Growth Performance Of Heifers Research Articles

18 Impacts of supplementing sulfate vs. hydroxychloride sources of Cu, Mn, and Zn on heifer growth performance and physiology during feed restriction and high-starch challenge periods

Abstract This study evaluated the effects of supplementing different sources (sulfate vs. hydroxychloride) of Cu, Mn, and Zn during feed restriction and high-starch challenge periods on heifer growth performance and physiology. On d 0, Nelore heifers (n = 40) were stratified by body weight (BW = 238 ± 38 kg) and age (21 ± 1 mo), and individually allocated into 1 of 40 drylot pens. The study was divided: washout (d 0 to 27), nutrient surplus (d 28 to 55), nutrient restriction (d 56 to 83), and high-starch challenge (d 84 to 112). The washout period consisted of limit-feeding Tifton hay (2.5% of BW; DM basis) and providing free choice access to white salt only. On d 28, heifers were randomly assigned to receive protein DM supplementation (0.10 to 0.20% of BW) added with sulfate (SUL) or hydroxychloride (HYD) sources of Cu, Mn, and Zn (≥ 260, 200, and 960 mg of Cu, Mn, and Zn per kg of supplement DM) from d 28 to 112 (n = 20 heifers/treatment). From d 28 to 55, heifers were offered ad libitum Tifton hay. From d 56 to 83, heifers were limit-fed 50% of average hay DM intake consumed in the last 6 d of the previous phase (d 50 to 55). From d 84 to 112, each respective protein supplement was mixed with a starch-based total mixed ration (TMR). Heifers were gradually adapted to the starch-based TMR by increasing the concentrate DM amount while simultaneously decreasing the hay DM amount by 20% every 7 d (starting with 35% concentrate and 65% hay on d 84 and ending with 80% concentrate and 20% hay from day 106 to 112). Individual heifer shrunk BW were collected on d 0, 28, 56, 84, and 112, following 12 h of feed and water withdrawal. Effects of treatment × day and treatment were not detected (P ≥ 0.37) for heifer BW, average daily gain (ADG), and dry matter (DM) intake, except for ADG from d 28 to 56, which was less (P = 0.05) for SUL vs. HYD heifers (-0.21 ± 0.05 vs. -0.10 ± 0.05 kg/day, respectively). Effects of day, but not treatment × day and treatment (P ≥ 0.43), were detected for fecal pH, which remained relatively constant from d 0 to 84, and then decreased (P < 0.01) from 7.2 on d 84 to 5.8-6.0 on d 110. Overall, protein supplementation added with hydroxychloride sources of Cu, Mn, and Zn had minor positive effects on heifer growth performance immediately following a washout period, but did not improve heifer growth performance and fecal pH during nutrient restriction and high-starch challenge periods, compared with protein supplementation added with sulfate sources of same metals.

249 Effects of sorghum silage kernel processing on growth performance and blood metabolites of beef heifers

Abstract Our previous studies suggested that using a shredlage (SHRD) processor or a conventional (CONV) sorghum kernel processor leads to similar apparent total tract nutrient digestibility of whole plant sorghum silage (WPSS). This study evaluated the effects of feeding WPSS harvested using different kernel processors (CONV vs. SHRD), on growth performance of beef heifers. Grain sorghum (ADV2450IG; Advanta Seeds, Argentina) was harvested at the hard-dough stage with a Class Jaguar 950 (Harsewinkel, Germany), switching the kernel processor to generate the forage material for the two treatments: CONV and SHRD. The material was bagged in two 2.7 m diameter bags and allowed to ferment for 3 mo. Black Angus heifers [n = 96; body weight (BW) = 15 ± 1 mo, 249.6 ± 28.6 kg] were blocked by initial BW, and randomly assigned to pens (8 heifers/pen, 6 pens/treatment). Diets consisted, all in DM basis, of WPSS of each respective type (SHRD or CONV) at 90.5%, expeller soybean meal at 7.0%, and a vitamin-mineral-NNP concentrate at 2.5%. The experiment consisted of a 14-d adaptation period, followed by a 56-d growing period; and feed was offered once daily. Data were analyzed as a randomized complete block design, using pen as the experimental unit, with the fixed effect of treatment and the random effect of block. No differences were observed (P > 0.10) for final BW, dry matter intake, and residual feed intake. However, CONV fed heifers tended to gain more BW per day (ADG, 0.83 vs. 0.77 kg/d; P = 0.07) and had greater gain to feed ratio (GF, 0.083 vs. 0.075 kg/kg; P = 0.05) and greater Kleiber ratio (KR, 12.1 vs 11.2 g/kg; P = 0.05) as compared with SHRD fed heifers. Furthermore, performance calculated dietary Net Energy of gain (NEg) in CONV fed heifers tended to be greater than that for SHRD (0.70 vs. 0.65 Mcal/kg of diet DM, respectively; P = 0.06). Moreover, blood serum from CONV fed heifers had 16% greater total bilirubin (P = 0.04), 12% greater cholesterol (P = 0.02), and slightly greater non esterified fatty acids (P = 0.03) concentrations. Noteworthy, serum concentrations of total bilirubin were correlated (P ≤ 0.03) with ADG, GF, KR and NEg. In conclusion, the type of kernel processor utilized for the harvest of sorghum silage may have an impact on feed efficiency of beef cattle. These differences could be related to changes on the site of utilization of nutrients, particularly starch; what could also explain the differences on blood metabolites. However, further research is needed to help explain these findings.

