Performance Of Heifers Research Articles

Supplementation frequency and amount modulate postweaning growth and reproductive performance of Bos indicus-influenced beef heifers.

This 2-yr study evaluated the growth and puberty attainment of Bos indicus-influenced beef heifers offered 2 different postweaning concentrate supplementation amounts and delivery frequencies. On day 0 of each year, 64 Brangus crossbred heifers were stratified by initial body weight (BW) and age (mean = 244 ± 22 kg; 314 ± 17 d) and assigned into 1 of 16 bahiagrass pastures (4 heifers/pasture/yr). Treatments were randomly assigned to pastures in a 2 × 2 factorial design (4 pastures/treatment/yr) and consisted of concentrate dry matter (DM) supplementation at 1.25% or 1.75% of BW which were offered either daily (7×) or 3 times weekly (3×) for 168 d. On day 56 of each year, heifers were assigned to an estrus synchronization protocol consisting of intravaginal controlled internal drug release (CIDR) insertion on day 56, CIDR removal on day 70, i.m. injection of 25 mg of prostaglandin F2α (PGF2α) on day 86, and i.m. injection of 100 µg of gonadotropin-releasing hormone and timed-AI at 66 h after PGF2α injection (day 89). Heifers were exposed to Angus bulls from day 89 to 168 (1 bull/pasture). Pregnancy diagnosis was assessed on day 213 of each year. Supplementation amount × frequency effects were not detected (P ≥ 0.12) for any variable, except for plasma concentrations of glucose (P = 0.10) and urea nitrogen (PUN; P = 0.01). Herbage mass, herbage allowance, and nutritive value did not differ (P ≥ 0.12) among treatments. Increasing supplementation DM amount from 1.25% to 1.75% of BW increased (P ≤ 0.05) plasma concentrations of insulin-like growth factor 1 (IGF-1), overall average daily gain (ADG), final BW, percentage of pubertal heifers on day 89, pregnancy and calving percentages, and percentage of heifers calving within the first 21 d of the calving season. However, reducing the supplementation frequency from daily to 3× weekly, regardless of supplementation amount, did not impact overall pregnancy and calving percentages (P ≥ 0.42), but caused (P ≤ 0.05) fluctuations in plasma concentrations of insulin and IGF-1 and decreased (P ≤ 0.03) overall ADG, final BW, puberty attainment on days 56, 89, and 168, and percentage of heifers calving during the first 21 d of the calving season. Hence, increasing the supplement DM amount did not prevent the negative effects of reducing the frequency of supplementation (3× vs. 7× weekly) on growth and reproduction of replacement Bos indicus-influenced beef heifers.

Physio-biochemical responses and growth performance of buffalo heifers to betaine supplementation during hot humid season under field conditions

In order to find out the effect of betaine supplementation on physiological (rectal temperature, skin temperature, respiration rate and pulse rate) responses, morphological (body length, heart girth and height at withers) parameters, stress markers (cortisol and NEFA levels), growth hormone, dry matter intake (DMI) and body weight of buffalo heifers during hot humid season under field conditions, 14 buffalo heifers were selected and equally divided into 2 groups, i.e. control and treatment (supplemented betaine @ 25 g/animal/day over the farmers practice). Blood samples were collected at fortnightly interval from both the groups and analyzed for stress markers. THI was calculated for measuring the stress levels on buffalo heifers, which remained 􀀡76 indicating severe stress. Physiological responses were significantly lower in treatment group than control. Morphological parameters, body weight and DMI were higher in treatment than control. Plasma cortisol and NEFA levels were significantly lower, whereas plasma growth hormone was significantly higher in treatment group compared to control. ADG was significantly higher in treatment group compared to control. Positive correlation was observed between THI and stress markers, physiological responses and negatively correlated with ADG, DMI and growth hormone. It can be concluded that betaine acted as a potent growth promoter by lowering the levels of stress markers and enhancing the ADG and DMI of buffalo heifers.

An Assessment of Secondary Clinical Disease, Milk Production and Quality, and the Impact on Reproduction in Holstein Heifers and Cows from a Single Large Commercial Herd Persistently Infected with Bovine Viral Diarrhea Virus Type 2.

