Association Between Milk Urea Nitrogen and Fertility in Ohio Dairy Cows

-This paper reviews important aspects of dry cow feeding with emphasis placed on the preparation of the cow for the subsequent lactation. A number of feeding strategies, which have been proposed in recent years, are examined, alongside considerations of the effects of dry period length, levels of body reserves at calving and parity. A number of studies have reported the effect of varying the length of the dry period (in the range 0 to 70 days) on subsequent production and health. An 8 week dry period seems optimal though this should be adjusted to allow for the body condition score of cows at drying off. Avoiding extremes of body condition score at calving is desirable, so condition should be monitored throughout the lactation cycle. Attempting to achieve large changes in body reserves in the dry period has been associated with increased problems postpartum. The feeding strategies that are reviewed are strategies to decrease body mobilisation, prime for body mobilisation, prime the rumen for increased intake, prime for milk protein production and prime for calcium mobilisation and absorption. These strategies are also evaluated relative to their biological basis and reported physiological effects. Feeding high starch feeds in the latter part of the dry period was found not to provide clear benefits in terms of decreasing early lactation body mobilisation or increasing early lactation intake. Strategies aimed at priming the cow for the increased mobilisation of body lipid and body calcium that occurs in early lactation appear more favourable both from the point of view of making biological sense and from the available results reviewed. dry period / feeding / body condition score / dairy cattle / health Résumé -Préparation des vaches laitières à la lactation : bilan des stratégies d'alimentation des vaches taries. Cet article passe en revue les aspects importants de l'alimentation des vaches taries en mettant l'accent sur la préparation de la vache à la lactation suivante. Plusieurs stratégies d'alimentation proposées au cours des dernières années sont examinées, dans le même temps que des considérations portant sur les effets de la durée de la période sèche, du niveau des réserves corporelles au vêlage et du rang de lactation. Un certain nombre d'études ont montré que le fait de * Corresponding author: n.friggens@agrsci.dk 454 N.C. Friggens et al.faire varier la durée de la période sèche (dans une plage de 0 à 70 jours) avait un effet sur la production et la santé lors de la lactation suivante. Une période sèche de 8 semaines semble optimale, quoiqu'elle doive être ajustée en tenant compte de la note d'état corporel des vaches au moment du tarissement. Il est préférable d'éviter des notes extrêmes au vêlage ; l'état corporel devrait donc être surveillé tout au long du cycle de lactation. Les tentatives de vouloir effectuer de grandes modifications du niveau des réserves corporelles pendant la période sèche ont été associées à une augmentation des problèmes postpartum. Les stratégies d'alimentation exposé...

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“…3.2). There is also the danger of a negative effect on reproduction due to higher circulating urea levels [94].…”

Section: Strategies To Prime For Milk Protein Productionmentioning

confidence: 99%

Priming the dairy cow for lactation: a review of dry cow feeding strategies

Friggens¹,

Andersen²,

Larsen³

et al. 2004

Anim. Res.

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“…Several studies have reported the negative effect of blood urea or MU on reproductive performance in dairy cows (Butler et al, 1996;Rajala-Schultz et al, 2001). Rhoads et al (2006) tested the pregnancy rate after embryo transfer from donors with medium or high PU concentration to the heifers with medium or high PU concentration.…”

Section: Introductionmentioning

confidence: 99%

“…Other studies, in spite of finding a positive relationship between dietary crude protein (CP) and PU-nitrogen concentrations or MUN (Godden et al, 2001), did not find an association between urea-nitrogen concentrations and reproduction. The amount of MUN at which substantial impairment of reproductive performance occurs remains unclear, particularly among herds under commercial conditions (Godden et al, 2001;Rajala-Schultz et al, 2001). In addition, it remains unclear whether the MUN immediately before or after a breeding are important considerations in interpreting the relationship between MUN and reproductive performance (Godden et al, 2001), with the exact mechanism of action yet to be determined.…”

