The batched stepped wedge design: A design robust to delays in cluster recruitment

Stepped wedge designs are an increasingly popular variant of longitudinal cluster randomized trial designs, and roll out interventions across clusters in a randomized, but step‐wise fashion. In the standard stepped wedge design, assumptions regarding the effect of time on outcomes may require that all clusters start and end trial participation at the same time. This would require ethics approvals and data collection procedures to be in place in all clusters before a stepped wedge trial can start in any cluster. Hence, although stepped wedge designs are useful for testing the impacts of many cluster‐based interventions on outcomes, there can be lengthy delays before a trial can commence. In this article, we introduce “batched” stepped wedge designs. Batched stepped wedge designs allow clusters to commence the study in batches, instead of all at once, allowing for staggered cluster recruitment. Like the stepped wedge, the batched stepped wedge rolls out the intervention to all clusters in a randomized and step‐wise fashion: a series of self‐contained stepped wedge designs. Provided that separate period effects are included for each batch, software for standard stepped wedge sample size calculations can be used. With this time parameterization, in many situations including when linear models are assumed, sample size calculations reduce to the setting of a single stepped wedge design with multiple clusters per sequence. In these situations, sample size calculations will not depend on the delays between the commencement of batches. Hence, the power of batched stepped wedge designs is robust to unexpected delays between batches

Divergent selection for fat index in Pannon Ka rabbits: genetic parameters, selection response

