Venkata Sayoji Rao Dukkipati

Paratuberculosis, or Johne’s disease (JD), is a chronic infectious disease of the digestive tract of cattle and other domestic and wild ruminants (Barkema et al. 2018), caused by Mycobacterium aviu...

Eradication of paratuberculosis is hindered by a lack of effective treatments and the difficulty of developing highly efficacious diagnostic tests. Breeding disease-resilient animals is a potential alternative strategy for controlling paratuberculosis. However, there is limited information available on the estimates of genetic parameters for paratuberculosis in New Zealand dairy cattle. The present study used enzyme-linked immunosorbent assay (ELISA) scores from 2 commercial kits (IDEXX and IDvet) using milk (n = 930 for both IDvet and IDEXX) and serum samples (n = 935 for IDvet and 1,121 for IDEXX) obtained from 4 dairy herds in the Manawatu region of New Zealand during the 2022/23 production season. To estimate the heritability of ELISA scores and their correlations with total milk, and fat yields, we used univariate and bivariate Bayesian animal models with a Markov Chain Monte Carlo sampling framework. Both continuous and binary scales for ELISA traits were modeled to assess whether binarization alters the underlying genetic signal of ELISA measurements. For ELISA scores on a continuous log-transformed scale, point estimates for heritability ranged from 0.21 to 0.34, whereas ELISA scores in binary form ranged from 0.02 to 0.03 with their 95% highest posterior density intervals (HDI) overlapping zero. The genetic correlations between ELISA and milk production traits were compatible with both effect and null effects. Between-kit (IDvet vs. IDEXX) genetic correlations were estimated at 0.48 (95% HDI: 0.14-0.74) in milk and 0.58 (95% HDI: 0.32-0.81) in serum, suggesting that these assays may capture partly distinct genomic architectures. In conclusion, the present study demonstrates low to moderate heritability of the humoral response to paratuberculosis measured using continuous ELISA scores in New Zealand dairy cattle.

The suboptimal accuracy of current diagnostic tests necessitates alternative testing strategies to improve the detection of Johne's disease. We studied parallel and serial testing strategies to quantify the association between milk production and Johne's disease status. For this, two commercial Johne's disease Enzyme‐Linked Immunosorbent Assay, ELISAs, (Kit A and Kit B) were used with milk and serum samples. A linear mixed model that included 2388 lactational records from 878 cows across three milk production seasons (2021/22, 2022/23 and 2023/24) was considered as a model. There was an interaction between production season and ELISA status in animals across seasons. When serial testing approach of ELISA assay (Kit B) was used with milk and serum samples, ELISA‐positive cows had 13.65 (95% CI: −4.69 to −22.62) fewer days in milk, produced 277.35 (95% CI: −37.98 to −516.73) kg lower milk yield and 36.35 (95% CI: −14.53 to −58.18) kg lower milk solids and had 366.09 (95% CI: −147.86 to −584.32) NZD lower milk income than negative cows during the 2023/24 production season. In contrast, when serial testing approach of ELISA assay (Kit A) was used with milk and serum samples, ELISA‐positive cows produced 355.61 (95% CI: 129.84–581.38) kg more milk yield and 24.58 (95% CI: 4.11–45.06) kg more milk solids and had 243.40 (95% CI: 38.73–448.06) NZD more milk income than negative cows during the 2021/22 production season. Despite the point estimate differences, the results of this study could not demonstrate the usefulness of different combinational testing strategies with confidence.

Skin thickness was found to be moderately heritable and genetically associated with lamb survival in a previous study on Romney sheep. The aims of this study were to estimate the heritabilities of skin thickness and skin temperature at around 5 and 11 mo of age and determine genetic and phenotypic correlations between them and with production traits such as fat depth, loin-eye muscle depth and width, live weights at weaning, scanning, and 12 mo, and 12-mo fleece weight, in FocusPrime (n = 2,088), Texel (n = 732), Romney (n = 825) and Highlander (n = 1,801) sheep breeds. Heritability estimates of skin thickness at 5-mo old were moderate in FocusPrime (0.39 ± 0.12) and low in Texel and Highlander (0.11 ± 0.15 and 0.13 ± 0.09, respectively). Heritability estimates of skin thickness at 11-mo old were moderate in all breeds (ranging from 0.19 ± 0.07 to 0.29 ± 0.15). Heritability estimates of skin temperature were high in FocusPrime (0.39 ± 0.11), low in Texel (0.17 ± 0.11) and Highlander (0.12 ± 0.06) and almost zero in Romney (0.04 ± 0.03). A tendency in all breeds for negative and favorable correlations was found between skin thickness and skin temperature at 11-mo old sheep. Skin thickness at 11-mo tended to have a positive genetic correlation with fat depth in all breeds except in Texel where the correlation tended to be negative (−0.10 ± 0.34). Genetic correlations of skin thickness at 11-mo old with the weight traits were variate. There tended to be a positive correlation with weaning weight in Texel (0.14 ± 0.34) and Highlander (0.29 ± 0.22). However, there tended to be negative correlations with live weight at scanning and at 12-mo of age in FocusPrime (−0.03 ± 0.18 and −0.13 ± 0.22, respectively) and tended to be positive in Romney (0.09 ± 0.25 and 0.10 ± 0.24, respectively) and Highlander (0.26 ± 0.22 and 0.39 ± 0.21, respectively). Moreover, genetic correlations of skin thickness at 11-mo of age with FW12 tended to be positive in both Romney (0.20 ± 0.22) and Highlander (0.55 ± 0.19). Further studies on the genetic correlations of skin thickness and skin temperature with lamb survival in these breeds are warranted.

