PSVIII-16 Effect of estrous synchronization with natural service or fixed-timed artificial insemination with conventional or gender-skewed semen in beef females

Reproductive efficiency is critical for profitability, and age at weaning critically impacts weaning weight. The objective was to evaluate estrous synchronization and/or AI with conventional (CON) or gender-skewed (SEXED) semen on calving distribution. Beef females (n=1,620) were either 1) synchronized (7-CIDR:Syn) or not synchronized (Nonsyn) and mated to bulls, 2) synchronized (7-d CIDR) and mated to bulls (SynNS) or artificially inseminated (SynAI), or 3) synchronized (7-d CO-Synch plus CIDR) and AIed with CON or SEXED semen. Calving distribution and gender were determined at birth and were analyzed using the GLIMMIX procedure in SAS. Synchronization resulted in more calves born from d1 to 14 (P < 0.01; 62% vs 47%) of the calving season. There was no differences (P = 0.31) between Syn and Nonsyn in the percent of calves born after d21, but between d22 and 42, more (P = 0.04) calves were born in the Nonsyn group. A greater proportion (P < 0.02; 46% vs 38%) of calves were born in SynNS between d1 and 14 compared to SynAI. There was no difference between treatments (P > 0.12) from d1 to 42, but more calves were born for SynAI after d43. With SEXED semen, there were no differences (P > 0.14) between CON and SEXED for the proportion of calves born from d1 to 14 or d1 to 21; however, more of the desired gender were born in the SEXED group during d1 to 14 of the calving season (P < 0.01; 84% vs 68%). More total calves were born from d22 to 42 in the SEXED group compared to the CON group (P < 0.05; 49% vs 33%). In summary, synchronization increased the proportion of females that calved early in the calving season, and SEXED semen increased the proportion of the desired gender born early in the calving season.

PSXIII-23 Influence of reproductive technologies on post weaning calf performance and carcass characteristics

The experiment objective was to evaluate the impact of assisted reproductive technologies on post weaning calf performance. Calves born following various reproductive treatments (synchronized natural service and synchronized AI) in 10 herds over 2 years were fed to reach a target backfat (BF) of 1.27 cm, sent to harvest, and carcass data collected. Calves were classified into calving groups as natural service born early (NS-Early, n = 189), natural service born late (NS-Late, n = 203), or AI sired born early (AI-Early, n = 116). Data were analyzed using the MIXED procedure in SAS with calving group, year and calf gender in the model. Weaning weights were similar between AI-Early and NS-Early; however, earlier born calves (AI-Early and NS-Early) were heavier (P < 0.0001) than NS-Late. AI-Early calves had heavier finished bodyweight (622.2 kg: P = 0.0024) compared to NS-Early (601.4 kg) and heavier HCW compared to both NS-Early and NS-Late (P < 0.01). NS-Early calves reached 1.27 cm BF in fewer days than AI-Early (261 d and 275 d, respectively; P < 0.01) with NS-late requiring the most days on feed to reach the same endpoint (296 d, P < 0.01). No differences in Quality Grade, Yield Grade, REA, marbling, or BF were detected between AI-Early, NS-Early, and NS-Late, or between early- and late-born calves (P > 0.38). Late-born calves required 29 more days on feed (P < 0.001) to reach 1.27 cm BF resulting in greater final bodyweight compared to early-born calves (625.5 kg and 612.8 kg, respectively; P = 0.04); however, hot carcass weights were similar between early- and late-born calves. Reproductive technologies that increase the number of calves born early in the calving season increased weaning weight and post weaning growth performance, but compared to high quality natural service sires, AI did not improve carcass characteristics.

Vaccination programs, parity, and calving season as factors affecting the risk of fetal losses and mummified fetuses in Holstein cows