The aim of this study was to evaluate secondary clinical disease, milk production efficiency and reproductive performance of heifers and cows persistently infected (PI) with bovine viral diarrhea virus type 2 (BVDV type 2). PI animals (n = 25) were identified using an antigen capture ELISA of ear notch samples. They were distributed into three age groups: ≤ 12 (n = 8), 13 to 24 (n = 6) and 25 to 34 (n = 11) months old. A control group of BVDV antigen ELISA negative female cattle that were age matched to the PI animals was utilized from the same herd. The PI group had a 1.29 higher odds ratio for diarrhea than controls (p = 0.001, IC95% = 1.032–1.623) and 1.615 greater chance of developing bovine respiratory disease (BRD) (p = 0.012, IC95% = 1.155–2.259). The age at first insemination (p = 0.012) and number of insemination attempts required to establish the first pregnancy (p = 0.016) were both higher for PI than controls. Milk production was higher for control cows than PI cows during most of the sampling periods. Somatic cell counts (SCC) were higher in PI cows than the controls at all sampling points across lactation (p ≤ 0.042). PI cattle had a higher incidence of disease, produced less milk, a higher SCC, and poorer reproductive performance than control cattle in this study.

The effect of gender status on the growth performance, carcass and meat quality traits of young crossbred Holstein-Friesian×Limousin cattle.

ObjectiveThe objective of this study was to compare growth performance, carcass traits and meat quality in young bulls, steers and heifers produced by crossing Limousin bulls with Holstein-Friesian cows, fattened semi-intensively and slaughtered at 18 months of age.MethodsThirty-one young calves were reared in a conventional production system, and were fed milk replacer, hay and concentrate. At 6 months of age, the animals were divided into groups based on gender, and were fed a total mixed ration composed of grass silage, concentrates I and II in a semi-intensive production system. At the end of the fattening period (18 months), the animals were slaughtered, carcass quality was evaluated, and samples of musculus longissimus thoracis were collected to determine the proximate composition and quality of meat.ResultsBulls were characterized by the highest percentage share of the most valuable cuts in the carcass, and three-rib sections from bull carcasses had the highest lean meat content with low intramuscular fat content (0.93%). No significant differences in carcass conformation, dressing percentage or the percentage share of round in the right half-carcass were found between bulls vs. steers and heifers. Heifers and steers had higher carcass fat content than bulls, which had a positive influence on the sensory properties of beef. In comparison with the meat of bulls, the meat of steers and heifers was characterized by more desirable physical properties and sensory attributes (water-holding capacity, shear force, color lightness, aroma, juiciness, tenderness, flavor).ConclusionUnder the semi-intensive production system, heifers and steers had higher carcass fat content than bulls, which had a positive effect on the sensory properties of beef. Bulls are better suited for intensive systems, which contribute to improving the quality of their meat. The results of this study may encourage producers to breed steers and heifers for beef.

Performance, carcass and meat quality of young bulls, steers and heifers slaughtered at a common body weight

Young bulls of lean continental cattle breeds raised on concentrates achieve high weight gains during fattening but may yield carcasses with low fat cover, which may have negative effects on meat quality. Fattening steers or heifers might be an alternative for these systems, but few studies have analysed in lean breeds the impact of castration of bulls at a similar BW or the performance of females. The aim of the trial was to characterise the growth, carcass and meat quality of bulls, steers and heifers of Pirenaica breed (lean beef breed) fed on concentrates and straw until a common body weight (475 kg). Bulls had greater weight gains than steers and heifers throughout the fattening period (P < 0.001). Bulls had greater plasma IGF-I concentration throughout the fattening period but lower leptin concentration from 400 kg onwards than steers and heifers when compared at the same BW. Regarding metabolites, the concentrations of glucose, beta‑hydroxy‑butyrate, urea and non-esterified fatty acids evolved differently in bulls, steers and heifers. At slaughter, steers and heifers had deposited more fat than bulls without other differences in carcass morphology. Regarding meat quality, meat of heifers had greater lightness and lower yellowness, chroma and hue value than that of bulls and steers. Meat shear force only tended to be different amongst sexes after 14 days of ageing (P < 0.10). Heifers had greater intramuscular fat content than steers and bulls. Total saturated fatty acids were similar amongst groups but monounsaturated fatty acids proportion was greatest in heifers, intermediate in steers and lowest in bulls. Polyunsaturated fatty acid proportion was greater in bulls than in steers and heifers. Only minor effects of sex were detected by the sensory panel, with more desirable flavours and higher tenderness in heifers. Therefore, despite the faster growth of entire bulls, fattening steers and especially heifers can lead to improved fat-related meat quality traits in lean breeds.

