Mature Cattle Research Articles

The Pharmacokinetics of Subcutaneous Eprinomectin in Plasma and Milk in Dry Dairy Cattle.

Parasitic infections in dairy cattle reduce herd immunity, milk production, and conception rates. This leads to higher production costs, compromised animal welfare, and increased interest in extralabel drug use. The extralabel use of anthelmintics poses food safety risks for consumers since appropriate withdrawal intervals in milk have yet to be established. Although topical eprinomectin has no milk withdrawal time, more research is needed to determine the residues present in milk after subcutaneous administration. This study aimed to characterize the pharmacokinetics of injectable eprinomectin in dry dairy cows. We hypothesized that, when given at the labeled dose, eprinomectin residues in dry dairy cattle would be below the FDA milk tolerance at the onset of lactation. Plasma was collected daily from 13 mature dairy cattle for 7 days postadministration, followed by periodic samples for 90 days. After calving, milk was collected daily until 90 days. Eprinomectin concentrations were measured using HPLC-fluorescence detection. The maximum eprinomectin concentration in plasma and milk was approximately 36 ng/mL 43 h after administration and 3 ng/mL at the onset of lactation, respectively. The low eprinomectin levels in milk collected from these lactating dairy cattle suggest that administering eprinomectin at dry-off is unlikely to result in violative residues. However, subcutaneous eprinomectin in lactating dairy cattle would be hard to justify unless there is evidence that the approved topical formulation is clinically ineffective.

Practical fluid therapy in ambulatory practice

Large animal practitioners are faced with varying levels of de­hydration in both mature and neonatal cattle. The goal of this talk will be to describe and formulate fluid therapy plans in varying circumstances in an ambulatory setting. Determining dehydration, acid-base status, and electrolyte abnormalities will be reviewed. Following this presentation, the practitioner will be able to identify the proper use of oral and intravenous fluid in clinical cases and appropriate volume to be adminis­tered. Homemade fluid recipes will be discussed including pros and cons compared to commercially available products.

PSII-8 Analysis of maternal influence on phenotypic ultrasound measurements of weaned Angus calves

Abstract Ultrasound carcass data can be used to accurately estimate the body composition of beef cattle in comparison with a body composition score. Literature regarding the analysis of phenotypic carcass data has focused predominately on yearling or mature cattle with limited measurements on weaned calves. Therefore, the influence of the milking ability of the dam on body composition traits measured via carcass ultrasound is unknown. The objective of this study was to estimate correlations between the maternal influence of the dam on the phenotypic ultrasound measurements of the calf. To quantify maternal influence, the expected progeny difference (EPD) for milk (MILK) of the dam was correlated to three ultrasound measurements of the calf: backfat thickness (BFAT), ribeye area (REA), and intramuscular fat (IMF). Ultrasound measurements were collected 1 wk after weaning on 104 purebred Angus heifer calves from the Iowa State University McNay Memorial Research and Demonstration Farm located outside Chariton, Iowa. The average age and body weight for heifers were 187 d and 195 kg, respectively. The milk EPD of the dam was correlated to the ultrasound measurements taken on the calves. For each trait, Pearson’s correlations were calculated between the ultrasound traits of the calf to the dam’s milk EPD using R Statistical Software version 4.3.1. A small positive correlation was identified between MILK and REA (r = 0.28, P = 0.004). This suggests a weak phenotypic relationship between MILK and REA for weaned heifers. The correlation between MILK to BFAT and IMF was 0.10 (P = 0.318) and -0.05 (P = 0.619), respectively. These correlations were not significantly different from zero. This suggests the potential for milk production of the dam has little association with BFAT and IMF for weaned heifers. Although further research is needed, the results from this study indicate little to no relationship between milk EPD of the dam on ultrasound measures of the calf for BFAT, REA, and IMF.

