Calf Weight Research Articles

Longitudinal genetic dynamics of weaning index and implications for cow-calf production efficiency

In beef cattle, the selection for higher weights at young ages has been questioned with the argument that this criterion may increase the adult weight of cows, resulting in higher costs. Therefore, selection criteria should be employed to increase weights at young ages with minimal impact on the adult weight of cows. Additionally, the relationship between measures of cow production efficiency and other well-established selection criteria in breeding programs remains poorly understood. The objective of this study was to longitudinally evaluate the relationship between the weaning index (WIndex) as a measure of efficiency and growth traits of the cows. Possible changes over time in WIndex due to selection applied for yearling weight (YW) were also investigated. The WIndex was proposed to maximize genetic response in the weaning weight of the calf while maintaining genetic gain in BW of the cow at zero. A random regression model was adopted to estimate correlations between WIndex, BW, hip height (HH), and body condition score (BCS) using records of Nelore cows from three lines. Genetic trends were calculated for the control line (NeC) and lines selected for greater YW (NeS and NeT). The age of 3 years was the most critical for the weaning efficiency of the cows. At this stage, young cows are still growing and wean lighter calves than their adult counterparts. The genetic correlation estimates between WIndex and BW (−0.58 to 0.04), HH (−0.05 to −0.34), and BCS (−0.51 to −0.17) were close to zero or negative. BW and HH were strongly correlated genetically across all ages (0.73–0.76). In general, HH exhibited a weak and negative genetic relationship with BCS. The genetic correlation between BW and BCS was stronger for advanced ages (0.45–0.68). In lines selected for YW, important increases in WIndex were observed. However, NeS has been selected since the 1980s until the present for YW, and thus, it showed a more pronounced trend of increasing BW and, consequently, a more modest trend of increasing WIndex compared to NeT. In contrast, WIndex exhibited a trend close to zero for NeC. In this context, monitoring HH and BCS can be useful to avoid losses in the weaning efficiency of cows. Furthermore, we suggest that one way to mitigate efficiency losses in calf production could involve stabilizing the BW of cows and increasing the weaning weight of calves using the WIndex.

Glucose Regulates Glucose Transport and Metabolism via mTOR Signaling Pathway in Bovine Placental Trophoblast Cells.

It has been confirmed that improving the energy level of the diet contributed to the greater reproductive performance and birth weight of calves in periparturient dairy cows. To investigate the effect of glucose on nutrient transport during fetal development, the bovine placental trophoblast cells (BPTCs) were cultured in media with different glucose concentrations (1, 2, 4, 8, or 16 mg/mL). Subsequently, the BPTCs were cultured in media with 1, 8 mg/mL glucose and 8 mg/mL glucose plus 100 nmol/L rapamycin (the inhibitor of mTOR pathway). Compared with the 1 mg/mL glucose, the addition of 8 mg/mL glucose stimulated cell proliferation, upregulated the mRNA abundance of the glucose transporter GLUT1 and GLUT4, and increased the activity of glucose metabolism-related enzyme glucose-6-phosphate dehydrogenease (G6PD), lactate dehydrogenase (LDHA) and phosphoglycerate kinase 1 (PGK1), as well as adenosine-triphosphate (ATP) content (p < 0.05).Furthermore, compared with the treatment of 1 mg/mL glucose, adding 8 mg/mL of glucose-upregulated gene expression in the mTOR signaling pathway, including phosphatidylinositol3-kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR) and 70 kDa ribosomal protein S6 kinase 2 (P70S6K) (p < 0.05).The supplementation of rapamycin downregulated the gene and protein expression of the mTOR signaling pathway, including mTOR, P70S6K, EIF4E-binding protein 1 (4EBP1), hypoxia-inducible factor 1-alpha (HIF-1α) and gene expression of glucose transporter upregulated by 8 mg/mL glucose (p < 0.05). Thus, these results indicated that the addition of 8 mg/mL glucose regulated the glucose transport and metabolism in BPTCs through the mTOR signaling pathway, thereby promoting the supply of nutrients to fetus.

Growth rate dependence on micronutrient provision in replacement heifers during the intrauterine period

According to the developmental origins of health and disease (DoHaD) hypothesis, the conditions during intrauterine development have a long-term effect on postnatal growth and animal health. This study aimed to determine the relationship between fetal micronutrient provision in the last three months of intrauterine development and growth intensity indicators in the first 180 days after birth. This study focused on 40 clinically healthy Simmental heifers. Samples of non-pigmented tail hair were collected from newborns before their first colostrum feeding. The micronutrient content (selenium, copper, zinc, manganese, cobalt, iron, chromium, and molybdenum) was analyzed using inductively coupled plasma mass spectrometry (Nexion 300D, Perkin Elmer, USA). Calf weight was measured on the first day of life and at 180 days, and average daily weight gain was calculated. The relationships between the variables were analyzed using Spearman’s rank correlation coefficient in IBM SPSS Statistics 20.0 (IBM Corp., USA). No significant correlations were found between the weights of the newborn calves and the micronutrient content in their hair samples. However, at 180 days of age, calf weight and average daily weight gain (in the first 180 days of life) correlated with the selenium (r = 0.349 and r = 0.408, p &lt; 0.05, respectively), copper (r = 0.378 and r = 0.440, p &lt; 0.01, respectively), zinc (r = 0.455 and r = 0.481, p &lt; 0.01, respectively), and cobalt (r = 0.304 and r = 0.344, p &lt; 0.05, respectively) contents in the hair samples of newborns. No correlations were found for manganese, iron, chromium, and molybdenum.