Section: Introductionmentioning

confidence: 99%

Genetic relationship between milk urea nitrogen and reproductive performance in Holstein dairy cows

Hossein-Zadeh

Ardalan

2011

Animal

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The objective of this study was to describe the genetic and phenotypic relationship between milk urea nitrogen (MUN) and reproductive traits in Iranian Holstein dairy cows. Test-day MUN data obtained from 57 301 dairy cows on 20 large dairy herds in Iran between January 2005 and June 2009. Genetic parameters for MUN and reproductive traits were estimated with a five-trait model using ASREML program. Random regression test-day models were used to estimate heritabilities separately for MUN from first, second and third lactations. Regression curves were modeled using Legendre polynomials of order 3. Herd-year-season along with age at calving was included as fixed effects in all models for reproductive traits. Heritabilities for MUN and reproductive traits were estimated separately for first lactation, second lactation and third lactation. The estimated heritabilities for MUN varied from 0.18 to 0.22. The heritability estimate was low for reproductive traits, which ranged from 0.02 to 0.06 for different traits and across parities. Except for days open, phenotypic and genetic correlations of MUN with reproductive performance traits were close to zero. Genetic correlations between MUN and days open were 0.23, 0.35 and 0.45 in first, second and third lactation, respectively. However, the phenotypic correlation between MUN at different parities was moderate (0.28 to 0.35), but the genetic correlation between MUN at different parities was high and ranged from 0.84 to 0.97. This study shows a limited application of MUN for use in selection programs to improve reproductive performance.

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“…survival after infection, length of productive life, or days open). To analyze such traits, the Weibull and Cox proportional hazards models are commonly employed [1,2,4,6,7,11,16,23,25,27]. The Weibull model, a generalization of the exponential model, is parametric and is therefore appropriate for only specific distributions; the Cox model is a rank-based semi-parametric method and, therefore, should be appropriate for all distributions for which the hazards between groups are proportional [26].…”

Section: Introductionmentioning

confidence: 99%

Comparison of methods for analysis of selective genotyping survival data

et al. 2006

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-Survival traits and selective genotyping datasets are typically not normally distributed, thus common models used to identify QTL may not be statistically appropriate for their analysis. The objective of the present study was to compare models for identification of QTL associated with survival traits, in particular when combined with selective genotyping. Data were simulated to model the survival distribution of a population of chickens challenged with Marek disease virus. Cox proportional hazards (CPH), linear regression (LR), and Weibull models were compared for their appropriateness to analyze the data, ability to identify associations of marker alleles with survival, and estimation of effects when all individuals were genotyped (full genotyping) and when selective genotyping was used. Little difference in power was found between the CPH and the LR model for low censoring cases for both full and selective genotyping. The simulated data were not transformed to follow a Weibull distribution and, as a result, the Weibull model generally resulted in less power than the other two models and overestimated effects. Effect estimates from LR and CPH were unbiased when all individuals were genotyped, but overestimated when selective genotyping was used. Thus, LR is preferred for analyzing survival data when the amount of censoring is low because of ease of implementation and interpretation. Including phenotypic data of non-genotyped individuals in selective genotyping analysis increased power, but resulted in LR having an inflated false positive rate, and therefore the CPH model is preferred for this scenario, although transformation of the data may also make the Weibull model appropriate for this case. The results from the research presented herein are directly applicable to interval mapping analyses.survival / Cox proportional hazards / Weibull / quantitative trait loci

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Association Between Milk Urea Nitrogen and Fertility in Ohio Dairy Cows

Cited by 124 publications

References 24 publications

Priming the dairy cow for lactation: a review of dry cow feeding strategies

Priming the dairy cow for lactation: a review of dry cow feeding strategies

Genetic relationship between milk urea nitrogen and reproductive performance in Holstein dairy cows

Comparison of methods for analysis of selective genotyping survival data

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