The influence of winter nutritional depressions on the growth, reproduction and production of cattle

Abstract

1. During the period May 1948 to May 1952, a study was made of the influence of seasonal fluctuations in the nutritive value of the natural pastures in the Bankenveld region of the Transvaal, on the growth, reproduction and production of cattle. The paired method of investigation was adopted, each heifer maintained on grazing alone having a related counterpart of the same age which received supplementary feeding during the winter months. The former treatment was termed ‘Low plane’, and the latter referred to as the ‘High plane’. Four breeds were included in the investigation, viz. Friesians and Jerseys, and Shorthorns and Afrikaners, thus representative of both dairy and beef types. The latter breed also represented the stock indigenous to South Africa. Initially five pairs per breed were studied, but deaths and other causes depleted the numbers to twenty-eight head after 4 years of investigation.2. Since the investigation formed part of a series of studies which have been in progress at the University of Pretoria and Agricultural Research Institute during the past two decades, the results of which hitherto remained unpublished, a review is provided in the early chapters. To furnish some indication of the natural conditions ruling in the Bankenveld region, the agro-ecological background is discussed, particular attention being paid to physical and nutritional factors. It is shown that for at least 6 months of the year the climate tends to be subtropical, whilst the results of digestion trials on pasture samples, indicated serious nutritional depressions in the natural grazing during winter.

Variação nas medidas corporais e desenvolvimento do trato reprodutivo de novilhas de corte recriadas para o acasalamento aos 18 meses de idade

“…Portanto, o crescimento do esqueleto, representado pela AG (BARKER et al, 1988;COSTA, 2006), é pouco afetado pelo nível nutricional. De acordo com JOUBERT et al (1954), a medida da AG não evidencia retardo no desenvolvimento nem mesmo em períodos de déficit nutricional. Deve-se considerar ainda que os ganhos de peso utilizados nos três grupos do presente trabalho foram relativamente altos, o que também contribuiu para não se verificarem diferenças na GAG das novilhas.…”

“…Entretanto, existem os efeitos da intensidade do ganho de peso (GRASS et al, 1982) e da fase pós-desmame, quando ocorre esse ganho (CRICHTON et al, 1959). Medidas lineares como a altura e o perímetro torácico constituem outros parâmetros de desenvolvimento físico do animal que também são relacionados ao desempenho reprodutivo (JOUBERT, 1954). Destaca-se a relação do perímetro torácico e da relação peso:altura com a condição corporal (THOMPSON et al, 1983) e a alta relação entre altura, peso e idade à puberdade (VARGAS et al, 1998).…”

Variation in the fecundity of roe deer in Britain: effects of age and body weight

“…In mammals, the critical factor by which sexual maturity is advanced or delayed is often variation in maternal body weight, with puberty dependent on some critical threshold body mass (cattle -Joubert 1954, rats -Widdowson et al 1964, humans -Frisch 1984. Furthermore, post-pubertal weight is often a highly influential factor determining subsequent pregnancy success, as has been shown in a variety of cervid species (red deer -Mitchell 1973, Hamilton and Blaxter 1980, Clutton--Brock et al 1983, Albon et al 1986, reindeer Rangifer tarandus -Reiners 1983, roe deer -Gaillard et al 1992.…”

Effet du niveau d'alimentation à la fin de la gestation sur le poids à la naissance des veaux et leur devenir

“…Il en résulte une inévitable sousalimentation lorsque l'ingestibilité et la digestibilité de la ration sont faibles à modérées. Ce phénomène peut être amplifié par une accélération de la vitesse de transit des aliments (Graham et Williams, 1962et Forbes, 1970 la brebis) entraînant parfois une réduction de la digestibilité, mise en évidence chez la vache (Flatt, Moe et Moore, 1969 ;Lamberth, 1969) (Blaxter,1944 ;Joubert,1954 ;Zimmerman et al,1959 ;Wiltbank et al,1962 ;Ridler, Broster et Foot,1963 ;Reid et al, 1964 ;Hight, 1966Hight, ,1968aTudor, 1972 (Bowden, 1974 ;Petit et Remond, 1977 (Mc Carrick et Crowley, 1968 ;Laster, 1974) (Joubert, 1954 ;Corah et al, 1975, 1 r e exp. Wiltbank, 1970 ;Corah et al, 1975) ou totale jusqu'au sevrage (Hight, 1966(Hight, et 1968aFalk et al,1975).…”