Human iPSC-derived Committed Cardiac Progenitors Generate Cardiac Tissue Grafts in a Swine Ischemic Cardiomyopathy Model without Triggering Ventricular Arrhythmias.

BACKGROUND: The adult human heart following a large myocardial infarction is unable to regenerate heart muscle and instead forms scar with the risk of progressive heart failure. Large animal studies have shown that intramyocardial injection of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) following a myocardial infarction result in cell grafts but also ventricular arrhythmias. We hypothesized that intramyocardial injection of committed cardiac progenitor cells (CCPs) derived from iPSCs, combined with cardiac fibroblast-derived extracellular matrix (cECM) to enhance cell retention will: i) form cardiomyocyte containing functional grafts, ii) be free of ventricular arrhythmias and iii) restore left ventricular contractility in a post-myocardial infarction (MI) cardiomyopathy swine model. METHODS: hiPSCs were differentiated using bioreactors and small molecules to produce a population of committed cardiac progenitor cells (CCPs). MI was created using a coronary artery balloon occlusion and reperfusion model in Yucatan mini pigs. Four weeks later, epicardial needle injections of CCPs+cECM were performed in a small initial feasibility cohort, and then transendocardial injections (TEI) of CCPs+cECM, CCPs alone, cECM alone or vehicle control into the peri-infarct region in a larger randomized cohort. A 4-drug immunosuppression regimen was administered to prevent rejection of human CCPs. Arrhythmias were evaluated using implanted event recorders. Magnetic resonance imaging (MRI) and invasive pressure volume assessment were used to evaluate left ventricular anatomic and functional performance, including viability. Detailed histology was performed on the heart to detect human grafts. RESULTS: A scalable biomanufacturing protocol was developed generating CCPs which can efficiently differentiate to cardiomyocytes or endothelial cells in vitro. Intramyocardial delivery of CCPs to post-MI porcine hearts resulted in engraftment and differentiation of CCPs to form ventricular cardiomyocyte rich grafts. There was no significant difference in cardiac MRI-based measured cardiac volumes or function between control, CCP and CCP+cECM groups; however, dobutamine stimulated functional reserve was improved in CCP and CCP+cECM groups. TEI delivery of CCPs with or without cECM did not result in tumors or trigger ventricular arrhythmias. CONCLUSIONS: CCPs are a promising cell source for post-MI heart repair using clinically relevant TEI with a low risk of engraftment ventricular arrhythmias.

Gut butyrate-producers confer post-infarction cardiac protection.

The gut microbiome and its metabolites are increasingly implicated in several cardiovascular diseases, but their role in human myocardial infarction (MI) injury responses have yet to be established. To address this, we examined stool samples from 77 ST-elevation MI (STEMI) patients using 16 S V3-V4 next-generation sequencing, metagenomics and machine learning. Our analysis identified an enriched population of butyrate-producing bacteria. These findings were then validated using a controlled ischemia/reperfusion model using eight nonhuman primates. To elucidate mechanisms, we inoculated gnotobiotic mice with these bacteria and found that they can produce beta-hydroxybutyrate, supporting cardiac function post-MI. This was further confirmed using HMGCS2-deficient mice which lack endogenous ketogenesis and have poor outcomes after MI. Inoculation increased plasma ketone levels and provided significant improvements in cardiac function post-MI. Together, this demonstrates a previously unknown role of gut butyrate-producers in the post-MI response.

Combined Treatment of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes and Endothelial Cells Regenerate the Infarcted Heart in Mice and Non-Human Primates.