Genome-Wide Association Analysis Identifies the PMEL Gene Affecting Coat Color and Birth Weight in Simmental × Holstein.

Coat color and birth weight, as easily selected traits in cattle, play important roles in cattle breeding. Therefore, we carried out a genome-wide association study on birth weight and coat color to identify loci or potential linkage regions in 233 Simmental × Holstein crossbred beef cattle. The results revealed that nine SNPs were significantly associated with coat color (rs137169378, rs110022687, rs136002689, Hypotrichosis_PMel17, PMEL_1, rs134930689, rs383170073, rs109924971, and rs109146332), and these were in RNF41, ZC3H10, ERBB3, PMEL, and OR10A7 on BTA5. Interestingly, rs137169378, rs110022687, rs136002689, Hypotrichosis_PMel17, and PMEL_1 showed strong linkage disequilibrium (r2 > 0.8) and were significantly associated with coat color. Notably, Hypotrichosis_PMel17 and PMEL_1 were located in the gene PMEL (p = 2.22 × 10-18). Among the five significant SNPs associated with coat color, the birth weight of heterozygous individuals (AB) was greater than that of homozygous individuals (AA). Notably, the birth weight of heterozygous individuals with Hypotrichosis_PMel17 and PMEL_1 genotypes was significantly greater than that of homozygous individuals (0.01 < p < 0.05). Interestingly, the two loci were homozygous in black/white individuals and heterozygous in gray/white individuals, and the birth weight of heterozygous brown/white individuals (43.82 ± 5.25 kg) was greater than that of homozygous individuals (42.58 ± 3.09 kg). The birth weight of calves with the parental color (41.95 ± 3.53 kg) was significantly lower than that of calves with a non-parental color (43.54 ± 4.78 kg) (p < 0.05), and the birth weight of gray/white individuals (49.40 ± 7.11 kg) was the highest. Overall, PMEL appears to be a candidate gene affecting coat color in cattle, and coat color may have a selective effect on birth weight. This study provides a foundation for the breeding of beef cattle through GWAS for coat color and birth weight.

BADANIA PORÓWNAWCZE UŻYTKOWOŚCI ROZPŁODOWEJ I MIĘSNEJ LOKALNEJ RASY BYDŁA POLSKIEGO CZERWONEGO Z RASĄ LIMOUSIN POCHODZENIA POLSKIEGO I FRANCUSKIEGO

The aim of the study was to compare of the reproductive and meat performance of meat breeds, such as the local Polish Red cattle and the Limousine cattle breed, which is dominant in Poland. The examined individuals of the Limousine breed, which were divided into two groups depending on the origin of the parents, the so-called Polish and French. The criterion for assigning the animals to the group of Polish origin was that the tested bulls did not have in their pedigree a descendant of the French line for two generations. Three groups of fatteners with 138 Polish Red bulls and 447 French and 478 Polish Limousin bulls were used to assess meat performance. All animals were kept in an extensive production system, using the pasture at will throughout the year, during the so-called peak season. At the end, they were fed additionally with haylage and concentrated feed. Reproductive parameters (type of calving and viability of calves) were assessed in 348 Polish Limousin cows, 367 French cows and 289 Polish Red cows. Calves were observed and measured throughout their life cycle from birth to slaughter. In the as- sessment of the utility value of meat, reference features were taken into account, e.g. body weight after calving, body weight at 210 and 420 days of age and gains, height at withers and chest circumference, and conformation assessment. The PRC group showed significantly greater ease of calving and vitality of calves compared to both groups of limousines. Calf and adult body weight measurements at 210 and 420 days were significantly higher in French Limousine cattle. Differences in body weight and gain were significant. There was a slight difference in height between Polish and French bulls. Native breed cattle were characterized by very good reproductive parameters and satisfactory meat performance charac- teristics in relation to the use of grassland fodder. Beef producers can be successfully recommended to use Polish Red cattle for meat purposes in an extensive production system.

