Percentage Of Calves Research Articles

128 Pregnancy and calving rates of beef cows comparing the sex-selected semen to conventional semen using timed artificial insemination

Abstract A study was conducted over three years to determine if differences in pregnancy rates existed between the use of commercially available sex-selected (SEXED) or conventional semen (STD) coupled to fixed-time artificial insemination (TAI). A total of 240 (2016: n = 80; 2017: n = 95; 2018: n = 65) primi- or multiparous Angus or Angus-cross cows being at 45 days post-partum or greater were blocked by weight and BCS and assigned to be inseminated using SEXED semen or STD semen. Artificial insemination was performed by the same AI technicians (n = 3) across all years. All cows were subjected to estrous synchronization and insemination using the SEXED semen or STD semen with TAI between 63 and 66 h post-CIDR removal. Fourteen days post-TAI all cows were exposed to bulls for natural service. Cows were subjected to transrectal ultrasonography at day 30 and day 45 post-TAI to determine pregnancy rates and calving dates in the subsequent calving seasons were recorded to determine calving rates to TAI. Pregnancy rates were compared using a Chi-square test of two proportions. All statistical calculations were performed using JMP software and statistical significance was based on p-values less than 0.05. Pregnancy rates at day 30 and day 45 were 39.67% and 48.76% for SEXED and 47.90% and 54.62% for STD, respectively (P > 0.05). The percentage of calves born to TAI pregnancies for sex-selected semen and conventional semen were 22.31% and 40.34%, respectively (P < 0.05). These data indicate that the use of sex-selected semen can give similar pregnancy results to conventional semen in beef cow operations using TAI at day 30 of gestation; however, there was a reduction in the number of offspring to TAI comparing calving dates to animals pregnant at day 30.

Consensus recommendations on calf- and herd-level passive immunity in dairy calves in the United States

Passive immunity in calves is evaluated or quantified by measuring serum or plasma IgG or serum total protein within the first 7 d of age. While these measurements inform about circulating concentrations of this important protein, they are also a proxy for evaluating all of the additional benefits of colostral ingestion. The current individual calf standard for categorizing dairy calves with successful passive transfer or failure of passive transfer of immunity are based on serum IgG concentrations of ≥10 and <10 g/L, respectively. This cutoff was based on higher mortality rates in calves with serum IgG <10 g/L. Mortality rates have decreased since 1991, but the percentage of calves with morbidity events has not changed over the same time period. Almost 90% of calves sampled in the USDA National Animal Health Monitoring System's Dairy 2014 study had successful passive immunity based on the dichotomous standard. Based on these observations, a group of calf experts were assembled to evaluate current data and determine if changes to the passive immunity standards were necessary to reduce morbidity and possibly mortality. In addition to the USDA National Animal Health Monitoring System's Dairy 2014 study, other peer-reviewed publications and personal experience were used to identify and evaluate potential standards. Four options were evaluated based on the observed statistical differences between categories. The proposed standard includes 4 serum IgG categories: excellent, good, fair, and poor with serum IgG levels of ≥25.0, 18.0-24.9, 10.0-17.9, and <10 g/L, respectively. At the herd level, we propose an achievable standard of >40, 30, 20, and <10% of calves in the excellent, good, fair, and poor categories, respectively. Because serum IgG concentrations are not practical for on-farm implementation, we provide corresponding serum total protein and %Brix values for use on farm. With one-third of heifer calves in 2014 already meeting the goal of ≥25 g/L serum IgG at 24 h of life, this achievable standard will require more refinement of colostrum management programs on many dairy farms. Implementation of the proposed standard should further reduce the risk of both mortality and morbidity in preweaned dairy calves, improving overall calf health and welfare.

PSVI-2 The effect of a recombinant Mannheimia haemolytica leukotoxoid on the health and growth performance of high-risk, newly received stocker cattle metaphylactically treated with tilmicosin