BACKGROUND: Remuscularization of the mammalian heart can be achieved after cell transplantation of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs). However, several hurdles remain before implementation into clinical practice. Poor survival of the implanted cells is related to insufficient vascularization, and the potential for fatal arrhythmogenesis is associated with the fetal cell-like nature of immature CMs. METHODS: We generated 3 lines of hiPSC-derived endothelial cells (ECs) and hiPSC-CMs from 3 independent donors and tested hiPSC-CM sarcomeric length, gap junction protein, and calcium-handling ability in coculture with ECs. Next, we examined the therapeutic effect of the cotransplantation of hiPSC-ECs and hiPSC-CMs in nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice undergoing myocardial infarction (n≥4). Cardiac function was assessed by echocardiography, whereas arrhythmic events were recorded using 3-lead ECGs. We further used healthy non-human primates (n=4) with cell injection to study the cell engraftment, maturation, and integration of transplanted hiPSC-CMs, alone or along with hiPSC-ECs, by histological analysis. Last, we tested the cell therapy in ischemic reperfusion injury in non-human primates (n=4, 3, and 4 for EC+CM, CM, and control, respectively). Cardiac function was evaluated by echocardiography and cardiac MRI, whereas arrhythmic events were monitored by telemetric ECG recorders. Cell engraftment, angiogenesis, and host-graft integration of human grafts were also investigated. RESULTS: We demonstrated that human iPSC-ECs promote the maturity and function of hiPSC-CMs in vitro and in vivo. When cocultured with ECs, CMs showed more mature phenotypes in cellular structure and function. In the mouse model, cotransplantation augmented the EC-accompanied vascularization in the grafts, promoted the maturity of CMs at the infarct area, and improved cardiac function after myocardial infarction. Furthermore, in non-human primates, transplantation of ECs and CMs significantly enhanced graft size and vasculature and improved cardiac function after ischemic reperfusion. CONCLUSIONS: These results demonstrate the synergistic effect of combining iPSC-derived ECs and CMs for therapy in the postmyocardial infarction heart, enabling a promising strategy toward clinical translation.

Increasing sustainability in pork production by using high inclusion levels of co-products distillers dried grains with solubles, wheat middling and canola meal doesn't affect pig growth performance and meat quality but reduces boar taint.

OBJECTIVE: The present study is to examine the effect of high inclusion of co-products in pig diets (referred to as an alternative diet) during the finishing stage on pig growth performance, meat quality and boar taint compounds. METHODS: Growing pigs were fed an alternative diet made with distillers dried grains with solubles (25%), canola meal (20%), and wheat middling (15%) or a control diet based on barley and soybean meal to investigate the impact of co-products on pig performance and meat quality. Sixteen female and sixteen entire male Duroc×(Large White×Landrace) pigs (22.6±2.07 kg, body weight±standard error) were equally allocated to the diets. RESULTS: Pigs fed the alternative diet had a lower feed intake; however, growth rate and feed conversion efficiency were unaffected by diet. A diet by sex interaction was found for gain:feed whereby males fed the alternative diet had the best feed conversion (p<0.01). Pork from pigs fed the alternative diet had lower a* and Chroma and protein % (p<0.05), while other meat quality characteristics were unaffected. The alternative diet reduced backfat skatole levels (p<0.001). CONCLUSION: A diet containing high inclusion levels of co-products can be fed to pigs during the finishing stage without detrimental effects on pig performance or meat quality and with the potential to enhance pork flavour. This finding suggests a solution to increase the sustainable development of pig production.

Factors Affecting Grazing and Rumination Behaviours of Dairy Cows in a Pasture-Based System in New Zealand.

This study investigated the variation in daily time spent grazing and rumination in spring-calved grazing dairy cows (n = 162) of three breeds, Holstein-Friesian (HFR), Jersey (JE), and KiwiCross (KC) with different breeding worth index, and in different years of lactation (1st, 2nd, 3rd, 4th). The cows were managed through a rotational grazing system and milked once a day at 05:00 a.m. The cows grazed mainly pasture and received supplementary feeds depending on the season. Automated AfiCollar device continuously monitored and recorded grazing time and rumination time of the individual cows throughout the lactation period for three study years (Year-1, Year-2, Year-3) with 54 cows per year. A general linear mixed model fitted with breed × lactation year with days in milk (DIM), breeding worth (BW) index value, individual cow, season, and feed, and their interactions was performed in SAS. Variance partitioning was used to quantify the effect size of study factors and their interactions. Individual cows, DIM, and BW (except Year-3) had effects on grazing and rumination times throughout the study years. Grazing time and rumination time were different for different seasons due to varying supplementary feeds. Grazing time varied among breeds in Year-2 and Year-3, and among lactation years only in Year-1. Although rumination time differed among breeds in Year-3, it remained the same within different lactation years. Grazing time and rumination time had a negative relationship with each other, and their regression lines varied for different seasons. The total variance explained by the model in grazing time was 36-39%, mainly contributed by the individual cow (12-20%), season (5-12%), supplementary feed (2-6%), breed (1-5%), and lactation year (1-6%). The total variance explained in rumination was 40-41%, mainly contributed by the individual cow (16-24%), season (2-17%), supplementary feed (1-2%), breed (2-8%), and lactation year (~1%). These findings could contribute to improving the measures for feed resource management during different seasons over the lactation period for a mixed herd comprising JE, HFR and KC breeds in different years of lactation.