Adapting cattle farming to climate change in the dry and sub-humid tropical zones in Benin: how adaptation strategies affect productivity

Cattle farmers are developing adaptation strategies to deal with the effects of climate change. Understanding how adaptation affects livestock productivity is, therefore, essential in order to identify and prioritize the optimal strategies. Yet, few studies have addressed this issue. This study aims to fill the gap, by assessing how the adaptation strategies developed by cattle farmers in Benin affect livestock productivity. We conducted surveys with 360 cattle farmers and monitored 30 farms in Benin’s dry and sub humid tropical zones. We collected data on the socio demographic characteristics of cattle farmers, their adaptation strategies and herd productivity. We carried out a multiple correspondence analysis, followed by an ascending hierarchical classification to establish the typology of the cattle farmers’ adaptation strategies. We tested data on livestock productivity using an analysis of variance with the generalized linear model procedure of R.3.5.1. software. The results revealed three groups of adaptation strategies: integrating livestock with crop production; use of supplemental feeding and fodder crops; pastoral mobility. The choice of strategy significantly affected livestock productivity. Animal mortality rates were lower on farms that adopted supplemental feeding (2.7%), and integrated crop/livestock systems (3.3%), compared to farms with pastoral mobility (5.2%). Supplementary feeding improved calf weights at birth and at 6 months and increased daily milk offtake. Based on the results obtained, we recommend that farmers adopt supplemental feeding and integrated crop/livestock strategies in the study zones to improve herd productivity.

Biometric Characteristics of Live Weight in Reindeer Populations of the Eastern Arctic and Subarctic

Purpose: the study of biometric data on live weight and their significance for artificial selection in the population of the northern deer (Rangifertarandus L.) ..Materials and methods. Information was used from annual reports of reindeer herding of the North of the Far East. The methods of variation statistics that are generally accepted in zootechnical research were applied. Extreme (LIM) and average values (M) of the sign, trust boundaries of the general average (M ± t ∙ m), the average square deviation (σ), the coefficient of variation (CV), the boundaries of the extreme class variation (M ± 2σ) are determined. Associations of a live mass of sexual age groups in the population of the northern deer were established by calculating the correlation coefficients (R) and rectilinear regression (B).Results. The consolidated correlation coefficient (RSV), reflecting the level of direct linear connection of the live weight of calves with a mass of uterus and manufacturers, was ≈ 0.7, which relates to the degree of close dependence. Using the regression equation (y = a+bx) calculated the predicted average size of the live weight of young animals in the average live weight of the importance. The data allow you to establish the threshold of selection of tribal animals in order to obtain offspring with a given value of the sign. In the study, the impact on the live mass of the season, year, range, and farms is leveled. It was established that throughout the generations a living mass is a stable phenotypic sign. Biometric data on live weight, as a quantitative attitude, indirectly reflect the state and movement of group genetic information in the populations of deer of the Far North-East of Russia.

Reproductive performance of Belgian Blue and Wagyu cross cows

Abstract. Tampubolon YK, Agus A, Hartatik T, Bintara S, Ismaya, Widyobroto BP, Budisatria IGS, Leroy P, Antoine-Moussiaux N, Panjono. 2023. Reproductive performance of Belgian Blue and Wagyu cross cows. Biodiversitas 24: 5352-5358. Double-Muscle (DM) cattle have been used in cattle breeding programs to increase body weight. This research aims to determine the reproductive performance of using DM cattle. Currently, cattle are produced from a cross between two breeds, namely Belgian Blue (BB) cross (50% BB, 50% BX) and Wagyu cross (50% Wagyu, 50% BX). Natural mating was carried out on nine BB cross cows mated with Wagyu cross bulls and nine Wagyu cross cows bred with BB cross cows. After calving, the cows were raised together with their calves for six months prior to weaning. The collected data were analyzed using One-Way analysis of variance. Calving Interval (CI), Cow Reproductivity Index (CRI), calf weaning weight, and Cow Productivity Index (CPI) of BB and Wagyu cross cows were 426.00±24.92 and 411.55±37.52 days, 0.86±0.05 and 0.89±0.08 head/year, 175.53±24.50 and 121.19±19.80 kg, and 148.46±24.61 and 102.41±20.84 kg/year, respectively. There was no significant difference in the CI and CRI between crosses. However, the weaning weight of BB cross calves was higher (p&lt;0.05) than that of Wagyu cross calves, whereas the CPI of BB cross cows was higher (p&lt;0.01) than that of Wagyu cross cows. It was concluded that the best reproductive performance was the BB cross, which had DM blood.