A randomized trial on the effects of heat abatement during the pre-weaning phase on growth and reproductive performance of heifers and health, reproductive and productive performances of cows

Evaluation of heat stress abatement for pre-weaned dairy calves is a rare endeavor. We aimed to assess the impacts of cooling the environment of pre-weaned calves through ceiling fans on their performance after weaning and during their first lactation. We randomly assigned female Holstein calves to one of two treatment at birth (day 0): individual frame-wire hutches in a non-cooled barn ("SH", n = 125) and individual frame-wire hutches in a barn equipped with ceiling fans ("SHF", n = 101). Calves were housed under the same barn, with treatments applied in three alternating sections. Ceiling fans (2.1 m in diameter) were positioned 4.1 m from the ground and 7.6 m apart (center-to-center). Shade cloths were used to separate the sections designated for the SH and SHF treatments. Post-weaning, heifers were commingled. We recorded body weight (BW) and average daily gain (ADG) at weaning, 5, 7, and 10 mo of age. Pregnancy to first artificial insemination (P/1AI), hazard of pregnancy, and the hazard of commencing the first lactation are reported. Body weight at first calving, P/1AI, hazard of pregnancy, and milk yield in the first lactation are reported. No differences in BW (5 mo: SH = 162.9 ± 1.6 kg vs. SHF = 162.3 ± 1.6 kg; 7 mo: SH = 200.8 ± 2.2 kg vs. SHF = 201.1 ± 2.3 kg; 10 mo: SH = 300.5 ± 2.6 kg vs. SHF = 300.0 ± 2.8 kg) and ADG (SH = 0.94 ± 0.02 kg/d, SHF = 0.94 ± 0.02 kg/d) from 5 to 10 mo of age were detected. Treatment did not affect P/1AI (SH = 53.5 %, SHF = 45.9 %) and hazard of pregnancy [SH = referent, SHF – adjusted hazard ratio (AHR) = 0.87 (95 % CI = 0.65, 1.18)], but heifers in the SHF treatment were less likely to initiate the first lactation (76.2 % vs. 86.4 %). Body weight at calving (SH = 612.4 ± 5.3 kg, SHF = 618.2 ± 5.9 kg) and milk yield (SH = 39.0 ± 0.48 kg/d, SHF = 38.3 ± 0.57 kg/d) were not different, but the SHF treatment resulted in lower P/1AI (38.4 % vs. 51.4 %) and hazard of pregnancy (AHR = 0.68, 95 % CI = 0.49, 0.93) and fewer cows starting their second lactation (57.4 % vs. 72.8 %). In our experiment, providing cooling through ceiling fans during the pre-weaning phase had a negative impact on the reproductive performance of Holstein cows during their first lactation.

110 Effects of sire selection on puberty and reproduction of offspring selected as replacement heifers

Abstract Sire selection is important to maintain the desired genetic capability of any cattle herd; therefore, selection of economic production traits affect profitability by increasing pre- and post-weaning gain and carcass quality potential. Using heifers developed from sires selected for growth and milk traits may have long-term impact on sustainability of the cowherd by influencing mature cow size and milk production. Our objective was to determine the impacts of sires selected for high and moderate growth and high and low milk traits on growth and reproductive performance of replacement heifers. Therefore, we selected replacement heifers sired by bulls within the upper 5th and 50th percentiles of the Angus breed for yearling weight (YW) EPD as high growth (HG) moderate growth (MG), the upper 15th percentile of the Angus breed for milk EPD as high milk (HM), and the lower 15th percentile for low milk (LM) in a 2×2 factorial design resulting in 4 treatments: HG/HM, HG/LM, MG/HM, and MG/LM. Heifers (n = 46) from appropriate AI sires that were born and developed at Oklahoma State University – Range Cow Research Center – South Range Unit were selected as replacements. They were raised on a base diet of dry, dormant tall grass prairie and moderate quality grass hay following weaning and 2 kg/d of 16% crude protein concentrate supplement. Body weights and biometrics were recorded at weaning and approximately at 1-yr of age, and blood was collected at 11 and 0 d before synchronization for progesterone analysis to determine pubertal status pre-breeding. Estrus was synchronized using the 14-d CIDR-PG with timed AI method followed by a 45-d natural service breeding period. Pregnancy checks were conducted by serum collection 35-d following AI and via rectal palpation by an experienced veterinarian 112 d after removal of the bulls. Statistical analyses were performed using the mixed procedure of SAS (SAS 9.4, SAS INC., Carey, NC). Heifers from high growth sires were 28 kg heavier at weaning (P < 0.01) and 26 kg heavier as yearlings (P < 0.01) than those sired by moderate growth sires, while sire milk EPD affected neither (P ≥ 0.55). High growth and high milk sired heifers had greater hip heights, frame scores and thus greater (P ≤ 0.05) estimated mature body weight (EMBW). Despite this, sire selection had no impact on percentage of heifers pubertal before breeding, AI pregnancy, or the total pregnancy rates (P > 0.24) Based on these data, selection of sires for HG and HM leads to increased productivity of the offspring but gives rise to larger mature cows, which may pressure grazing resources in limited resource environments impacting the long-term sustainability of the cow-calf enterprise.