Opportunities and Challenges of Human IPSC Technology in Kidney Disease Research.

Human induced pluripotent stem cells (iPSCs), since their discovery in 2007, open a broad array of opportunities for research and potential therapeutic uses. The substantial progress in iPSC reprogramming, maintenance, differentiation, and characterization technologies since then has supported their applications from disease modeling and preclinical experimental platforms to the initiation of cell therapies. In this review, we started with a background introduction about stem cells and the discovery of iPSCs, examined the developing technologies in reprogramming and characterization, and provided the updated list of stem cell biobanks. We highlighted several important iPSC-based research including that on autosomal dominant kidney disease and SARS-CoV-2 kidney involvement and discussed challenges and future perspectives.

Porous scaffold for mesenchymal cell encapsulation and exosome-based therapy of ischemic diseases.

Ischemic diseases including myocardial infarction (MI) and limb ischemia are some of the greatest causes of morbidity and mortality worldwide. Cell therapy is a potential treatment but is usually limited by poor survival and retention of donor cells injected at the target site. Since much of the therapeutic effects occur via cell-secreted paracrine factors, including extracellular vesicles (EVs), we developed a porous material for cell encapsulation which would improve donor cell retention and survival, while allowing EV secretion. Human donor cardiac mesenchymal cells were used as a model therapeutic cell and the encapsulation system could sustain three-dimensional cell growth and secretion of therapeutic factors. Secretion of EVs and protective growth factors were increased by encapsulation, and secreted EVs had hypoxia-protective, pro-angiogenic activities in in vitro assays. In a mouse model of limb ischemia the implant improved angiogenesis and blood flow, and in an MI model the system preserved ejection fraction %. In both instances, the encapsulation system greatly extended donor cell retention and survival compared to directly injected cells. This system represents a promising therapy for ischemic diseases and could be adapted for treatment of other diseases in the future.

Animal Welfare Compromises Associated with Causes of Death in Neonatal Piglets.

This pilot study aimed to assess the welfare impacts of different causes of pre-weaning deaths in piglets. Piglets that died between 0-7 days after birth (n = 106) were collected from two commercial pig farms and subject to post-mortem examination to confirm their cause of death as well as any contributing factors. Using the Five Domains Model, the most likely affective experiences associated with the pathological findings were carefully inferred to better understand affective experience as it related to known causes of liveborn piglet mortality. The most common causes of liveborn piglet mortality were starvation (23%), crushing (23%) and non-viable (21%). Thirty one piglets had evidence of starvation, but it was only considered the primary cause of death in 15 piglets, as cofactors such as poor viability (n = 13) were also present in many piglets with evidence of starvation. All 15 piglets that were crushed died within 24 h after birth and most had evidence of thoracic and/or abdominal internal bleeding. This study found that common causes of liveborn piglet death were associated with compromises in Domains 1 (Nutrition/hydration), 3 (Health/function), and4 (Behavioural interactions), with the most likely resulting affective states described in Domain 5 (Mental state). This highlights the interaction between physical/functional and situation-related (behavioural) aspects that influence an animals' welfare status.

Metabolic Changes Associated With Cardiomyocyte Dedifferentiation Enable Adult Mammalian Cardiac Regeneration.