136 Evaluation of internal parasite burden in grazing beef cattle in North Carolina over a production lifecycle

Abstract Gastrointestinal nematode (GIN) parasite infections can be detrimental to not only cattle health and immunity, but also result in economic loss and poor performance. Cattle grazing in the southeast are challenged even further by the favorable environmental conditions for parasite development, especially those animals who have yet to develop an immunity to combat parasitism. To diminish potential economic and performance-based losses, many beef producers treat animals for GIN parasites with anthelmintics on a regular basis without proper diagnosis. Anthelmintic resistance(AR) develops when deworming products are overused and misused. To minimize the development of AR, selective deworming and sustainable management practices should be implemented. However, the severity of parasite burden over the production cycle needs to be better understood in beef cattle herds before recommendations can be made. Thus, the objective was to investigate the rates of GIN parasite infections through fecal egg counts (FEC) and the impact on body weight (BW) and body condition score (BCS). Angus-based cattle (6 mo-13 yr, n = 1,154) on a were utilized from five different research and educational herds across North Carolina. Cattle were categorized based on their age at the start of the project as either calves (n = 446), yearling heifers (n = 205), 2 year old (n = 260), 3-5 year old (n = 501), or 6+ year old (n = 206). Starting in September, FEC, BW, and BCS were collected and analyzed every 90 d at critical production timepoints (calving, breeding, weaning, and 90d post-weaning) to monitor the severity of GIN parasite challenge. Cattle on study were not treated with anthelmintics regardless of parasite load, with the exception of calves at four of the locations at the time of weaning. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 > P > 0.05. Age of cattle had an impact on FEC overall (P < 0.05), however, there was no difference between FEC of mature cattle over 3 yr (4.29 ± 4.9 eggs/gm). Calves had the greatest FEC (120.59 ± 4.2 eggs/gm) while cattle 6+ yr had the least (3.68 ± 4.5 eggs/gm). Cattle age at each location affected BCS and BW (P < 0.05). Between age groups across locations, time had an impact on FEC, BW, and BCS (P < 0.05). There was also a tendency (P = 0.6) for location to impact FEC. Calf sex did not affect (P > 0.05) FEC. Further FEC analysis of cattle under 2 yrof age is required to better understand when a natural immune response to GIN parasite infections develops.

Evidence of Active Orbivirus Transmission in 2016 in Kansas and Nebraska.

Retrospective serological and case diagnostic data of endemic bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) provide evidence of viral transmission among livestock and wildlife from 2016 in Kansas and Nebraska. Serological testing of mature cattle in nine distinct regional zones of Kansas revealed 76% to 100% had detectable antibodies to BTV and/or EHDV. Specimens tested in the Kansas Veterinary Diagnostic Laboratory (55 submissions) were 51% test positive for antibodies to BTV and/or EHDV. Specimens tested in the Nebraska Veterinary Diagnostic Center (283 submissions) were 25% test positive for antibodies to BTV and/or EHDV. Low disease incidence in white-tailed deer and other susceptible wild ungulates was observed during 2016. However, there were no confirmed reports of disease in livestock in either state. The reasons for emergence of significant clinical disease in livestock and wildlife populations remain undefined.

Epidemiology of Bovine Hemorrhagic Bowel Syndrome in Belgium and The Netherlands.

Hemorrhagic bowel syndrome (HBS) is a poorly understood, sporadic and often fatal disease in cattle. Although, HBS is considered an important disease in dairy cattle, epidemiological data is largely lacking. This study describes the epidemiology of HBS in Belgium and the Netherlands, based on necropsy records from 2009 to 2022, and reports characteristics from 27 cows and 35 dairy operations with HBS, gathered through a survey. The annual incidence of HBS has a significantly increasing trend both at cow and herd level, with incidence above 3.2% in necropsied mature dairy cattle in the most recent years. Estimated herd-level incidence in the Netherlands was double the estimated incidence in Belgium, which might be explained by higher herd size in the Netherlands. Occurrence of HBS was most prevalent in fall, being 40.1% higher than the average of the other seasons. In 35 Flemish (Belgian) surveyed dairy herds with HBS, manifestation of HBS was mostly as solitary cases, and if multiple cases occurred, the time interval was highly variable. In addition, the majority of cows with HBS (61.1%; 16/26) were in more than 100 days lactation. In conclusion, HBS is an important and possibly emerging disease in dairy cattle in Belgium and the Netherlands.

Effects of an Hourly Bolus Postruminal Infusion of Flaxseed Oil or Palm Oil on Circulating Fatty Acid Concentrations and Hepatic Expression of Pyruvate Carboxylase and Phosphoenolpyruvate Carboxykinase in Dairy Cattle.