[EN] The objective of this study was to estimate the response to selection for total body fat content of rabbits measured by computer tomography (CT). A divergent selection experiment was performed using Pannon Ka rabbits, which were previously selected for number of kits born alive. The so-called zero generation consisted of 351 Pannon Ka rabbits, from which the index, total body fat volume (cm3) divided by the body weight (kg), was measured. Rabbits with low and high fat index values were selected to form the parent groups of the lean and fat lines, respectively. The lines consisted of 55-72 females and 35-47 males, depending on the line and generation. After three generations, the rabbits were evaluated by means of a single trait animal model. The fat index showed a moderate heritability estimate (0.28±0.03). The magnitude of the common litter effect was small (0.10±0.02). The breeding values averaged per generation provided slightly asymmetrical responses. Based on the results, the divergent selection was successful in confirming that CT is a very suitable method for performing selection for body composition traits.EFOP-3.6.3-VEKOP-16-2017-00008 project. The project is co-financed by the European Union and the European Social Fund and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences (BO/00871/19)Kasza, R.; Matics, Z.; Gerencsér, Z.; Donkó, T.; Radnai, I.; Szendrő, Z.; Nagy, I. (2020). Divergent selection for fat index in Pannon Ka rabbits: genetic parameters, selection response. World Rabbit Science. 28(3):129-133. https://doi.org/10.4995/wrs.2020.12733OJS129133283Al-Saef A.M., Khalil M.H., Al-Dobaib S.N., Al-Homidan A.H., García M.L., Baselga M. 2008. Comparing Saudi synthetic lines of rabbits with the founder breeds for carcass, lean composition and meat quality traits. Livest. Res. Rural Dev., 20: 1-12.Donkó T., Czakó B., Kovács Gy., Petneházy Ö., Kasza R., Szendrő Zs., Garamvölgyi R., Matics Zs. 2016. Total body fat content determination by means of computed tomography (CT) in rabbits. In: Proceedings of the 11th World Rabbit Congress, 16-18 June 2016, Qingdao, China, pp. 753-756.Fortun-Lamothe L. 2006. Energy balance and reproductive performance in rabbit does. Anim. Reprod. Sci., 93: 1-15. https://doi.org/10.1016/j.anireprosci.2005.06.009Garreau H., Eady S.J., Hurtaud J., Legarra A. 2008. Genetic parameters of production traits and resistance to digestive disorders in a commercial rabbit population. In: Xiccato G., Trocino A., Lukefahr S. (eds.) In Proc.: 9th World Rabbit Congress. Fondazione Iniziative Zooprofilattiche e Zootechniche, Verona, Italy, pp. 103-108.Falconer D.S., Mackay T.F.C. 1996. Introduction to Quantitative Genetics. 4th Ed. Longman, London, UK. 1-464.Garreau H., Larzul C., Tudela F., Ruesche J., Ducqrocq V., Fortun-Lamothe L. 2017. Energy balance and body reserves in rabbit females selected for longevity. World Rabbit Sci., 25: 205-213. https://doi.org/10.4995/wrs.2017.5216Groeneveld E. 1990. PEST Users' Manual. Institute of Animal Husbandry and Animal Behaviour Federal Research Centre, Neustadt, Germany 1-61.Groeneveld E., Kovac M., Mielenz N. 2008. VCE User's Guide and Reference manual. Version 6.0. Institute of Farm Animal Genetics, Neustadt, Germany, 1-125.Larzul C., de Rochambeau H. 2005. Selection for residual feed consumption in the rabbit. Livest. Prod. Sci., 95: 67-72. https://doi.org/10.1016/j.livprodsci.2004.12.007Larzul C., Gondret F., Combes S., de Rochambeau H. 2005. Divergent selection on 63-day body weight in the rabbit: response on growth, carcass and muscle traits. Genet. Sel. Evol., 37: 105-122. https://doi.org/10.1051/gse:2004038Martínez-Álvaro M., Hernández P., Blasco A. 2016. Divergent selection on intramuscular fat in rabbits: Responses to selection and genetic parameters. J. Anim. Sci., 94: 4993-5003. https://doi.org/10.2527/jas.2016-0590Matics Zs., Nagy I., Gerencsér Zs., Radnai I., Gyovai P., Donkó T., Dalle Zotte A., Curik I., Szendrő Zs. 2014. Pannon breeding program in rabbit at Kaposvár University. World Rabbit Sci., 22: 287-300. https://doi.org/10.4995/wrs.2014.1511Milisits G., Romvári R., Dalle Zotte A., Szendrő Zs. 1999. Non-invasive study of changes in body composition in rabbits during pregnancy using X-ray computerized tomography. Ann. Zootech., 48: 25-34. https://doi.org/10.1051/animres:19990103Nagy I., Ibáñez N., Mekkawy W., Metzger Sz., Horn P., Szendrő Zs. 2006. Genetic parameters of growth and in vivo computerized tomography based carcass traits in Pannon White rabbits. Livest. Sci., 104: 46-52. https://doi.org/10.1016/j.livsci.2006.03.009Romvári R., Milisits G., Szendrő Zs., Sørensen P. 1996. Non invasive method to study the body composition of rabbits by X-ray computerized tomography. World Rabbit Sci., 4: 219-224. https://doi.org/10.4995/wrs.1996.298Rouvier R. 1970. Variabilité génétique du rendement a l'abattage et de la composition anatomique de lapins de trois races. Ann Genet. Sel. Anim., 2: 325-346. https://doi.org/10.1186/1297-9686-2-3-325Shemeis A., Abdallah O.Y. 2000. Possibilities of developing favourable body fat partition via selection indexes - application on rabbits. Arch. Anim. Breed., 43: 193-202. https://doi.org/10.5194/aab-43-193-2000Szendrő Zs., Romvári R., Horn P., Radnai I., Bíró-Németh E., Milisits G. 1996. Two-way selection for carcass traits by computerised tomography. In: Proc. 6th World Rabbit Congress, Toulouse, 2, 371-375.Szendrő Zs., Metzger Sz., Nagy I., Szabó A., Petrási Zs., Donkó T., Horn P. 2012. Effect of divergent selection for the computer tomography measured thigh muscle volume on productive and carcass traits of growing rabbits. Livest. Sci., 149: 167-172. https://doi.org/10.1016/j.livsci.2012.07.011Zomeño C., Hernández P., Blasco A. 2013. Divergent selection for intramuscular fat content in rabbits. 1. Direct response to selection. J. Anim. Sci., 91: 4526-4531. https://doi.org/10.2527/jas.2013-636

Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature

[EN] The aim of the study was to examine the effect of hair shearing in growing rabbits reared at high ambient temperature. The live performance and carcass traits of growing rabbits reared at 20°C (not sheared, C, n=50) or at 28°C (not sheared, H, n=50, or sheared at 5, 7 and 9 wk, HS, n=50) were compared. The ambient temperature and relative humidity were 20.5±1.1°C and 54±11% in the 20°C room and 28.8±0.2°C and 35±8% in 28°C room, respectively. Feed intake of H and HS groups decreased by 29.0 and 20.4%, respectively, compared to C rabbits (P<0.001). The same data for weight gain were 24.6 and 16.9% (P<0.001), and for body weight at 12 wk were 16.8 and 11.5% (P<0.001). At the same time, the feed conversion ratio improved (C: 3.53, HS: 3.34, H: 3.31; P<0.001). Nevertheless, the mortality rate of rabbits was not affected by the studied treatment and was overall low (0-4%). No differences were observed in dressing out percentages either (ratio of chilled carcass (CC) to the slaughter weight: 61.6-61.9%). The ratio of liver to CC differed among the experimental groups, with the highest value recorded in C group and the lowest in H group; HS rabbits showed intermediate results (C: 4.86%, HS: 4.27%, H: 3.91%; P<0.001). Lower ratios of fat deposits to reference carcass were also observed in rabbits kept at high ambient temperature (perirenal fat: C: 2.59%, HS: 1.82%, H: 1.60%; P<0.001; scapular fat: C: 0.89%, HS: 0.66%, H: 0.51%; P<0.001). It can be concluded that the negative effect of higher ambient temperature (28 vs. 20°C) on production in growing rabbits can be reduced significantly by hair shearing.En este agradecimieento: "The work was supported by the GINOP-2.3.4-15-2016-00005 project. Publication was supported by the EFOP-3.6.3-VEKOP-16–2017–00008 project. The project is co-funded by the European Union and the European Social Fund"Matics, Z.; Kasza, R.; Gerencsér, Z.; Radnai, I.; Dalle Zotte, A.; Cullere, M.; Szendrő, Z. (2020). Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature. World Rabbit Science. 28(3):161-167. https://doi.org/10.4995/wrs.2020.13164OJS161167283Balnave D. 1972. The effect of temperature and length of exposure on liver composition and hepatic lipogenic enzyme activity in the immature male chick (Gallus domesticus). Comp. Biochem. Physiol., 438: 999-1007. https://doi.org/10.1016/0305-0491(72)90244-1Blasco A., Ouhayoun J. 1996. Harmonization of criteria and terminology in rabbit meat research. Revised proposal. World Rabbit Sci., 4: 93-99. https://doi.org/10.4995/wrs.1996.278Chiericato G.M., Rizzi C., Rostellato V. 1993. Effect of genotype and environmental temperature on performance of the young meat rabbit. World Rabbit Sci., 1: 119-125. https://doi.org/10.4995/wrs.1993.204Chiericato G.M., Ravarotto L., Rizzi R. 1994. Study of the metabolic profile of rabbits in relation to two different environmental temperatures. World Rabbit Sci., 2: 153-160. https://doi.org/10.4995/wrs.1994.232Chiericato G.M., Rizzi C., Rostellato V. 1996. Growth and slaughtering performance of three rabbit genotypes under different environmental conditions. Ann. Zootech., 45: 311-318. https://doi.org/10.1051/animres:19960403Deltoro J., López A.M. 1986. Development of commercial characteristics of rabbit carcasses during growth. Livest. Prod. Sci., 15: 271-283. https://doi.org/10.1016/0301-6226(86)90034-5EC 2010. Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes. Official Journal of the European Union L276: 33-79.Fernández-Carmona J., Cervera C., Sabater C., Blas E. 1995. Effect of diet composition on the production of rabbit breeding does housed in a traditional building and at 30°C. Anim. Feed Sci. Technol., 52: 289-297. https://doi.org/10.1016/0377-8401(94)00715-LFinzi A., Morera P., Kuzminsky G. 1992. Effect of shearing on rabbit bucks performances in hot ambient conditions. J. Appl. Rabbit Res., 15: 489-494.Fuquay J.W. 1981. Heat stress as it affects animal production. J. Anim. Sci., 52: 164-174. https://doi.org/10.2527/jas1981.521164xHermes I.H., Ahmed B.M., Khalil M.H., Salah M.S., Al-Homidan A.A. 1999. Growth performance, nutrients utilization and carcass traits of growing Californian rabbits raised under different ambient temperatures. Egypt. J. Rabbit Sci., 9: 117-138.Jackson R., Rogers A.D, Lukefahr S.D. 2006. Effects of the naked gene on postweaning performance and thermotolerance characters in fryer rabbits: Final results. World Rabbit Sci., 14: 147-155. https://doi.org/10.4995/wrs.2006.559Kovitvadhi A., Chundang P., Thongprajukaew K., Tirawattanawanich C. 2019. Effects of different ambient temperatures on growth performances, digestibility, carcass traits and meat chemical components in fattening rabbits. J. Agriculture, 35: 495-502.Lebas F., Ouhayoun J. 1987. Incidence du niveau protéique de l'aliment, de milieu d'élevage et de la saison sur la croissance et les qualités bouchéres du lapin. Ann. Zootech., 36: 421-432. https://doi.org/10.1051/animres:19870406Lebas F., Coudert P., de Rochambeau H., Thébault R.G. 1997. The rabbit: husbandry, health and production. FAO Anim. Prod. and Health Series No. 21Lukefahr S.D., Ruiz-Feria C.A. 2003. Rabbit growth performance in a subtropical and semi-arid environment: Effects of fur clipping, ear length, and body temperature. Livest. Res. Rural Devel. 15: 2. Available at http://www.cipav.org.co/lrrd/lrrd15/2/luke152.htm Accessed October 2019.Marai I.F.M., Habeeb A.A.M., Gad A.E. 2002. Rabbits' productive, reproductive and physiological performance traits as affected by heat stress: a review. Livest. Prod. Sci., 78: 71-90. https://doi.org/10.1016/S0301-6226(02)00091-XMaya-Soriano M.J., Taberner E., Sabes-Alsina M., Ramon J., Rafel O., Tusell L., Piles M., López-Béjar M. 2015. Daily exposure to summer temperatures affects the motile subpopulation structure of epididymal sperm cells but not male fertility in an in vivo rabbit model. Theriogenology, 84: 384-389. https://doi.org/10.1016/j.theriogenology.2015.03.033Metzger Sz. 2006. Examination on carcass traits and meat quality of rabbit. (in Hung.) Doctoral (Ph.D.) dissertation. pp. 135.NASA https://climate.nasa.gov/Perez J.M., Lebas F., Gidenne T., Maertens L., Xiccato G., Parigi-Bini R., Dalle Zotte A., Cossu M.E., Carazzolo A., Villamide M.J., Carabaño R., Fraga M.J., Ramos M.A., Cervera C., Blas E., Fernández J., Falcão-e-Cunha L., Bengala Freire J. 1995. European reference method for in vivo determination of diet digestibility in rabbits. World Rabbit Sci. 3: 41-43. https://doi.org/10.4995/wrs.1995.239Renaudeau D., Collin A., Yahav S., de Basilio V., Gourdine J.L., Collier R.J. 2012. Adaptation to hot climate and strategies to alleviate heat stress in livestock production. Animal, 6: 707-728. https://doi.org/10.1017/S1751731111002448SAS Version 9.4. 2014. SAS Institute Inc; Cary, NC. Schlolaut W. 1995. Das grosse Buch vom Kaninchen. DLG-Verlag, Frankfurt am Main.Stephan E. 1980. The influence of environmental temperatures on meat rabbits of different breeds. Commercial Rabbit, 8: 12-15.Szendrő Zs., Rashwan R.R., Biró-Németh E., Radnai I., Orova Z. 2007. Effect of shearing of hair in summer on production of rabbit does. Acta Agr. Kapos., 11: 37-42.Szendrő Zs., Papp Z., Kustos K. 2018. Effect of ambient temperature and restricted feeding on the production of rabbit does and their kits. Acta Agr. Kapos., 22: 1-17. https://doi.org/10.31914/aak.2272Verga M., Luzi F., Carenzi C., 2007. Effects of husbandry and management systems on physiology and behaviour of farmed and laboratory rabbits. Horm. Behav., 52, 122-129. https://doi.org/10.1016/j.yhbeh.2007.03.024Zeferino P.C., Moura T.M.A.S.A., Fernandes S., Kanayama S.J., Scapinello C., Sartori R.J. 2011. Genetic group × ambient temperature interaction effects on physiological responses and growth performance of rabbits. Livest. Sci., 140: 177-183. https://doi.org/10.1016/j.livsci.2011.03.02