176 Relationships Among Early Life Weight and Growth Among Halfblood Bos Indicus Male Calves and Associations with Carcass Weight

Abstract Nellore-Angus steers (n = 572) born in 2009-2013, 2015, and 2019 and Brahman-Angus reciprocal steers (n = 73) born in 2019 and 2020 were evaluated for calf and carcass weights (HCW). Calves were born and reared at the McGregor Research Center and included F2, F3, F4, and F5 Nellore-Angus and F1 Brahman-Angus. Calves were weighed at 4 approximate times: within 48 h of birth (BWT), 50 d age (spring-working, SWWT, not available for 2009-2010), 180 d age (pre-weaning, PRWWT), and approximately 210 d age (weaning, WWT). Animals born in the same year were managed similarly, and cow herds were managed together in most cases except during annual natural service, multi-sire breeding seasons. Animals born in the same year were managed as contemporaries post-weaning and for feedlot finishing. Mixed model analyses of variance for calf traits included genetic type (nested within calf birth year), calf birth year, age of dam category, and covariates of Julian birth date (BWT, SWWT) or calf age (PRWWT and WWT) as fixed effects. In each year at least 2 genetic types were present; however, because of imbalance across years, only genetic types produced in the same years were compared following significant F-tests. For these analyses cow age category did not affect calf BWT or SWWT, but showed influence for PRWWT (P = 0.006) and WWT (P &amp;lt; 0.001); cow age category did not affect calf ADG. Differences in calf weights (P &amp;lt; 0.001) and calf ADG (P &amp;lt; 0.001) due to the genetic type were driven by reciprocal differences between Brahman-Angus crosses and potential maternal hybrid vigor advantages for F2 Nellore-Angus calves from F1 dams vs. other genetic types. Brahman-sired F1 (B × A) males were 12.7 to 14.1 kg heavier for BWT (P &amp;lt; 0.001) and 14.9 to 19.2 kg heavier for SWWT (P &amp;lt; 0.001) than Angus-sired F1 males (A × B), but persistence to weaning varied across years. It appears in these data that some genetic types may be more sensitive to individual year effects, but it is uncertain why. Correlations of calf weight traits with HCW were inconsistent across genetic types. No calf weight was associated with HCW in A × B crosses, and only PRWWT in B × A related to HCW (r = 0.44, P = 0.007). Among Nellore-Angus crosses, BWT showed small to moderate correlation to HCW (0.23 &amp;lt; r &amp;lt; 0.46); however, among the F4 and F5 calves, later weights (SSWT, PRWWT and WWT) had large correlations with HCW (0.50 &amp;lt; r &amp;lt; 0.79) whereas these correlations ranged from 0.24 to 0.37 in F2 and F3 steers. It appears animals of similar Bos indicus percentage may have quite different calf growth patterns related to HCW.

357 The Influence of Supplemental Protein Levels on Beef Cattle Grazing Winter Foothill Rangelands: Cow and Subsequent Calf Performance

Abstract Angus based bred cows [n = 150; initial shrunk body weight (BW) = 615 ± 6.61 kg; initial body condition score (BCS) = 5.2] were used in an 84-d winter grazing experiment that took place over two consecutive years. Cattle were stratified by age and body condition and, within stratum, randomly assigned to one of three protein supplementation treatments: 1) no supplement, 2) cows fed 0.20% BW· d-1 of a 30% protein supplement, and 3) cows fed 0.40% BW · d-1 of a 30% protein supplement. Protein supplement was a 30% CP canola-based pelleted supplement with 9 units protein from urea. Cows were gathered three-times weekly and provided supplement on a replicated pen basis. Performance data were analyzed as a completely randomized design with linear and quadratic contrasts used for mean separation (reps = 5; n = 7). Body weights and BCS were recorded every 28-d period throughout the study and calf BW were obtained at birth and weaning. A treatment × period interaction was detected for body weight change (P &amp;lt; 0.01) where a linear response (P &amp;lt; 0.01) where increasing protein status resulted in modest weight gains relative to the control treatment. BCS also exhibited a linear response for two of the three weight periods (P &amp;lt; 0.01) where level of BCS lost was least in cows with the higher supplemental protein levels. A year × period interaction was detected where cows from year two exhibited less BW change on days 28, 56, and 84 of the study (P &amp;lt; 0.01) and had greater BCS (P &amp;lt; 0.01) than those from year one during these periods. In addition, we observed a treatment × year interaction where cows from year two experienced less BW change and had greater BCS than cows from year one (P &amp;lt; 0.01). No treatment × year interactions were detected for birth weight, average daily gain (ADG), or adjusted 205-d weight in calves. A tendency was noted for cows offered 0.4% BW· d-1 supplement to have heavier calves at birth than their counterparts (P = 0.09) over both years. A year effect was detected where calves born in year two had increased ADG and adjusted 205-d weights compared with those from year one. A tendency (P = 0.09) for the calves in year two of the study to have heavier weights at birth compared with those from year one was also noted. In summary, increasing levels of supplemental protein resulted in linear improvements of BW and BCS of grazing beef cattle during the winter. While birth weights of calves tended to differ due to the gestational nutrition of the dam, calf growth and weaning weights were not affected.