Abstract Crossbred male beef calves (n = 259; bulls = 134, steers = 125; body weight = 250 ± 3.4 kg) approximately 6 months of age and considered high-risk for developing bovine respiratory disease arrived on 3 dates (block) and were stratified by arrival castrate status and weight to be evenly distributed across pens (8 pens/block; 9 to 12 calves/pen). The pens were randomly assigned to 1 of 2 treatments: 1) Nuplura PH (administration of a Mannheimia haemolytica leukotoxoid at processing) or 2) Control (no M. haemolytica leukotoxoid). All cattle received tilmicosin on d 0 with a 5-d post-metaphylactic interval. Body weights were recorded on d -1, 0, 14, 28, 41 and 42. Blood was collected on d -1, 14, 28, and 42 and sera were harvested to determine serum neutralization titers for bovine virus diarrhea (BVD) type I and bovine anti-M. haemolytica leukotoxin antibodies. Calves were observed daily for signs of morbidity. Body weight and average daily gain were not affected (P ≥ 0.26) by treatment. The percentage of calves administered 1, 2, or 3 antibiotic treatments for clinical bovine respiratory disease did not differ (P ≥ 0.35). There was a tendency for mortality to be greater for Control compared to Nuplura PH (1.6 vs 0.0%; P = 0.10). Calves administered Nuplura PH possessed greater antibody response against M. haemolytica leukotoxin on d 14, 28, and 42 compared to Control calves (P &amp;lt; 0.01). There was no treatment × day interaction for antibody titers against BVD (P = 0.98). The use of a M. haemolytica leukotoxoid had no effect on growth performance and morbidity for the 42-d following receiving in this small-pen study, but reduced the incidence of mortality and did not interfere with antibody response to BVD vaccination in high-risk, newly received calves metaphylactically treated with tilmicosin on arrival.

PSIV-15 Effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, performance, and blood parameters of high-risk cattle during the feedlot receiving period

Abstract The objective was to determine the effects of Bacillus subtilis PB6 and/or chromium propionate supplementation on health, performance, and blood parameters in high-risk beef calves during a 56-day receiving period. Four truckload blocks of crossbred beef calves (n = 384; BW=220±16.2 kg) were assigned randomly to treatments arranged in a 2 × 2 factorial. The generalized complete block design consisted of 12 pen replications per treatment with pen as the experimental unit. Treatments were: 1) placebo control (CON); 2) 13 g/animal/d Bacillus subtilis PB6 (CLOSTAT®, Kemin Industries; CST); 3) 1 g/animal/d Cr propionate (KemTRACE® Chromium, Kemin Industries; CHR); and 4) CST+CHR. Treatments were top dressed in feed bunks daily using 0.45 kg/animal/d ground corn carrier. Blood samples were collected on days 0, 14, 28, and 56 for analysis of serum chemistry and complete blood count variables from a pen subset (n = 2/pen). Data were analyzed using MIXED and GLIMMIX procedures of SAS. The DMI was increased for CST during each interim period (P ≤ 0.03) and overall DMI was increased by 0.78 lb/animal/d for CST (P = 0.01). The CST supplemented cattle had greater BW on days 14, 28, and 56 (P ≤ 0.06). Likewise, ADG was improved for CST from day 0 to 14 (P = 0.04) and for the overall receiving period (P = 0.04). Main effects of CST (P = 0.02) and CHR (P = 0.03) decreased the percentage of calves treated for bovine respiratory disease (BRD). Morbidity was 28.0 and 39.9% for cattle with and without CST supplementation and 28.6 and 39.3% for cattle with and without CHR supplementation, respectively. Cattle fed CHR had increased (P ≤ 0.04) total leukocytes, neutrophils, serum aspartate aminotransferase and less (P = 0.02) serum calcium. Performance was improved by CST and BRD morbidity was less for CST and CHR.

PSXIV-35 Evaluation of a direct fed microbial in newly received, high-risk beef calves and the subsequent impact on performance and health

Abstract Crossbred beef calves [n = 240, body weight (BW) = 257 ± 3.5 kg] were obtained on 3 dates (block, 8 pens/block) and were assigned randomly to 1 of 2 treatments: 1) CON = top-dress supplement (0.11 kg/d) with no direct-fed microbial, 2) BOV = top dress supplement (0.11 kg/d) that provided 113.5 mg/d of a direct-fed microbial (BOVAMINE DEFEND®, 2 g/d, Lactobacillus animalis, Propionibacterium freudenreichii, 1 × 109 CFU2/g). Study objective was to determine the effect of BOV on growth performance and health when included in the diet. From d 0 to 14, ADG was improved (P = 0.05) for BOV compared to CON as ADG were 0.89 and 0.74 kg, respectively. Overall ADG over the 43-d receiving period was not different (P = 0.65); numerically there was a 0.03 kg improvement in BOV (0.90) compared to CON (0.87 kg). The percentage of calves treated for clinical BRD with the first treatment antibiotic (florfenicol) was not affected (P = 0.40); however, was numerically reduced by 6.8% for BOV (61.2% morbidity) compared to CON (68.0% morbidity). There was a trend for the percentage of calves treated with a second antibiotic (enrofloxacin) to be reduced (P = 0.17) for calves supplemented with BOV (9.1%) compared to CON (15.2%). There was also a trend for the mean total number of antibiotics used to be reduced (P = 0.16) in BOV compared to CON. Overall antibiotic cost, was not affected (P = 0.23) by BOV supplementation; however, numerically there was a $3.27 reduction in antibiotic cost for BOV compared to CON. The supplementation of BOV in high-risk calves may improve growth performance and health, reduce clinical BRD in calves after first treatment and could potentially reduce the use of antibiotics in calves at a high risk for BRD during the receiving period.