83 Effects of cottonseed meal supplementation on growth performance of heifers grazing mature summer forage

Abstract As perennial warm-season grasses mature in late summer, dry matter intake (DMI) of growing heifers may be limited due to low protein (7.2 ± 2.5 %) and increased NDF content (67.5 ± 2.7%), which may compromise growth potential. Cottonseed meal (CSM) supplementation may improve forage digestibility by increasing rumen degradable protein offered, but research regarding the specific effects of CSM supplementation on gain performance and composition of gain in heifers is limited. It was hypothesized that supplementation of CSM to heifers grazing mature forage would have greater growth performance compared with heifers not receiving CSM. Objectives for this experiment were to compare the effects of two CSM supplementation strategies on the growth performance of heifers grazing mature summer forage. In two consecutive summers, commercial Angus cross heifers (n = 63) weighing 266.08 ± 32.74 kg were blocked by BW (light, medium, and heavy) and allocated to 9 paddocks (1.64 ha) of WW-B. Dahl Bluestem (Bothriochloa bladhii) for 67 to 70 d. This was a RCBD with a factorial arrangement of 3 treatments by 3 BW blocks, with paddock and year as random effects. Heifers received one of three supplementation strategies: no cottonseed meal (CON), 454 g/animal of CSM daily (CSM1), or 908 g/animal of CSM every other day (CSM2). Initial and final shrunk BW were measured; ADG and percent of BW gained were calculated. Ultrasound of initial and final longissimus muscle area (LMA), backfat (BF), and intramuscular fat (IMF) were measured; percent gained was calculated, respectively. There were no treatment by block interactions for any measured variable. Heifers receiving CSM1 and CSM2 had greater final BW than heifers receiving CON (317 and 320.8 vs 302.6 kg, respectively; (P = 0.01). Likewise, percent of BW gained was greater (P = 0.02) for CSM1 and CSM2 supplemented heifers compared with CON heifers (19.4 and 20.2 vs 14.6%, respectively). The ADG of CSM1 and CSM2 supplemented heifers was greater (P = 0.01) than CON (0.74 and 0.78 vs 0.54 kg/d, respectively). Treatment did not affect the percent of BF (P = 0.24) or IMF gained (P = 0.39). Heifers receiving CSM1 and CSM2 tended to gain proportionally more LMA than heifers receiving CON (13.58 and 13.77 % vs 7.24%, respectively; P = 0.07). As anticipated, BW block affected final BW (P < 0.001) and percent BW gained (P = 0.02), as well as percent LMA gained (P = 0.02). In conclusion, CSM supplementation significantly affected growth performance of heifers grazing late summer WW-B. Dahl Bluestem forage versus no supplementation. In addition, there was no difference in growth performance between heifers receiving 454 g/d of CSM supplementation or 908 g/animal every other day, indicating flexibility for feeding strategy.

Effects of Moringa oleifera leaf meal supplementation on growth performance and blood profiles of cattle heifers

Effects of Moringa oleifera leaf meal supplementation on growth performance and blood profiles of cattle heifers

Effect of beef heifer development systems utilizing corn residue and late summer planted cover crops on growth, reproductive performance, and economics.

