Basal levels and diurnal variations of some hormones and metabolites in blood of dairy cows treated daily with rbSTin early and late lactation

• Main Authors: Jurgen Blum, Rosanna Lombardelli, Fiorenzo Piccioli-Cappelli, Giuseppe Bertoni
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2010-01-01
• Series: Italian Journal of Animal Science
• Subjects: Somatotropin, Dairy cow, Metabolic hormone, Metabolite
• Online Access: http://www.aspajournal.it/index.php/ijas/article/view/266
• ISSN: 1594-4077; 1828-051X

<p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">The variations of basal value (before morning feeding at 3-4 days interval) and daily pattern (on 4and 18day of treat-<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">ment with 8 blood collections within 24h) of hormones and metabolites were studied in four dairy cows; 2 in early and<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">2 in late lactation, which were alternatively injected daily for a period of 21 days with 26.3 mg rbST or saline.&nbsp; The rbST<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">injection significantly increased the basal and daily levels of GH, IGF-I in both stages of lactation. Daily levels of NEFA<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">were significantly increased by rbST in both stages of lactation and their variations, due to the effect of meals, were coun-<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">teracted by the rbST; the higher level of NEFA allowed a greater sparing of glucose, the blood level of which resulted<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">higher (P<0.05) in late lactation (mainly for less lactose yield), as well as a sparing of amino acid that resulted in a lower<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">blood urea level (P<0.05, only in late lactation). Moreover, these metabolic changes in late lactating cows, and in par-<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">ticular the high availability of glucose, determined a significantly higher blood level of insulin and T3, and lower level of<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">glucagon. Despite the similar GH, IGF-I and NEFA increases observed in the cows treated in early and late lactation, other<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">metabolic and endocrine consequences resulted more evident in late lactation. Furthermore, some of these variations<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">were affected by the forage meals. It can be concluded, therefore, that the changes occurring in the blood subsequent<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">to a rbST treatment are not equal to those which occur at the start of lactation; moreover, they are affected by the daily<span style="font: 12.0px Helvetica;">&nbsp;</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 8.0px Verdana;">feeding pattern and perhaps by the stage of&nbsp; lactation.<span style="font: 12.0px Helvetica;">&nbsp;</span></p><div><span style="font-family: Helvetica, Arial, Helvetica, sans-serif; font-size: small;"><span style="font-size: 12px;"><br /></span></span></div>