Palmitic (C16:0), α-linolenic acid (C18:3n-3 cis), and propionate regulate bovine pyruvate carboxylase (PC) and phosphoenolpyruvate carboxykinase (PCK1) expression in vitro. The objective of this experiment was to determine the impact of C16:0, C18:3n-3 cis, propionate, and acetate postruminal infusions on hepatic PC and PCK1 expression. We hypothesized that circulating fatty acids alter hepatic PC and PCK1 in lactating dairy cows. Acetate, propionate, palm oil, and flaxseed oil were supplied postruminally to lactating cows (n = 4) using two 4 × 4 Latin square studies. For Experiment 1, cows were infused on an hourly basis with either a bolus of propionate, acetate, or the combination of propionate and palm oil, or acetate and palm oil, and Experiment 2 was similar, but flaxseed oil replaced palm oil. Flaxseed infusions increased plasma concentration and the molar percent of C18:3n-3 cis and decreased C16:0 but did not affect PC or PCK1 expression. Palm infusions did not affect blood metabolites or the hepatic expression of PC or PCK1. The lack of responses to short-chain fatty acid infusions and changes in circulating long-chain fatty acids in mature cattle are not suitable models to study the effects of α-linolenic acid and propionate on bovine PC and PCK1 expression previously observed in vitro.

Characterization and Evaluation of Vermicomposting Materials

Abstract The agricultural sector and growing food production needs rely on chemical fertilizers. This initially had positive effects on production, but over the last decade, the negative impacts of overuse have resulted in low crop productivity, increased pest and disease infestation, soil degradation, and consequent adverse effects on environmental parameters. As one of the possibilities in organic farming, we found vermicomposting as the most sustainable practice. For the assembly of vermicomposting, mature cattle manure was utilized in three different combinations with organic material and earthworm inoculations (the household waste, the grass clippings, and mixture). The experiment was set up by random block design in three replications. Analyses of qualitative parameters of the final product showed a pH reaction from neutral to slightly alkaline. The nitrogen compound varied between 2.7% and 2.9% and the organic carbon varied between 45.59% and 47.41%, showing a C/N ratio of 16.7‒16.67. The potassium content varied between 1.1% and 1.2% K2O, and the phosphorus content varied from 0.3% to 0.5%. The experiment gave quite good results of vermicomposting of household waste with manure, showing a neutral pH reaction, optimal content of ash and carbon with almost similar and good NPK contents and increased C/N ratio of 16.7, and with satisfying levels of trace elements and the heavy metal content under the limits. This combination of household waste and manure also showed best characterization of humic and fulvic acids in vermicompost, ranging from 1505 to 1778 cm−1 and from 729 to 998 cm−1, respectively. These results indicate that vermicomposting can increase the quality of the final product.

Differential gene expression in peripheral leukocytes of pre-weaned Holstein heifer calves with respiratory disease.

Bovine respiratory disease (BRD) is a leading cause of calf morbidity and mortality, and prevalence remains high despite current management practices. Differential gene expression (DGE) provides detailed insight into individual immune responses and can illuminate enriched pathways and biomarkers that contribute to disease susceptibility and outcomes. The aims of this study were to investigate differences in peripheral leukocyte gene expression in Holstein preweaned heifer calves 1) with and without BRD, and 2) across weeks of age. Calves were enrolled for this short-term longitudinal study on two commercial dairies in Washington State. Calves were assessed every two weeks throughout the pre-weaning period using clinical respiratory scoring (CRS) and thoracic ultrasonography (TUS), and blood samples were collected. Calves were selected that were either healthy (n = 10) or had BRD diagnosed by CRS (n = 7), TUS (n = 6), or both (n = 6) in weeks 5 or 7 of life). Three consecutive time point samples were analyzed for each BRD calf consisting of PRE, ONSET, and POST samples. Nineteen genes of interest were selected based on previous gene expression studies in cattle: ALOX15, BPI, CATHL6, CXCL8, DHX58, GZMB, HPGD, IFNG, IL17D, IL1R2, ISG15, LCN2, LIF, MX1, OAS2, PGLYRP1, S100A8, SELP, and TNF. Comparisons were made between age and disease time point matched BRD and healthy calves as well as between calf weeks of age. No DGE was observed between diseased and healthy calves; however, DGE was observed between calf weeks of age regardless of disease state. Developmental differences in leukocyte gene expression, phenotype, and functionality make pre-weaned calves immunologically distinct from mature cattle, and early life shifts in calf leukocyte populations likely contribute to the age-related gene expression differences we observed. Age overshadows disease impacts to influence gene expression in young calves, and immune development progresses upon a common trajectory regardless of disease during the preweaning period.

