Calving Difficulty Score Research Articles

Intake of conserved and grazed grass and performance traits in beef suckler cows differing in phenotypic residual feed intake

The objectives of the study were to quantify the phenotypic variation in residual feed intake (RFI) and productivity of beef suckler cows offered grass silage during pregnancy and, to determine the effect of RFI classification on herbage intake during lactation. Data were collected on 39 Simmental and Simmental×Holstein-Friesian cows. During the winter indoor feeding period cows were offered grass silage ad libitum daily and their individual DMI was recorded over 73d. Cow LW, BCS, skeletal measurements, ultrasonic fat and muscle depth, visual muscularity score, rumen fermentation, total tract digestibility, blood metabolites and haematological variables, as well as feeding behaviour were measured. Phenotypic RFI was calculated for each animal as the difference between actual silage DMI and expected silage DMI. Expected silage DMI was computed for each animal by regressing average daily silage DMI on conceptus adjusted mean LW0.75 and conceptus adjusted ADG over a 73-d period. Within breed, cows were ranked by RFI into low (efficient), medium and high (inefficient) groups by dividing them into thirds. Overall mean (SD) values for grass silage DMI (kg/d), grazed grass DMI (kg/d), feed conversion ratio (FCR) kgDMI/kg of LW gain (kg/d) and RFI (kgDM/d) were 9.08 (1.15), 9.98 (1.86), 24.66 (29.61), 0.00 (1.00), respectively. The RFI groups did not differ (P>0.05) in LW or ADG at any stage of measurement. Residual feed intake was positively correlated with silage DMI (r=0.87; P<0.001) but not with grass DMI (r=−0.03; P>0.05). Cows in the low RFI group consumed 14% (P<0.05) and 22% (P<0.001) less silage than those in medium and high RFI groups, respectively. Corresponding values for grazed herbage were 3% and 2% (P>0.05). Cow RFI groups did not differ (P>0.05) in BCS, ultrasonic backfat or rump fat thickness, visual muscle scores or total tract digestibility, cow milk yield, calving difficulty score, calf birth weight and ADG of calves did not differ (P>0.05) between RFI groups. Overall, this study showed that low RFI cows were more biologically and economically efficient, as they consumed less feed during the indoor winter period and a similar amount of herbage during the grazing season compared to high RFI cows, without any compromise in growth, body composition or production traits measured.

Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows

The aim of this study was to evaluate the effect of postpartum mastitis between first calving and subsequent conception on production and reproduction performance as well as culling of Holstein cows. A data set of 9,183 first lactation cows was used. Results showed that the first cumulative 100 days' milk production and the milk yield standardized to 305 days were affected by the interval from calving to first mastitis (P < 0.05). Cows with one episode of mastitis produced more milk than those with repeated episodes of mastitis (P < 0.01). Increase in the number of mastitis episodes and also decrease in interval between first calving and mastitis increased services per conception (P < 0.001). Mastitis episode and the interval between calving and first mastitis had no apparent impact on the calving to conception interval (P > 0.05). Calving year, calving difficulty score, and cumulative first 60 days milk production had significant impacts on mastitis risk (P < 0.05). The interval from calving to the first incidence of mastitis decreased over the period studied (P < 0.001). Productive life tended to be decreased due to mastitis (P = 0.07). Survival analysis showed a significant difference between the lengths of productive life for cows with different intervals from calving to first mastitis (P < 0.01). The results demonstrated that clinical mastitis between first calving and conception reduced production and reproduction performance with an increase in chance of culling.

Effect of intensified feeding of heifer calves on growth, pubertal age, calving age, milk yield, and economics