Aims:To evaluate and compare the pharmacokinetics of IM and oral firocoxib, and IM meloxicam, and detect their effect on renal function and average daily gain (ADG) in lambs undergoing tail docking and castration.Methods:Seventy-five male Romney lambs, aged 3-6 weeks, were randomised into five treatment groups (n = 15 per group): IM firocoxib (1 mg/kg); oral firocoxib (1 mg/kg); IM meloxicam (1 mg/kg); normal saline (approximately 2 mL, oral); or sham. Following the treatment administration, hot-iron tail docking and rubber ring castration were performed in all groups except the sham group, which did not undergo the procedures, but the animals were handled in the same manner as castrated and tail docked lambs. Blood samples were collected before and 1, 2, 4, 6, 8, 24, 48, 72, 96 and 120 hours after treatment administration, and drug concentrations in plasma were quantified by liquid chromatography and mass spectrometry. Plasma urea and creatinine concentrations were determined at a commercial laboratory. Lamb body weights were recorded before and 2, 4 and 8 weeks after tail docking and castration. The pharmacokinetic analysis was carried out using a non-compartmental approach. Between-group and between-time-point differences were compared using mixed model analyses.Results:There was no evidence for a difference in plasma elimination half-life between firocoxib given IM (LSM 18.6 (SE 1.4) hours), firocoxib given orally (LSM 18.2 (SE 1.4) hours), and meloxicam given IM (LSM 17. 0 (SE 1.4) hours). Firocoxib (IM) had a significantly greater volume of distribution (LSM 3.7 (SE 0.2) L/kg) than IM meloxicam (LSM 0.2 (SE 0.2) L/kg). Lambs in the meloxicam group had higher (p < 0.05) plasma urea and creatinine concentrations than those in the firocoxib, saline and sham groups. Lambs' ADG was decreased (p < 0.01) compared to the other treatment groups in the 0-2 week period following meloxicam administration.

During the early postnatal period, lambs have the ability to thermoregulate body temperature via non-shivering thermogenesis through brown adipose tissue (BAT), which soon after birth begins to transform into white adipose tissue. An RNA seq approach was used to characterize the transcriptome of BAT and thyroid tissue in newborn lambs exposed to cold conditions. Fifteen newborn Romney lambs were selected and divided into three groups: group 1 (n = 3) was a control, and groups 2 and 3 (n = 6 each) were kept indoors for two days at an ambient temperature (20–22 °C) or at a cold temperature (4 °C), respectively. Sequencing was performed using a paired-end strategy through the BGISEQ-500 platform, followed by the identification of differentially expressed genes using DESeq2 and an enrichment analysis by g:Profiler. This study provides an in-depth expression network of the main characters involved in the thermogenesis and fat-whitening mechanisms that take place in the newborn lamb. Data revealed no significant differential expression of key thermogenic factors such as uncoupling protein 1, suggesting that the heat production peak under cold exposure might occur so rapidly and in such an immediate way that it may seem undetectable in BAT by day three of life. Moreover, these changes in expression might indicate the start of the whitening process of the adipose tissue, concluding the non-shivering thermogenesis period.

