need available forage.

Effects of molasses-based creep-feeding supplementation on growth performance of pre- and post-weaned beef calves

Two 2-year experiments were conducted to evaluate the effects of molasses-based creep-feeding supplements fortified with DL-methionine hydroxyl analog (MHA; Exp 1), or different supplemental nitrogen sources (Exp. 2), on growth performance of pre- and post-weaned beef calves. In both experiments, cows and calves were stratified by calving date and randomly assigned to pastures (n=8 and 12 pastures for Exp. 1 and 2, respectively). Treatments were randomly assigned to pastures. In Exp. 1, treatments consisted of no creep-feeding supplementation (NoCreep), creep-feeding supplementation of sugarcane molasses plus 4% of a 50:50 urea+hot water blend (as-fed; Mol+U) or Mol+U plus 0.22% of MHA (as-fed; Mol+MHA). In Exp. 2, treatments consisted of NoCreep, creep-feeding supplementation of sugarcane molasses added with 4% of 50:50 urea+hot water blend (50:50, as-fed; Mol+U) or 20% cottonseed meal (as-fed; Mol+CSM). Calves were supplemented in cow exclusion areas for 122, 117, 104 and 102 days prior to weaning in years 1 and 2 of Exp. 1 and 2, respectively. In year 2 (Exp. 2), 18 heifers (2 heifers/pen; 3 pens/treatment) were randomly selected for a 17-day post-weaning evaluation and were provided free-choice access to a grain-based concentrate. In Exp. 1, Mol+U calves had similar (P=1.00) voluntary creep-feed supplement intake in year 1, but greater (P<0.01) voluntary creep-feed supplement intake in year 2, compared with Mol+MHA calves. In Exp. 2, voluntary creep-feed supplement intake was not affected (P=0.39) by treatment. In Exp. 1, but not in Exp. 2, creep-feeding supplementation increased (P≤0.01) calf BW at weaning and pre-weaning ADG compared with NoCreep calves. Calves supplemented with MHA had lesser (P=0.03) pre-weaning ADG than Mol+U calves. In Exp. 2, nitrogen source added to creep-feed supplement did not affect (P=0.15) calf pre-weaning ADG. Additionally, pre-weaning creep-feeding supplementation of heifers did not affect (P≥0.25) post-weaning growth performance or plasma concentrations of haptoglobin and fibrinogen during the receiving period. At weaning, heifers fed Mol+U had greater (P=0.03) plasma concentrations of ceruloplasmin (Cp) than Mol+CSM heifers (23.8 versus 18.7±1.62mg/dL, respectively), with NoCreep heifers being intermediate. On day 9, relative to weaning, Mol+U heifers had greater (P=0.03) plasma Cp concentrations than NoCreep heifers (31.6 versus 26.6±1.62mg/dL, respectively), with Mol+CSM heifers being intermediate. In conclusion, molasses-based creep-feed supplements increased pre-weaning growth performance of calves in Exp. 1, but not in Exp. 2, and did not affect post-weaning growth performance of heifers.

Growth and reproductive performance of beef replacement heifers fed development diets containing soybean meal or wet distillers grains

ABSTRACT Our objective was to evaluate the effects of replacing soybean meal with wet distillers grains plus solubles (WDG) in beef heifer development diets on growth and reproductive performance. Weaned heifers (n = 172; initial BW 319 ± 2 kg; age 282 ± 1 d) were stratified by BW and age and assigned randomly to be fed development diets using soybean meal (CON) or WDG as the primary source of CP in the diet. Heifers were allotted equally to 8 pens, adapted to diets for 14 d, and fed for ad libitum intake for 94 d. Heifer BW was measured on d 28, 56, and 84 relative to the beginning of the experiment and at breeding; paired serum samples were collected at these times to define puberty status. After 94 d, treatments were combined in a native short- grass rangeland pasture. Heifers from each treatment were exposed to ovulation synchronization and fixed-time AI 23 or 51 d after diets ended. Total DM delivered was 4,695 kg less (P 0.10). Conception to fixed-time AI and overall pregnancy rates were not different (P > 0.60) between treatments. Under the conditions of our study, developing replacement heifer diets using WDG as the primary source of CP had negative temporal effects on growth performance and age at puberty; however, these effects were nullified when heifers were allowed to graze native range for at least 23 d before breeding.