The objective of this study was to determine if increasing the energy and protein intake of heifer calves would affect growth rates, age at puberty, age at calving, and first lactation milk yield. A second objective was to perform an economic analysis of this feeding program using feed costs, number of nonproductive days, and milk yield data. Holstein heifer calves born at the Michigan State Dairy Cattle Teaching and Research Center were randomly assigned to 1 of 2 dietary treatments (n=40/treatment) that continued from 2 d of age until weaning at 42 d of age. The conventional diet consisted of a standard milk replacer [21.5% crude protein (CP), 21.5% fat] fed at 1.2% of body weight (BW) on a dry matter basis and starter grain (19.9% CP) to attain 0.45kg of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6% CP, 16.1% fat) fed at 2.1% of BW on a dry matter basis and starter grain (24.3% CP) to achieve 0.68kg of daily gain. Calves were gradually weaned from milk replacer by decreasing the amount offered for 5 and 12 d before weaning for the conventional and intensive diets, respectively. All calves were completely weaned at 42 d of age and kept in hutches to monitor individual starter consumption in the early postweaning period. Starting from 8 wk of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 wk of age, and once every 4 wk thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a BW difference was no longer evident by 12 wk of age. Calves fed the intensive diet were younger and lighter at the onset of puberty. Heifers fed the high-energy and protein diet were 15 d younger at conception and 14 d younger at calving than heifers fed the conventional diet. Body weight after calving, daily gain during gestation, withers height at calving, body condition score at calving, calving difficulty score, and calf BW were not different. Energy-corrected, age-uncorrected 305-d milk yield was not different, averaging 9,778kg and 10,069kg for heifers fed the conventional and intensive diets, respectively. However, removing genetic variation in milk using parent average values as a covariate resulted in a tendency for greater milk from heifers fed the intensive diet. Preweaning costs were higher for heifers fed the intensive diet. However, total costs measured through first lactation were not different. Intensified feeding of calves can be used to decrease age at first calving without negatively affecting milk yield or economics.

Calving difficulty in dairy cows has a longer effect on saleable milk yield than on estimated milk production

A difficult calving affects the welfare of the cow and has economic implications for the farm. The degree of calving difficulty can vary from no assistance needed through a slight pull required to surgery being needed. With respect to milk production, it is not clear at which degree of calving difficulty adverse effects occur or for how long they last. Studies usually only consider the milk produced by animals who completed full lactations but the saleable milk production of the whole herd, regardless of each cow having achieved a full lactation, might be a better indicator of the productivity of the cows and the underlying stresses they experience, as well as being more representative of the real losses that producers incur. The objective of this study was to investigate how various degrees of calving difficulty would alter both the cow's milk production and their production of saleable milk over different stages of their subsequent lactation. The calving difficulty scores and the subsequent milk production were retrieved from an experimental dairy farm (in the United Kingdom) for 2 herds that contained 2,430 and 1,413 lactations. To account for milk saleable by the farmer, individual cumulative saleable milk yields, referred to as saleable milk yields (SMY), were calculated at 30, 60, 90, and 300 d in milk unconditional on the animal having achieved the lactation stage of interest. Lactation SMY were obtained based on the real lactation length achieved by the animal. Mean daily milk yields were also calculated for the same lactation stages as an estimate of the cow's milk production (CMP). Calving difficulty impaired milk production of dairy cows in terms of CMP and SMY in both herds, highlighting impaired income for dairy producers as well as detrimental effects to the productivity of the cows and potentially impaired health and survival. The management of the herd affected the presence of an effect of each degree of difficulty on SMY and CMP as well as its magnitude and duration. The analysis of SMY, independently of each animal having achieved a full lactation, could be a more sensitive indicator of the subsequent long-lasting biological stresses than CMP alone.

Economic weights of production and functional traits for Holstein‐Friesian cattle in Hungary

A bio-economic model was used to estimate economic values of 15 milk production, functional, growth and carcass traits for Hungarian Holstein-Friesian cattle. The calculations were carried out for the situation in Hungary from 2000 to 2007, assuming no production quotas. The marginal economic values were defined as partial derivatives of the profit function with respect to each trait in a production system with dairy cow herds and with sales of surplus male calves. The economic weights for maternal and direct components of traits were calculated multiplying the marginal economic values by the number of discounted expression summed over a 25-year investment period for 2-year-old bulls (candidates for selection). The standardized economic weight (economic weight x genetic standard deviation) of the trait or trait component expressed as percentage of the sum of the standardized economic weights for all traits and trait components represented the relative economic importance of this trait or trait component. The highest relative economic importance was obtained for milk yield (25%), followed by productive lifetime of cows (23%), protein yield and the direct component of a cow's total conception rate (9% each), the maternal effect of the total conception rate of cows and the somatic cell score (approximately 7% each), fat yield (5%) and mature weight of cows and daily gain in rearing of calves (approximately 4% each). Other functional traits (clinical mastitis incidence, calving difficulty score, total conception rate of heifers and calf mortality) reached a relative economic importance between 0.5% and 2%. Birth weight and dressing percentage were least important (<0.5%). Based on these results, the inclusion of productive lifetime and cow fertility in the breeding programme for Holstein-Friesian cattle in Hungary is advisable.