103 Impact of Fescue Variety on Fecal Egg Counts in Mature Beef Cattle

Abstract Fescue toxicosis decreases beef cattle performance in a multitude of ways, including decreased health and immunity. Cattle challenged by fescue toxicosis are often grazing in an environment favorable for development of gastrointestinal nematodes (GIN). Interactions of fescue toxicosis and parasite challenge may result in further performance and economic losses. Many beef producers treat animals regularly for GIN parasites with little insight on necessity or effectiveness of anthelmintic products. Overuse of anthelmintics can result in development of anthelmintic resistance in GIN populations. To minimize the development of anthelmintic resistance, implementation of selective deworming practices should be considered. However, level of parasite burden and effects of fescue toxicosis on parasite burden need to be better understood in beef cattle herds before recommendations can be offered. Therefore, the objective was to investigate the impact of fescue toxicosis on GIN parasite infection rates through fecal egg counts (FEC), body weight (BW), hematocrit (HCT), and body condition score (BCS). Starting in April, for 14 consecutive weeks post-weaning, pregnant Angus-based cows (2 to 4 years old, n = 65) were rotationally grazed on either novel endophyte (EN) fescue or endophyte-infected (EI) fescue pastures. Hematocrit, BCS, and BW were assessed weekly, while FEC were measured bi-weekly to monitor the physiological changes as a result of consuming endophyte-infected tall fescue. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 > P > 0.05. Overall, FEC were low (4.2 ± 0.9 eggs/gm) in these mature cattle and grazing EI or EN fescue did not have any overall effect (P > 0.05) on the FEC. However, FEC decreased (P < 0.05) over the course of the study from week 1 to week 13. Body weight, HCT, and BCS were not affected (P > 0.05) by the type of fescue grazed. There was a tendency (P < 0.10) for 2-3 and 4-6 year old cattle to have lower BW when grazing EI compared with EN fescue while cattle >7 were not affected. Cattle gained BW (P < 0.05) over the 14-week study (471.4 and 527.7 ± 0.6 kg, 0 and4 week respectively). For cattle grazing EI fescue, HCT linearly decreased (P < 0.05) from week 1 to week 14 whereas cattle grazing EN fescue had a linear increase (P < 0.05) in HCT from week 1 to week 14. More research is warranted to investigate beef cattle FEC and the potential impact of fescue type on FEC in younger beef cattle.

Uterine Tube Resection by Vaginotomy as an Alternative to Ovariectomy in Mature Cattle

The prevention of pregnancy is desirable for female cattle destined for sale in the northern Australian rangelands for both economic and welfare reasons. Controlled access to bulls is often not feasible, nor are any non-surgical methods currently available. Many females are therefore surgically spayed. This study describes a technique for uterine tube resection (UTR), which leaves the ovaries intact and is performed using a vaginal approach, and compares the outcomes from 70 Brahman cows subjected to the procedure with 60 heifers spayed using the dropped ovary technique. The animals were monitored for 10 days following the surgery. There were no mortalities, and two animals were treated for illnesses after the UTRs and recovered. The animals subjected to both surgical procedures showed signs of pelvic discomfort and mild inflammation during recovery. The cows gained an average of 9.3 kg (SD 14.5 kg) of weight over the 10 days of the study compared to the spayed heifers, which lost 3.5 kg (SD 13.3 kg), with 19 and 63% of the animals in each of the groups losing weight, respectively. Uterine tube resection can be considered as a viable alternative to surgical spaying.

Bovine muscle satellite cells in calves and cattle: A comparative study of cellular and genetic characteristics for cultivated meat production

This study compared the cellular and genetic characteristics of bovine skeletal muscle satellite cells (SMSCs) from Hanwoo (a Korean native cattle breed), including calves and mature cattle. SMSCs were isolated using magnetic-activated cell sorting (MACS) from tissue samples of six Hanwoo (three calves and three mature cattle) using the CD29 antibody. Calves’ SMSCs exhibited significantly faster growth rates than did those from cattle (P < 0.01), with a doubling time of 2.43 days. Genetic analysis revealed higher MyoD and Pax7 expression in SMSCs from calves during proliferation than in those from mature cattle (P < 0.001). However, FASN and PLAG1 expression levels were higher in mature cattle than in calves during both proliferation and differentiation (P < 0.001). These findings highlight the need for strategies to improve bovine muscle cell growth to produce competitive cultivated meat at a competitive price.