Performance and optimization of an ear tag automated activity monitor for estrus prediction in dairy heifers

The objectives of this study were to evaluate the performance of the SCR eSense ear tag automated activity monitor (AAM) to detect estrus behavior in Holstein heifers and to determine the optimal time from estrus alert to artificial insemination (AI) using sex-sorted or conventional semen. In total, 281 heifers were fitted with the AAM once eligible for breeding (>13.5 m of age). For the first AI, estrus was synchronized using 500 μg of cloprostenol (PGF), given 14 d apart, and heifers were given estrus detection patches (Estrotect™) after the second PGF. Heifers were inseminated at randomly attributed times after high activity alert from the AAM system or if the estrus patch had ≥ 50% colour change. Most heifers received sex-sorted semen for the first AI and conventional semen for subsequent inseminations. Pregnancy diagnosis was performed at 30 d post AI and heifers had four opportunities to become pregnant. In a subset of heifers (n = 149), ovaries were scanned every 12 h from the time of AI until ovulation (OV). The system recorded a heat index (measure of estrus strength), maximum activity change, maximum rumination change and duration of high activity. The sensitivity was 91.0%, with a false positive and false negative rate of 8.0%, and the positive predictive value to detect true estrus events was 83.5%. Pregnancy per AI to first AI was 67.6% and 97.9% of heifers become pregnant after four inseminations. Most false positive estrus events had a heat index < 45 and a rumination change < -20, while false negative events had a rumination change ≥ -20. Odds of pregnancy was not associated with any estrus characteristics measured by the system. However, pre-ovulatory follicle diameter had a weak correlation (r < 0.25) with all estrus characteristics. The average (range) interval of onset of high activity, peak activity and end of high activity to OV was 28 h (16–46 h), 22 h (10–40 h) and 16 h (0–36 h), respectively. For conventional semen, each hour increase in interval from activity onset or peak activity to AI reduced the predicted probability of pregnancy by 3.8 and 4.2%, respectively. For sex-sorted semen, the relationship between activity onset or peak activity to AI and predicted probability of pregnancy was quadratic, but not significant. Overall, the SCR eSense ear tag AAM performed well and strategies to identify false positive and false negative estrus events, along with optimization of timing of AI, should further improve performance in Holstein heifers.

Effect of increasing pre-pubertal concentrate levels on reproductive and lactation performance of Nili-Ravi Buffalo heifers.

The objective of this study was to determine the effect of increasing total nutrient supply by increasing level of concentrate supplementation in forage-based diet of growing Nili-Ravi buffalo replacement heifers on pre-pubertal growth rate and its impact on age at puberty and post-pubertal productive and reproductive performance. Twenty-eight Nili-Ravi buffalo heifers of 7 ± 1month age were divided into 3 groups. The treatments were 3 levels of concentrate (crude protein (CP) = 17.9%, metabolisable energy (ME) = 2.66Mcal/kg), i.e. 0.5, 1, and 1.5% of the body weight referred as low, medium, and high treatments, respectively. Irrespective of pre-pubertal treatment, all the heifers received similar feed after puberty up to completion of their first lactation. The results of the study showed a similar response across the treatments in age, weight, and condition at puberty, weight at calving, lactation length, and yield. The medium and high treatments resulted in poor reproductive performance because of higher services per conception and less number of heifers confirmed conceived compared with low treatment. The low treatment resulted in less mortality compared with medium and high treatments. The feeding cost per animal at puberty, conception, and calving was lowest for treatment low as compared with medium and high. In conclusion, the results of the study showed that Nili-Ravi buffalo heifers achieved puberty at 23months with feeding of concentrate (CP = 17.9%, ME = 2.66Mcal/kg) during pre-pubertal stage at the rate of 0.5% of the body weight with better reproductive performance.