BACKGROUND: Cardiac regeneration after injury is limited by the low proliferative capacity of adult mammalian cardiomyocytes (CMs). However, certain animals readily regenerate lost myocardium through a process involving dedifferentiation, which unlocks their proliferative capacities. METHODS: We bred mice with inducible, CM-specific expression of the Yamanaka factors, enabling adult CM reprogramming and dedifferentiation in vivo. RESULTS: Two days after induction, adult CMs presented a dedifferentiated phenotype and increased proliferation in vivo. Microarray analysis revealed that upregulation of ketogenesis was central to this process. Adeno-associated virus-driven HMGCS2 overexpression induced ketogenesis in adult CMs and recapitulated CM dedifferentiation and proliferation observed during partial reprogramming. This same phenomenon was found to occur after myocardial infarction, specifically in the border zone tissue, and HMGCS2 knockout mice showed impaired cardiac function and response to injury. Finally, we showed that exogenous HMGCS2 rescues cardiac function after ischemic injury. CONCLUSIONS: Our data demonstrate the importance of HMGCS2-induced ketogenesis as a means to regulate metabolic response to CM injury, thus allowing cell dedifferentiation and proliferation as a regenerative response.

Commensal gut microbiota-derived acetate and propionate enhance heart adaptation in response to cardiac pressure overload in mice.

Background: The gut microbiota plays a vital role in maintaining tissue homeostasis and regulating disease pathophysiology; however, the underlying mechanisms remain to be elucidated. We previously showed that mice depleted of gut microbiota with antibiotics (ABX mice) were more prone to cardiac rupture after infarction, suggesting that the gut microbiota impacts cardiac structural remodeling following injury. Here, we aimed to determine whether the gut microbiota is required for adaptive cardiac remodeling in response to pressure overload stress. Methods: Transverse aortic constriction (TAC) surgery was performed and cardiac function was evaluated by echocardiography and catheterization, followed by mechanical tests and extracellular matrix (ECM) studies. Germ-free mice with cecal microbiota transplantation were used for validation. 16S ribosomal DNA sequencing and PICRUSt2 analysis were applied to predict the key metabolic pathways. ABX mice were supplemented with the derived metabolic products and their efficacy was tested. To elucidate the underlying mechanism, we isolated mouse primary cardiac fibroblasts and treated them with the metabolites. Lastly, G-coupled protein receptor 41 (GPR41) and GPR43 double knockdown cardiac fibroblasts were generated and the anti-fibrogenic effect of metabolites was determined. Results: Cardiac hypertrophy and dysfunction were more severe in ABX-TAC mice compared to the controls. Moreover, TAC-induced fibrosis was more profound in ABX hearts, which was accompanied by disrupted ECM structure making the heart tissues mechanically weaker and more brittle. Reconstruction of healthy gut microbiota in germ-free mice successfully restored cardiac function and prevented excessive fibrosis and ECM disarray under stress. Furthermore, functional prediction identified acetate and propionate as critical mediators in the gut microbiota-modulated cardiac mechanics. Supplementation of acetate and propionate improved heart function, attenuated fibrosis, and reversed ECM disarray after TAC. In addition, treating primary cardiac fibroblasts with acetate and propionate attenuated cell contraction, inhibited myofibroblast formation, and reduced collagen formation after TGF-ß1 stimulus. Finally, knocking down GPR41 and GPR43 receptors in cardiac fibroblasts blunted the inhibitory effects of acetate and propionate. Conclusions: The gut microbiota is a potential therapeutic target for cardiac ECM remodeling and heart structural integrity. By establishing a healthy gut microbiome or replenishing the derived metabolites, we could improve cardiac health under dysbiosis after pressure-overload stress.

PEGylation of Phosphatidylglycerol/Docosahexaenoic Acid Hexosomes with d-α-Tocopheryl Succinate Poly(ethylene glycol)2000 Induces Morphological Transformation into Vesicles with Prolonged Circulation Times.

