B. K. Ahunu

University of Ghana, Accra, Greater Accra Region, Ghana

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Publications (5)1.21 Total impact

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    ABSTRACT: Calf records for a 30 year period (1965–1995) on purebred and crossbred Ndama and West African Shorthorn (WASH) cattle and their crosses with Santa Gertrudis or Red Poll were analyzed to determine factors affecting birth and weaning weights and to estimate genetic parameters. Male calves weighed heavier (P < 0.05) at birth and at weaning. Similarly period (year grouping) significantly influenced birth and weaning weights of calves. Season of birth did not influence calf weight at birth but significantly affected calf weaning weights. Purebred calves were similar in weight at birth and at weaning. Santa Gertrudis crossbreds weighed heavier than Red Poll crossbreds at birth only but not at weaning. Generally the poor level of nutrition of the natural pasture did not permit improved weaning weights in calves which were heavier at birth. Additive direct heritability estimates were 0.45 ± 0.08 for birth weight and 038 ± 0.18 for weaning weight. Moderate genetic correlation (0.48) between birth and weaning weights indicates that selection for one trait would lead to moderate positive correlated response in the other trait. Due to negative genetic correlation (−0.29 ± 0.16) between direct and maternal effects for weaning weight, and moderate heritabilities for both traits, selection for both the direct and maternal components of preweaning traits is advised.
    Livestock Production Science. 01/1997;
  • B. K. Ahunu, R. Osei-Amponsah
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    ABSTRACT: Ahunu, B.K. and Osei-Amponsah, R. 1996. Influence of terminal age of weighing on growth curve parameters in N'dama cattle. J. Appl. Anim. Res., 10: 49–58.
    Journal of Applied Animal Research 01/1996; 10(1):49-58. · 0.12 Impact Factor
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    ABSTRACT: Crossbreeding data involving Ghana Shorthorn, Sokoto Gudali and their Jersey F1s and backcrosses collected over a 16-year period were analysed to estimate additive and heterotic effects for milk production, reproduction and calf growth traits. Sokoto Gudali was significantly better than Ghana Shorthorn in all milk production traits. Calving interval and annualized milk production were better in Gudali than in the Shorthorn. The F1s had higher lactation milk yield, milked longer, produced their first calves earlier and had shorter dry periods and calving intervals than their corresponding purebreds. However, genotype was not significant for number of services per conception. Both F1s had higher average daily gain and weaning weight than their corresponding purebreds. Sokoto Gudali backcross (Jersey × F1) was significantly (P < 0·05) better than the F1 in lactation length. However, in Gudali crosses, there was no advantage in increasing the proportion of Jersey genes beyond 0·5 for milk production traits. Additive effects were significantly (at least P < 0·05) lower in the Shorthorn and the Gudali than in Jersey for milk production traits except proportion of butterfat. Heterosis estimates were significant (P < 0·01) for milk production traits for the Shorthorn but not for the Gudali. Heterotic effects were large and significant (at least P < 0·05) in improving annualized milk production in Shorthorn crosses, whilst none of the heterotic effects for reproductive traits was significant. At both 0 and 0·5 levels of Jersey inheritance, the Gudali was superior (P < 0·01) to the Shorthorn in birth weight, weaning weight and pre-weaning average daily gain. Heterotic effects for calf traits were positive and much larger in Gudali crosses than in Shorthorn crosses. In general, backcrosses were, at best, similar to the F1s implying that upgrading these indigenous breeds beyond 0·5 European inheritance may not be desirable.
    Animal Production. 07/1994; 59(01):21 - 29.
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    ABSTRACT: Calf records on 621 West African Shorthorn (WASH) and 3 grades of Jersey x WASH crossbreds were analysed for the effects of the level of Jersey breeding and other factors on birth weight, 205-day weaning weight and average daily gain (ADG). Crossbred calves were significantly (P < 0.01) heavier at birth than purebred WASH and birth weights increased with increasing level of Jersey breeding. No significant differences were established for 205-day weaning weight, however ADG declined with increasing level of Jersey breeding suggesting possible problems of adaptation for calves of over 75% Jersey breeding. Age of dam effect was significant and linear (P < 0.0001) for birth weight and significant and quadratic (P < 0.01) for weaning weight and ADG, with values increasing from 3-year old dams to a peak in 7 year old dams.
    Tropical Animal Health and Production 02/1993; 25(1):33-40. · 1.09 Impact Factor
  • P.F Arthur, B.K Ahunu
