RESUMEN
The objective of this field study with an automatic milking system was to evaluate the effects of omitting the dry period on health and productivity during the subsequent lactation in dairy cows. A total of 98 German Simmental cows of six Southern German farms were assigned randomly to two experimental groups: The first group was dried-off 56 days before calving (D for dried-off, n=49), and the second group was milked continuously during this period until calving (CM for continuous milking, n=49). From the latter a third group emerged, including cows that dried-off themselves spontaneously (DS for dried-off spontaneously, n=14). Blood serum values of glucose, ß-hydroxybutyrate (BHBA), non-esterified fatty acids (NEFA) and IGF-1 showed most pronounced fluctuations in D cows. Over the entire study period, the concentrations of BHBA and NEFA were markedly lower in the CM and DS groups. Furthermore, IGF-1 concentration was lowest for D cows and also decrease in back fat thickness was more pronounced. Mean concentration of milk protein was markedly higher in CM and DS cows (3.70% and 3.71%) compared with D cows (3.38%). Owing to the lower 305-day milk yield (-15.6%) and the lower total milk yield (-3.1%), the total amount of produced protein in the subsequent lactation was 2.5% (6.8 kg) lower, although the additional protein amount in CM cows from week -8 to calving was 35.7 kg. The greatest benefit resulted from positive effects on fertility and the lower incidence of diseases: CM cows had their first oestrus 1 week earlier compared with D cows, they also conceived earlier and showed a significantly lower risk of developing hypocalcaemia, ketosis and puerperal disorders. The present study showed that the costs of medical treatment and milk losses were twice as high in D cows, compared with CM and DS cows, and thus the reduced costs because of the more stable health outweighed the financial losses of milk yield by +18.49 per cow and lactation.
Asunto(s)
Crianza de Animales Domésticos/métodos , Bovinos/fisiología , Lactancia/fisiología , Proteínas de la Leche/metabolismo , Leche/química , Ácido 3-Hidroxibutírico/sangre , Animales , Composición Corporal , Industria Lechera/métodos , Ácidos Grasos no Esterificados/sangre , Femenino , Fertilidad , Glucosa/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Leche/metabolismoRESUMEN
The objective of this experiment was to study milk productivity, metabolic adaptation and effect of a short-term feed restriction (FR) on key performance indicators during early lactation in cows classified according to energy-corrected milk (ECM) yield and milk protein concentration. Twenty-three multiparous Holstein-Friesian cows were categorized in four groups according to respective averaged values on Days 23-25 postpartum: high ECM yield and high protein concentration; low ECM yield and low protein concentration; high ECM yield and low protein concentration and low ECM yield and high protein concentration. Dry matter intake was reduced to 68.3% for three subsequent days. Our results showed that short-time FR in early lactation succeeded in enhancing energy deficit of cows in all groups. Milk fat, milk protein and lactose concentrations as well as milk fat yield were not influenced by FR. Several hepatic genes encoding for enzymes involved in catabolism of amino acids, ß-oxidation, gluconeogenesis and ketogenesis as well as mRNA encoding for insulin receptor showed increased transcript abundances after FR, primarily in cows with high milk yield and low milk protein concentration.