Estimation of genetic and crossbreeding parameters for preweaning traits in German Angus and Simmental beef cattle and the reciprocal crosses1

Data from pure breeds, as well as reciprocal crosses of German Angus (GA) and Simmental (SIM) beef cattle, were used to estimate genetic parameters and to evaluate the suitability for crossbreeding in terms of increasing productivity. Traits of interest were calving difficulty, birth weight (BWT), weaning weight (WWT), and ADG from birth to weaning. Data were collected over a period of 7 yr from 1997 and 1998 until 2003 and 2004, whereas crossbreeding was carried out in 2002 and 2003, and 2003 and 2004 only. Variance components and differences between breeds, individual heterosis, and maternal breed effects were analyzed based on 1,441 purebred and 329 crossbred records for BWT and 1,319 purebred and 316 crossbred records for WWT and ADG, respectively. Mean calving difficulty scores were greater in SIM than in GA (P < 0.001). For BWT, WWT, and ADG both reciprocal crosses fell between the purebreds, and for all 3 traits SIM showed greater average values compared with GA. The estimated heritabilities were 0.23 for BWT and 0.12 for WWT. Values for the maternal effect and the correlation between additive and maternal effect were 0.18 for BWT, 0.08 for WWT, 0.32 for BWT, and 0.50 for WWT, respectively. Individual heterosis was only significant for BWT (3.7%; P < 0.01). Superior mothering ability of SIM was implicated by greater WWT and ADG of SIM as dam against the reciprocal cross (P < 0.001). The results provide information about the extent of individual heterosis and maternal breed effects.

Relationship between accumulated heat stress during the dry period, body condition score, and reproduction parameters of Holstein cows in tropical conditions

To estimate the relationship between heat stress during the last 60 days prepartum, body condition score and certain reproductive traits in the subsequent lactation of Holstein cows, 564 multiparous cows and 290 primiparous cows from four dairy herds were used in a hot, humid region. Maximum prepartum degree days were estimated to quantify the degree of heat stress. Multiple regressions analyses and logistic regression analysis were performed to determine the effect of prepartum heat stress and body condition change on reproductive parameters, which were obtained from DHIA forms at the end of the lactation. Multiparous and primiparous cows which gained body condition score from calving to 60 d postpartum exhibited 28 and 27 fewer days open (P < 0.05), respectively, than cows not gaining. There was no effect (P > 0.05) of heat stress measurement on days open or services per conception in either multiparous or primiparous cows. During hotter months of calving, multiparous cows showed higher services per conception and primiparous cows showed higher days open and services per conception (P < 0.05). Maximum prepartum degree-days were positively associated (P < 0.05) with calving difficulty score. Multiparous cows with high body condition score at calving were 1.47 times more likely to present a very difficult calving than cows that calved in October (P < 0.05). Collectively, these results suggest that reproductive performance was not affected by cumulative prepartum heat stress although it was associated with very difficult calving score.

Predictive ability of models for calving difficulty in US Holsteins

The performance of alternative threshold models for analyzing calving difficulty (CD) in Holstein cows was evaluated in terms of predictive ability. Four models were considered, with CD classified into either three or four categories and analysed either as a single trait or jointly with gestation length (GL). The data contained GL and CD records from 90 393 primiparous cows, sired by 1122 bulls and distributed over 935 herd-calving year classes. Predictive ability of each model was evaluated using four criteria: mean squared error of the difference between observed and predicted CD scores; a Kullback-Leibler divergence measure between the observed and predicted distributions of CD scores; Pearson's correlation between observed and predicted CD scores and ability to correctly classify bulls as above or below average for incidence of CD. In general, the four models had similar predictive abilities. The joint analysis of CD with GL produced little, if any, improvement in predictive ability over univariate models. In light of the small difference in predictive ability between models treating CD with three or four categories and considering that a greater number of categories can provide more information, analysis of CD classified into four categories seems warranted.