Considering the broad therapeutic potential of omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA), here we study the effect of PEGylation of DHA-incorporated hexosomes on their physicochemical characteristics and biodistribution following intravenous injection into mice. Hexosomes were formed from phosphatidylglycerol and DHA with a weight ratio of 3:2. PEGylation was achieved through the incorporation of either d-α-tocopheryl succinate poly(ethylene glycol)2000 (TPGS-mPEG2000) or 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol)2000 (DSPE-mPEG2000) at a concentration of 1.5 wt %. Nanoparticle tracking analysis, synchrotron small-angle scattering, and cryo-transmission electron microscopy were employed to characterize the nanodispersions. The results show that PEGylated lipids induce a structural transition from an inverse hexagonal (H2) phase inside the nanoparticles (hexosomes) to a lamellar (Lα) phase (vesicles). We also followed the effect of mouse plasma on the nanodispersion size distribution, number, and morphology because changes brought by plasma constituents could regulate the in vivo performance of intravenously injected nanodispersions. For comparative biodistribution studies, fluorescently labeled nanodispersions of equivalent quantum yields were injected intravenously into healthy mice. TPGS-mPEG2000-induced vesicles were most effective in avoiding hepatosplenic clearance at early time points. In an orthotopic xenograft murine model of glioblastoma, TPGS-mPEG2000-induced vesicles also showed improved localization to the brain compared with native hexosomes. We discuss these observations and their implications for the future design of injectable lyotropic nonlamellar liquid crystalline drug delivery nanosystems for therapeutic interventions of brain and liver diseases.

The gut microbiota regulates acute foreign body reaction and tissue repair after biomaterial implantation.

We hypothesized that the host microbiome may influence foreign body responses following biomaterial implantation. To test this, we implanted a variety of clinically relevant biomaterials into germ-free or antibiotic-treated mice. Surprisingly, these mice displayed less fibrous tissue deposition, reduced host cell recruitment to the implant site, and differential expression of angiogenic and inflammatory markers. These observations were reversed upon fecal microbiome reconstitution, confirming a causal role of the host microbiome. In a clinically relevant disease model, microbiome-depleted mice cleared hyaluronic acid and bone marrow mononuclear cells from ischemic hind limb tissues more slowly, resulting in an improved therapeutic response. Findings were confirmed in pigs which showed reduced fibrotic responses to a variety of implanted materials. Lastly, we profiled changes in the host microbiome following material implantation, implicating several key bacteria phyla.

In Vitro Fermentation of Browsable Native Shrubs in New Zealand.

Information on the nutritive value and in vitro fermentation characteristics of native shrubs in New Zealand is scant. This is despite their potential as alternatives to exotic trees and shrubs for supplementary fodder, and their mitigation of greenhouse gases and soil erosion on hill-country sheep and beef farms. The objectives of this study were to measure the in vitro fermentation gas production, predict the parameters of the in vitro fermentation kinetics, and estimate the in vitro fermentation of volatile fatty acids (VFA), microbial biomass (MBM), and greenhouse gases of four native shrubs (Coprosma robusta, Griselinia littoralis, Hoheria populnea, and Pittosporum crassifolium) and an exotic fodder tree species, Salix schwerinii. The total in vitro gas production was higher (p < 0.05) for the natives than for the S. schwerinii. A prediction using the single-pool model resulted in biologically incorrect negative in vitro total gas production from the immediately soluble fraction of the native shrubs. However, the dual pool model better predicted the in vitro total gas production and was in alignment with the measured in vitro fermentation end products. The in vitro VFA and greenhouse gas production from the fermentation of leaf and stem material was higher (p < 0.05), and the MBM lower (p < 0.05), for the native shrubs compared to the S. schwerinii. The lower in vitro total gas production, VFA, and greenhouse gases production and higher MBM of the S. schwerinii may be explained by the presence of condensed tannins (CT), although this was not measured and requires further study. In conclusion, the results from this study suggest that when consumed by ruminant livestock, browsable native shrubs can provide adequate energy and microbial protein, and that greenhouse-gas production from these species is within the ranges reported for typical New Zealand pastures.

Utility of iPSC-Derived Cells for Disease Modeling, Drug Development, and Cell Therapy.

The advent of induced pluripotent stem cells (iPSCs) has advanced our understanding of the molecular mechanisms of human disease, drug discovery, and regenerative medicine. As such, the use of iPSCs in drug development and validation has shown a sharp increase in the past 15 years. Furthermore, many labs have been successful in reproducing many disease phenotypes, often difficult or impossible to capture, in commonly used cell lines or animal models. However, there still remain limitations such as the variability between iPSC lines as well as their maturity. Here, we aim to discuss the strategies in generating iPSC-derived cardiomyocytes and neurons for use in disease modeling, drug development and their use in cell therapy.