Comparison of treatment protocols for bovine respiratory disease in high-risk, newly received beef calves

ABSTRACT Objective This research evaluated the effects of different antibiotic treatment protocols on performance, morbidity, antibiotic usage, and cost in high-risk, newly received beef calves. Materials and Methods Crossbred male calves (n = 176; BW = 232 ± 1.6 kg) were stratified by BW and castration status and assigned randomly to 1 of 2 treatments in a randomized complete block design. Calves were administered either 2.5 mg/kg of BW of tulathromycin (TUL, Draxxin, Zoetis, Florham Park, NJ) with a 7-d post-metaphylactic treatment or 10 mg/kg of BW of tilmicosin (TIL, Micotil, Elanco Animal Health, Greenfield, IN) with a 1-d post-metaphylactic treatment. Clinical attitude scores [0 (normal) to 4 (moribund)] were assigned daily to assess morbidity and when ≥ 1, and if rectal temperature exceeded 40°C, an antibiotic was administered per preplanned protocol. Calves that received TUL on d 0 received ceftiofur with a 7-d post-treatment interval, and those that received TIL received enrofloxacin with a 3-d post-treatment interval. A final antibiotic was administered to calves that were pulled a second time and met the treatment criteria. Results and Discussion Percentage morbidity was greater for the first treatment, the second treatment, and relapse in TIL compared with TUL (P Implications and Applications Metaphylactic treatment protocols did not affect growth performance, but differences were found in the percentage of calves treated for clinical bovine respiratory disease and in number of antibiotics used.

Transfer of passive immunity in dairy calves: the effectiveness of providing a supplementary colostrum meal in addition to nursing from the dam

Failed transfer of passive immunity (FTPI) in dairy calves – which is often due to the low amount of colostrum provided within a few hours after birth – remains a crucial issue. Enabling dairy calves to nurse colostrum from their dams could be useful in increasing intake and thus avoiding FTPI, but further potential effects on the health and welfare of both calves and dams should also be considered. In this study, 107 calf-dam pairs from two Italian dairy farms were alternately assigned to one of the following colostrum provision methods (CPMs): ‘hand-fed method’ (HFM) – the calf was separated from the dam immediately after birth and colostrum was provided by nipple-bottle (n = 50); ‘nursing method’ (NM) – the calf nursed colostrum from the dam for the first 12 h of life without farmer assistance (n = 30); and ‘mixed method’ (MM) – the nursing calf received a supplementary colostrum meal by nipple-bottle (n = 27). Serum of calves (1 to 5 days of age) and samples of their first colostrum meal were analysed by electrophoresis to assess immunoglobulin (Ig) concentration. Additionally, behavioural indicators of separation distress (calf and dam vocalisations; calf refusal of the first meal after separation; undesirable dam behaviour at milking) in the following 24 h were recorded as binary variables (Yes/No), and the health status of calves (disease occurrence and mortality) and dams (postpartum disorders and mastitis occurrence) were monitored for the first 3 months of life and 7 days after parturition, respectively. The lowest FTPI occurrence (calf serum Ig concentration <10.0 g/l) was found in the MM (11.1%) and the HFM (22.0%) compared with the NM (60.0%) (P<0.05), and the highest percentage of calves with optimal transfer of passive immunity (serum Ig concentration ≥16.0 g/l) was observed in the MM (55.6%). The lowest calf–dam separation distress was observed in the HFM (P<0.05). The highest calf disease occurrence was recorded in the HFM (64.0%) and the lowest in the NM (33.3%), with an intermediate value for the MM (44.4%) (P<0.05). No effect of the CPM was observed on dam health or calf mortality (P>0.05). The results of this study indicated that providing calves with a supplementary colostrum meal in addition to nursing from the dam (MM) is truly effective in maximizing passive immunity transfer. Anyway, specific strategies should be studied to minimise calf-dam separation distress.

407 Implementation of an Integrated Farm Management Plan to Enhance Reproductive Performance in Beef Cow-Calf Operations.