A Comprehensive Sequencing Analysis of Testis-Born miRNAs in Immature and Mature Indigenous Wandong Cattle (Bos taurus).

Micro RNAs (miRNAs) have been recognized as important regulators that are indispensable for testicular development and spermatogenesis. miRNAs are endogenous transcriptomic elements and mainly regulate the gene expression at post-transcriptional levels; however, the key role of miRNA in bovine testicular growth is not clearly understood. Thus, supposing to unveil the transcriptomics expression changes in the developmental processes of bovine testes, we selected three immature calves and three sexually mature bulls of the local Wandong breed for testicular-tissue sample collection. The cDNA libraries of experimental animals were established for RNA-sequencing analysis. We detected the miRNA expression in testes by using high-throughput sequencing technology, and bioinformatics analysis followed. The differentially expressed (DE) data showed that 151 miRNAs linked genes were significantly DE between immature and mature bull testes. Further, in detail, 64 were significantly up-regulated and 87 were down-regulated in the immature vs. mature testes (p-value &lt; 0.05). Pathway analyses for miRNA-linked genes were performed and identified JAG2, BCL6, CFAP157, PHC2, TYRO3, SEPTIN6, and BSP3; these genes were involved in biological pathways such as TNF signaling, T cell receptor, PI3KAkt signaling, and functions affecting testes development and spermatogenesis. The DE miRNAs including MIR425, MIR98, MIR34C, MIR184, MIR18A, MIR136, MIR15A, MIR1388 and MIR210 were associated with cattle-bull sexual maturation and sperm production. RT-qPCR validation analysis showed a consistent correlation to the sequencing data findings. The current study provides a good framework for understanding the mechanism of miRNAs in the development of testes and spermatogenesis.

Glycine Improved Cryopreserved Spermatozoa Quality in Achai Bull.

Achai is a small size cattle breed, resilient to harsh and cold environment. Cryopreservation of Achai bull semen may help to improve its genetics and preserve the germplasm. Reactive oxygen species (ROS) affects the structural and functional integrity of the spermatozoa. During freezing and thawing processes, the ROS make changes in the spermatozoa quality parameters and reduce total antioxidant capacity (T-AOC) of semen that is considered as marker of oxidative stress. This study was designed to determine the effect of glycine along with vitamin E on post-thawed spermatozoa quality and total antioxidant capacity in Achai cattle. The semen collection was done twice a week from four mature fertile Achai cattle bulls (n = 4). The glycine was utilized as 0 mM, 5 mM, 10 mM, 15 mM, and 20 mM along with vitamin E @ 2.3 mM added constantly in each concentration. The control group contained all extenders except glycine. The results revealed that post-thawed spermatozoa motility was found significantly higher (P < 0.05) at 10 mM as compared to 5 mM, 15 mM, and 20 mM. Compared with control group, glycine concentration at 10 mM and other concentrations increased progressive and fast motility (%), curvilinear, straight line, and average path velocity (μm/s). Moreover, beat cross frequency (Hz) was higher (P < 0.05), and post-thaw viability (%), plasma membrane integrity, and mitochondrial membrane potential were significantly higher (P < 0.05) at 10 mM of glycine concentration in comparison to control and other glycine concentrations. Besides, acrosome integrity (%) and DNA integrity (%) as well as post-thawed T-AOC were also significantly higher (P < 0.05) at 10 mM of glycine concentration as compared to other glycine concentrations and control group. It is concluded that 10 mM of glycine along with vitamin E @ 2.3 mM improved cryopreserved semen quality of Achai bull.

Prevalence and Management Practices of Lumpy Skin Disease (LSD) in Cattle at Natore District of Bangladesh