Effects of feedbunk restrictions and push-up frequency on the growth performance of Holstein dairy heifers offered a forage-based diet with a limit-feeding strategy

Conceptually, there are 2 feeding strategies for avoiding over-conditioning, which can be problematic for gravid dairy heifers that have reduced dietary energy density requirements relative to younger animals: (1) diluting the ad libitum-fed diet with low-energy forages; or (2) offering a diet of greater nutrient density but intentionally restricting the DM available for consumption (limit-feeding). Our objectives for this study were to evaluate the effects of feedbunk restriction and feed push-up frequency on the growth performance of gravid Holstein dairy heifers. A total of 128 Holstein heifers (434 ± 46.7 kg) were enrolled in the trial. Heifers were blocked by weight, and assigned to 1 of 16 identical research pens (4 pens/weight block; 8 heifers/pen), where the mean initial body weight (BW; ± SD) for the 4 blocks were 491 ± 19.0, 450 ± 16.5, 419 ± 10.6, 374 ± 23.0 kg. Within each block, a 2 × 2 factorial arrangement of treatments was assigned; treatments consisted of feedbunk access [full (FUL) or restricted (RES] and feed push-up frequency [1.5- or 3.0-h intervals]. The RES treatment was applied by covering 2 of the 8 head-locking feed gates in assigned pens with plywood partitions, thereby creating a feedbunk-stocking rate of 133%. A total mixed ration diet composed of alfalfa haylage (60.5%), corn silage (38.0%), and mineral (1.5%) was offered once daily for 91 d; daily feed allotments (overall mean = 9.11 kg dry matter (DM)/d) were generally consumed entirely within 9 h of feeding. Nutrient intakes were not affected by push-up frequency or the interaction of main effects, but all intakes were affected by feedbunk access, except for DM and neutral detergent fiber expressed as a percentage of BW (overall means = 1.93 and 0.80%, respectively). In each case, intakes for FUL were greater than those observed for RES; for DM intake, this amounted to a difference of 0.20 kg/d between those main-effect treatments. After 91 d, heifers without feedbunk restriction exhibited greater final BW, but total gain and average daily gain differed only numerically between FUL and RES. Under the conditions of this trial, heifers were blocked by weight, such that BW were relatively uniform within each pen, and head-locking feed gates were used, which also provided some protection from adjacent aggressive heifers. These results suggest heifers can exhibit acceptable growth performance on high-forage diets in a limit-feeding program that includes moderate feedbunk restriction provided other forms of stress are minimized.

Growth of beef cattle as prediction for meat production: A review

Growth of beef cattle as prediction for meat production: A review

Body Temperature and Reproductive Performance of Beef Heifers Supplemented With Rumen-Protected Methionine

This study aimed to assess the reproductive performance and body temperature of beef heifers supplemented with rumen-protected methionine (RPM) in an extensive grazing system and mated during the summer. One hundred 5/8 Angus 3/8 Brahman heifers were homogeneously divided into the control group (n=48, CG) supplemented with mineral salt ad libitum and methionine group (n=52, MG) who received the same supplementation plus 4 g of methionine per 100 g of mineral salt. The groups were fixed-time artificial inseminated (FTAI) 45 days after starting the supplementation. On day 0 of the FTAI protocol, ten animals per group received data-logger thermometers attached in progesterone implants recording the body temperature of the animals every 30 minutes. Pregnancy diagnosis was performed on days 30 and 60 after the artificial insemination to determine the rates of conception, pregnancy, and pregnancy loss. At the beginning of the supplementation, both groups had similar weights (MG was 304.6 kg and CG 304.4 kg), while on days 0 and 30 about the FTAI protocol, the MG was higher weight (365.9 vs. 346.7 and 384.8 vs. 371.5 Kg). During the FTAI protocol, the MG had lower body temperatures (38.77 vs. 38.99 °C) and a tendency to have larger dominant follicles than the CG (11.76 mm x 10.8 mm). Although it did not impact reproductive performance, the observed higher weight, dominant follicle sizes, and lower body temperatures during FTAI protocols show the potential benefits of methionine supplementation in beef heifers mated during the summer.

