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Feeding and reproduction strategies in dairy cows

Reproduction has been on the wane for the past 30 years in numerous dairy systems. The literature on the relationship between diet and reproduction and/or dairy productivity and reproduction often focuses on a single stage in the reproductive process (recovery of cyclicity or embryonic mortality), and the results can be conflicting. A better understanding of the effects of dairy production and controlled body reserves on all of the stages of the reproductive process could contribute to physiologists’ knowledge of underlying mechanisms, and help livestock specialists improve breeding strategies according to the objectives of a given production system.

Cette vache de race Normande ruminant illustre les relations pâturage et bien-être animal.. © INRA, PEYRAUD Jean-Louis
By Sylvie André, translated by Inge Laino
Updated on 06/11/2013
Published on 04/16/2013

The goal of this study was to evaluate the reproduction of dairy cows subject to synchronized calving in winter using different feeding strategies for two different races: Holstein cows (dairy) and Norman cows (dual-purpose meat and dairy). The combination of a tri-weekly dose of progesterone in milk, monitoring when the animals are in heat, and a diagnosis of gestation allowed the successive stages in the reproductive process - cyclicity, heat, fertility - to be studied. Each year for three consecutive years, the consequences of a High- or Low-level food intake were evaluated in each stage for 72 cows (36 Holstein and 36 Norman). The High-level group was given a full ration consisting of 55% maize ensilage, 15% dehydrated alfalfa, 30% concentrates in winter and 4kg of concentrates during grazing. The Low-level group was fed without concentrates: 50% grass ensilage and 50% partially wilted ensilage in winter, followed by grazing grass alone.

The Low-level group produced less milk over 44 weeks but shed more weight after calving than the High-level group (5,207kg vs 7,457 kg, -1.28 vs -0.96 fattening score). The Norman cows produced less milk and shed less weight than the Holstein cows. Diet did not have a significant effect on cyclicity but had notable effects on heat in both races, and on fertility in the Holstein cows. Ovulation was easier to detect in the Low-level group (74% vs 59%). In the Holstein race, after the first and second inseminations, non-fertilization or early embryonic mortality was significantly more prevalent in the Low-level group than in the High-level group (52% vs 27%), but late embryonic mortality was more frequent in the High-level group (30% vs 9%). At the end of the study, the rate of pregnancy did not therefore differ much between the two feeding groups. The pregnancy rate among Norman cows was higher at the end of the study (72% vs 54%), as this race presented fewer cyclicity-related anomalies and a lower rate of late embryonic mortality. For the Norman race alone, the rate of pregnancy was higher in the Low-level feeding group, thanks to the fact that ovulation was more easily detected.

The same feeding strategy can have beneficial effects at certain stages of the reproduction cycle and negative effects at others; these effects can be significant for one race while affecting another only minimally. This experiment allowed the respective effects to be isolated from one another in order to establish trends in different dairy production systems and determine how body reserves affect the successive stages of the reproductive process. The results allow the reproduction performance of the herd to be modeled according to production and weight loss, and therefore contribute to improved coherency between feeding strategies and dairy productivity and reproduction objectives in dairy farming.

For more information, contact:

Catherine Disenhaus
INRA - Joint Research Unit for the Physiology, Enviroment and Genetics of Animals and Livestock Systems (PEGASE)
35590 St-Gilles
Tel: 33 (0)2 23 48 53 75
Fax: 33 (0)2 23 48 51 01

e-mail: Catherine.Disenhaus@agrocampus-ouest.fr

Thanks to all the staff on the INRA Pin au Haras Experimental Farm.

Reference: Cutullic, E., Delaby L., Gallard, Y., Disenhaus C., 2011, Dairy cows’ reproductive response to feeding level differs according to the reproductive stage and the breed, Animal, 5, 731-740.