Influence of a rumen-protected conjugated linoleic acid mixture on carcass traits and meat quality in young simmental heifers

The aim of the present study was to investigate the influence of feeding rumen-protected CLA during the early growing period on physical and chemical beef properties in young Simmental heifers. A total of 36 heifers (5 mo old; initial BW 185 ± 21 kg) were fed 250 g of different rumen-protected fats daily for 16 wk in 1 of 3 treatment groups: 250 g of a CLA-free control fat; 100 g of a CLA fat containing 2.4% of cis-9,trans-11 CLA and 2.1% of trans-10,cis-12 CLA and 150 g control fat; or 250 g of the CLA fat. Heifer growth performance variables as well as carcass weight, classification (conformation and fatness), and weights of organs and fat depots were not affected (P > 0.05) by CLA supplementation. Concentration of trans-10,cis-12 CLA in tissues (LM and subcutaneous fat) was dose-dependently increased (P < 0.01) by CLA supplementation, whereas that of cis-9,trans-11 CLA in these tissues did not differ (P > 0.05) between groups. The ratio of SFA to MUFA was increased (P < 0.01) in tissues of CLA-fed heifers compared with control heifers. Concentration of α-tocopherol in LM was greater (P = 0.01) in heifers of the 2 CLA groups than in control heifers. Other quality characteristics such as drip loss during storage, cooking loss, intramuscular fat content, and color variables in LM did not differ (P > 0.05) between groups. In conclusion, the present study demonstrates that feeding rumen-protected CLA during the early growing period changes tissue fatty acid composition but does not influence beef quality variables. Performance variables and carcass traits in young heifers, unlike in pigs and laboratory animals, are not influenced by CLA feeding.

Growth performance, carcass traits and meat quality of bulls and heifers slaughtered at different ages

The effects of sex and slaughter age on growth, feed intake, carcass composition and meat quality attributes of musculus longissimus lumborum were investigated in Charolais &amp;times; Simmental bulls (n = 12) and heifers (n = 12) reared and finished under identical management conditions. The animals entered the experiment at similar age (251 days) and were slaughtered at 14 or 18 months of age. Bulls gained more rapidly (P &amp;nbsp;&amp;lt; 0.001), consumed more dry matter daily (P &amp;lt; 0.05), and had a higher killing-out proportion (P&amp;nbsp;&amp;lt;&amp;nbsp;0.05). The sex &amp;times; slaughter age interaction was significant (P &amp;lt; 0.01) for feed conversion ratio, which deteriorated markedly more in heifers than in bulls as slaughter age increased. Bulls produced leaner carcasses with a higher proportion of total meat (P &amp;lt; 0.001). While bulls contributed to high-priced meat by a higher proportion of meat from the shoulder (P &amp;lt; 0.01), heifers had higher proportions of meat from the rump and loin (P&amp;nbsp;&amp;lt; 0.05). Older animals were generally fatter and their carcasses contained lower proportions of high-priced meat (P&amp;nbsp;&amp;lt; 0.01) and bones (P &amp;lt; 0.05). Bulls exhibited lower contents of dry matter (P &amp;lt;&amp;nbsp;0.001), protein (P &amp;lt; 0.05) and intramuscular fat (P &amp;lt; 0.001), and a higher content of collagen (P &amp;lt; 0.001) in musculus longissimus lumborum than hei-fers. The meat from heifers was assessed by the sensory panel as more tender and, when aged for 11&amp;nbsp;days, more acceptable than the meat from bulls. Older animals obtained higher scores for beef flavour intensity (P &amp;lt; 0.01), tenderness (P &amp;lt; 0.001), juiciness (P &amp;lt; 0.05), and overall acceptance (P &amp;lt; 0.001). &amp;nbsp;

Effects of a Hot and Humid Environment on the Performance of Holstein Heifers

A series of studies were performed to determine the effects of increasing environmental temperature and relative humidity on the performance of Holstein heifers. In heifers of 200 kg body weight, the effects on dry matter intake and daily weight gain were small at 28°C and 60% relative humidity, but dry matter intake and daily weight gain were seen to start declining at 28°C and 80% relative humidity. Moreover, in heifers of 400 kg body weight, even at relative humidity of 60%, dry matter intake and daily weight gain started to decline at 28°C. At 60% relative humidity, the rate of decline in daily weight gain in heifers of 200 kg body weight at 33°C was similar to that of those of 400 kg body weight at 28°C. These results indicated that the influence of high temperature on the performance of heifers intensified at a late stage, and under high relative humidity. An assessment of the impact of global warming on heifer growth performance in the Japanese summer was made using ‘Climate change 10 × 10 km mesh data (Japan)’, which is one of the models assuming progressive global warming. In the 2060s, compared to the end of the 20 th century, areas showing a decline in the rate of body weight gain in heifers will expand from Kanto to the western Hokkaido area, and the rate of decline will accelerate over time from the present to the 2020s, 2040s and 2060s, especially in July and August. As high humidity under hot temperatures significantly affect heifer growth, global warming and high humidity in the Japanese summer will have the negative effect.