Aim of the study: To investigate vaccination programs, parity, and calving season as factors affecting the risk of abortion and mummified fetuses in Holstein cows. Area of study: Hot zone of Northeast Mexico. Material and methods: Multiple logistic regression models were used to examine the relationship between peripartum disorders, parity, previous occurrence of abortion, season of calving, vaccination program, incidence of abortion, and mummified fetuses in Holstein cows. Main results: For 7014 pregnancies (2886 cows), the percentage of cows aborting and having mummified fetuses was 17.7 and 1.1, respectively. As the number of brucellosis vaccinations increased, the incidence of abortion increased (10.4% for a single vaccination and 38.0% for 6 accumulated vaccinations). Abortion for cows having 1-2 previous abortions (56%) and >2 abortions (77%) was fivefold and sevenfold greater (p<0.01), respectively, than that for cows without previous abortion. Other important risk factors for abortion were number of calvings (19.8% for nulliparous and primiparous vs. 13.8% for >3 parturitions; OR=1.7, p<0.01), leptospirosis vaccine application <55 days postpartum (dpp; OR=1.3, p<0.05), viral vaccine application >37 dpp (OR=1.3, p<0.01), brucellosis vaccine application >20 dpp (OR=1.6, p<0.01), and no application of clostridial vaccine (OR=3.7, p<0.01). Significant risk factors for mummified fetuses were application of ≥3 brucellosis vaccinations (OR=3.3, p<0.01), no application of 10-way clostridial vaccine (OR=2.3, p<0.01), >2 previous abortions (OR=18.4, p<0.01), and calving in autumn (OR=0.4, compared to winter, p<0.05). Research highlights: Risk of abortion and mummified fetuses in Holstein cows has been found to be related to vaccination programs.

Prevalence of Potential Indicators of Welfare Status in Young Calves at Meat Processing Premises in New Zealand

In New Zealand, over two million dairy calves between four and seven days of age are sent to meat processing premises every year. There is a need to develop protocols for holistically assessing the welfare of calves sent to slaughter in the first week of life. This study aimed to determine the prevalence of potential animal-based indicators of the welfare state in bobby calves in lairage. The study observed calves in lairage between June and October 2016. Data collection involved assessing groups of calves in pens followed by non-invasive measurements on up to five calves within each pen. We made 23 visits to 12 meat processing premises with group-level observations made on 5910 calves in 102 pens, followed by a non-invasive examination of 504 calves. During the group level observations, none of the calves had their heads tilted or were panting, and coughing and play behaviour were observed in only 1% of pens. In contrast, at least one calf had faecal soiling in all the observed pens, with the percentage of calves affected in each pen ranging from 1% to 48%. In the individual observations, more than 60% of calves had signs of some degree of dehydration, and nearly 40% had some faecal soiling present. In addition, 24% of calves had a respiratory rate over 36 breaths per minute, considered higher than normal. The change in prevalence of some indicators—as time spent in lairage increased or as the calving season progressed—is worth further exploration. Identification of prevalent animal-based indicators facilitates better understanding of the welfare status of young calves in lairage, and these should be incorporated into more holistic calf welfare assessment schemes.

Reproductive Potential of Red Chittagong Cattle in Bangladesh

The study was carried out to investigate the phenotypic and genetic potential of reproductive traits of Red Chittagong Cattle (RCC) of Bangladesh. For that purpose accumulated data on a total of 101 animals from four different herds covering a period from 2005 to 2011 were used for analyses. The overall mean (±SE) values of age at first heat (AFH), age at first conception (AFC), age at first calving (AC), calving rate per productive year (CR), interval to post partum heat (IPPH), days open (DO), calving interval (CI) and generation interval (GI) were 35.9±1.1 month, 42.1±1.3 month, 50.6±1.1 month, 0.87±0.01 month, 149.4±9.5 days, 178.6±11.0 days, 454.9±10.4 days and 4.2±0.1 year, respectively. The factors having significant effects on reproductive traits were herd on DO and CI and calving year on DO. Calving parity and calving season had no significant effect on those traits. The heritability estimates of IPPH, DO and CI were very low (0, 0.06 and 0.09) and that of corresponding repeatability estimates were also low (0.06, 0.08 and 0.09, respectively). The heritability estimates for other traits were moderate (0.39 to 0.50). The results indicated that though reproductive potential of RCC for most of the traits are below than expected, that may be due to their lower inherent capability of indigenous Zebu compared to Taurus, but there is still opportunity of considerable improvement of these traits studied as indicated by their phenotypic variations among population.