171 Supplementing Ca Salts of Soybean Oil Via Low-Moisture Molasses-Based Blocks to Improve Reproductive Performance and Overall Productivity of Beef Cows

Abstract This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckling multiparous Angus-influenced cows (n = 554) were assigned to a fixed-time artificial insemination (AI) protocol (day -10 to 0) followed by natural service (day 15 to 70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25% (as-fed basis) of CSSO or ground corn (CON) from day -10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Groups were enrolled in an estrus-synchronization + fixed-time AI protocol from day -10 to 0 (AI occurred on day 0) of the experiment and beginning 15 days after AI cows were exposed to mature Angus bulls for 55 d. Pregnancy status was verified on day 55 and 100 of the experiment, and cows that gave birth during the initial two weeks were considered pregnant to fixed-time AI. Calf birthdate and weight was recorded during the subsequent breeding season. All calves were weaned at the same time, and a calf BW and age were recorded. Blood samples were also collected from a subsample of cows on days -10, 0 (fixed-time AI), and 55 (pregnancy diagnosis). All data were analyzed using group as the experimental unit and Satterthwaite approximation to determine the denominator df for the tests of fixed effects. Quantitative data were analyzed with the MIXED procedure of SAS, and binary data analyzed with the GLIMMIX procedure of SAS with a binomial distribution and logit link function. Data were analyzed with group (treatment × location), cow(group), and location as random variables. Significance was set at P ≤ 0.05 and tendencies were determined if P &amp;gt; 0.05 and ≤ 0.10. Cows receiving CSSO had greater (P &amp;lt; 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3%), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04%), which also calved earlier during the calving season (treatment × week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4%), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle.

361 The Effects of Feeding Sprouted Barley on Cow Calf Pairs Health and Performance

Abstract Currently the world population is growing exponentially, which increases the demand to produce high-quality protein. Changes in weather patterns, such as drought, and decreased land resources due to urbanization, increase the strain on the agriculture sector to meet world demands. An alternative method to remedy these issues and still produce high quality livestock feed is through controlled environment vertical farming systems. Sprouted grains are one feed these systems can produce. However, there is little information on the effects of feeding sprouted grains to cattle. Angus cows with a steer calf were fed either feeder quality alfalfa (n =10 pairs) or the same alfalfa and sprouted barley (12.5% DM; n = 10 pairs) for 90 days. On days 0 and 90, body weight, milk, rumen fluid and BCS were collected from cows and hip height and weight were recorded for calves. On day 10, weight was recorded for cows and calves and rumen fluid and milk were obtained from cows. On day 45, rumen fluid and milk were collected from cows. On day 55, body weights were collected for both cows and calves and milk from cows. Intake was recorded throughout the trial via bunks with Vytelle technology. PROC MIXED procedure of SAS was used to analyze all data with day as a repeated measure to determine the main effect of treatment. Individual volatile fatty acids (VFA) were measured as a percent of total VFA present. No differences (P ≥ 0.16) were observed in calf weight, hip height, milk protein, fat, lactose, calf DM intake, or cow DM intake. Cows fed barley sprouts tended (P = 0.08) to have a decreased somatic cell count compared with alfalfa fed cows. There was a treatmentxday effect (P = 0.004) for isobutyrate, such that the treatment and control decreased over time, but the control remained consistent the last 45 days. A treatmentxday effect (P = 0.02) was also observed for butyrate indicating that both remained consistent over the first 45 days and then treatment increased over the last 45 days. Additionally, treatmentxday effect (P = 0.001) for rumen pH demonstrated that both groups stayed consistent until day 45 and then treatment pH decreased the last 45 days. There was a day affect for total VFA (P = 0.0009), acetate:propionate (P &amp;lt; 0.0001), acetate (P &amp;lt; 0.0001), and propionate (P &amp;lt; 0.0001) demonstrating that total VFA and acetate increased throughout the duration of the trial and acetate:propionate and propionate decreased throughout the trial, while the acetate:propionate ratio increased (P &amp;lt; 0.0001) the duration of the trial. Cows receiving sprouted barley produced more (P = 0.02) capronate than control. These results indicate that sprouted barley can be an alternative feed at this stage in production without having a negative impact on health or production but does change the rumen pH and proportion of some VFA.

PSVI-23 Effects of Creep-Feeding Supplementation on Growth Performance of Nellore Calves and Milk Yield of Dams