Lumpy skin disease (LSD) is a potentially contagious viral disease in cattle, caused by the Lumpy skin disease virus (LSDV), which belongs to the family Poxviridae. The virus is suspected to spread via biological vectors such as mosquitoes, flies, ticks, and direct contact. It is a significant economic disease caused by a virus that causes significant losses in milk production, fertility, abortions, import restrictions, and, in some cases, death in the livestock animals. This study aimed to assess the current state of LSD and its management on several farms in the north-western region of Bangladesh. Data were obtained from two Upazilas in the Natore district (Natore Sadar and Baraigram) using a structured questionnaire. During the study period of 1 June to 20 December 2020, a total of 34 small farms and 87 animals were monitored. The OIE guidelines directed the diagnosis of LSD based on current clinical indicators. MS Excel and SPSS statistical software were used to evaluate all of the data. Morbidity, mortality, and case-fatality rates were found to be 64.70%, 2.94 %, and 4.53 % in Natore Sadar and 83.02 %, 3.77 %, and 4.55 % in Baraigram Upazilas, respectively. Female animals that were newly matured (2-4 years) were a larger prone to LSD infection (43.1%) than animals of other ages. A total of 34.43% illness was found in young bull cattle aged (2-4). Bull and heifer calves are also vulnerable populations, with reports of LSD infection leading to mortality. Limb swelling is a common clinical symptom, and LSD-positive young mature (2-4 year) cattle had the most significant rate (18.39%) of limb swelling. The farm hygiene practice is a critical determinant in the spread of LSDV, and a large proportion of cattle (48.27 %) infected with LSD were on farms with poor hygienic management, compared to good (01.14 %) and medium (01.14 %) hygienic management practices (26.43 %). Despite the fact that mosquito nets help prevent mosquitoes, most owners (91.17 %) did not use one in their cattle barn at night. More study is needed in Bangladesh to improve the clinical management of LSD, identify risk factors, and understand the molecular characteristics of diseases.

Enteric methane emission estimates for Kenyan cattle in a nighttime enclosure using a backward Lagrangian Stochastic dispersion technique

This study provides methane (CH4) emission estimates for mature female African beef cattle in a semi-arid region in Southern Kenya using open-path laser spectroscopy together with a backward Lagrangian Stochastic (bLS) dispersion modeling technique. We deployed two open-path lasers to determine 10-min averages of line-integrated CH4 measurements upwind and downwind of fenced enclosures (so-called bomas: a location where the cattle are gathered at night) during 14 nights in September/October 2019. The measurements were filtered for wind direction deviations and friction velocity before the model was applied. We compared the obtained emission factors (EFs) with the Intergovernmental Panel on Climate Change (IPCC) Tier 1 estimates for the Sub-Saharan African (SSA) countries, which were mostly derived from studies carried out in developed countries and adapted to the conditions in Africa. The resulting EF of 75.4 ± 15.99 kg year−1 and the EFs calculated from other studies carried out in Africa indicate the need for the further development of region-specific EFs depending on animal breed, livestock systems, feed quantity, and composition to improve the IPCC Tier 1 estimates.

Land use influences stream bacterial communities in lowland tropical watersheds

Land use is known to affect water quality yet the impact it has on aquatic microbial communities in tropical systems is poorly understood. We used 16S metabarcoding to assess the impact of land use on bacterial communities in the water column of four streams in central Panama. Each stream was influenced by a common Neotropical land use: mature forest, secondary forest, silvopasture and traditional cattle pasture. Bacterial community diversity and composition were significantly influenced by nearby land uses. Streams bordered by forests had higher phylogenetic diversity (Faith’s PD) and similar community structure (based on weighted UniFrac distance), whereas the stream surrounded by traditional cattle pasture had lower diversity and unique bacterial communities. The silvopasture stream showed strong seasonal shifts, with communities similar to forested catchments during the wet seasons and cattle pasture during dry seasons. We demonstrate that natural forest regrowth and targeted management, such as maintaining and restoring riparian corridors, benefit stream-water microbiomes in tropical landscapes and can provide a rapid and efficient approach to balancing agricultural activities and water quality protection.

PSXIII-29 Late-Breaking: Relationships between feed efficiency traits, gas emissions, and calculated heat production and respiratory quotients in mature beef cows