Cardio- and Neurotoxicity of Selected Anti-COVID-19 Drugs.

Since December 2019, the novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected ~435 million people and caused ~6 million related deaths as of March 2022. To combat COVID-19, there have been many attempts to repurpose FDA-approved drugs or revive old drugs. However, many of the current treatment options have been known to cause adverse drug reactions. We employed a population-based drug screening platform using 13 human leukocyte antigen (HLA) homozygous human induced pluripotent cell (iPSC) lines to assess the cardiotoxicity and neurotoxicity of the first line of anti-COVID-19 drugs. We also infected iPSC-derived cells to understand the viral infection of cardiomyocytes and neurons. We found that iPSC-derived cardiomyocytes express the ACE2 receptor which correlated with a higher infection of the SARS-CoV-2 virus (r = 0.86). However, we were unable to detect ACE2 expression in neurons which correlated with a low infection rate. We then assessed the toxicity of anti-COVID-19 drugs and identified two cardiotoxic compounds (remdesivir and arbidol) and four neurotoxic compounds (arbidol, remdesivir, hydroxychloroquine, and chloroquine). These data show that this platform can quickly and easily be employed to further our understanding of cell-specific infection and identify drug toxicity of potential treatment options helping clinicians better decide on treatment options.

Population-based high-throughput toxicity screen of human iPSC-derived cardiomyocytes and neurons.

In this study, we establish a population-based human induced pluripotent stem cell (hiPSC) drug screening platform for toxicity assessment. After recruiting 1,000 healthy donors and screening for high-frequency human leukocyte antigen (HLA) haplotypes, we identify 13 HLA-homozygous "super donors" to represent the population. These "super donors" are also expected to represent at least 477,611,135 of the global population. By differentiating these representative hiPSCs into cardiomyocytes and neurons we show their utility in a high-throughput toxicity screen. To validate hit compounds, we demonstrate dose-dependent toxicity of the hit compounds and assess functional modulation. We also show reproducible in vivo drug toxicity results using mouse models with select hit compounds. This study shows the feasibility of using a population-based hiPSC drug screening platform to assess cytotoxicity, which can be used as an innovative tool to study inter-population differences in drug toxicity and adverse drug reactions in drug discovery applications.

Reproduction of Black Soldier Fly (Diptera: Stratiomyidae) Under Different Adult Densities and Light Regimes.

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) has been recognized as a promising insect species for sustainable management of organic waste and by-products. Indoor breeding of BSF with artificial lighting has been proved successful, but efforts are still needed to optimize BSF reproductive output. Increasing adult density seems an option to exploit space, whereas decreasing artificial lighting duration may reduce unnecessary power consumption. This study aimed at investigating the effects of adult density (10, 25, and 50 pairs per 30 × 30 × 30 cm cage; i.e., 370, 926, and 1,852 pairs/m3), light regime (8:16, 12:12, and 16:8 [L:D] h), and their possible interactions, on some BSF life history traits relevant to reproduction. The results show that the overall BSF reproductive output increased with increasing adult density but was not affected by light regimes per se. With the highest BSF adult density tested, an average of more than 20,000 neonate larvae were produced from a cage within 10 d. At this density, increasing photoperiod increased neonate production, but also decreased the number of neonates per watt used for artificial illumination. The temporal oviposition patterns, mean individual female reproductive output, mating success, egg hatching rate, and insect survival rate were not affected by adult density or light regime as simple effects. However, the interaction between adult density and light regime was significant for the first oviposition peak, mean individual female reproductive output, and insect survival rate. The possible mechanisms behind our results are discussed.

Growth and Body Composition of Artificially-Reared Lambs Exposed to Three Different Rearing Regimens.