The objective of this study was to evaluate growth and reproductive performance of heifers developed using 3 different winter systems in the midwestern U.S. Spring-born heifers (n = 1,156; 214 d of age; SD ± 17 d) were used in a 3-yr study to evaluate performance in winter development systems, which utilized cover crop (CC) and corn residue grazing. Heifers were assigned to 1 of 3 treatments: grazing corn residue with 0.77kg/d dried distillers grains (CD) or 1.69kg/d wheat midds (CW) supplementation followed by a grower ration in the drylot, or grazing late summer planted oat-brassica CC followed by corn residue grazing with 0.35kg/d dried distillers grains supplementation (CC). Supplementation during the corn residue phase was targeted to result in a common body weight (BW) (276kg; ~45% of mature BW) by the end of the winter development period. Grazing of corn residue (CD and CW) and CC began in early November. After 63 d, heifers assigned to CC were moved to corn residue; on day 77 heifers assigned to CD and CW began receiving a grower ration in the drylot. In mid-February (day 98), heifers were comingled and managed in a single group. Breeding season began in June and lasted for 29 d. The ADG of heifers assigned to CC when grazing CC (days 1 to 63) was greater (0.76kg/d; P < 0.01) than those assigned to CD or CW (0.58kg/d and 0.49kg/d, respectively). Gain during the last 35 d of the winter period for heifers assigned to CC (0.36kg/d) was less (P < 0.01) than those assigned to CW (0.49kg/d) but not different from CD heifers (0.41kg/d). Overall (days 1 to 98), winter ADG was greater (P < 0.05) for heifers assigned to CC (0.62kg/d) than CD (0.53kg/d) or CW (0.50kg/d), which did not differ (P = 0.42). Percent of mature BW in May (27 d pre-breeding) was greater (P < 0.01) for heifers assigned to CC (52%) than for those on CD and CW (50%), which did not differ (P = 0.64). Pregnancy rates were affected by treatment (P < 0.03), with heifers assigned to CC (76%) being greater than CW (64%) and CD heifers being intermediate (70%). When accounting for the differences in cost and the value of open and bred heifers, the economic return tended to differ (P = 0.07) among treatments, with CC and CW not differing (P ≥ 0.20) from CD but return for CC being $73 greater than CW (P = 0.02). Utilizing oat-brassica CCs early in the winter followed by a slower rate of gain while grazing corn residue with distillers supplementation appears to be as effective for developing beef heifers in the midwestern U.S. as supplementing distillers grains.

Effect of Creep Feeding Supplementation on Growth Performance and Metabolic Characteristics of Nellore Heifers

The objective of this paper is to evaluate the effects of creep feeding supplementation during the preweaning phase on the growth performance and metabolic characteristics of Nellore heifers. Forty-two female Nellore calves (age = 100 ± 25 d; initial body weight (BW) = 113.4 ± 16.6 kg) were randomly assigned to the following treatments: control, where calves received mineral mix supplementation (n = 21); supplemented in creep feeding, where calves received 6 g/kg BW of a concentrate supplement (n = 21) during a period of 140 d. In the postweaning phase, all heifers received 6 g/kg BW of a concentrate supplement during a period of 210 d. Supplemented heifers had a greater average daily gain (ADG) than control heifers during the preweaning phase and, consequently, were heavier at weaning and at the end of the growing phase (p &lt; 0.05). However, preweaning supplementation did not influence (p &gt; 0.05) the body measurements or BW at the end of the growing period. Greater (p &lt; 0.05) rib fat was observed in supplemented heifers. Concentrations of metabolites were not affected by preweaning supplementation (p &gt; 0.05). Thus, supplementing heifers in the preweaning phase improved growth performance of weaning and body adiposity.

Effect of food supplementation on in vitro embryo production and growth performance in prepubertal Nelore heifers

In vitro embryos production from prepubertal heifers can help contribute to breeding programs; however, strategies are necessary to increase their embryo production. The aim of this study was to investigate the effects of two nutritional plans on oocyte recovery, embryo production and growth performance of prepubertal Nelore heifers. Thirty-four Nelore heifers with age of 6.5 months were divided into two feeding treatments (NP1 and NP2). The NP1 diets served as the control and NP2 diets were formulated to contain an average of 1.22-fold more energy than NP1. After 3 months of supplementation, the animals underwent follicular aspiration (ovum pick-up, OPU) every 21 d for 3 months and embryos were produced in vitro. Wither height, chest depth, body weight and subcutaneous fat of animals were measured. The number of retrieved and viable oocytes per OPU were 1.49-fold and 1.42-fold greater in NP2 heifers (p = 0.018 and p = 0.049, respectively) than those in NP1 heifers. Heifers administered NP2 produced 29.7% blastocysts, a percentage higher than NP1 animals that produced 24.40% embryos (p < 0.05). Consequently, females in the NP2 treatment showed improved body development. These results indicate a positive effect of a higher energy diet on assisted reproduction and body development in prepubertal heifers.