The University of Kentucky Beef IRM team has developed a project-based educational program (UK IRM Farm Program) designed to instigate long-term adoption of production practices and increase productivity and profitability. Our current objective was to elucidate changes in production for operations (n=14) after one year of program participation. Prior to enrolling in the IRM Farm Program, producers provided historical production records to obtain baseline information. Comprehensive individual management plans were developed and data was collected at breeding, pregnancy diagnosis, calving, and weaning. Operations were categorized as either controlled (90), extended (120), or year-round (365; n=6, 4, 4, respectively) based upon their prior calving season length. Average herd size was 92, 54, and 22 cows for the 90, 120, and 365 groups, respectively. The calving and weaning percentages increased in four of the six farms in the 90 group. Productivity (kg calf weaned per cow exposed) increased by 34 kg in half of the 90 group operations. In the 120 group, calving season length decreased 5 d, calving percentage decreased 1.2%, but the weaning percentage increased 4.5%. Since there were more and older calves weaned in this group, an average increase of 26 kg of calf weaned per cow exposed was observed. For those in the 365 group, calving season length was reduced by 110 days, calving percentage increased 3.7%, weaning percentage increased 3.2%, and kg of calf weaned per cow exposed increased 15 kg. Across all groups, productivity increased by 11 kg of calf weaned per cow exposed on average. Assuming a price of $162/45 kg, revenue increased $41 per cow exposed or $2,476 per producer. From these data we conclude that an integrated methodology combined with hands-on training could be an effective pedagogy for increasing adoption of production practices and enhancing productivity and profitability in beef cow-calf operations.

Evaluation of two-stage weaning and trace mineral injection on receiving cattle growth performance and behavior.

The objective was to evaluate the effects of two-stage weaning and injectable trace mineral (ITM) on receiving cattle growth performance and behavior. Angus and Simmental × Angus steers (n = 136; body weight [BW] = 200 ± 26 kg) were utilized in a 2 × 2 factorial design. Calves were blocked by source, and assigned to one of four treatments: 1) two-stage weaning and ITM (2MM), 2) two-stage weaning and saline injection (2SAL), 3) abrupt weaning and ITM (AbtMM), or 4) abrupt weaning and saline injection (AbtSAL). On d−6, calves were weighed, plastic calf weaner devices (used to prevent calf from nursing) were inserted in two-stage weaned calves, and ITM or saline injections (1 mL/45.4 kg BW) were administered. On day 0, plastic calf weaner devices were removed, and calves were weighed and shipped 272 km to Urbana, IL. Steer behavior was observed the 2 d following separation from dam. Receiving period was day 0 to 42 and growing period was day 42 to 124. Data were analyzed using the MIXED procedure of SAS and pen (six per treatment) was the experimental unit. Abruptly weaned calves had greater (P < 0.01) preweaning average daily gain (ADG) than two-stage weaned calves. Treatment did not affect (P ≥ 0.16) ADG during the receiving or growing period; however, calves that received ITM tended (P 0.06) to have greater ADG from day 0 to 124. During the receiving period, abruptly weaned calves tended (P = 0.08) to eat more than two-stage calves and ITM calves ate more (P = 0.03) than calves that received saline. There was a weaning strategy × ITM interaction (P < 0.01) for dry matter intake (DMI) from day 0 to 124; 2MM calves ate more (P < 0.01) than 2SAL, but DMI was not different (P = 0.58) between AbtMM and AbtSAL calves. There was a weaning strategy × ITM interaction (P < 0.01) for gain-to-feed ratio (G:F) from day 0 to 124; 2SAL calves had greater (P = 0.05) G:F than AbtSAL, with 2MM and AbtMM calves being intermediate and not different (P = 0.38) than each other. Two-stage weaning decreased (P ≤ 0.02) the percentage of calves walking, standing, and vocalizing, and increased (P ≤ 0.02) the percentage of calves lying and eating following separation from dam. Two-stage weaning decreased preweaning ADG and behavioral signs of stress at feedlot arrival, but had no effect on overall growth. In addition, ITM had no effect on calf BW or behavior, but increased overall DMI in two-stage weaned calves compared to abruptly weaned calves and tended to increase overall ADG regardless of weaning strategy.