Comparative effects of zilpaterol hydrochloride and ractopamine hydrochloride on growth performance, carcass characteristics, and longissimus tenderness of feedlot heifers fed barley-based diets

ABSTRACT A randomized complete block design trial was conducted with 3,444 beef heifers housed in 10 pens per treatment and fed barley-based diets to evaluate the effects of ractopamine (Optaflexx, Elanco Animal Health, Greenfield, IN) and zilpaterol (Zilmax, Intervet/Schering-Plough Animal Health, De soto, KS) on health, performance, carcass traits, and longissimus muscle tenderness in a commercial feedlot in western Canada. Treatments consisted of feeding Optaflexx at 20 mg/kg (100% DM basis) for 29 d at the end of the feeding period or Zilmax at 8.3 mg/kg (100% DM basis) for 20 d at the end of the feeding period, followed by a 4-d withdrawal period before slaughter. No differences (P > 0.05) were detected in morbidity, mortality, number of salvaged animals, ADG, feed efficiency, or final BW between heifers fed Zilmax or Optaflexx. Dry matter intake was reduced (P

Effect of supplementation with urea, blood meal, and rumen-protected methionine on growth performance of Holstein heifers grazing kikuyu pasture

Supplements with corn grain, molasses cane, and different nitrogen sources were evaluated in 16 growing Hosltein heifers [227 ± 33 kg body weight (BW)] grazing kikuyu (Pennisetum clandestinum) pasture in a 10-ha sward (rotational grazing with electric fences) during 90 days in the summer season. The nitrogen sources were urea (U); urea and blood meal (U+BM); and urea, blood meal, and rumen-protected methionine (U+BM +RPM). Heifers were randomly assigned to four experimental supplements defined as follows: control (no supplementation), U, U+BM, and U+BM +RPM. Two kilograms (as fed) of supplement was offered daily. The final BW of heifers fed U+BM +RPM was higher (P<0.05) than heifers not supplemented. The total and average daily weight gain of heifers supplemented with U+BM +RPM were higher than heifers not supplemented or supplemented with U and U+BM (P<0.05). The average daily gain of heifers supplemented with U and U+BM were higher than heifers not supplemented (P<0.05). Grass intake was not affected by supplementation, but total dry matter intake was increased by supplements with U, U+BM, and U+BM +RPM (P<0.05). Feed conversion was improved by U+BM +RPM (P<0.05). Total tract digestion was not affected by supplements. Blood urea nitrogen concentrations of heifers supplemented with U, U+BM, and U+BM +RPM were higher than heifers not supplemented (P<0.05). It is concluded that supplements with U+BM +RPM improved growth performance and feed conversion in heifers grazing kikuyu pasture.

Comparison of growth performance and slaughter characteristics of Limousin and Charolais heifers

Abstract. The objective of this study was to determine the effects of breed and a diet containing linseed on the growth and carcass composition characteristics of heifers. A total of 48 Limousin (LI) and Charolais (CH) heifers with an average weight of 270 kg were assigned to two diets containing either extruded linseed (LIN) or no supplemental oilseed (CON). The target slaughter weight was set at 500 kg. The diet had no effect on any of the observed production traits. The CH heifers had higher live weight gains (P&lt;0.001) and a lower feed conversion ratio (P&lt;0.001). The LI heifers had a higher dressing percentage (P&lt;0.001), higher meat to bone ratio (P&lt;0.001), greater m. longissimus lumborum et thoracis area (P&lt;0.05), and produced more internal and carcass fat (P&lt;0.05). It was concluded that purebred LI heifers grew less rapidly and less efficiently but produced heavier carcasses with a more favourable meat to bone ratio compared to purebred CH heifers.

Growth and Reproductive Performance of Beef Heifers Fed Carnival or Forager Field Peas

<h2>ABSTRACT</h2> Carnival or Forager field peas were evaluated as replacements for a cornsoybean meal supplement in the diets of peripubertal beef heifers. Beginning 60 d before estrous synchronization, 90 Angus×Gelbvieh rotationally crossed heifers (330±1.0kg initial BW) were stratified by BW and allotted to 1 of 3 dietary treatments in a randomized complete block design experiment (10 heifers/pen). Diets included limited access to bromegrass hay plus a 62.6% ground corn and 37.4% soybean meal (DM basis; control) supplement fed at 1.36kg of DM/heifer per day, ground Carnival peas at 1.41kg of DM/heifer per day, and 90.7% ground Forager peas and 9.3% soybean meal at 1.41kg of DM/heifer per day. Data were analyzed using pen (3/treatment) as the experimental unit and means were compared using the contrasts control versus field peas and Carnival versus Forager peas. Heifers fed field peas tended (P=0.08) to have greater ADG and G:F than heifers fed the control during the first 30 d. Growth performance was not affected (P=0.18 to 0.19) by dietary supplement during the second 30 d, but over the course of the 60-d feeding period, heifers fed field peas had greater (P=0.04) ADG and G:F than heifers fed the control supplement. Variety of field peas did not influence (P=0.18 to 0.47) the growth performance of heifers throughout the experiment. Pregnancy rate to AI was 43.3% for all dietary treatments. Forager and Carnival peas can replace conventional corn-soybean meal supplements fed to peripubertal beef heifers for 60 d before estrous synchronization.