MINERAL, PROTEIN, AND ENERGY SUPPLEMENTATION IN HEIFERS IN A NATIVE PAMPA BIOME PASTURE DURING WINTER

This study evaluated the effect of different supplements during winter on the performance of heifers in a native Pampa biome field using deferred grazing and evaluated the economic viability of each treatment. A total of 124 heifers from Brangus and Angus breeds, 18 months old, and with an average weight of 301.6 kg were included in this experiment. The treatments applied were: control with only native grassland, native grassland + 80P mineral salt treatment (MS), native grassland + protein salt treatment (PS), and native grassland + protein/energy salt treatment (PES). Besides the productive, botanical, and bromatological characteristics of the pasture, the average daily gain and the live weight gain per hectare were evaluated. The economic viability of the treatments was evaluated through partial budgeting. Weight loss was observed in all treatments. However, only the PES treatment differed from the others, with an average daily gain of -0.046 kg dia-1 (p value &lt; 0.005). The MS treatment was the best regarding economic viability. Despite that, the smallest weight loss was observed in the PES treatment, which may be a determinant in the development and future performance of heifers. Despite the small net margin, this treatment did not incur additional costs to the system.

Performance of Purunã beef heifers and pasture productivity in a long-term integrated crop-livestock system: the effect of trees and nitrogen fertilization

The incorporation of trees in integrated crop-livestock systems (ICLS) has been suggested to recovery degraded pastures and to improve production and environmental outcomes in livestock systems. A challenge for their long-term productive stability is to minimize competition (especially for light) among components of the systems. The objective of this study was to evaluate the performance of beef heifers grazing cool-season grasses in two different ICLS, crop-livestock only and crop-livestock with trees (CLT), and at two N supply levels (90 and 180 kg N ha−1), in the subtropical region of Brazil. This study was performed over two consecutive years (2017 and 2018), in 11–12-year-old tree plantation (238 trees ha−1) and after a drastic reduction in tree density (remaining ~ 40 eucalyptus trees ha−1). The experimental design was randomized blocks with treatments set up in split plots with three replications. Main plots were treatments (ICLS * N) and subplots were years. The results indicate that the moderate shading level (~ 36%) provided by trees in the CLT system affected pasture growth (the total herbage accumulation was reduced in 2.02 Mg ha−1), the daily gain per animal (− 27%) and, consequently, decreased carrying capacity (− 28%) and weight gain per area (− 42%). An increase in N availability was not enough to overcome these differences. The possible influence of previous periods with intense shading (> 50%) in this long-term experiment on the current results, via reduction in the quantity of residues (plant and animal) deposited on soil surface, is discussed, as well as possible strategies to reduce losses in animal production in CLT systems.

Effects of a vitamin and mineral bolus on beef heifer feedlot performance, feeding behavior, carcass characteristics, and liver mineral concentrations.