Case Study: Effect of exercise programs during receiving in a commercial feedlot on behavior and productivity of Brahman crossbred calves: Results from a commercial environment and a comparison to the research environment

ABSTRACT Exercising receiving cattle is hypothesized to be a management strategy that could mitigate receiving stress in cattle. Little empirical research has been published on the quantifiable (productivity, health, behavior) effects of this strategy in a commercial feedyard setting. In a single Texas feedyard case study, high-risk Brahman-crossbred receiving calves (n = 688; 184 ± 5 kg) were exercised during the receiving period in the fall. Upon arrival, calves were sorted into single-sex pens (n = 6 pens: n = 3 pens heifers, n = 3 pens steers) and randomly assigned to 1 of 3 treatments within sex blocks: (1) programmatic exercise (PRO; cattle moved to drive alley and encouraged to maintain movement for 20 min), (2) free exercise (FRE; cattle moved to drive alley and allowed free movement without access to the pen for 60 min), or (3) no exercise (CON). Treatments were applied (n = 12 sessions; 3 sessions per week) across a 30-d period, between 0800 and 1000 h at least 1 h after feed delivery. Gain-to-feed ratio and mortality rate were similar among treatments. Cattle assigned to CON had greater ADG than did those assigned to FRE or PRO (1.52, 1.39, and 1.44 kg/d). Percentage of calves treated for respiratory disease was greater in FRE and PRO compared with CON. The proportion of the pen lying and resting simultaneously increased and the proportion of the pen feeding, drinking, ruminating, and walking decreased over time. Exercise treatments did not compromise gain efficiency or behavior; however, exercised cattle had smaller ADG. These results suggest that exercise reduces receiving-period gains without improving animal health or altering behaviors.

Colostrum transfer of neutralizing antibodies against lumpy skin disease virus from vaccinated cows to their calves.

The objective of the present study was to access the titres and duration of maternally derived neutralizing antibodies against lumpy skin disease virus (LSDV) in calves born to immunized dairy cows. The study was conducted in a Greek farm of 200 Holstein cows which were immunized with a homologous Neethling strain-based attenuated vaccine. Composite colostrum samples were obtained from 18 selected cows at the day of calving. Blood samples were obtained from each dam-calf pair prior to the first colostrum feeding and from the calves successively on the third day after calving and on monthly intervals thereafter, until day 150. Passive transfer of antibodies in calves was evaluated by determining the levels of total protein in serum samples collected on day 3. Neutralizing antibody (NAb) titres against LSDV in colostrum and serum samples were determined by virus neutralization test. Colostrum NAb titres >1:160 were associated with the presence of NAbs in serum from calves 3days after birth. Out of the 18 calves, which received colostrum with NAbs, 16 (88.9%) had detectable NAbs in their serum. Thereafter, a declining percentage of calves with detectable serum NAbs was recorded (38.5% on day 90 and 0% on days 120 and 150). Only calves with high NAb titres on day 3 had detectable serum NAbs until day 90 after calving. Thus, a significant number of calves were not protected by maternal antibodies against the disease after the age of 3months and likely even after the age of 2months. The findings of the present study substantiate that current recommendation for vaccination can be amended, so as to minimize the susceptible bovine population and enable optimized LSD prevention and eradication.

Calving distributions of individual bulls in multiple-sire pastures

The objective of this project was to quantify patterns in the calving rate of sires in multiple-sire pastures over seven years at a large-scale cow-calf operation. Data consisted of reproductive and genomic records from multiple-sire breeding pastures (n = 33) at the United States Meat Animal Research Center (USMARC) from 2007 to 2013. Calving intervals were analyzed in 21-day periods. A ranking system for each bull was developed based on the calving rate per pasture over the breeding season, with Rank 1 = the bull with greatest calving rate, Rank 3 = the bull with the least calving rate, and Rank 2 = all other bulls. A total of 179 bulls and 3703 calves were successfully genotyped over seven years. A uniform distribution described the expected percentage of calves sired per rank within pasture. Rank 1 bulls sired 113% greater calves than the expected pasture-average, Rank 2 bulls sired 6% less than expected, and Rank 3 bulls sired 81% less than expected. A rank by calving interval interaction effect was identified (P < 0.05). A Rank 1 bull in calving interval 1 produced a greater average percent of the total calf crop over the entire season, compared to a Rank 2 and Rank 3 bull. The calving rate for individual sires is not homogeneous and there is a large difference between bulls siring the greatest and least number of calves. More research is needed to determine how rank changes over multiple breeding years and its association with dominance, libido, and fertility.