Effect of feeding rumen-protected nutrients on growth, hemato-biochemical and reproductive performance of indigenous cattle heifers

Effect of feeding rumen-protected nutrients on growth, hemato-biochemical and reproductive performance of indigenous cattle heifers

Impact of incorporating Asparagus racemosus (Shatavari) into the diet on the growth performance of Murrah buffalo heifers (Bubalus bubalis)

Impact of incorporating Asparagus racemosus (Shatavari) into the diet on the growth performance of Murrah buffalo heifers (Bubalus bubalis)

PSVIII-8 Impacts of Phosphorus Intake on Beef Heifer Growth Performance and Conception Rates

Abstract The objective of this experiment was to further investigate the effects of phosphorus intake on beef heifer growth performance and conception rates. An increase in phosphorus soil concentrations from use of livestock manure as fertilizer in Northwest Arkansas has led to greater phosphorus concentrations available in forages. This study was designed to determine if phosphorus supplementation is warranted when adequate phosphorus soil concentrations exist. This experiment was conducted over 2 years using two separate groups of weaned crossbred Angus heifers (n=72/year). Approximately 30 d after weaning, heifers were stratified by body weight (average initial weight 262kg) and allocated randomly to 14 groups (8 in Year 1, 6 in Year 2). Groups were assigned randomly to 1 of 2 treatments: 1) a free-choice-mineral mix that contained no supplemental phosphorus (CON), or 2) a free-choice-mineral mix with 4% supplemental phosphorus and identical concentrations of other supplemental minerals (4PMIN). Heifers grazed 2.24 ha mixed grass pastures with a history of livestock manure application and were supplemented with soy hulls (0.5% of body weight) daily. On d 112, heifers &amp;gt; 273 kg body weight had an ultrasound evaluation of reproductive tracts (1= infantile, 5= cyclic). Heifers were determined pregnant or open via rectal ultrasonography. Data were analyzed using the MIXED or GLIMMIX procedures of SAS 9.4 with group within year as the experimental unit. There were no differences in gain for either treatments for the 224-day period (P ≥ 0.14). Reproductive tract scores did not differ (P = 0.95). There were no differences for conception rates (AI or natural bred) (P ≥ 0.55). Overall pregnancy was 79% for CON and 83% for 4PMIN. Heifers grazing pastures with a history of livestock manure application did not benefit from adding supplemental phosphorus in the free choice mineral offered.

Growth Performance, Carcass Characteristics and Economic Viability of Nguni Cattle Fed Diets Containing Graded Levels of Opuntia ficus-indica

Given the severe droughts caused by global warming, smallholder beef cattle farmers are faced with serious forage and feed scarcity. This becomes worse for resource-poor farmers who cannot afford commercial feeds. It is therefore crucial to assess the use of low-cost alternative feed resources to supplement free-range beef cattle and ensure sustainable livestock production in ways that stimulate free-range beef farmers’ participation in mainstream beef market. In an attempt to improve free-range beef cattle herds and explore the economic viability of utilizing Opuntia ficus-indica (spineless cactus) cladodes as a supplementary feed, we investigated the impact of cactus diets on animal growth performance and carcass characteristics of Nguni cattle heifers. Four dietary treatments were randomly assigned to thirty-two heifers aged 24 months, weighing, on average, 172.20 ± 27.10 kg, with each dietary treatment replicated to eight individually penned heifers for 90 days. The dietary treatments were control diet (pasture-based energy + protein sources), 10% cactus diet, 20% cactus diet and commercial diet (crop-based energy and commercial protein source). The energy concentration of the control diet was 9.35 MJ/Kg DM and the cactus was included on dry matter basis during formulation of compound diets. Thus, cactus was administered in a dry rather than wet form. The animals were confined in feeding pens 24/7 without access to pasture, with feed and water provided ad libitum. The heifers fed commercial and control diets attained significantly (p &lt; 0.05) higher dry matter intake, average daily gains, fat thickness, carcass conformation scores and lower feed conversion ratio than those fed cactus diets. However, the final body weight gains and carcass weights, rib-eye muscle area and meat pH45min and 24h were comparable (p &gt; 0.05) between heifers fed cactus diets and those fed commercial and control diets. The 10 and 20% cactus diets had greater gross margins (p &lt; 0.05) of $17.47 and $18.62, respectively, than the other diets, due largely to reduced total variable costs. The comparability of carcass traits of heifers fed cactus diets and those fed non-cactus diets as well as higher economic returns from cactus inclusion warrants the use of cactus diets, particularly during drought when commercial feed prices rise.

Effect of a High Welfare Floor and a Concrete Slatted Floor on the Growth Performance, Behavior and Cleanliness of Charolais and Limousin Heifers: A Case Study.