Hybrid Poly(<i>β</i>‐amino ester) Triblock Copolymers Utilizing a RAFT Polymerization Grafting‐From Methodology

The biocompatibility, biodegradability, and responsiveness of poly(β‐amino esters) (PBAEs) has led to their widespread use as biomaterials for drug and gene delivery. Nonetheless, the step‐growth polymerization mechanism that yields PBAEs limits the scope for their structural optimization toward specific applications because of limited monomer choice and end‐group modifications. Moreover, to date the post‐synthetic functionalization of PBAEs has relied on grafting‐to approaches, challenged by the need for efficient polymer–polymer coupling and potentially difficult post‐conjugation purification. Here a novel grafting‐from approach to grow reversible addition–fragmentation chain transfer (RAFT) polymers from a PBAE scaffold is described. This is achieved through PBAE conversion into a macromolecular chain transfer agent through a multistep capping procedure, followed by RAFT polymerization with a range of monomers to produce PBAE–RAFT hybrid triblock copolymers. Following successful synthesis, the potential biological applications of these ABA triblock copolymers are illustrated through assembly into polymeric micelles and encapsulation of a model hydrophobic drug, followed by successful nanoparticle (NP) uptake in breast cancer cells. The findings demonstrate this novel synthetic methodology can expand the scope of PBAEs as biomaterials