Abstract The study aimed to evaluate the effect of creep-feeding on growth performance of beef calves and milk yield of dams, during nursing phase. The experiment lasted 170 days, from December/2021 to May/2022, the calves were born in September/2021 and creep-feeding supplementation started from approximately 70 days of life until weaning. The experimental design used was a randomized block [blocked by body weight (BW) of calves]. The experimental units were the paddocks (8 units per treatment, and ten replicates per paddock), totalling 156 pairs cow/calf (86 pairs of male calves and 70 pairs of female calves). The treatments consisted of creep-feeding or not creep-feeding the calves: control treatment (CONT; mineral supplement ad libitum) and creep-feeding treatment (CREEP; energetic protein supplement; 5 g/kg of BW· animal-1· /day-1). There was mineral supplement ad libitum for all the dams. The pairs cow/calf were kept in an area of Urochloa brizantha cv. Marandu. The data were analyzed using the SAS PROC MIXED. Male calves subjected to CONT showed less BW (-15 kg) at weaning and decreased average daily gain (ADG; -100g/day) until weaning (P &amp;lt; 0.01; Figure 1), while female calves showed no difference in BW and ADG (P &amp;gt; 0.12; Figure 2). The dams did not show difference in milk yield until weaning (P &amp;gt; 0.27) for male and female calves (Figure 3). This difference in results related to gender is explained by the fact that there are differences in the performance of males and females, mainly due to hormonal issues. Usually, females are born lighter than males and tend to have decreased performance throughout the whole production cycle. For milk yield and performance of dams, our results agree with what is found in the literature. There are some studies which also evaluated milk production of dams when the offspring were creep-fed, and found similar milk yield for those whose offspring received supplement in relation to those who did not receive it. This is likely because calves prefer milk, supplement, and forage, in that order, so it seems unlikely that calves would replace milk with supplements. And these results show us that the difference in the BW at weaning of males was caused by the creep-feeding supplementation.

PSV-16 Different Late Gestation Heat Stress Time-Windows and Their Effects on Newborn Holstein Calves from Northwest México

Abstract Exposure to heat stress (HS) during the dry period not only exerts negative effects on the welfare of pregnant cows, but also impairs the development of the fetus in the utero. When dams are subjected to late-gestation HS, affectations to their placental function and blood placental flow occur, generating fetal hypoxia and growth retardation of their calves. Since on the last 60 d of gestation bovine fetuses undergo through a phase of accelerated growth where they accrue around 60% of their birth weight, the number of days that their dams become exposed to HS during this period could affect differently their body weight and oxygenation status at birth. Therefore, the objective of this study was to determine the effects of different late-gestation HS time-windows on the birth weight and oxygen saturation of newborn Holstein calves. The study was conducted at the Yaqui valley in northwest México, a semiarid zone where the temperature and humidity index (THI) exceeds the dairy cattle thermal threshold from mid-March to mid-October (~7 months). Under such environmental dynamic, all cows within this geographical zone experience HS at some point during their gestation; nonetheless, depending on the conception date of the cow, different late-gestation HS time-windows arise. To assess the influence of the number of days of intrauterine HS exposure during late gestation (e.g., days with an average THI &amp;gt; 72 units), three intrauterine heat-stressed groups of calves were formed: G1 = calves born to dams exposed to HS less than 20 d within the last 60 d of gestation (n = 30), G2 = calves born to dams exposed to HS between 21 and 40 d within the last 60 d of gestation (n = 20), and G3 = calves born to dams exposed to HS for more than 40 d within the last 60 d of gestation (n = 16). Upon calving, variables such as sex, birth weight (BW, kg) and oxygen saturation (SpO2, %) were recorded. A general linear model that included the effects of sex of the calf and intrauterine HS calves’ group was implemented to analyze BW and SpO2. Harmonic means were compared via the Tukey-Kramer test. Harmonic means (±SE) for BW and SpO2 among groups were 42.42 ± 0.92, 40.84 ± 1.11, and 34.73 ± 1.24 kg, and 78.16 ± 2.71, 82.52 ± 3.28, and 82.29 ± 3.68 %, for G1, G2 and G3, respectively. Significant differences (P &amp;lt; 0.001) were found only for BW, with calves of G3 exhibiting the lowest BW in comparison to calves within G1 and G2, which were not statistically different among themselves (P &amp;gt; 0.05). Results of this study indicated that intrauterine HS exposures of &amp;gt;40 d strive deleterious effects on fetal growth and reduce the BW of newborn Holstein calves from northwest México.

PSVI-22 Effect of Creep-Feeding on Feeding Behavior of Nellore Calves

Abstract The study aimed to evaluate the effect of creep-feeding on feeding behavior of beef calves, during nursing phase. The experiment lasted 170 days; from December/2021 to May/2022, the calves were born in September/2021 and creep-feeding supplementation started from approximately 70 days of life until weaning. The feeding behavior was evaluated twice on d 70 and d 120 post creep-feeding). The experimental design used was a randomized block [blocked by body weight (BW) of calves]. The experimental units were the paddocks (8 units per treatment, ten replicates per paddock), totalling 156 pairs cow/calf (86 pairs of male calves and 70 pairs of female calves). Two paddocks per treatment and 8 pairs per paddock were sorted for behavior analysis, totalling 32 pairs cow/calf (16 pairs of male calves and 16 pairs of female calves). The treatments consisted of creep-feeding or not creep-feeding the calves: control treatment (CONT; mineral suppement ad libitum) and creep-feeding treatment (CREEP; energetic protein supplement; 5 g/kg of BW· animal-1· /day-1). There was mineral supplement ad libitum for all the dams. The pairs cow/calf were kept in an area composed of Urochloa brizantha cv. Marandu. and idleness, suckling, grazing and creep-feeding or mineral supplementation were evaluated. The data were analyzed using the SAS PROC MIXED. There was no difference in feeding behavior of calves at 70 days of creep-feeding for idleness (P = 0.80), grazing (P = 0.59) and suckling (P = 0.30; Figure 1). Creep-feeding calves spent 14 minutes longer on supplementation than non-creep-feeding calves (P &amp;lt; 0.01). At 120 days of creep-feeding (180 days of age), calves that received creep feeding supplementation spent less time grazing (difference of 67 min; P &amp;lt; 0.01), more time on supplementation (+28 min; P &amp;lt; 0.01) and idleness (+42 min; P = 0.05) and similar time on suckling (P = 0.76; Figure 2).There was no difference in any of the variables at different times (P &amp;gt;0.08) for the dams (Figure 3). Animals in creep-feeding spend less time grazing but suckling in a similar amount of time compared with those that consumed only mineral supplement, which corroborates with the results on milk yield of dams, which were similar for both treatments.