Crossbred beef heifers (n = 23; initial body weight [BW] = 370 ± 12 kg) housed at the North Dakota State University Beef Cattle Research Complex in Fargo, ND, were used to evaluate the effects of a 250-d slow-release vitamin and mineral bolus on feedlot performance, feeding behavior, carcass characteristics, and liver mineral concentrations. Heifers were assigned to one of two treatments: 1) received no supplemental mineral or vitamin (CON, n = 12) or 2) received two boluses on day 0 (minimum of 3,740 mg Ca, 16,456 mg Mg, 112 mg Na, 11,220 mg Cu, 2,995 mg I, 2,805 mg Mn, 505 mg Se, 48,620 mg Zn, 468 mg Co, 824,296 IU vitamin A, 173,102 IU vitamin D3, and 4,121 IU vitamin E bases on company analysis; Reloader 250 Mineral Bolus, Cargill Inc., Minneapolis, MN; MIN, n = 11). Heifers were fed a total mixed ration containing corn silage, grass hay, dried distillers grains with solubles, and dry-rolled corn (16.05% crude protein, 1.44 Mcal/kg NEg) with no added vitamin or mineral supplement. Feed intake and number and time of visits were recorded for each heifer using the Insentec feeding system (Hokofarm Group B.V., the Netherlands) during the feeding period. Liver biopsies were collected from heifers on days 0, 69, and 134 of the feeding period for analysis of mineral concentrations and analyzed as repeated measures. Heifers were slaughtered after 150 or 169 d on feed, and carcass characteristics were determined. Final BW, average daily gain, dry matter index, gain:feed, and carcass characteristics were not influenced (P > 0.19) by treatment. Control heifers visited feeders more but spent less time per visit and ate less per visit compared with MIN heifers (P < 0.03). No differences (P > 0.06) in liver mineral concentrations were observed between treatments, and concentrations of Se, Cu, Mo, Mn, and Co decreased (P < 0.05) over the feeding period. In this experiment, the slow-release vitamin and mineral bolus evaluated failed to increase liver mineral concentrations during the finishing period or influence heifer performance and carcass characteristics.

Fertility and Productive Performance of Cattle at Different Levels of Atmospheric Pressure

The objective of the surveys was to study fertility and productive performance of heifers and cows of the Red Steppe breed under different atmospheric pressure gradients of 725–750, 751–775, 774 mm Hg, and higher pressure gradients. On the days with the indicated atmospheric gradient frontiers, the heifer and cow insemination and milk yield control procedures with the analysis of the milk chemical composition were performed. It was ascertained that both cows and heifers demonstrated the highest conception rates at the first insemination (61.1 and 58%, respectively) on the days with the atmospheric pressure of 751–755 mm Hg. The maximum percentage of dry cows was registered during insemination of the animals on the indicated days. The highest daily milk yields were recorded in cows on the days of lactation, when the atmospheric pressure gradient did not exceed 775 mm Hg. Predominance of milk production over the milk yield obtained in the periods with the maximum atmospheric pressure comprised 3.1–3.6 kg (P > 0.99–0.999). The same trend could be observed in the dry matter content and the basic milk components. The survey outcomes show that conception rates and productive performance of the Red Steppe cattle are characterized by maximum values under the atmospheric pressure gradients (751–775 mm Hg) considered comfortable and suitable for animals.

Body weight of dairy heifers is positively associated with reproduction and stayability

This study investigated the relationships between body weight (BW) and stayability, and BW and calving pattern, of 189,936 New Zealand dairy heifers. Heifers were classified into 5 breed groups: Holstein-Friesian (F), Holstein-Friesian crossbred (FX), Jersey (J), Jersey crossbred (JX), and Holstein-Friesian × Jersey crossbred (FJ). Body weight was predicted using Legendre polynomials at 6, 12, and 15 mo of age, and we analyzed their relationships with stayability, calving rate, and re-calving rate over the first 3 calvings. Approximately 92% of heifers calved for the first time at age 2 yr, 76% a second time at 3 yr, and 61% a third time at 4 yr. Heifers that were heavier were more likely to remain in the herd for first, second, and third calving compared with heifers that were lighter. Furthermore, we found positive curvilinear relationships between pre-breeding BW and reproductive performance of dairy heifers. Heifers that were heavier at 6, 12, and 15 mo were more likely to calve early for first calving compared with heifers that were lighter, regardless of breed group. In addition, we found a large range in BW where the probability of calving or re-calving early was high. For example, FJ heifers that were between 255 and 396 kg at 15 mo of age had 21-d calving and re-calving rates above 75 and 70%, respectively. For second and third lactations, however, heifer pre-breeding BW showed only small effects on the 21-d calving and re-calving rates. For heifers that were at the heaviest end of the BW range in the current study, slight declines in stayability and reproductive performance occurred, compared with heifers in the mid-range of BW. Consequently, for heifers that were above average in BW, the benefit of increasing BW before first breeding would be small and might even result in slight declines in stayability and reproductive performance. For heifers that were below average in BW, considerable beneficial effects on stayability and reproductive performance are predicted as a result of improving rearing practices to produce heavier heifers throughout the pre-breeding rearing phase.