Abstract This research evaluated relationships between feed efficiency measurements including residual feed intake (RFI), gain to feed ratio (G:F) and enteric gas production of methane (CH4), carbon dioxide (CO2), oxygen, (O2) along with calculated respiratory quotient (RQ) and heat production (HP) of mature beef cows. Sixty pregnant multiparous Angus beef cows were measured for individual intake for 10 weeks leading up to parturition. Cows were individually fed using the Insentec feeding system to measure individual feed intake. Pens of cows were rotated weekly to the C-Lock Greenfeed trailer (C-Lock Inc.) to measure gas production for a minimum 2 periods per group. Cows were weighed, body condition scored, and ultrasound performed for rib and rump fat depth every 28 days and calf birth weight was recorded. Pearson correlations were conducted to determine relationships between gas exchange measurements and feed efficiency measures. The model for RFI included ADG, pregnancy corrected BW, and ultrasound measures of rib and rump fat (R2= 0.32). Methane emissions were 263±40.3 g CH4/d in dry lot, and daily enteric CH4 emissions per kg of pregnancy corrected body weight ranging from 0.26 to 0.53 g CH4/kg pcBW. Pearson correlations found positive correlations between DMI and CH4 and CO2 (P ≤ 0.001). Pregnancy corrected BW was also positively correlated with total O2 consumption and calculated HP (P ≤ 0.001) and negatively correlated with RQ (P = 0.04). However, RFI and feed conversion ratio were not significantly correlated with gas measurements, or calculated HP or RQ (P ≥ 0.1), although DMI/kg of BW tended (P = 0.098) to be negatively correlated with O2 consumption. In conclusion, accurately identifying feed efficiency in mature beef cows continues to be a challenge. However, the inclusion of gas exchange measures and calorimetry measurements may be able to better assess metabolic efficiency in mature beef cattle.

Hematocrit estimates comparing centrifugation to a point-of-care method in beef cattle living at high altitude.

The hematocrit (Hct) or packed cell volume (PCV) reflects the blood volume occupied by red blood cells. The development of point-of-care (PoC) instruments can accelerate the ease of measuring Hct/PCV compared with traditional capillary centrifugation (TCC) methods. However, no studies have compared Hct/PCV levels in cattle at high elevation with other measurement methods. In this study, we aimed to compare methods to estimate Hcts/PCVs of rangeland cattle at high elevation. We specifically wanted to determine if Hct/PCV levels measured with a commercial PoC instrument (i-Stat with CHEM8+ cartridges [PoCi ]) were comparable to Hct/PCV levels measured with traditional laboratory methods. We assessed the Hct/PCV of 94 mature beef cattle (black Angus; Bos taurus) at ~2195m above sea level using paired analyses of the PoCi and TCC methods from each animal. We used paired samples t-tests to compare mean Hct/PCVs. Correlation analyses relative to the line of identity and Passing-Bablok regression were used to assess systematic and proportional differences, respectively, and Bland-Altman plots were used to assess agreement between the two methods. The PoCi estimated a Hct of 28.2% ± 0.7% (SE), which was lower than the TCC estimated PCV of 39.2% ± 0.5%. The Bland-Altman plot revealed poor agreement between the two methods in addition to a -11% bias for the PoCi . The Passing-Bablok regression revealed both systematic and proportional bias between the two methods. Point-of-care blood instruments were not comparable to TCC methods for quantifying Hct/PCVs of cattle living at high elevations.

Crop Morpho-Histological Peculiarities in Domesticated Pigeons (Columba livia domestica), Cattle Egret (Bubulcus ibis) and Domesticated Ducks (Anas platyrhynchos domestica)

The crop architecture varies among different avian species consistent with their feeding habits. Therefore, twenty-one of mature healthy male pigeons (granivorous), cattle egrets (carnivorous), and ducks (omnivorous), seven per species, were utilized for the histological, immunohistochemical, and ultrastructural analyses. Histologically, the mucosal folds were covered by non-keratinized stratified squamous epithelium in the three investigated species. The mucosal glands are only peculiar to the crops of the cattle egrets as well as the ducks, while the pigeons' crops were devoid of any secretory units. Morphometrically, the optical densities of the Alcian blue (AB) and periodic acid Schiff (PAS) reactions in the secretory glands, the area % of collagen fibers, the thickness of the tunica musculosa were measured and declared significant differences among the three studied avian species. Immunohistochemical reaction revealed ki-67 immuno-positive reactivity in the nuclei of basal cell layers of the crop epithelium in pigeons only. Regarding ultrastructure investigation, the covering epithelium of all studied species had been shown to be the basal layer of cuboidal to tall columnar cells with desmosomal junctions at the level of their cellular interdigitation, intermediate layers of large irregular polygonal cells with obviously increased cytokeratin filaments especially in the ducks and cellular interdigitation in between. The superficial layer of flat-shaped cells in the three investigated species manifested by desmosomal junctions in between but at the level of the surface squamous cells of the superficial layer, a fine lateral process is only inspected in the pigeons. In conclusion, the crop glands characterized by supranuclear electron dense secretory granules in the cattle egrets and electron-lucent in ducks.