Experimental selection for calving ease and postnatal growth in seven cattle populations. I. Changes in estimated breeding values1,2

Selection was used to create select and control lines within 4 purebred and 3 composite cattle populations. Both lines were selected for similar direct yearling weight and maternal weaning weight EBV. Select lines were selected for lower 2-yr-old heifer calving difficulty score EBV and control lines were selected for average birth weight EBV. Select (n = 6,926) and control (n = 2,043) line calves were born from 1993 through 1999 and selection began with the 1992 mating. High replacement rates resulted in 2,188 births to select line and 598 births to control line heifers. Data used to calculate EBV came from these populations and from 15 yr of data preceding the experiment. Calving difficulty was scored from 1 (no assistance) to 7 (cesarean). Calving difficulty scores from all twins, malpresentations, and cows 3 yr old and older were eliminated. Except for the first year, when a single-trait BLUP was used, a multiple-trait BLUP was used to calculate direct and maternal EBV for calving difficulty score, birth weight, and weaning weight, and direct EBV for postweaning gain. Sires (n = 498) were selected from those born in both the preceding populations and the select and control lines. In purebred populations, some industry sires (n = 88) were introduced based on their EPD. Tests of mean select and control line EBV differences of calves born in the final 2 yr were based on population variation. Select line direct EBV were 1.06 lower for heifer calving difficulty score (P < 0.001) and 3.5 kg lower (P < 0.001) for birth weight than controls. Average differences for other EBV were small and not significant. Yearling weight EBV was intentionally increased in both select and control lines of purebred populations. Angus, Hereford, Charolais, and Gelbvieh yearling weight EBV in control lines increased by 32.4, 27.2, 21.0, and 10.5 kg, respectively, from 1991 and 1992 to 1998 and 1999 compared with an average increase of 2.7 kg in composite populations. Birth weight direct EBV in purebred control lines increased by approximately 8% of yearling weight EBV increases. Selection based on a multiple-trait BLUP was able to create lines differing in calving difficulty score and birth weight EBV, but not in weaning weight and postweaning gain EBV. Differences between lines should be useful for evaluating BLUP and other traits and for identifying potential limitations of genetically decreasing calving difficulty score and birth weight.

Experimental selection for calving ease and postnatal growth in seven cattle populations. II. Phenotypic differences1,2

Effects of selection for 2-yr-old heifer calving ease (reduced calving difficulty score) on phenotypic differences between select and control lines of cattle for birth, growth, yearling hip height, and pelvic measurements were estimated. The selection objective was to decrease calving difficulty score in 2-yr-old heifers, while either maintaining or increasing yearling weight. The control line objective was to maintain or increase yearling weight by the same amount as the select lines and to maintain or proportionally increase birth weight. Select and control lines were formed in 4 purebred and 3 composite populations. Selection began in 1992 and select (n = 6,926) and control (n = 2,043) line calves were born from 1993 through 1999. Selection was based on EBV calculated from a 4-trait BLUP with observations on 2-yr-old calving difficulty scores, birth weight, weaning weight, and postweaning gain. Calving difficulty was scored on a scale from 1 (unassisted) to 7 (caesarean). All birth traits in select lines differed significantly from control lines. Averaged over 7 yr, select lines calved 3.0 +/- 0.5 d earlier, had 1.8 +/- 0.5 d shorter gestations, were 2.99 +/- 0.32 kg lighter at birth, had 5.6 +/- 1.5% fewer calves assisted at birth (averaged across dam ages), and 2-yr-old heifers had 0.80 +/- 0.08 lower calving difficulty score. Select lines averaged 19.8% lower 2-yr-old heifer calving assistance, but there was no difference in calving assistance of older cows, resulting in a highly significant interaction of selection and dam classification. Preweaning ADG was increased 15 +/- 9 g/d (1.7%) in select lines. Increased preweaning gain offset decreased birth weights in select lines, resulting in weaning weights that did not differ (P = 0.71). Postweaning ADG (P = 0.16) and yearling weight (P = 0.41) also did not differ. Increased preweaning ADG in select lines was not maintained after weaning. Select line hip heights were 0.70 +/- 0.21 cm shorter when measured as yearlings. Pelvic height, width, and area of select heifers measured 25 to 74 d after yearling weights were not significantly different. The differences between select and control lines significantly changed over the course of the experiment for some traits. In the final 2 yr of the experiment, select lines had 3.9 kg lower birth weight and 1.3 cm shorter hip heights. Selection can be used effectively to reduce 2-yr-old calving difficulty and calving assistance while maintaining or increasing yearling weight.