PSI-7 Vitamin a and D Pre-Exposure to Prime Reproductive Success in Breeding Beef Cows

Abstract Vitamins A and D are important for immunity, reproduction, and overall health. The need for supplementation is often overlooked in beef cattle production because it is assumed that beef cows receive adequate amounts of these micronutrients from their environment. However, there is an increasing incidence of vitamin A and D deficiencies in beef cattle due to challenges of environment, forage access and quality. It is well known that nutrition has a major effect on reproduction, but direct effects of vitamins A and D on beef cow reproduction and fertility are understudied. We previously reported increased rates of fertilization after co-culture of bovine embryos with vitamin A and D in vitro. The objective of this study is to determine how vitamin A and D supplementation in mid- to late gestation affects calving ease and birth weights of calves at parturition, as well as cow fertility at the following breeding. Angus and Angus crossbred females (Bos taurus) of first (n = 20) or second (n = 10) parity were selected based on pregnancy status and gestational age and then randomly assigned to treatment groups. Starting in October 2021, pregnant cows were injected monthly with either a vehicle (control) or a commercial supplement made up of 300,000 IU vitamin A and 45,000 IU vitamin D (Vitamin AD, Vet One; n = 15/ treatment group). Blood samples were collected before each injection for analysis of vitamin and hormone concentrations. All cows were monitored from January-April 2022 for signs of parturition to determine calving date and time, calving ease, birth weight, and to provide assistance if necessary. Serum samples were collected from the calves within 12 hours of parturition for analysis of vitamin D concentrations. There was no effect of vitamin A and D treatment on calving ease (Generalized Linear Model analyses; P = 0.58; 1.44 ± 0.2 treated, 1.29 ± 0.19 control group) or on birth weight (Generalized Linear Model; P = 0.52, 32.6 ± 1.24 kg treated, 33.8 ± 1.38 kg control group). Estrus synchronization, additional blood sampling, vitamin/vehicle injections, and artificial insemination (AI) was performed in late April 2022. Conception rates were determined by transrectal ultrasonography 30 to 40 days post-AI. Interestingly, 7 of 15 controls were determined to be pregnant by AI, while this improved to 10 of14 in AD-injected females (one female could not undergo AI due to late calving). Cows not pregnant by AI were pastured with a bull of proven fertility, and rectal palpation was used in the fall to determine overall pregnancy rates and any pregnancy loss. These data suggest a modest increase in serum vitamin A and D will improve pregnancy rates after AI. Additional studies should reveal if these treatments improve markers of calf health. Supported by The Oregon Beef Council (C. Bishop).

Assessing short-term economic consequences of cow-calf contact systems in dairy production using a stochastic partial budgeting approach

IntroductionWhile early separation of dairy calves after birth has been debated from an ethical and animal welfare lens, the economic evidence surrounding alternative cow-calf contact (CCC) systems is scarce.MethodsTo address this knowledge gap, we assessed the economic consequences of CCC systems using data from the Agriwise database as well as parameters from published literature in a stochastic partial budget model. The implementation of CCC is very diverse between farms, so in our study we therefore selected a limited number of CCC systems to assess. The examined CCC systems were: (i) dam rearing with limited contact at milking (15 minutes twice a day for 115 days) with no manual milk feeding; (ii) dam rearing with 21-day full contact, after which calves are manually fed 8 kg of whole milk for 94 days; and (iii) mixed calf rearing with using both dams and foster cows with full contact; calves are initially kept with their dams and then moved to foster cows at 9 days of age.ResultsWe found that adoption of CCC systems was associated with decreases in contribution margins in the range of 1 to 5.4%, as compared to a rearing system where the calves were separated from their dams after one day and were manually fed 8 kg of milk for 12 weeks. These results illustrated that the costs associated with CCC systems may be fairly high under certain circumstances and may prohibit farmers from adopting this practice. Sensitivity analysis suggested that differences in milk sales, assumptions on changes in labor requirements, and changes in daily calf weight gain depending on CCC system were the main variables that governed the net impact on the contribution margins.DiscussionWe did not include building costs in the analyses assuming that barn structures may not change in the short-term. The study focused only on short-term pecuniary associations between changes in CCC systems and contribution margins. To strengthen the economic decision-making around CCC systems, future research should consider non-monetary impacts of different CCC systems, as well as long-term economic impacts of these production strategies.