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

The development of anthelmintic resistance by helminths can be slowed by maintaining refugia on pasture or in untreated hosts. Targeted selective treatments (TST) may achieve this through the treatment only of individuals that would benefit most from anthelmintic, according to certain criteria. However TST consequences on cattle are uncertain, mainly due to difficulties of comparison between alternative strategies. We developed a mathematical model to compare: 1) the most ‘beneficial’ indicator for treatment selection and 2) the method of selection of calves exposed to Ostertagia ostertagi, i.e. treating a fixed percentage of the population with the lowest (or highest) indicator values versus treating individuals who exceed (or are below) a given indicator threshold. The indicators evaluated were average daily gain (ADG), faecal egg counts (FEC), plasma pepsinogen, combined FEC and plasma pepsinogen, versus random selection of individuals. Treatment success was assessed in terms of benefit per R (BPR), the ratio of average benefit in weight gain to change in frequency of resistance alleles R (relative to an untreated population). The optimal indicator in terms of BPR for fixed percentages of calves treated was plasma pepsinogen and the worst ADG; in the latter case treatment was applied to some individuals who were not in need of treatment. The reverse was found when calves were treated according to threshold criteria, with ADG being the best target indicator for treatment. This was also the most beneficial strategy overall, with a significantly higher BPR value than any other strategy, but its degree of success depended on the chosen threshold of the indicator. The study shows strong support for TST, with all strategies showing improvements on calves treated selectively, compared with whole-herd treatment at 3, 8, 13 weeks post-turnout. The developed model appeared capable of assessing the consequences of other TST strategies on calf populations.

A survey of lick supplementation and management practices of commercial beef farmers in the Zastron District

A study was conducted to determine the supplementation and management practices of commercial beef farmers. 48 commercial farmers from the Zastron district were selected for this study out of a prospective of 60 farmers that were bona fide commercial farmers and members of Free State Agriculture. The farmers reported the following calving percentage ranges: one farmer (2.1%) between 50 and 59%, three farmers (6.3%) between 60 and 69%, 19 farmers between 70 and 79%, 22 farmers between 80 and 89% and three farmers between 90 and 99%. Preventative vaccination was common practice as only one farmer did not vaccinate any of his cattle (n = 48). The provision of supplements seemed to be general practice (100%, n = 48) in the district as all the farmers gave some form of supplementation to their cattle. Only 22.9% (n = 11) of the farmers provided supplements according to the production status of the animals and the main reason for not doing so is that 37.8% (n = 14) of the respondents believed that it complicated management and 18.9% (n = 7) thought it not necessary. It is believed that a lack of understanding of the function of supplements by some of the farmers in the district could be the cause of what could be considered as insufficient supplementation by animal nutritionists. Keywords: Cattle, supplementation, licks, management, extension implication

Comparative effect of direct-fed microbial regimen on health and performance of neonatal dairy heifer calves

This study was conducted to compare health and performance in neonatal dairy heifer calves supplemented with direct-fed microbial products in milk: (1) Propionibacterium freudenreichii NP24 and Lactobacillus acidophilus NP51 (BVM) or (2) Kluyveromyces m/f B0399 and Saccharomyces c/f 1026 (PBST). A total of 770 individually housed Holstein (n = 528), Jersey (n = 212), and crossbred (n = 30) heifers at a commercial calf-rearing facility were used for the primary group. Body weight was recorded on d 0 and 60 to determine ADG and percentage of daily BW gain, and health was monitored daily from arrival (d 0) through weaning (d 60). A subset group comprising 50 (n = 25 per treatment) Holstein (n = 32) and Jersey (n = 18) heifer calves were weighed periodically and analyzed separately to evaluate interim and overall performance and health. For both groups, heifers between 1 and 3 d of age were assigned randomly to treatment, and treatments were arranged within a single hutch row consisting of 100 heifers. A tendency (P = 0.09) for an improvement in ADG was observed for PBST heifers in the primary group. For the subset group, PBST had improved ADG from d 0 to 10 (0.29 vs. 0.05; P < 0.001), d 0 to 22 (0.31 vs. 0.23; P = 0.003), and overall (0.51 vs. 0.44 kg/d; P = 0.002). The percentage of daily BW gain was increased for PBST from d 0 to 10 (0.45 vs. 0.09%; P < 0.001) and overall (0.78 vs. 0.64%; P = 0.002). Also, PBST had a greater (P = 0.05) percentage of calves requiring a second respiratory disease treatment, but no other health differences were observed in this experiment. Results indicate PBST improved performance compared with BVM, but health was not clearly affected.

Woodland caribou calf mortality in Newfoundland: insights into the role of climate, predation and population density over three decades of study

AbstractThe rates and causes of juvenile mortality are central features of the dynamics and conservation of large mammals, like woodland caribou (Rangifer tarandus caribou(Gmelin, 1788)), but intrinsic and extrinsic factors may be modified by variations in animal abundance. We tested the influences of population size, climate, calf weight and sex on survival to 6 months of age of 1241 radio‐collared caribou calves over three decades, spanning periods of population growth (1979–1997) and decline (2003–2012) in Newfoundland, Canada. Daily survival rates were higher and rose more quickly with calf age during the population growth period compared to the decline. Population size (negatively) and calf weight (positively) affected survival during the decline but neither had a detectable influence during the growth phase. Sex, climate and plant productivity (the latter two derived from the North Atlantic Oscillation and Normalized Difference Vegetation Index, respectively) exerted minimal influence during either phase. Predation was the dominant source of mortality. The mean percentage of calves killed by predators was 30 % higher during the decline compared to the growth phase. Black bears (Ursus americanus) and lynx (Lynx canadensis) were the major predators during the population increase but this changed during the decrease to black bears and coyotes (Canis latrans). Our findings are consistent with the hypothesis that Newfoundland caribou experienced phase‐dependent survival mediated proximally by predation and competition for food.