Short Communication: Prepartal Concentration of Estradiol-17β in Heifers with Stillborn Calves

This study was conducted to investigate hormonal imbalances preceding stillbirths and dystocia in primiparous heifers. The study was conducted between 2003 and 2004 on a German dairy farm, including 433 heifers. Starting 3wk before calving, a weekly blood sample was collected. At calving, another blood sample was obtained, and the calving ease (grade 0=unassisted to grade 2=heavy pull with mechanical calf puller), sex, birth weight, as well as vitality status (stillborn, alive) of the calf were recorded. The blood serum was analyzed for estradiol-17β and progesterone concentration. At parturition, the measured estradiol-17β concentration was greater in heifers delivering bulls than in those with female calves and was increasing with greater birth weight of the calf and increasing calving difficulty score. Already 2wk before calving, the serum estradiol-17β concentration was significantly smaller in heifers with stillborn than live calves. On the other hand, the progesterone concentration was greater 2wk before calving in heifers with stillborn calves, but it was unaffected by the birth weight or sex of the calf or the calving difficulty score. Stillborn and live calves did not differ in birth weight or pregnancy duration. The smaller estradiol-17β concentrations of the heifers with stillborn calves could indicate an abnormality of the placenta or an abnormality of hormonal signals from the calf to the placenta in the weeks before the calving.

Retrospective Video Analysis of the Behavior of Periparturient Dairy Cattle

The impact of calving difficulty on the behavior of periparturient dairy cattle has not been reported. The objective of this study was to measure variables associated with difficulty of calving, and to identify the associations of parameters with periparturient behavior. Previously recorded videotapes of 23 cows on day -1, 0 and +1 relative to calving were analyzed. Data included frequency and duration of standing and lying behavior, calving difficulty score, duration of calving and calf body measurements. Calving difficulty was scored as: 0-unassisted, 1-easy pull, 2-hard pull. Video information was analyzed, interpreted and entered. Data were analyzed using logistic and linear regression with Statistix. Heifers were more likely to require assistance during calving (P&lt;0.01). Male calves weighed significantly more than female calves (P&lt;0.05). Cow standing and lying behavior differed on the day of calving. Pre-calving, heifers lie for 18 fewer minutes per lying bout compared to cows (37.1 ± 3.8 versus 55.1 ± 6.4 minutes per bout, P&lt;0.02). Mean pre-calving lying time was also influenced by calving difficulty, as cows requiring assistance spent 15 minutes less lying down per bout (P&lt;0.05). Post-calving, heifers lie for 13 minutes less per bout than cows (40.4 ± 3.1 versus 53. 7 ± 8.8, P=0.09). Cows taking longer to calve lie for fewer minutes each bout (P&lt;0.02). Finally, dams that had hard pulls lie for 12.5 fewer minutes each bout (P=0.11). When mean lying bouts post-calving was analyzed, controlling for pre-calving mean lying time, only calving duration remained significant. Calving duration also positively influenced the number of post-calving lying bouts (P=0.05). Lying behaviour, both pre and post-calving, was the most significant measurement related to calving. Cows with longer calvings spent less time lying down after calving. Differences between lying time for cows and heifers merits further investigation. It is possible that this difference is related to the presence of pain, and that there are opportunities for pain management at calving.