Impact of Two Grazing Strategies on Rangeland Basal Cover and Beef Production in the Sourish Mixed Bushveld

The sustainability of beef cattle producers in South Africa is greatly dependent on the availability of natural resources. The aim of the study was first to evaluate the effect of two different strategies in the utilisation of rangeland over four years (2011/12 – 2014/15) on the basal cover—secondly, the study compared animal production results from the two extensively managed rotational grazing strategies. Grazing strategies include a traditional rotational system (TRG), where approximately 60% of fodder was utilised, compared with light selective grazing (LSG), where about 30% of fodder was used. Basal cover for TRG ranged from 19% (2011/12) to 15% (2014/15) and for LSG from 18% (2011/12) to 16% (2014/15). The calving percentage varied between 62% and 73%. The calving percentage and cow and calf weight did not differ between the two grazing strategies, although differences between years were observed. Both grazing systems can be implemented successfully in the Sourish Mixed Bushveld without negatively affecting the rangeland. However, basal cover may be more vulnerable during drought conditions under a TRG system. The study further indicates that mainly small-scale farmers, where utilisation levels of rangelands are usually high, are more vulnerable to drought conditions.

Calf Performance Offspring of Cow Fed with Depolarizing Katuk Leaves

The birth and growth of dairy calves are important factors in the dairy cattle business. The growth of calves and mothers needs to be monitored in production management so that they can produce good seeds or milk according to the expected quality. This study aims to determine the effect of feeding depolarized katuk leaves on the performance of calves from cow consuming depolarized katuk. 21 gestation cows were three groups of seven cows each, the control group (feed complete),CF-DKPo (complete feed added with Depolarized Katuk Powder), CF-DKPe (complete feed added with Depolarized Katuk Pellets). As a feed addition, 100 grams of depolarized katuk feed were provided daily to each head which is given in the morning by mixing it with the morning feed. The treatment was served during at 10 days before calving day and up to 7 days birth. The research data consisted of gestational days data, daily gain data and calf body weight data from 0 – 90 days old. Data analysis on gestational age, body weight, and average daily gain of calf were by using one-way analysis of variance (ANOVA), and if there is a difference, continue with further testing (Dunnett’s test) using SPSS. The results showed that there were differences in birth weight and body weight in calves from mothers that were given depolarized katuk leaves. Calves from broodstock that consumed depolarized katuk leaves in pellet form had higher weights compared to the control and BKD treatments. Significant differences occurred in birth weight and calf ADG for each treatment. Katuk leaves that have been depolarized can be added to feed to help calves grow bigger.

Influence of fetus weight at birth on the productive traits of first-calf heifers

The purpose of the research was to study the infl uence of live weight of calves at birth on indicators of dairy productivity and reproductive ability of fi rst-calf heifers. In order to conduct the experiment 3 groups of fi rst-calf heifers (n=41) of Black-and-White breed were formed depending on the live weight of heifers at birth: the 1th group calves with a live weight of up to 31 kg, 2nd group calves with the live weight from 31 to 36 kg, 3rd group calves with a live weight with of more than 36 kg.It was found as a result of studies that the live weight of heifers at birth with an embryonic development period of more than 280 days signifi cantly exceeded the weight of herdmates with the embryonic development period of 276–280 days by 7,3 % and 275 days or less by 18,8 % (p &lt; 0,01). It was found that the nature of calving and the weight of the fetus at the calving aff ected the further productiv indicators of the fi rst-calf heifers. Thus, 305 days of lactation of cows of the 2nd group signifi cantly exceeded the yield of milk fat of herdmates of the 1st group by 37,1 kg or 26,2 % (p ≤ 0,001), and the yield of milk protein by 33,0 kg or 29,9 % (p ≤ 0,001). At the same time, their superiority over the herdmates of the 3rd group was noted in the yield of milk fat by 6,7 kg or 3,9 % and milk protein by 13,5 kg or 10,4 %. In cows of the 1st group the duration of the open days period was longer by 14 days or 15,0 %, and in the 3rd group by 23 days or 24,7 % (p &lt;0,05) compared with herdmates of the 2nd group. The milk yield for the entire lactation in cows of the 2nd group exceeded the corresponding indicator of herdmates of the 1st group by 260 kg or by 5,7 % (p ≤ 0,01), and the 2nd group by 224 kg or by 4,9 % (p ≤ 0,05). The largest profi t from the conditional sale of products from cows of the 2nd group also provided a high level of profitability in the amount of 36,7 %, which was 22,8 and 27,4 abs.% higher than the corresponding indicators of cows of the 1st and 3rd groups.