Fatoriais fixos desbalanceados: uma analise mal compreendida.

Poucos sao os usuarios de aplicativos estatisticos que sabem analisar adequadamente fatoriais desbalanceados, pois compendios introdutorios nao tratam do assunto em detalhe. Este trabalho visa a explanar a pesquisadores de ciencias agrarias as diferencas entre os principais programas. Mostra-se como testar hipoteses de interesse relativas a medias populacionais, em modelos com fatores qualitativos e quantitativos. Enfatizam-se os perigos de empregar cegamente os aplicativos sem antes conhecer as hipoteses por eles testadas.199

Growth, carcass and meat quality traits of straightbred and crossbred botucatu rabbits

[EN] The objective was to evaluate the effects of genetic group and age on growth, carcass, and meattraits of rabbits. A total of 144 straightbred Botucatu and White German Giant x Botucatu crossbred rabbitswere involved. Rabbits were weaned at 35 d and sequentially slaughtered, four per genetic group x sexcombination, at: 42, 49, 56, 63, 70, 77, 84 and 91 d. A 2-2 factorial arrangement was employed in a completelyrandomized design with repeated measures for growth traits, and a split-plot for carcass and meat traits.Crossbred rabbits were heavier (2032 vs. 1962 g; P<0.01), consumed more feed (143.5 vs. 131.0 g/d; P<0.01),and presented higher slaughter weight (2169 vs. 2093 g; P=0.02) and dressing percentage (59.0 vs. 58.2%;P=0.07) than straightbreds throughout the experiment. No difference between genetic groups was detectedfor feed conversion and empty gastrointestinal weight corrected for slaughter weight (SW). Crossbredsshowed higher skin weight (308.2 vs. 299.7 g; P=0.06) and distal parts of leg weight (75.7 vs. 71.4 g; P<0.01),both corrected for SW. No genetic group effect was detected on dissectible fat and hind part weights. Chilledcommercial carcass (1284 vs. 1229 g; P=0.02), chilled reference carcass (1036 vs. 1000 g; P=0.06), fore part(297.9 vs. 283.3 g; P=0.01) and loin (308.7 vs. 295.5 g; P=0.05) were heavier in crossbreds than in straightbreds,but these differences were attributed to differences in SW. Uncorrected weights of head, kidneys, liver andthoracic viscera were higher in the crossbred group, but only head (116.6 vs. 113.6 g; P=0.06) and thoracicviscera (30.4 vs. 28.6 g; P=0.01) were, in fact, proportionately heavier in crossbreds than in straightbreds. Noeffect of genetic group was detected on meat to bone ratio, muscle ultimate pH and chemical composition of theLongissimus dorsi muscle. All traits, except for ash and fat contents of the Longissimus muscle, showed ageeffects (P<0.01). Crossbreeding may be recommended for the production of whole commercial carcasses, butit is not clearly advantageous for the production of retail cuts. Slaughter should take place between 63 and 70d of age for both genetic groups.This research received financial support from the “Fundação de Amparo à Pesquisa do Estado de São Paulo” (FAPESP), Brazil. Elaine Bianospino received a scholarship from CAPES, Brazil. The authors thank Mrs. I. F. Arruda, M. C. Francisco and C. B. do Nascimento for technical assistance.Bianospino, E.; Wechsler, F.; Fernandes, S.; Roça, R.; Moura, A. (2006). Growth, carcass and meat quality traits of straightbred and crossbred botucatu rabbits. World Rabbit Science. 14(4). https://doi.org/10.4995/wrs.2006.563SWORD14