Genetic relationships between calving performance and beef production traits in Piemontese cattle

The aim of the study was to obtain estimates of genetic correlations between direct and maternal calving performance of heifers and cows and beef production traits in Piemontese cattle. Beef production traits were daily gain, live fleshiness, and bone thinness measured on 1,602 young bulls tested at a central station. Live fleshiness (six traits) and bone thinness were subjectively scored by classifiers using a nine-point linear grid. Data on calving performance were calving difficulty scores (five classes from unassisted to embryotomy) routinely recorded in the farms. Calving performance of heifers and cows were considered different traits. A total of 30,763 and 80,474 calving scores in first and later parities, respectively, were used to estimate covariance components with beef traits. Data were analyzed using bivariate linear animal models, including direct genetic effects for calving performance and beef traits and maternal genetic effects only for calving performance. Due to the nature of the data structure, which involved traits measured in different environments and on different animals, covariances were estimated mostly through pedigree information. Genetic correlations of daily gain were positive with direct calving performance (0.43 in heifers and 0.50 in cows) and negative with maternal calving performance (-0.23 and -0.28 for heifers and cows, respectively). Live fleshiness traits were moderately correlated with maternal calving performance in both parities, ranging from 0.06 to 0.33. Correlations between live fleshiness traits and direct calving performance were low to moderate and positive in the first parity, but trivial in later parities. Bone thinness was negatively correlated with direct calving performance (-0.17 and -0.38 in heifers and cows, respectively), but it was positively correlated to maternal calving performance (0.31 and 0.40). Estimated residual correlations were close to zero. Results indicate that, due to the existence of antagonistic relationships between the investigated traits, specific selection strategies need to be studied.

Genetic relationships between calving and carcass traits for Charolais and Hereford cattle in Sweden.

The objective of this study was to estimate genetic correlations between calving difficulty score and carcass traits in Charolais and Hereford cattle, treating first and later parity calvings as different traits. Genetic correlations between birth weight and carcass traits were also estimated. Field data on 59,182 Charolais and 27,051 Hereford calvings, and carcass traits of 5,260 Charolais and 1,232 Hereford bulls, were used in bivariate linear animal model analyses. Estimated heritabilities were moderate to high (0.22 to 0.50) for direct effects on birth weight, carcass weight, and (S)EUROP (European Community scale for carcass classification) grades for carcass fleshiness and fatness. Heritabilities of 0.07 to 0.18 were estimated for maternal effect on birth weight, and for direct and maternal effects on calving difficulty score at first parity. Lower heritabilities (0.01 to 0.05) were estimated for calving difficulty score at later parities. Carcass weight was positively genetically correlated (0.11 to 0.53) with both direct and maternal effects on birth weight and with direct effects on calving difficulty score. Carcass weight was, however, weakly or negatively (-0.70 to 0.07) correlated with maternal calving difficulty score. Higher carcass fatness grade was genetically associated with lower birth weight, and in most cases, also with less difficult calving. Genetic correlations with carcass fleshiness grade were highly variable. Moderately unfavorable correlations between carcass fleshiness grade and maternal calving difficulty score at first parity were estimated for both Charolais (0.42) and Hereford (0.54). This study found certain antagonistic genetic relationships between calving performance and carcass traits for both Charolais and Hereford cattle. Both direct and maternal calving performance, as well as carcass traits, should be included in the breeding goal and selected for in beef breeds.

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. 152 Holstein cows that calved during October through December of 1997 All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.

Genetic parameters for birth and weaning traits in French specialized beef cattle breeds

Genetic parameters for birth and weaning traits of beef calves were estimated in Charolais, Limousin, Blonde d'Aquitaine and Maine-Anjou breeds. These traits took into account the following calf and cow abilities: calving (calving difficulty score, calf birth weight), calf growth and muscular development (direct effects on weaning weight and muscle score) and suckling ability (maternal effects on calf weaning weight). Data sets consisted of the observations of the largest 236 Charolais and 120 Limousin herds recorded from 1985 to 1999 and the observations of the largest 147 Blonde d'Aquitaine and 116 Maine-Anjou herds recorded from 1986 to 2002. In general, estimates of heritability were in the range of values given in the litterature and were relatively similar across breeds. Concerning birth traits, estimates were around 0.10 for both direct and maternal effects on calving difficulty score, around 0.30 (Charolais and Maine-Anjou breeds) or 0.40 (Limousin and Blonde d'Aquitaine breeds) for direct effects on birth weight and 0.10 for the corresponding maternal effects. Concerning weaning traits, estimates for heritability of direct effects on weaning weight were around 0.10 in the Charolais breed, 0.20 in the Maine-Anjou breed and around 0.30 in the other breeds with corresponding estimates on maternal effects around 0.10. Maternal heritabilities on muscular development score were small and corresponding direct heritabilities were estimated around 0.20 in the Charolais and Maine-Anjou breeds and 0.30 in the other breeds. Most of the genetic correlation estimates between direct and maternal effects were significantly negative. In general, correlation estimates between traits were low to moderate (below 0.50) and similar from one breed to another. A higher association was only estimated between direct effects on birth weight and calving difficulty score in three out of the four breeds. Direct and maternal genetic correlations between calving difficulty score and weaning traits were slightly unfavourable in the four breeds.