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    ABSTRACT: Eight body measurements including body weight were recorded on 45 crossbred West African hair sheep of 2 breed types at birth and at various age intervals to characterize and describe changes in size and shape with time in the 2 breed types using least squares, principal components and discriminant analyses. Differences in breed type and sex of lamb were not significant (P > 0.05) for body weight at all ages up to 32 weeks. Season of birth effect on body weight was not significant (P > 0.05) for birth weight. At subsequent ages, however, lambs born early in the rainy season were significantly (P < 0.05) heavier than those born in the middle of the season. Discriminant analyses, however, showed significant differences between the 2 breed types. The results were discussed for data recorded at birth, 8, 16 and 32 weeks of age. As distinguishing characteristics, different body features seem to be more prominent at different ages in the growing sheep. This is a reflection of the differences in growth rates of the different parts of the body considered. Characterization of the 2 breed types at different ages is provided. At birth 2 principal components were extracted for each breed type. The first principal component (PC1) accounted for over 60% of the variation in the dependency structure and provided a measure of general body size in each breed type. The second principal component (PC2) accounted for over 13% of the variation and provided a linear measure of head size and shape in each breed type. At 4 and 32 weeks, only one principal component (PC1) was extracted for each age and breed type. In each case the component accounted for 70% or more of the variation in the dependency structure and it represented general body size. The results suggest that while at older ages head size and shape may not be important when body size is being considered, they are of great importance at birth. This is consistent with the fact that at birth the head is big in proportion to the body but is small in proportion at older ages.RésuméOn a enregistré à la naissance et à différents âges 8 mesures corporelles, dont le poids vif, sur 45 moutons croisés de 2 races de type Afrique de l'Ouest à poils, afin de caractériser et de décrire l'évolution de leur taille et de leur forme. On a utilisé des analyses en moindres carrés, en composantes principales de discriminantes. Jusqu'à l'âge de 32 semaines, on n'a pas observé de différences significatives selon la race et le sexe. La saison de naissance n'a pas eu d'influence significative (P > 0,05) sur le poids à la naissance. Cependant, par la suite, les agneaux nés au début de la saison des pluies sont significativement (P < 0,05) plus lourds que ceux nés au milieu de cette saison. L'analyse discriminante montre des différences entre les deux races. Les résultats aux âges de 8, 16 et 32 semaines sont discutés. Les caractéristiques corporelles les plus discriminantes varient avec l'âge, traduisant les différences dans la vitesse de croissance entre les différences parties du corps. Elles sont présentées pour les deux races à différents âges. A la naissance, deux composantes principales ont été mises en évidence pour chaque race. La première (PC1) explique plus de 60% de la variation et fournit une mesure du format de chaque race. La deuxième composante principale (PC2) explique 13% de la variation et fournit une mesure linéaire de la taille et de la forme de la tête de chaque race. Aux àges de 4 et de 32 semaines, on n'a isolé qu'une seule composante principale (PC1) pour chaque race. Elle rend compte de 70% ou plus de la variation et représente le format global. Il ressort que la taille et la forme de la tête sont d'une grande importance à la naissance mais non ensuite. Ce doit traduire le fait que la proportion de la tête dans le corps est élevée à la naissance et faible ensuite.ZusammenfassungBei 45 Kreuzungstieren zweier Zuchttypen der Westafrikanischen Haarschafe wurden 8 Körpermaβse einschlieβlich des Körpergewichts zum Zeitpunkt der Geburt und bei verschiedenen Altersstufen registiert um unter Verwendung von Least-squares, Hauptkomponente- und Diskriminanzanalysen die zeitabhängigen Gröβen und Gestaltsveränderungen der beiden Zuchttypen zu charakterisieren und zu beschreiben. Hinsichtlich des Körpergewichtes waren die Unterschiede zwischen Zuchttypen und Geschlechtern in jeder Altersstufe bis zum Alter von 32 Wochen nicht signifikant (P > 0,05). Der Einflugb der Jahreszeit auf das Körpergewicht war für das Geburtsgewicht nicht signifikant (P > 0,05). Mit zunehmendem Alter waren jedoch Lämmer, die am Anfang der Regenzeit geboren worden waren, signifikant schwerer (P < 0,05) als Lämmer, die in der Mitte dieser Jahreszeit geboren wurden. Die Diskriminanzanalysen weisen jedoch signifikante Unterschiede zwischen den beiden Rassetypen aus. Diese Ergebnisse wurden für die bei der Geburt und im Alter von 8, 16 und 32 Wochen erhobenen Daten diskutiert. Als Untercheidungs- Charakteristikum scheinen verschiedene Körpermerkmale bei verschiedenen Altersstufen der wachsenden Schafe mehr herauszuragen. Dies ist eine Auswirkung der unterschiedlichen Wachstumsraten der verschiedenen berücksichtigten Körperteile. Für die zwei Zuchttypen wurde eine Körpercharakterisierung bei unterschiedlichen Altersstufen vorgenommen. Zum Zeitpunkt der Geburt wurden zwei Hauptkomponenten für jeden Zuchttyp extrahiert. Die erste Hauptkompnente (PC1) ist für mehr als 60% der Variation der Abhängigkeitsstruktur verantwortlich und lieferte ein Maβ für die allgemeine Körpergröβe bei jedem Zuchttyp. Die zweite Hauptkomponente (PC2) erklärte über 13% der Variation und lieferte ein lineares Maβ für die Kopfgröβe und -form bei jedem Zuchttryp. Im Alter von 4 und 32 Wochen wurde nur eine Hauptkomponente (PC1) für jede Alterstufe und jeden Zuchttyp extrahiert. In jedem Fall erklärte die Komponente über 70% der Variation der Abhängigkeitsstruktur und war repräsentativ für die allgemeine Körpergröβe. Die Ergebnisse deuten an, daβ mit zunehmendem Alter, im Gegensatz sum Zeitpunkt der Eburt, Kopfgröβe und -form für die Untersuchung der Körpergröβe nicht wichtig sind. Dies stimmt mit der Tatsache überein, daβ der Kopf zum Zeitpunkt der Geburt im Verhältnis zum übrigen Körper groβ ist, was bei höherem Alter nicht mehr der Fall ist.
    Livestock Production Science. 03/1989;