Measurement of velocity profiles in a stratified pipe flow recirculatory shear zone using laser flow visualization

Argonne National Laboratory is studying pipe-flow/plenum thermal-plume interactions induced by a pipe-to-plenum temperature difference. Under these conditions a pipe-flow-generated thermal plume is produced in the plenum and a stratified recirculation zone is produced in the pipe resulting in cold fluid being drawn out of the plenum into the bottom of the horizontal pipe conveying hot fluid into the plenum. These phenomena produce plenum wall and pipe nozzle thermal distributions conductive to detrimental structural thermal stresses. In order to study these phenomena studies are being conducted in the ANL Buoyancy Effects Tank (BET), a 3.41-m/sup 3/ plenum containing cold water which is interfaced with a horizontal transparent pipe conveying hot water into the plenum

Sample size and power calculations for open cohort longitudinal cluster randomized trials.

When calculating sample size or power for stepped wedge or other types of longitudinal cluster randomized trials, it is critical that the planned sampling structure be accurately specified. One common assumption is that participants will provide measurements in each trial period, that is, a closed cohort, and another is that each participant provides only one measurement during the course of the trial. However some studies have an "open cohort" sampling structure, where participants may provide measurements in variable numbers of periods. To date, sample size calculations for longitudinal cluster randomized trials have not accommodated open cohorts. Feldman and McKinlay (1994) provided some guidance, stating that the participant-level autocorrelation could be varied to account for the degree of overlap in different periods of the study, but did not indicate precisely how to do so. We present sample size and power formulas that allow for open cohorts and discuss the impact of the degree of "openness" on sample size and power. We consider designs where the number of participants in each cluster will be maintained throughout the trial, but individual participants may provide differing numbers of measurements. Our results are a unification of closed cohort and repeated cross-sectional sample results of Hooper et al (2016), and indicate precisely how participant autocorrelation of Feldman and McKinlay should be varied to account for an open cohort sampling structure. We discuss different types of open cohort sampling schemes and how open cohort sampling structure impacts on power in the presence of decaying within-cluster correlations and autoregressive participant-level errors

Effect of hair shearing on live performance and carcass traits of growing rabbits under hot ambient temperature

The aim of the study was to examine the effect of hair shearing in growing rabbits reared at high ambient temperature. The live performance and carcass traits of growing rabbits reared at 20°C (not sheared, C, n=50) or at 28°C (not sheared, H, n=50, or sheared at 5, 7 and 9 wk, HS, n=50) were compared. The ambient temperature and relative humidity were 20.5±1.1°C and 54±11% in the 20°C room and 28.8±0.2°C and 35±8% in 28°C room, respectively. Feed intake of H and HS groups decreased by 29.0 and 20.4%, respectively, compared to C rabbits (P<0.001). The same data for weight gain were 24.6 and 16.9% (P<0.001), and for body weight at 12 wk were 16.8 and 11.5% (P<0.001). At the same time, the feed conversion ratio improved (C: 3.53, HS: 3.34, H: 3.31; P<0.001). Nevertheless, the mortality rate of rabbits was not affected by the studied treatment and was overall low (0-4%). No differences were observed in dressing out percentages either (ratio of chilled carcass (CC) to the slaughter weight: 61.6-61.9%). The ratio of liver to CC differed among the experimental groups, with the highest value recorded in C group and the lowest in H group; HS rabbits showed intermediate results (C: 4.86%, HS: 4.27%, H: 3.91%; P<0.001). Lower ratios of fat deposits to reference carcass were also observed in rabbits kept at high ambient temperature (perirenal fat: C: 2.59%, HS: 1.82%, H: 1.60%; P<0.001; scapular fat: C: 0.89%, HS: 0.66%, H: 0.51%; P<0.001). It can be concluded that the negative effect of higher ambient temperature (28 vs. 20°C) on production in growing rabbits can be reduced significantly by hair shearing