Simple SummaryThe barn floor needs to provide a confident and comfortable walking surface while retaining durability and affordability. The floor of the barn is also important in order to achieve the best performance, health and welfare of the animals. Therefore, we compared a high welfare floor (HWF), which should offer higher comfort, to a concrete slatted floor (CSF), which is a standard housing system for cattle rearing. In the trials, Charolais and Limousin heifers were used testing the latter systems. We observed that heifers housed on an HWF tended to exhibit more species-specific behaviors, namely rubbing, grooming and aggression, and seemed to be cleaner than those housed on a CSF.Various floor systems are used in cattle housing with different characteristics in terms of roughness, abrasion, wetness, bedding material, ease of cleaning, etc. Thus, the activity and welfare of the animals are greatly influenced by the type of floor. The floor of the barn can influence the development of health diseases, technopathies and the production and quality of animal products. Therefore, in the present case study, we studied the effects of two different flooring systems on the performance and on some behavioral and cleanliness parameters in heifers. Two floor systems (concrete slatted flooring (CSF) and high welfare flooring (HWF)) and two breeds (Charolais and Limousin) were used in the experiment. Heifers on HWF tended to show a higher frequency of grooming, rubbing and aggression than those on CSF, but not of standing, lying, eating, drinking, rumination, resting, stereotypies and covering of the animals. In addition, animals housed on HWF also appeared to show higher cleanliness than those housed on CSF. Results indicated that animals housed on HWF exhibited more social and self-care behaviors, suggesting that animals housed on such floors show more species-specific behaviors and have higher welfare.

Effects of feeding duration, implant dose, and terminal window duration on growth performance and carcass characteristics of feedyard steers and heifers

Our objective was to evaluate effects of feeding duration (days on feed, DOF), terminal window (TW), and implant program dose on growth performance and carcass characteristics of beef steers and heifers. Heifers in Exp. 1 (n = 3,360; 351 ± 31 kg) and Exp. 2 (n = 3,778; 310 ± 28 kg) were used in randomized complete block designs with 3 × 2 factorial treatment arrangements. In Exp. 1, factor 1 was DOF (139, 162, and 183) and factor 2 was TW (60 or 100). In Exp. 2, factor 1 was implant program {(1) IH/H—Component TE-IH with Tylan on d 0 followed by a Component TE-H with Tylan [140 mg of trenbolone acetate (TBA):14 mg of estradiol; Elanco], (2) IH/200—Component TE-IH with Tylan on d 0 followed by a Component TE-200 with Tylan, and (3) 200/200—Component TE-200 with Tylan on d 0 and at reimplant} and factor 2 was TW (60 or 100). In Exp. 3, feedlot data from an industry database (Benchmark, Elanco Knowledge Solutions, Kansas City, KS) was used in an observational study and organized by sex and implant program [steers = IS/200 (total of 280 mg of TBA and 36 mg of estradiol), XS (200 mg of TBA and 40 mg of estradiol), and 200/200 (a total dose of 400 mg of TBA and 40 to 56 mg of estradiol or estradiol benzoate); heifers = IH/200 (total of 280 mg of TBA and 28 mg of estradiol) and 200/200]. Repeated-measure and nonlinear broken-slope models were used to evaluate TW on live performance. In Exp. 1, ADG decreased ( P = 0.03) and final BW, marbling score, hot carcass weight (HCW), backfat thickness, and calculated empty body fat (EBF) increased ( P < 0.03) as DOF increased. In Exp. 2, greater implant program dose tended ( P ≤ 0.10) to increase ADG and DMI and increase ( P ≤ 0.02) G:F, HCW, DP, and LM area. Furthermore, overall dose reduced ( P ≤ 0.03) marbling score and EBF. In Exp. 3, interactions between implant program, live performance, and TW were detected ( P < 0.001). Steers given 200/200 exhibited the greatest ( P < 0.05) ADG, followed by XS and IS/200 from TW 50 to 100. Inversely, steers given XS had the greatest ( P < 0.05) F:G, followed by IS/200 and 200/200 from TW 50 to 90. Heifers administered 200/200 exhibited greater ( P < 0.05) ADG between TW 50 to 70 and reduced ( P < 0.05) F:G through TW 110 compared with IH/200. Increased DOF resulted in reduced ADG and increased HCW and EBF. Increased implant dose improved live performance and HCW. There is a finite number of TW days before growth suffers from inadequate stimuli. Furthermore, cattle type, implant program dose, DOF, and TW all require consideration when designing implant programs.

Effects of a combination of live yeast and yeast cell wall products supplemented before and after weaning on beef heifer growth performance, immune function, and body temperature

