On the thyroid morphology and the level of milk yield among the progeny of goitrous and apparently normal cows

Authors

• Vappu Kossila Department of Animal Husbandry, University of Helsinki

DOI: https://doi.org/10.23986/afsci.71740

Abstract

The thyroid morphology and the level FCM yield were studied in 84 dam-daughter pairs discarded from the Ayrshire herd of the Viik Experimental Farm. Data was divided into three groups according to the thyroid weight of the dam: less than 30 g in group I, from 30 to 50 g in group II, and 50 g or over in group III. The following mean values were obtained for the dams and their daughters: thyroid weight in grams: I 24.17 and 21.07, II 38.13 and 24.51, III 61.22 and 31.58; thyroid weight in grams per 100 kg corrected body weight (BRT): I 4.55 and 4.18, II 7.42 and 4.92, III 11.46 and 6.29; absolute amount of epithelial tissue contained per thyroid in grams (Eg); I 4.81 and 4.13, II 5.37 and 4.81, III 6.96 and 5.61; corrected body weight in kg: I 497 and 474, II 507 and 462, III 517 and 489; age in months: I 85.6 and 61.8, II 107.7 and 59.8, III 119,2 and 64.0; mean FCM yield in kg during productional lifetime; I 14.64 and 15.06, II 13.93 and 13.78, III 13.48 and 13.94; FCM yield in kg per 500 kg corrected body weight: I 14.73 and 15.87, II 13.74 and 14.92, III 13.04 and 14.28. The lower thyroid weight in daughters was apparently due to their lower body weight and age as well as to the higher iodine content of the ration. The dam-daughter correlations in respect of the thyroid weight, the BRT, the Eg, the corrected body weight, age, and FCM-yield were: I 0.13, 0.07, 0.27, 0.22, 0.25, and 0.42**, II + III 0.40**, 0.41**, 0.24, 0.07, 0.15, and 0.22, I + II + III 0.47***, 0.49***, 0.30**, 0.13, 0.16, and 0.35***. The results of this study indicate a) that the incidence of goiter was higher in the progeny of goitrous than in that of normal dams, b) that the incidence of goiter in the daughters decreased if the goitrous dam received supplemental iodine during the gestation period from which the daughter was born, c) that a heavier thyroid weight resulted in a lower FCM yield.