Genetic parameters for growth, reproductive performance, calving ease and suckling performance in beef cattle heifers

AbstractThere is considerable concern about the consequences on fitness-related traits of using narrow breeding objectives for production traits. The aim of this study was to assess the potential consequences of selection for growth in French beef cattle breeds by estimating genetic correlations between growth, reproduction, calving and suckling traits of Charolais, Limousin and Blonde d’Aquitaine heifers. Data consisted of the records collected from 1985 to 2002 in progeny test stations that were used in the genetic evaluation of 284 Charolais, 125 Limousin and 118 Blonde d’Aquitaine AI sires. Seven traits were considered simultaneously in the analysis: weights at 18 months and after calving (for measuring heifer growth), sexual precocity and fertility (for measuring heifer reproductive performance), calving difficulty score and pelvic opening (for measuring calving ease) and milk yield (for measuring the suckling ability of the primiparous cow). REML (co)variance estimates were derived using linear multitrait sire models. Estimates of heritability were in the range of values given in the literature. They were very similar in the Charolais and Blonde d’Aquitaine breeds, and rather different for reproductive and suckling performance in the Limousin breed. Estimates were about 0·35 for heifer growth traits and about 0·15 for calving difficulty score in the three breeds. In the Charolais and Blonde d’Aquitaine breeds, estimates of heritability were 0·15 for sexual precocity and 0·05 for heifer fertility. These estimates were close to zero in the Limousin breed. Heritabilities of pelvic opening and milk yield were, respectively, 0·2 and 0·6 in the Limousin breed and around 0·3 in the other two breeds. Genetic correlations between traits concerning the same ability (as, for instance, weight at 18 months and weight at calving) were high and, in general, similar among breeds. Genetic correlations between heifer growth, reproductive traits, calving ease and suckling performance were nil or slightly favourable in the three breeds. Consequently, past selection mainly directed towards increasing growth seems not to have adversely affected the efficiency of female reproduction and the maternal abilities of French specialized beef cattle breeds.

Genetic parameters for calving difficulty, stillbirth, and birth weight for Hereford and Charolais at first and later parities.

The aim of this study was to estimate direct and maternal genetic parameters for calving difficulty score, stillbirth, and birth weight at first and later parities for Charolais and Hereford cattle in Sweden. Calving traits have long been recorded for pure-bred beef cattle in Sweden, but only birth weight has been used in the selection in order to avoid calving difficulties. Linear animal model analyses included records on birth weight for 60,309 Charolais and 30,789 Hereford calves born from 1980 to 1999, and calving traits for 74,538 Charolais and 37,077 Hereford calves born from 1980 to 2001. The frequencies of difficult calvings and stillbirths were approximately 6% at first and 1 to 2% at later parities for both breeds. Fewer than half the stillborn calves were born from difficult calvings. Heritabilities estimated for birth weight in different univariate and bivariate analyses for Charolais and Hereford calves born at first and later parities ranged from 0.44 to 0.51 for direct effects and 0.06 to 0.15 for maternal effects. Heritabilities on the observable scale for calving difficulty score of Charolais and Hereford, scored in three classes, ranged from 0.11 to 0.16 for direct and 0.07 to 0.12 for maternal effects at first parity, and lower at later parities. All estimated heritabilities for stillbirth were very low (0.002 to 0.016 on the observable scale). Direct-maternal genetic correlations were negative, with few exceptions. Genetic correlations between the traits and between parities within traits were generally moderate to high and positive. Calving difficulty score should be included in the genetic evaluation of beef breeds in Sweden, whereas progeny groups in Swedish beef populations are too small for stillbirth to be considered directly.