Factors affecting neonatal beef calf metabolism and vigor

Two studies were conducted to investigate factors affecting neonatal beef calf metabolism and vigor. In the first study, effects of late gestational nutrient restriction on colostrum yield, neonatal vigor, and blood chemistry and hematology measures were investigated in beef cattle. Colostrum volume and weight from nutrient restricted dams was 40 percent less compared with control dams. Although gestational nutrition did not affect gestation length or calf birth weight, calves born to control dams had faster times to attempt to stand and to stand. Calves born to nutrient restricted dams had greater serum protein metabolites from 6 to 48 h of age. Serum aspartate aminotransferase and creatine kinase concentrations were greater in nutrient restricted calves until 24 h postnatal. Red blood cells, hemoglobin, and hematocrit were greater in control calves at 6 and 12 h of age. In conclusion, calves born to nutrient restricted dams experienced more trauma at birth, reduced neonatal vigor, and had less colostrum available but greater serum protein concentrations. The objectives of the second study were to determine the effect of calving season on perinatal nutrient availability and neonatal vigor. Fall-born calves tended to have lighter birth weight and faster time to stand than spring-born calves. Spring-born calves had greater circulating 0 h glucose, 0 and 6 h NEFA, and 0, 6, 12, and 48 h triglycerides. Fall-born calves had greater sodium and magnesium during the first 48 h postnatal. Spring-born calves had greater aspartate aminotransferase and creatine kinase concentrations until 48 h of age. Albumin, chloride, calcium, and anion gap were greater in fall-born calves. Bicarbonate and direct bilirubin were greater in spring-born calves. In conclusion, spring-born calves are heavier at birth but were slower to stand. Additionally, differences in metabolites over time suggest that spring- and fall-born calves adapt to postnatal life differently where thermoregulation plays an important role.

Genetic and non-genetic factors associated with health and vitality traits in beef calves

Awareness and interest in calf health and wellbeing is intensifying, prompting change in the management and breeding decisions of producers and associated policy-makers. The objectives of the present study were to 1) quantify the risk factors associated with subjectively-measured scores of vigour and birth size as well as diagnoses of scour and pneumonia in a large national dataset of beef calves, and 2) to estimate the contribution of genetic variance to such phenotypic measures. After edits, the data consisted of health and birth size data subjectively scored by producers on 88,207 calves born in 6,126 Irish beef herds. Vigour was recorded on a scale of 1 (very poor) to 5 (very good). Birth size was also scored on a scale of 1 (very small) to 5 (very large). Scour and pneumonia were both scored independently based on the suspected number of occurrence of each (0 = no occurrence, 1 = one occurrence or 2 = more than one occurrence). On average, 14.7% of calves were recorded as having had at least one occurrence of scour within the first 5 months of life, whereas 6.4% of calves were recorded as having had at least one occurrence of pneumonia within the first 5 months of life. Relative to female calves, male calves had a worse vigour score and a suspected greater incidence of both scour and pneumonia. Relative to singletons, twins were, on average, smaller at birth, they had a worse vigour score, and they were more prone to scour. Calves born in the later periods of the calving season (i.e., late and very late) had a greater incidence of scour relative to calves in the herd born earlier in the calving season. Heritability estimates for vigour, birth size and pneumonia were 0.12 (0.02), 0.33 (0.03) and 0.08 (0.02), respectively; no genetic variance was detected for scour. Breeding for vigorous calves that are less susceptible to pneumonia could provide producers with an additional strategy to ensure consumer concerns regarding food quality, safety and calf wellbeing are being met.

24 Effects of Spring versus Fall Calving on Fetal Growth, Vigor at Birth, and Neonatal Circulating Metabolites in Beef Calves

To determine the effect of season on perinatal nutrient availability, assessed through fetal growth, calf vigor, and neonatal circulating metabolites, multiparous and primiparous dams (age: 4.7 ± 2.4 yr; BCS: 5.3 ± 0.6) from 4 spring (2014–2017; n = 202) and 4 fall (2015, 2017–2019; n = 177) calving experiments were observed during parturition. Time to stand (spring: 67; fall: 104) was determined as minutes from birth to standing for 5 sec. After birth, calf BW and size (spring: 99; fall: 169; length, heart girth, abdominal girth, and cannon circumference) were recorded. Jugular blood samples were obtained from 63 spring and 89 fall calves at 0 (pre-suckling), 6, 12, 24, and 48 h postnatally. Data were analyzed either with the fixed effect of season (single point) or the fixed effects of season, hour, and their interaction with hour as a repeated effect (over time); calf sex was included when P &lt; 0.25. Experiment was a random effect. Fall-born calves tended to have lighter (P = 0.09) BW and faster (P = 0.05) time to stand than spring-born calves. Season did not affect (P ≥ 0.18) other calf size measures. The season x hour interaction (P ≤ 0.07) affected circulating glucose, non-esterified fatty acids (NEFA), triglycerides, urea nitrogen, globulin, and total protein. Spring-born calves had greater (P ≤ 0.009) 0 h glucose, 0 and 6 h NEFA, and 0, 6, 12, and 48 h triglycerides than fall-born calves. Fall-born calves had greater (P = 0.03) total protein at 24 h and tended to have greater (P ≤ 0.10) total protein and urea nitrogen at 48 h and globulin at 24 h. Season affected albumin, which was greater (P = 0.003) in fall-born calves. These data suggest that calving season influences perinatal nutrient availability, which may impact the transition to postnatal life.