Physiology of acid-base balance in bovines with diarrhea backgrounds from Monteria, Colombia

ABSTRACTObjective. Evaluate the acid-base balance (ABB) in bovines with diarrheic backgrounds in four areas of Montería, Colombia. Materials and methods. From a total of 300 pregnant cows, 60 were selected with their newborns. A direct inspection was performed of vital signs on the calves and the ABB indicators were determined using a gasometric method. Data were processed by means of descriptive statistics and the Duncan test was used to differentiate between the averages. The degree of association was established between the ABB indicators in cows and calves by using the Pearson correlation and a comparison of proportions was performed on the indexes of the newborns. Results. Regarding the cows, the ABB indicators were found within the reference values; however, in the calves the pH, pCO2, HCO3-, the anion gap (AG) and the bases excess (BE) varied. A correlation was found between AG, BE and metabolic hydrogen ions (M*H). The AG in cows and calves showed notable differences (p&lt;0.05) among the farms in the study. According to the numeric classification system, the suction reflect indicated a greater percentage of calves in group one. Conclusions. The ABB analyte measurement in cows was similar to the consulted reference; however, in calves some analytes did not coincide. This suggests metabolic acidosis in newborn calves due to the increase of AG and the decrease of BE. Additionally, its correlation with M*H opens the possibility of new proposals to determine ABB in bovines.RESUMENObjetivo. Evaluar el equilibrio ácido-básico (EAB) en bovinos con antecedentes diarreicos de cuatro zonas de Montería, Colombia. Materiales y métodos. De un total de 300 vacas preñadas se seleccionaron 60 vacas y sus recién nacidos. Se realizó una inspección directa de los signos vitales en terneros y los indicadores del EAB se determinaron mediante técnica gasométrica. Los datos se procesaron mediante estadística descriptiva y para la diferencia entre medias se empleó la prueba de Duncan. El grado de asociación se estableció entre los indicadores del EAB en vacas y terneros mediante la correlación de Pearson y una comparación de proporciones se realizó en los índices del recién nacido. Resultados. En las vacas, los indicadores del EAB se encontraron dentro de los valores de referencia; sin embargo, en los terneros varió el pH, pCO2, HCO3-, la brecha aniónica (AG) y el excesode bases (EB). Se encontró correlación entre AG, EB e hidrogeniones metabólicos (H+M). El AG envacas y terneros indicó diferencias notables (p&lt;0.05) entre las fincas de estudio. De acuerdo con elsistema de calificación numérica, el signo reflejo de succión indicó el mayor porcentaje de terneros enel grupo uno. Conclusiones. La medición de los analitos del EAB en vacas fue similar a la referenciaconsultada; sin embargo, en terneros no coincidió con algunos analitos. Se sugiere acidosis metabólicaen los terneros recién nacidos por el aumento del AG y descenso del EB, además, su correlación conlos H+M abre la posibilidad de nuevas propuestas para la determinación del EAB en bovinos.

Risk factors for infection with Foot-and-Mouth Disease virus in a cattle population vaccinated with a non-purified vaccine in Iran