This study was designed to investigate the influence of pellet fibre level, milk replacer composition and age at weaning on growth and body composition of lambs reared artificially. Romney ram lambs were randomly allocated to one of three rearing treatments; HFP57: commercial milk replacer to 57 days of age, and high fibre concentrate pellets; HFP42: commercial milk replacer with early weaning at 42 days of age, and high fibre concentrate pellets; LFP42: high protein milk replacer from 2-16 days of age followed by commercial milk replacer with early weaning at 42 days of age, and low fibre concentrate pellets. Lambs were slaughtered at 57 days of age. Overall average daily liveweight gain of lambs did not differ (p > 0.05) between treatments. Dressing out percentage, carcass weight, empty small intestine and omental fat were higher (p < 0.05) in HFP57 than in both HFP42 and LFP42 lambs. HFP42 and LFP42 lambs had heavier (p < 0.05) empty rumen weights. Whole body protein content was higher (p < 0.05) in HFP42 lambs compared to both HFP57 and LFP42 lambs. Fat content and daily fat deposition were greater (p < 0.05) in HFP57 lambs than HFP42 and LFP42 lambs. Weaning lambs at 42 days of age with provision of either low or high fibre concentrate pellets, resulted in similar growth rates, reduced whole body fat deposition and was a more cost-effective rearing regimen.

Rumen Development of Artificially-Reared Lambs Exposed to Three Different Rearing Regimens.

The objective of this study was to examine the effect of three different rearing regimens on rumen development in lambs reared artificially. Romney ram lambs were randomly allocated to one of three treatments: commercial milk replacer fed to 57 d of age and high fibre concentrate pellets (HFP57); commercial milk replacer, high fibre concentrate pellets, and early weaning from milk replacer at 42 d of age (HFP42); high protein milk replacer from 2-16 d of age followed by commercial milk replacer, low fibre concentrate pellets, and early weaning from milk replacer at 42 d of age (LFP42). Lambs were slaughtered at 57 d of age. Volatile fatty acid content in rumen fluid at slaughter was analysed and rumen tissue samples were collected for histological examination. The rumen n-butyric content was greater (p < 0.05) in both LFP42 and HFP42 treatment lambs compared to HFP57 lambs. The n-valeric content was greater (p < 0.05) in LFP42 lambs compared to both HFP57 and HFP42 treatment lambs. Thickness of the rumen dorsal wall determined by ultrasound scanning at 49 d was greater (p < 0.05) in both HFP42 and LFP42 lambs compared to HFP57 lambs. There was an interaction (p < 0.05) between treatment and site of rumen tissue sampling on papillae width, density, and rumen muscular layer thickness. Collectively, early weaning and the provision of a low fibre pellet leads to improved rumen function and physical development.

Validation of an Accelerometer Sensor-Based Collar for Monitoring Grazing and Rumination Behaviours in Grazing Dairy Cows.

This study evaluated the accuracy of a sensor-based device (AfiCollar) to automatically monitor and record grazing and rumination behaviours of grazing dairy cows on a real-time basis. Multiparous spring-calved dairy cows (n = 48) wearing the AfiCollar were selected for the visual observation of their grazing and rumination behaviours. The total observation period was 36 days, divided into four recording periods performed at different times of the year, using 12 cows in each period. Each recording period consisted of nine daily observation sessions (three days a week for three consecutive weeks). A continuous behaviour monitoring protocol was followed to visually observe four cows at a time for each daily observation session, from 9:00 a.m. to 5:00 p.m. Overall, 144 observations were collected and the data were presented as behaviour activity per daily observation session. The behaviours visually observed were also recorded through an automated AfiCollar device on a real-time basis over the observation period. Automatic recordings and visual observations were compared with each other using Pearson's correlation coefficient (r), Concordance correlation coefficient (CCC), and linear regression. Compared to visual observation (VO), AfiCollar (AC) showed slightly higher (10%) grazing time and lower (4%) rumination time. AC results and VO results had strong associations with each other for grazing time (r = 0.91, CCC = 0.71) and rumination time (r = 0.89, CCC = 0.80). Regression analysis showed a significant linear relationship between AC and VO for grazing time (R2 = 0.83, p < 0.05) and rumination time (R2 = 0.78, p < 0.05). The relative prediction error (RPE) values for grazing time and rumination time were 0.17 and 0.40, respectively. Overall, the results indicated that AfiCollar is a reliable device to accurately monitor and record grazing and rumination behaviours of grazing dairy cows, although, some minor improvements can be made in algorithm calibrations to further improve its accuracy.