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The aim of the present study was to derive individual methane (CH 4 ) emissions in ewes separated in CH 4 respiration and eructation traits. The generated longitudinal CH 4 data structure was used to estimate phenotypic and genetic relationships between ewe CH 4 records and energy efficiency indicator traits from same ewes as well as from their lambs (intergenerational perspective). In this regard, we recorded CH 4 emissions via mobile laser methane detector (LMD) technique, body weight (EBW), backfat thickness (BFT) and body condition score (BCS) from 330 ewes (253 Merinoland (ML), 77 Rhön sheep (RH)) and their 629 lambs (478 ML, 151 RH). The interval between repeated measurements (for ewe traits and lamb body weight (LBW)) was 3 weeks during lactation. For methane concentration (µL L −1 ) determinations in the exhaled air, we considered short time measurements (3 min). Afterwards, CH 4 emissions were portioned into a respiration and eructation fraction, based on a double normal distribution. Data preparation enabled the following CH 4 trait definitions: mean CH 4 concentration during respiration and eructation (CH 4 r+e ), mean CH 4 concentration during respiration (CH 4 r ), mean CH 4 concentration during eructation (CH 4 e ), sum of CH 4 concentrations per minute during respiration (CH 4 rsum ), sum of CH 4 concentrations per minute during eructation (CH 4 esum ), maximal CH 4 concentration during respiration (CH 4 rmax ), maximal CH 4 concentration during eructation (CH 4 emax ), and eructation events per minute (CH 4 event ). Large levels of ewe CH 4 emissions representing energy losses were significantly associated with lower LBW (P <0.05), lower EBW (P <0.01) and lower BFT (P <0.05). For genetic parameter estimations, we applied single-and multiple-trait animal models. Heritabilities and additive genetic variances for CH 4 traits were small, i.e., heritabilities in the range from <0.01 (CH 4 r+e , CH 4 r , CH 4 rmax , CH 4 esum ) to 0.03 (CH 4 rsum ). We estimated negative genetic correlations between CH 4 traits and EBW in the range from −0.44 (CH 4 r+e ) to −0.05 (CH 4 rsum ). Most of the CH 4 traits were genetically negatively correlated with BCS (−0.81 for CH 4 esum ) and with BFT (−0.72 for CH 4 emax ), indicating same genetic mechanisms for CH 4 output and energy efficiency indicators. Addressing the intergenerational aspect, genetic correlations between CH 4 emissions from ewes and LBW ranged between −0.35 (CH 4 r+e ) and 0.01 (CH 4 rsum , CH 4 rmax ), indicating that breeding on reduced CH 4 emissions (especially eructation traits) contribute to genetic improvements in lamb weaning performance.

No abstract

A total of 391 goats from 13 dairy flocks from all Costa Rican regions were analyzed for Toxoplasma gondii-, Neospora caninum-and Coxiella burnetii-related seroprevalence by enzyme-linked immunosorbent assays (ELISA). Additionally, a risk factor analysis for these parasitic infections was performed based on a questionnaire considering several environmental and housing/management factors. A total of 62.1% (243/391) of individual serum samples revealed seropositive for T. gondii, 7.9% (31/391) for N. caninum, and 1.8% (7/391) for C. burnetii. At herd level, the overall seroprevalence for T. gondii was 100%, for N. caninum 69.2% and for C. burnetii 7.7%. However, no clinical signs related to toxoplasmosis, neosporosis or Q fever were apparent in these flocks. T. gondii-related risk factors were the contact with cats (OR = 3.44; CI 95%; 2.0-5.91), dogs (OR = 5.75; CI 95%; 2.84-11.66), and white-tailed deer (Odocoileus virginianus) (OR = 0.15; CI 95%; 0.08-0.26) within or around the farms. The presence of reproductive males in each flock (OR = 0.32; CI 95%; 0.14-0.74) and the coexistence of sheep (OR = 0.46; CI 95%; 0.2-1.08) and cattle (OR = 5.94; CI 95%; 1.70-20.78) revealed as protective and risk factors respectively for N. caninum infections. This study determined for the first time the seroprevalences of N. caninum, T. gondii and C. burnetii in Costa Rican goat flocks. Particularly, the high withinherd seroprevalences determined for T. gondii requires further surveillance to complement these findings.

ZusammenfassungEine Möglichkeit, das Kopieren von Schwänzen bei Schafen in der Zukunft zu vermeiden, stellt die Zucht auf Kurzschwänzigkeit dar. Dies erscheint vielversprechend, da die Urform der Hausschafe, der Mufflon, einen relativ kurzen schmalen Schwanz besitzt. Es kann folglich davon ausgegangen werden, dass längere Schwänze ein Resultat der Domestikation sind. Ältere Untersuchungen zur Heritabilität der Schwanzlänge beim Hausschaf konnten rasseabhängig Werte von 0,38 bis 0,77 nachweisen. Bei der Zucht auf Kurzschwänzigkeit muss jedoch darauf geachtet werden, dass keine Missbildungen der Wirbelsäule und benachbarter Strukturen auftreten. Bis in diesem Bereich ein Zuchtfortschritt erreicht ist, können durch Managementmaßnahmen die negativen Auswirkungen länger bewollter Schwänze (z. B. Myiasisbefall, Dermatitis) gemindert werden. Dazu gehören die Vermeidung von Durchfällen durch eine ausgewogene wiederkäuergerechte Fütterung, ein betriebsspezifisch angepasstes nachhaltiges Parasitenmanagementprogramm und die gezielte Schur unkupierter Schwänze.