In this study, we estimated the level of Foot-and-Mouth (FMD) virus infection in a cattle-dense north-western province of Islamic Republic of Iran and analyzed putative risk factors for FMD infection. Calves (6–24 months of age) from all 17 districts of West Azerbaijan were tested for antibodies against non-structural proteins (NSP-Ab) of FMD virus. A proportional stratification with a minimum of 30 epi-units was applied for 3 different husbandry systems: villages, dairy and mixed farms. Within an epi-unit, 30 calves were sampled. For the interpretation of ELISA test results, we used the 50% inhibition (50PI) cut-off as per producer's instructions and created one at 75% inhibition (75PI) based on the lowest point of the histogram of PI results. This approach resulted in three categories of outcomes; negative (N), low-positive (LP) and high-positive (HP). A generalized mixed-effect model for binary outcomes was used for analysing putative risk factors and was run for both cut-off values.A total of 8378 calves from 202 villages, 51 dairy farms and 28 mixed farms were eligible for analysis. The percentage of calves testing positive (LP+HP) was 53.7% (95% Confidence interval (CI): 52.6%–54.8%), with 39.6% (95% CI: 38.6–40.7%) testing HP (n=3309) while 14.1% (95% CI: 13.5–15.0%) of calves tested LP (n=1188). Of 281 epi-units sampled, all calves sampled tested negative in only 2 epi-units (0.7% (95% CI: 0.1–2.5%)) and more than 25 calves tested positive in 29 epi-units (10.3% (95% CI: 7.0–14.5%)). Outcomes of regression modelling using the 50 PI cut-off indicated that, for each month increase in age, the odds of testing positive increased 1.01 times (95% CI: 1.00–1.03). The odds of calves testing NSP-positive increased 1.46 times (95% CI: 1.22–1.77) for calves residing in epi-units that had experienced clinical FMD in the 12 months preceding this study. The odds of calves owned by livestock owners who traded livestock testing positive were 1.4–1.6 times higher than those owned by persons not engaged in trading while the odds for calves testing positive in dairy herds was 1.62 (95% CI: 1.10–2.35) times higher compared with calves in villages. The results of the model using the 75 PI cut-off value resulted in comparable estimates, with the age-effect becoming more evident. These results have confirmed widespread FMD infection and were used in developing a risk-based control strategy on FMD, in line with Stage 1 of the Progressive Control Pathway for FMD (PCP-FMD).

Crossbreeding to increase beef production: Additive and non-additive effects on fitness traits

Fitness is of paramount importance to efficient and profitable beef production. Thus, the objective of this study was to estimate genetic components of fitness traits measured in Afrikaner (A), Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S). For this study, the fitness traits recorded were percentage of cows exposed that were subsequently certified pregnant (PR), percentage of certified pregnant cows that subsequently calved (CR), percentage of calves born that survived to weaning (SV) and the percentage of cows exposed that ultimately weaned a calf (WR). Data were mean performance of straightbred, F1 cross, backcross and three-breed cross females. All crossbred females were of at least 25% A heritage. Breed group means were equated with their genetic expectations assuming recombination effects were nil and the heterosis effects were proportional to the expected heterozygosity in the crosses relative to the purebreds. With the exception of B-sired females from CA cross dams, the genetic model fit the breed group means with a high degree of fidelity. Breed-specific genetic effects tended not to individually exceed the magnitude of their standard errors. However, when the breed-specific genetic effects were combined to predict breed group means, the fitness of crossbred females, on average, exceeded that of their straightbred contemporaries. No particular advantage was noted for adding Brahman to the breed composition of crossbred females with at least 25% Afrikaner heritage. In summary, these data are viewed as being supportive of the use of breed resources in organized crossbreeding systems, such as two- and three-breed rotations that maintain at least 25% Afrikaner germplasm in the breeding females. Keywords : Afrikaner cattle genotypes, heterosis effects, predicted phenotypic values, weaning rate

Evaluation of a protocol to reduce the incidence of neonatal calf diarrhoea on dairy herds

Calf diarrhoea causes substantial economic losses in cattle herds worldwide. Neonatal calves are particularly sensitive to infections with enteropathogens. The present study focused on prevention against the main infectious causes of neonatal calf diarrhoea i.e. Escherichia coli, rota- and coronavirus, and Cryptosporidium parvum. Dairy herds (n=24) with a high percentage of neonatal calves scouring (>10%) were included and calves were sampled for the presence of these four enteropathogens. To decrease diarrhoea problems among neonatal calves, a standard protocol was tested on 13 herds (treatment group) where both C. parvum and either E. coli or rota- or coronavirus were identified as being involved, the other 11 herds served as control group. The protocol consisted of 2 points of action: preventive vaccination of dams against E. coli, rota- and coronavirus, and preventive administration of halofuginone lactate to newborn calves. The average percentage of calves suffering from neonatal diarrhoea (39.7% versus 14.3%, P<0.01) and the average percentage of faecal samples positive for C. parvum (34% versus 11%, P<0.05) differed significantly between control herds and treatment herds after implementation of the protocol. No significant differences between control and treatment group were observed in the percentage of calves excreting E. coli, rotavirus and coronavirus, both before and at the end of the trial. Furthermore, risk factors potentially associated with the development of neonatal calf scours were determined. Non-significant results were obtained for the effect of the protocol on duration of diarrhoea and the effect of the colostral IgG quantity on the risk of diarrhoea. Passive immunity transfer status of the calves, measured both before the onset and at the end of the study, were non-significant between groups.