This study aimed to evaluate the effects of a combination of live yeast and yeast cell wall fed before weaning and through backgrounding on heifer growth performance, health, and body temperature. Angus crossbred cow-calf pairs with heifer calves (n = 95; BW = 165 ± 27 kg) were stratified based on BW, birth date, sire, and dam parity and assigned randomly to pasture (10 pastures, 9 or 10 cow-calf pairs/pasture). Pastures were assigned randomly to treatments: (1) no yeast (CON) or (2) addition of 3 g of live yeast and 1 g of yeast cell wall (Y+CW; Phileo by Lesaffre) in a randomized design with 5 replicates. Calves were offered creep-feed at 0.5% of BW (as fed) for 35 d before weaning. Heifers remained in preweaning treatment groups and were fed 1.8 kg/d of a concentrate supplement while grazing bermudagrass ( Cynodon dactylon ) pastures for 42 d with Y+CW continuing to provide 4 g of Y+CW per day. Average daily gain and creep-feed consumption before weaning did not differ ( P ≥ 0.29) between treatments. However, CON heifers had greater ( P = 0.01) ADG from weaning to the end of the backgrounding period compared with Y+CW heifers. Body temperatures were not affected ( P ≥ 0.31) by treatment before or after weaning. White blood cell concentrations, serum haptoglobin concentrations, and the percentage of cells positive for phagocytic activity did not differ ( P ≥ 0.15) between CON and Y+CW heifers. Based on the results of this study, Y+CW supplementation before or following weaning was not efficacious.

Effects of feeding treatment on growth rate and performance of primiparous Holstein dairy heifers

The objective of this study was to investigate effects of feeding-rearing programs that aim for first calving at 20-27 months (mo) of age on growth, reproduction and production performance of Holstein cows at nulliparous and primiparous stages. We hypothesised that, in a seasonal autumn-calving strategy, heifers born late in the season could catch up to the growth of heifers born earlier and be inseminated during the same period, at a body weight (BW) of at least 370 kg. This approach would result in first calving age at 21-22 mo of age without impairing their later performance. To test this hypothesis, we studied 217 heifers over 3 years. They were split into three treatment groups: control feeding (SD), an intensive-plane diet (ID1) from birth to 6 mo of age or an intensive-plane diet from birth to one year of age. Heifers in groups SD and ID1 were born from September until the end of November, while those in ID2 were born later. The present study showed that late-born heifers (ID2) could catch up with the growth of the others due to the feeding treatment, although they were still 42 kg lighter than the SD and ID1 heifers at first calving. No difference in reproductive performance was observed among groups. Once primiparous, the cows reared with the ID2 treatment tended to produce less milk than SD and ID1 cows (ca. 400 kg less on a 305 d basis throughout lactation), and no differences in milk composition, feed intake, body condition score or BW were observed among groups. Age at first service (AFS) was classified a posteriori into three classes: 12.5 (AFS12.5), 14.0 (AFS14.0) and 15.5 mo (AFS15.5) of age. Heifers in AFS12.5 grew faster than those in AFS14.0 and AFS15.5. Once primiparous, the AFS12.5 cows tended to produce less milk at peak than AFS14.0 and AFS15.5 cows (ca. 1.5 kg/d less) although no difference in total milk yield during lactation was observed. No differences in milk composition, feed intake, body condition score or BW were observed among groups. These results support the conclusion that the feeding treatment can enable late-born heifers to catch up to the growth of heifers born earlier in the season. This strategy results in an earlier first calving that does not impair their reproductive performance but does decrease milk yield slightly during first lactation. Future studies should investigate long-term effects of this strategy.

Effects of Revalor-XH, Revalor-200, and combination Revalor-IH/Revalor-200 on yearling beef heifer growth performance and carcass characteristics for 138 days on feed

The objective was to evaluate finishing heifer implant programs including a single noncoated implant (Revalor-200; REV-200); an initial noncoated implant (Revalor-IH) followed by another noncoated implant (Revalor-200; REV-IH/200) 80 d before slaughter; or a partially coated, delayed-release implant (Revalor-XH; REV-XH) on growth performance and carcass characteristics when heifers were fed for 138 d. A commercial feedlot trial used 1,728 crossbred heifers (initial BW = 412 kg; SD = 28.2 kg) to examine the 3 implant strategies. Only heifers implanted with REV-IH/200 were removed from their pen at re-implantation. Heifers implanted with REV-IH/200 had greater (P ≤ 0.05) carcass-adjusted final BW, calculated as hot carcass weight/DP, and G:F compared with heifers implanted with REV-200 or REV-XH. Treatment did not affect (P ≥ 0.24) final BW or ADG on a live basis. Heifers implanted with REV-IH/200 had greater (P ≤ 0.05) hot carcass weight and LM area compared with heifers implanted with REV-200 or REV-XH. Marbling score and 12th-rib fat thickness were not different (P ≥ 0.12) among implant treatments. Calculated YG were decreased (P = 0.05) for heifers implanted with REV-IH/200 compared with heifers implanted with REV-200, with a significant (P < 0.01) shift to a lower calculated YG distribution for heifers implanted with REV-IH/200 compared with REV-200 or REV-XH. Greater concentrations of trenbolone acetate and estradiol-17β improved carcass-adjusted G:F and hot carcass weight but did not significantly decrease marbling despite heifers having a lower calculated YG.

