Age in Brahman cattle (Zebu) observed by theelh replacement

Abstract

A statistical study is presented in this paper dealing with the average time at which the replacement of the temporary incisors teeth by the permanent ones is performed in Brahman (Zebu) cattle. Observations were made inicially during the Shows of Bauru (S. Paulo State, April 1946), Uberaba (Minas Gerais State, April 1946) and Ribeirão Preto (S. Paulo State, July 1946). Various examinations were accomplished on private farms at Taquaritinga (S. Paulo State, July 1946), Bauru (S. Paulo State, November 1946) and in the cattle exhibited during the Nacional Shows of S. Paulo (S. Paulo State, October 1946) and Belo Horizonte (Minas Gerais State, August 1947). Data were taken of 708 cattle, from which 428 were considered fitable for examination. Animals without change, at less than 18 months of age; those with eight teeth and more than five years, finally, individuals out of the Herd Book were eliminated. The limits of age were taken from MAGLIANO’s table because of its current use. With the purpose of establishing the time at which the first temporary incisors are replaced, all the specimens having 18 months or older, without change, were picked out. Individual records indicating breed, name, sex and permanent incisors erupted were organized. The change was considered done, since one of the incisors corresponding to her, of any side, had erupted. The real age was obtained through the examination of Herd Books and private record books. Among the 428 cattle gathered for the study, 237 were Gir: 113 males and 124 females; 191 were Nellore (Ongole) from which 51 males and 140 females.The data were catalogued as to breed, change and sex; by means of a statistical study, the AA verified that the breed, and sex differences were of no statistical significance, thus, permiting the addition of all variants into one mean. The conclusions are the following:

1.°) The replacement of the deciduous first incisors does not occurs until 661.3 ± 11.5 days (22 months) in Gir and before 690.9 ± 8.4 days (23 months) in the Nellore (Ongole), males and females considered all together. Gir and Nellore (Ongole) breeds offered a general mean equal to: 671.7 ± 2.6 days (22.4 months).

2.°) The change of the first temporary incisors in Gir cattle averaged 843.1 ± 36.5 days in males (28.1 months) and 827.8 ± 30.7 days (27.6 months) in females; i. e. jointly 833.9 ± 28.4 days (27.8 months). The Nellore (Ongole) changes the first temporary incisors at 809.6 ± 21.3 days (27 months) in males and at 875.7 ± 16.4 days (29.2 months) in females; the general mean reaches 859.9 ± 13.5 days (28.7 months). The whole mean for Gir and Nellore breeds, both males and females, was 845.2 ± 11.6 days (28.2 months).

3.°) Following the same order, the values concerning the replacement of the second incisors were: Gir — Males: 1013.4 ± 27.2 days (33.8 months); females: 1099.4 ± 39.2 days (36.6 months); total: 1056.4 ± 24.5 days (35.2 months). Nellore — Males: 1049.5 ± 21.1 days (35 months); females: 1069.5 ± 27.4 days (35.6 months); global: 1065.6 ± 22.4 days (35.5 months). Both breeds, jointly, presented: 1061.3 ± 8.2 days (35.4 months).

4.°) The change of the second incisors occurs as follows: Gir — Males: 1229.6 ± 39.0 days (41 months); females: 1202.9 ± 49.9 days (40.1 months); global: 1218.0 ± 30.6 days (40.6 months). Nellore — Males: 1221.8 ± 63.1 days (40.7 months); females: 1333.6 ± 35.8 days (44.5 months); global: 1304.1 ± 31.8 days (43.5 months). Both breeds, jointly, presented: 1257.0 ± 22.8 days (41.9 months).

5.°) The substitution of the corners can be summed up thus: Gir — Males: 1440.2 ± 80.5 days (48 months); females: 1634.5 ± 88.1 days (54.5 months); global: 1555.0 ± 64.9 days (51.8 months). Nellore — Males: 1536.6 ± 33.6 days (51.2 months); females: 1474.3 ± 35.5 days (40.1 months); global: 1498.0 ± 25.6 days (49.9 months). Both breeds, jointly, presented: 1522.0 ± 31.0 days (50.8months).

6.°) The teething precocity considered independently of the economic production was appreciated under three different aspects refering to beginning, duration and limit of the changing period:

a) the beginning of the substitution of the deciduous by the permanent teeth attains a delay unknown in any other breed;

b) the average duration of the changing period in Gir and Nellore cattle shows the same lenght as those of precocious cattle classified in different grades;

c) the limit of the changing period occurs in Gir and Nellore cattle with a worthy gain of time as compared with the tardy individual cattle. Briefly, the Gir and Nellore cattle begin with valuable delay the change of the first temporary incisors and through a process of acceleration in the following changes, restores the equilibrium, showing eight teeth with gain of time in comparison to tardy individual cattle.