DAM AND LITTER INBREEDING AND ENVIRONMENTAL EFFECTS ON LITTER PERFORMANCE IN BOTUCATU RABBITS

[EN] The purpose of this study was to evaluate the effects of the inbreeding of the dam (Fd) and of the litter (F1), parity of dam, and month and year of birth on number of young born alive (NBA) and weaned per litter (NW), total litter weaning weight (LWW), mean weaning weight (MVVW) and litter pre-weaning mortality rate (LM) in Botucatu rabbits. Data on 1,065 litters were collected from 1992 to 1994 at the UNESP rabbitry located in Botucatu, SP, Brazil, and analysed by least-squares method. Litters were weaned at 30 days of age. Values of Fd and F1 ranged from zero to 0.3309 and averaged 0.0717 ± 0.0015 and 0.0979 ± 0.0018, respectively. The overall means and standard-errors of NBA, NW, LWW, MWW, and LM were 7.458 ± 0.076, 5.869 ± 0.067, 3576 ± 36 g, 626.6 ± 3.4 g, and 0.1954 ± 0.0063, respectively. Year and month of birth influenced MWW (P < 0.001) and tended to affect LWW (P < 0.07). Parity number affected (P < 0.001) NBA, NW and LWW. The first litter of a female presented (P < 0.05) lower NBA NW, and also LWW when individually compared to parities two to five. The inbreeding coefficient of the dam showed a negative linear association with NBA (P < 0.001 ), NW (P < 0.001 ), LWW (P = 0.007), and MWW (P < 0.001 ), but not with LM (P = 0.576), suggesting that the reduction in NW reflected a decrease in NBA but notan increase in LM. lt was predicted that for ea ch increment of 1 O % in F d, a corresponding reduction of 0.805 young born, 0.589 young weaned, and 211 g in LWW were observed, while MWW increased by. 29.1 g. The reduction in NW (10.0 % of the overall mean of~the trait) was proportionally greater !han the reduction in LWW (5.9 % of the overall mean of the trait), providing a partial explanation for the increase in MWW. No effect of F1 (P > 0.05) was detected for any litter performance traits.[FR] Le but de cette étude a été d'évaluer les effets de la consanguinité des femelles (Fd) et des portées F1), de la parité des femelles et du mois et de l'année de naissance sur le nombre de lapereaux nés vivants (NBA) et sevrés (NW) par portée, du poids total de la portée au sevrage (LWW) du poids moyen au sevrage (MWW) et du taux de mortalité au sevrage (LM) chez les lapins de Botucatu. Les données ont été récoltées sur 1065 portées entre 1992 et 1994 dans l'élevage de l'UNSEP a Botucatu, SP, au Brésil, et analysées par la méthode des moindres carrés. Les portées ont été sevrées a 30 jours d'í3ge. Les valeurs de Fd et de F1 vont de zéro a 0,3309, avec une moyenne de 0,0717 ± 0,0015 et 0,0979 ± 0,0018 respectivement. Les moyennes générales et les écarts types de NBA, NW, LWW, MWW, et LM son! de 7,458 ± 0,076, 5,869 ± 0,067, 3576 ± 36 g, 626,6 ± 3,4 g, et O, 1954 ± 0,0063 respectivement. L'année et le mois de naissance influencent MWW (P<0,001) et tendent a affecter LWW (P<0,07). Le numéro de parité affecte NBA, NW et LWW (P<0,001). Les premiéres portées des femelles ont un nombre de lapereaux nés vivants et sevrés plus faible (P<0,05) ; il en va de meme pour le poids de portée au sevrage quand il est comparé individuellement aux parités de 2 a 5. Le coefficient de consanguinité des femelles montre une liaison linéaire négative avec le nombre de nés vivants (P<0,001), NW (P < 0,001), LWW (P = 0,007), et MWW (P< 0,001), mais pas avec le taux de mortalité naissance-sevrage (P = 0,576), suggérant que la diminution de nombre de sevrés découle de celle des nés vivants et non d'une augmentation de la mortalité. Pour chaque augmentation de 10% du taux de consanguinité Fd, il y a une réduction correspondante de 0,805 lapereau né, 0,589 lapereau sevré et 211 g du poids de portée au sevrage tandis que le poids moyen au sevrage augmente de 29, 1 g. La réduction de NW (10% de la moyenne générale de ce paramétre) est proportionnellement plus grande que la diminution de LWW (5,9% de la moyenne générale du paramétre) donnant une explication partielle de l'augmentation de MWW. Aucun effet de F1 n'a été détecté pour aucun des critéres de performance de la portée.Moura, A.; Polastre, R.; Wechsler, F. (2001). DAM AND LITTER INBREEDING AND ENVIRONMENTAL EFFECTS ON LITTER PERFORMANCE IN BOTUCATU RABBITS. World Rabbit Science. doi:10.4995/wrs.2000.433SWORD08