Effects of Melatonin Supplementation During Mid- to Late-gestation Nutrient Restriction on Maternal and Fetal Amino Acid Concentrations

Nutrient restriction during mid- to late-gestation compromises pregnancy, alters maternal metabolism, and afflicts fetal growth and development. The objective of this study was to determine if dietary melatonin supplementation in global nutrient-restricted cows alters fetal-maternal circulating amino acids. In a 2x2 factorial, Brangus heifers of two calving seasons, spring (n = 29) and fall (n = 25) were fed a total mixed ration at either 100% (adequate; ADQ) or 60% (nutrient restricted; RES) of nutritional requirements based on NRC guidelines and were either supplemented with dietary melatonin (MEL; 20 mg/d) or no supplemented control (CON) from d 160 to d 240 of gestation. Heifers were supplemented and fed at 0900 h daily. Maternal blood, fetal blood, and amniotic fluid were collected at Cesarean section on d 240 of gestation in either the morning (AM; 0500 h) or afternoon (PM; 1330 h). Plasma and amniotic fluid AA were determined by a gas chromatography - mass spectrometry method with internal standard calibration using authentic amino acid standards. Total AA concentrations (mM) were calculated and the total fetal AA concentration was subtracted from the total maternal AA concentration to calculate maternal-fetal differences. Data were analyzed separately by calving season, using the MIXED procedure of SAS 9.4 to determine the effects of nutritional plane, melatonin supplementation, time of day, and their interaction on AA concentrations. Spring fetal-maternal AA differences were less (321±194 vs. 935±190 vs. 1,135±194 vs. 1,352±212 mM, respectively; P &lt; 0.05) in RES-CON than in RES-MEL, ADQ-MEL, and ADQ-CON groups. Fall fetal-maternal AA differences did not differ (P &gt; 0.05). Spring amniotic fluid AA concentrations were less (919±208 vs. 1,416±212 vs. 1,174±213 mM, respectively; P &lt; 0.01) in RES-MEL heifers than in ADQ-MEL and RES-CON groups. Fall amniotic fluid AA concentrations were less (1,132±258 vs. 2,877±308 mM, respectively; P &lt; 0.05) in all groups compared with ADQ-CON-AM. These findings demonstrate nutrient restriction during mid- to late-gestation alters circulating maternal AA concentrations, affecting fetal AA concentrations.

Timing of Protein/energy Supplementation in Late Gestating Bos Indicus-influenced Beef Cows Influences Postnatal Growth, Immunity and Carcass Characteristics of Their Offspring

This 2-yr study investigated the timing of dried distillers grains (DDG) supplementation of Bos indicus-influenced cows during late gestation and its impacts on offspring performance. On d 0, 84 Brangus cows/yr were stratified by BW (482 ± 75 kg) and BCS (5.3 ± 0.8) and randomly assigned to bahiagrass pastures (14 cows/pasture). Treatments were randomly assigned to pastures (2 pastures/treatment/yr) and consisted of no prepartum supplementation (CON), 2 kg/d of DDG from d 0 to 42 (LATE42), or 1 kg/d of DDG from d 0 to 84 (LATE84). At weaning (d 347), 38 steers/yr were vaccinated against bovine respiratory disease, transported for 720 mi to the feedlot, penned according to prepartum pasture distribution, and fed the same corn silage-based diet until harvest. Data were analyzed using SAS GLIMMIX procedure. Cow BCS at calving was greater (P ≤ 0.05) for LATE84 and LATE42 vs. CON cows and did not differ (P = 0.16) between LATE84 and LATE 42 cows. Cows offered LATE42 supplementation had greater (P ≤ 0.05) calving percentage from wk 2 to 6 of the subsequent calving season than CON and LATE84 cows. Calf BW at weaning was greater (P ≤ 0.05) for LATE 84 vs. LATE42 calves, and the latter greater than CON calves (269, 261, and 255 ± 2.6 kg, respectively). Seroconversion against parainfluenza-3 virus at weaning was greater (P ≤ 0.05) for LATE42 vs. CON steers, with LATE84 being intermediate. Feedlot BW and carcass weight did not differ (P ≥ 0.36) among treatments, but marbling scores and carcasses grading choice tended (P ≤ 0.10) to be greater for LATE42 vs. CON steers, with LATE84 being intermediate. Therefore, timing of DDG supplementation during late gestation in Bos indicus-influenced cows enhanced calf weaning weight, humoral immunity, and carcass characteristics at different magnitudes than cohorts born from non-supplemented cows.