Influence of bull biostimulation on age at puberty and reproductive performance of Sahiwal heifers

Present study was undertaken to compare the effect of biostimulation by exposing the heifers to fenceline bull contact and fenceline + direct contact on age at puberty and reproductive performance of Sahiwal heifers. Pre-pubertal heifers (24) were allotted to 3 groups (8 animals each), i.e. non-bull exposed (NBE), fenceline bull exposed (FBE) and FBE + direct bull exposed (DBE) on the basis of age and body weight. In NBE group, heifers were not exposed to bull; in FBE group, heifers were exposed to the bull through a fenceline contact (24 h) and in FBE+DBE group, heifers were housed in a fenceline contact (24 h) with bull along with direct contact for 6 h through another bull in the heifer shed. Heifers were considered to have attained puberty if progesterone concentration was &gt;1 ng/ml. The mean age and body weight at puberty in FBE (19.33±0.36 months and 226.20±6.35 kg) and FBE+DBE (19.11±0.58 months and 224.19±4.54 kg) heifers were almost similar but significantly lower than NBE heifers (24.13±0.16 months and 262.50±8.50 kg). The average age at first service and first calving was similar in FBE (20.41±0.45 and 30.20±0.73 months) and FBE+DBE (20.78±0.36 and 29.90±0.44 months) heifers but significantly lower than NBE heifers (25.15±0.14 and 34.29±0.53 months). We conclude that biostimulation of heifers by fenceline contact with the bull is as effective as FBE + 6 h of daily direct bull contact in hastening the age at puberty and improving reproductive performance.

Nutritional strategies for heifers under grazing system: productive and nutritional performance, metabolic profile and ovarian activity

The objective of this study was to evaluate the effects of nutritional strategies on productive and nutritional performance, metabolic profile, and ovarian activity in heifers under grazing in the tropics in Brazil. Forty Nellore heifers averaging 8.5 ± 0.06months and 248.6 ± 3.3kg body weight (BW) were distributed in a completely randomized 2 × 2 factorial design with four treatments and ten replicates. The evaluated strategies consisted of different amounts of energetic-protein supplement: (1) 4g/kg of BW of supplement in the pre-weaning and post-weaning; (2) 4g/kg of BW of supplement pre-weaning and 6g/kg in the post-weaning; (3) 6g/kg of BW of supplement in the pre-weaning and 4g/kg of BW in the post-weaning and; (4) 6g/kg of BW of supplement in the pre-weaning and post-weaning. Crude protein (CP) and organic matter (OM) intake were increased (P < 0.05) by increasing the amounts of supplement in the post-weaning. Additionally, increasing supplement amounts in the post-weaning increased the digestibility of OM and CP (P < 0.05). Means insulin and glucose concentrations were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. Average daily gain and fat thickness in the rump were increased (P < 0.05) by increasing supplement amounts in the post-weaning. Amounts of supplement did not influence the body growth of heifers. However, follicular number, diameter, and progesterone concentration were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. In summary, increasing supplement amounts in the post-weaning improve the performance, energy and metabolic status, and ovarian activity in beef heifers under grazing in the tropics. Due to higher intake of supplement, the heifers receiving 6g/kg of BW post-weaning had greater responses, independently of the supplement amount received pre-weaning.

Replacement of a protein–energy supplement by a same-cost maize-based supplement on performance and product quality of pasture-finished Nellore heifers