Plasma hormones and metabolites in Piedmontese cows during late pregnancy: relationships with calf birth weight.

Relationships among plasma hormonal and metabolic variables in the last trimester of gestation in 59 Piedmontese dams (n = 15 heifers, n = 44 cows) and the calf birth weight (BWT) class of their offspring were investigated in seven herds. The BWT data were categorized as follows: > 50 kg (BWT-A), 46 to 50 kg (BWT-B), 41 to 45 kg (BWT-C), and < 41 kg (BWT-D). Blood samples were collected at 33, 36, and 39 wk of gestation. Packed cell volume (PCV) and plasma concentrations of insulin, estrone sulfate (E1SO4), NEFA, and creatinine were determined and correlated to BWT class. Creatinine: E1SO4 ratio also was calculated. Duration of gestation was greater for dams producing a BWT-A calf than for the other BWT classes, and calf BWT was heavier (P < 0.001) for calves in the BWT-A vs. BWT-D class. The heaviest calf in BWT-A was associated with the highest calving difficulty score. Insulin and PCV values were not affected by week of gestation, whereas plasma E1SO4, NEFA, and creatinine content increased (P < 0.001) and creatinine:E1SO4 decreased (P < 0.001) during late gestation. Calf BWT class did not affect PCV value. Plasma E1SO4 concentrations were lower (P < 0.01) in BWT-D dams than the other dams, showing the greatest difference at 39 wk of gestation. At 36 and 39 wk of gestation, dams bearing BWT-C and BWT-D calves had a higher (P < 0.01) plasma insulin concentration than those bearing BWT-A and BWT-B calves. Plasma NEFA concentrations at 39 wk of gestation were higher (P < 0.05) in dams of calf BWT-A than in the other dams. We conclude that plasma E1SO4 level is a variable that can be used to monitor problems related to a small size calf. Conversely, the forthcoming birth of a calf with a heavy BW seems to be preceded by a pronounced increase in plasma NEFA level in the dam just a few days before calving.

Plasma hormones and metabolites in Piedmontese cows during late pregnancy: Relationships with calf birth weight1

Relationships among plasma hormonal and metabolic variables in the last trimester of gestation in 59 Piedmontese dams (n = 15 heifers, n = 44 cows) and the calf birth weight (BWT) class of their offspring were investigated in seven herds. The BWT data were categorized as follows: >50 kg (BWT-A), 46 to 50 kg (BWT-B), 41 to 45 kg (BWT-C), and <41 kg (BWT-D). Blood samples were collected at 33, 36, and 39 wk of gestation. Packed cell volume (PCV) and plasma concentrations of insulin, estrone sulfate (E1SO4), NEFA, and creatinine were determined and correlated to BWT class. Creatinine:E1 SO4 ratio also was calculated. Duration of gestation was greater for dams producing a BWT-A calf than for the other BWT classes, and calf BWT was heavier (P < 0.001) for calves in the BWT-A vs. BWT-D class. The heaviest calf in BWT-A was associated with the highest calving difficulty score. Insulin and PCV values were not affected by week of gestation, whereas plasma E1SO4, NEFA, and creatinine content increased (P < 0.001) and creatinine:E1SO4 decreased (P < 0.001) during late gestation. Calf BWT class did not affect PCV value. Plasma E1SO4 concentrations were lower (P < 0.01) in BWT-D dams than the other dams, showing the greatest difference at 39 wk of gestation. At 36 and 39 wk of gestation, dams bearing BWT-C and BWT-D calves had a higher (P < 0.01) plasma insulin concentration than those bearing BWT-A and BWT-B calves. Plasma NEFA concentrations at 39 wk of gestation were higher (P < 0.05) in dams of calf BWT-A than in the other dams. We conclude that plasma E1SO4 level is a variable that can be used to monitor problems related to a small size calf. Conversely, the forthcoming birth of a calf with a heavy BW seems to be preceded by a pronounced increase in plasma NEFA level in the dam just a few days before calving.