Ensiled biomass of Solaris tobacco variety used as forage: chemical characteristics and effects on growth, welfare, and follow-up of Holstein heifers

This study examined the use of an innovative tobacco variety, Nicotiana tabacum L., cv. Solaris, as forage. The whole plant biomass was ensiled, and the composition of SiloSolaris from bunker-silo and mini-silos was investigated. The effects of dietary inclusion of SiloSolaris on the growth, welfare, and nutritional profile of sixteen Holstein heifers, divided into two groups (n = 8), SiloSolaris (SS) and Control (CTR), were investigated. Heifers were group-fed diets with a 70:30 forage to concentrate ratio (on a DM basis). Both groups received 16.24 kg DM of concentrate mixture daily, including corn meal, wheat middlings and soybean meal. The CTR group was fed 39.43 kg DM of hay daily, and the SS group received 23.00 kg DM of the same hay and 12.69 kg DM SiloSolaris blended with the concentrate mixture. The feeding trial lasted eighty-one days with a thirty-six day adaptation phase. Data on forty-five days of diet administration are reported. At the end of the feeding trial, the plasma constituents of the heifers were studied. Moreover, heifers were monitored during a follow-up period, lasting up to 1 year after calving, for age at first insemination, age at first calving and daily milk yield. The SiloSolaris chemical composition showed an average DM content of 24.1 (±0.65) g/100 g. During ensiling, a decrease in CP and an increase in ammonia nitrogen contents were observed. The lactic acid content was variable (9.00 ± 2.66 g/100 g DM), while the acetic acid concentration was stable (4.27 ± 0.21 g/100 g DM). No butyric acid was detected in SiloSolaris, whose ammonia nitrogen content accounted for 15.7 (±1.86)% of the total nitrogen on average, and the mean pH value was 5.02 (±0.08). The SiloSolaris diet did not affect heifer growth performance. No differences were detected for body condition, fecal consistency, or locomotion scores. All the investigated plasma constituents were within or very close to the ranges reported for heifers; however, significant differences between the experimental groups were observed for triglycerides, cholesterol, albumin, and magnesium. The follow-up results did not differ between the experimental groups. These initial findings suggest that Nicotiana tabacum cv. Solaris is a promising ensiled forage for growing heifers that deserve to be further investigated.

Effects of providing artificial shade to pregnant grazing beef heifers on vaginal temperature, growth, activity, and behavior.

This experiment evaluated the effects of providing artificial shade during summer on activity, behavior, and growth performance of pregnant grazing beef heifers. Thirty-six black-hided Angus and Angus crossbred pregnant heifers [418 ± 9 kg body weight (BW); approximately 90 d of gestation] were stratified by breed, blocked by BW, and allocated to 12 “Pensacola” bahiagrass pastures (Paspalum notatum Flüggé; 1.3 ha, n = 3 heifers/pasture) with or without access to artificial shade (SHADE vs. NO SHADE; 6 pastures each) for 7 wk during summer. The shade structures were composed of shade cloth (11 × 7.3 m length, 2.4 m height: 26.8 m2 of shade per heifer). Shrunk BW was recorded on enrollment (day 0) and week 7 (day 47), whereas full BW was obtained on week 2 (day 14), 4 (day 28), and 6 (day 42) to assess average daily gain (ADG). Vaginal temperature was recorded for five consecutive days during weeks 1, 3, 5, and 7 using an intravaginal digital thermo-logger, and individual GPS devices were used to quantify the use of shade for an 8-h period. Activity was monitored using automated monitoring devices (HR-LDn tags SCR Engineers Ltd., Netanya, Israel) through the experimental period. Vaginal temperature was lower (P < 0.01) for heifers in the SHADE compared with heifers in the NO SHADE treatment from 1200 to 1600 h and 1100 to 1900 h for weeks 1 and 3, respectively. Heifers in the SHADE treatment spent 70% of the 8-h period evaluated under the shaded structure. Provision of shade increased (P < 0.01) daily lying time (11.4 ± 0.2 vs. 10.3 ± 0.2 h/d) and standing bouts per day (P < 0.01; 12.6 ± 0.4 vs. 10.8 ± 0.4 bouts/d), whereas it reduced (P < 0.01) standing bout duration (61.6 ± 3.0 vs. 82.9 ± 3.0 min/bout) relative to heifers without access to shade. The interaction between treatment and hour affected (P < 0.01) daily rumination time because heifers with access to SHADE had greater rumination between 1000 and 1200 h. Although ADG tended (P = 0.08) to be greater for the heifers in the SHADE treatment (0.20 vs. −0.02 kg, respectively), the access to shade did not (P = 0.79) affect the final BW. In conclusion, providing artificial shade during summer to pregnant grazing beef heifers was effective in reducing vaginal temperatures and exerted changes in heifer behaviors that translated into slight improvements in growth performance.