Context In the largest beef-producing countries in the world, the slaughter of female cows accounts for ~30–40% of all beef produced. Aims The objective of this study was to evaluate the replacement of a protein–energy supplement (PES) by a same-cost maize-based supplement (MBS) on the performance and final product of Nellore heifers grazing Brachiaria brizantha cv. Marandu pasture during the wet season in Brazil. Methods Ninety-six Nellore heifers of bodyweight (BW) 281 ± 7.55 kg and aged 23 months were used. Six were slaughtered at the start of the experiment. The remaining 90 heifers received one of the following three supplements with their predominantly pasture diet for 133 days: control, mineral salt ad libitum; PES, with protein 250 g/kg dry matter (DM) and total digestible nutrient 600 g/kg DM, offered at 3 g/kg BW.day (as-fed basis); MBS, with crude protein 90 g/kg DM and total digestible nutrient 850 g/kg DM, offered at 7 g/kg BW.day (as-fed basis). The variables were evaluated in a completely randomised block design with 30 heifers per treatment. Key results Average daily gain and final BW were similar (P &amp;gt; 0.05) in PES and MBS treatments, and relative to the control increased (P &amp;lt; 0.01) average daily gain by ~24% and final BW by 7%. Pasture intakes were decreased, with substitution levels of 8.0% for heifers receiving PES and 10.4% for those receiving MBS. Carcass weight (kg/day) and carcass gain (g carcass/kg BW) were greater (P &amp;lt; 0.001) for heifers receiving MBS and PES than for the control group. Backfat depth was greater (P &amp;lt; 0.001) in heifers receiving MBS (7.91 mm) than in those receiving PES (6.25 mm), and the lowest (P &amp;lt; 0.001) measurement was observed in the control group (4.85 mm). Conclusions Maize-based supplement (7 g/kg BW.day) provided the same growth rate as PES (3 g/kg BW.day) but yielded heavier and slightly fatter carcasses of pasture-finished Nellore heifers during the wet season (133 days) with a similar cost, and with more total digestible nutrients than pasture plus mineral salt. Implications Maize-based supplement provided to Nellore heifers on pasture may improve performance despite lower pasture intakes but needs to be evaluated carefully in terms of costs involved.

Effects of mineral supplementation on cattle performance when grazed mature wheat

ABSTRACT This research paper addresses the hypothesis that mineral supplementation (sodium chloride and magnesium oxide at 1:1 weight ratio) for dairy heifers grazing mature wheat in the spring-summer period will improve live weight gain compared with the non-supplemented group. In addition, the potential of mineral supplementation to reduce environmental pollution through diluting urinary nitrogen content was evaluated in this study. The grazing study was conducted at the Dookie Campus, The University of Melbourne, Australia between September and November 2017. The study comprised two temporal trial replications with two dietary treatments; graze wheat with (supplemented, SUP) or without mineral supplementation (control, CTR). The first and second trial replications used 22 and 24 heifers, respectively to conduct a 22-day and 21-day weight gain measurement. Heifers in the CTR group had 11% lower daily water intake than those in the SUP group. No differences were observed in heifers’ weight gain and urinary nitrogen content and excretion. The study indicates that protein deficiency may override the mineral deficiency when heifer grazed mature wheat, and this may have led to no mineral supplementation effect on heifer performance. The level of protein in grazing wheat needs to be considered in feeding minerals to heifers.

Replacing corn with ground or pelleted citrus pulp in diets of Nellore heifers

SUMMARY Citrus pulp can replace corn in feedlot diets in order to decrease metabolic problems by reducing formation of lactate ruminal. However, while eating, animals can easily select against pelleted citrus pulp due to the greater particle size of the pellet. Therefore, grinding citrus pulp pellet can be an alternative to decrease particle selectivity. This study was realized to evaluate the replacement of ground corn by pelleted citrus pulp and ground citrus pulp on animal performance, sorting index, and feeding behavior of Nellore heifers. Thirty-six Nellore heifers were randomly assigned to three treatments: control diet based on ground corn (GC), partial replacement of GC by ground citrus pulp (GCP), and partial replacement of GC by pelleted citrus pulp (PCP). . Heifers fed with the GC diet had higher final body weight (BW), average daily gain (ADG), and dry matter intake (DMI) compared with heifers fed with citrus pulp (P &lt; 0.05). Ground citrus pulp increased DMI and fiber intake compared with the PCP group (P &lt; 0.05). Heifers fed with PCP and GCP sorted for diet particles from 8 to 19 mm and selected particles with less than 1.18 mm (P &lt; 0.05). Thus, the ground citrus pulp is better than pelleted citrus pulp due to higher feed intake and ADG, in consequence of lower selection index.