During cold exposure, brown adipose tissue (BAT) holds the key mechanism in the generation of heat, thus inducing thermogenic adaptation in response to cooler environmental changes. This process can lead to a major lipidome remodelling in BAT, where the increase in abundance of many lipid classes plays a significant role in the thermogenic mechanisms for heat production. This study aimed to identify different types of lipids, through liquid chromatography–mass spectrometry (LC-MS), in BAT and plasma during a short-term cold challenge (2-days), or not, in new-born lambs. Fifteen new-born Romney lambs were selected randomly and divided into three groups: Group 1 (n = 3) with BAT and plasma obtained within 24 h after birth, as a control; Group 2 (n = 6) kept indoors for two days at an ambient temperature (20–22 °C) and Group 3 (n = 6) kept indoors for two days at a cold temperature (4 °C). Significant differences in lipid composition of many lipid categories (such as glycerolipids, glycerophospholipids, sphingolipids and sterol lipids) were observed in BAT and plasma under cold conditions, compared with ambient conditions. Data obtained from the present study suggest that short-term cold exposure induces profound changes in BAT and plasma lipidome composition of new-born lambs, which may enhance lipid metabolism via BAT thermogenic activation and adipocyte survival during cold adaptation. Further analysis on the roles of these lipid changes, validation of potential biomarkers for BAT activity, such as LPC 18:1 and PC 35:6, should contribute to the improvement of new-born lamb survival. Collectively, these observations help broaden the knowledge on the variations of lipid composition during cold exposure.

Calf disbudding is a painful husbandry practice on dairy and beef cattle farms. An objective measurement of pain is useful to reliably evaluate the pain intensity and anti-nociceptive (analgesic) efficacy of therapeutic agents. The aim of this study was to investigate the changes in peripheral leucocyte inflammatory cytokine gene expression in calves after disbudding, and to assess whether the changes in cytokine gene expression could be an indicator of the efficacy of analgesic drugs. In a randomised controlled study, 16 calves (aged 31 to 41 days and weighing 58 to 73 kg), undergoing routine disbudding, were randomly allocated into two groups (n = 8 in each group). Calves in the control group received no analgesic, while those in the treatment group received 0.5 mg kg⁻¹ meloxicam subcutaneously prior to disbudding. Disbudding was performed using an electric debudder. Blood (10 mL) was sampled from the jugular vein just before and 4 and 24 h post-disbudding, RNA was extracted from leukocytes, and the transcription of 12 genes of interest was assessed using nCounter gene expression assay. The results showed significantly higher transcription (compared to baseline values) of the studied genes (except CRH, IFNγ, and IL10) in the control group calves at either 4 or 24 h post-disbudding. The administration of meloxicam one hour before disbudding significantly attenuated the upregulation of IL6, PGHS2, TAC1, NOS1, and CRH gene transcription post-disbudding, while it did not suppress the elevated transcription of acute and pro-inflammatory cytokines such as IL1β, IFNγ, IL8, and TNFα genes. In conclusion, nCounter gene expression assay seems to be a promising tool to study the expression of cytokine genes and thus could be used for the pre-clinical evaluation of novel analgesics.

The objective of this study was to compare the changes in the electroencephalogram (EEG) in response to noxious stimuli with tail flick and hot plate responses of rats administered opiorphin. Female Sprague -Dawley rats (n = 8 per group) randomly received intravenous (IV) injection of morphine (1 mg/kg,) or opiorphin (2 mg/kg,) or saline (0.5 ml,) in each of the three testing methods (EEG, tail flick and hot plate). Each type of test (n = 24 per test) was conducted in different population of rats on separate occasions. The tail flick and hot plate latencies were recorded until 5 min after test drug administration to conscious rats. The EEG was recorded in anaesthetised rats subjected to noxious thermal and electrical stimuli after test drug administration. At the end of 5 min in each of the testing methods rats were administered naloxone subcutaneously (SC) (1 mg/kg) and the test procedure was repeated. There was no significant increase in the median frequency and spectral edge frequency (F50 & F95) of EEG, indicators of nociception, of morphine and opiorphin groups after noxious stimulation. Noxious stimuli caused a significant increase in both F50 and F95 of the saline group. An injection of naloxone significantly increased the F50, thus blocking the action of both opiorphin and morphine. There was a significant increase in the tail flick latency after administration of opiorphin and morphine as compared to the baseline values. Rats of morphine group spent significantly longer on the hot plate when compared to those of the opiorphin and saline groups. There was no significant difference in the hot plate latencies of opiorphin and saline groups. The results of this study suggest that the analgesic effect of opiorphin occurs at the spinal level and it is not as effective as morphine at supraspinal level. It may be due to rapid degradation of opiorphin or limited ability of opiorphin to cross the blood brain barrier or a higher dose of opiorphin is required for its action in the brain. Pharmacokinetic/pharmacodynamics studies along with in vivo penetration of opiorphin in the cerebrospinal fluid are required for further evaluation of opiorphin analgesia.