Cattle transferrins and milk production

1967 ◽  
Vol 9 (4) ◽  
pp. 491-500 ◽  
Author(s):  
Alan Jamieson ◽  
Alan Robertson
Keyword(s):  
Genetic Variation ◽  
Great Britain ◽  
Dairy Cattle ◽  
Milk Production ◽  
Milk Yield ◽  
Opposite Direction ◽  
Artificial Insemination ◽  
Fat Content ◽  
Progeny Test ◽  
Cattle Breeds

1. An analysis has been made of the association between transferrin genotype and progeny test for both milk yield and fat content in a sample of 879 bulls of five dairy cattle breeds, the majority used in artificial insemination in Great Britain. Although significant effects were found in only one of the ten analyses when the breeds were considered separately, a significant effect on milk yield was found when the results from all breeds were combined. A significant effect was not found for fat content, although the effects of the allele substitutions were in the opposite direction to that on milk yield in five cases out of six.2. Although our results were in the same direction as those of Ashton, the effects were smaller. It was estimated that the locus accounted for 1·1% of the genetic variation in yield and 0·4% of the genetic variation in fat content.3. Some information based on the production records of 178 experimental cows with known genotypes was also analysed. For milk yield, the pattern of effects was similar to that in the sire data though the differences were much larger. The variance removed by fitting constants was not statistically significant for milk yield or fat content. It was estimated that the sire data contained some fifty times as much information as did the cow data.

scholarly journals PRODUCTIVITY OF COWS OF UKRAINIAN BLACK-AND-WHITE AND RED-AND-WHITE DAIRY BREEDS

2018 ◽  
Vol 51 ◽  
pp. 112-118
Author(s):  
V. V. Machulnyi
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Fat Content ◽  
Reproductive Capacity ◽  
Black And White ◽  
Reproductive Ability ◽  
Service Period ◽  
Dairy Breed

Milk yield of cows in breeding herds, Cherkassy region, for last completed lactation averaged 6442 kg of milk with 3.62 % fat content. Currently the question of interconnection of cows’ milk production and reproductive capacity is especially important, because the significant increase in milk yields makes minimize calves. The successful conduct of breeding had set the goal to detect the best options for combining milk production and reproductive ability of animals.To characterize the level of milk production including reproductive ability of cows we used indicator of daily average milk yield per one day of periods between calving (PBC). The best service period can be considered period of 51-90 days, that allows you to get one calf per cow per year (average PBC is 351 days) and maintain high milk production (6431 ± 39.6 kg during 305 days of lactation). With this service period all indicators of milk production and reproductive ability are at high level. Reduced service period below recommended levels will reduce the duration of lactation and milk production, and increasing service period will increase the duration of lactation with a simultaneous reduction in milk production for 305 days. Herewith deterioration of reproductive ability is marked and manifested in the increase of the insemination index, decline in the reproductive capacity, increase of periods between calving and as a result, reduce of calves and culling barren cows.Analysis of genealogical structure of the studied herds points to low diversity (Ukrainian Black-and-White dairy cows belong to 6 lines and Ukrainian Red-and-White dairy cows – to 8 ones) with high affinity (by Chief 1427381.62 to R. Sovereign 198998 bloodline, by Starbuck 352790.79 to Elevation 1491007 and Ideal1013415 bloodlines).Genealogical structure of the herds is saturated a lot of bulls genealogical groups of Holstein cattle: Chief 1427381 – 11 bulls in the array of Ukrainian Black-and-White dairy breed and 5 ones in Ukrainian Red-and-White dairy breed, Starbuck 352790.79 – 10 sires in the array of Ukrainian Black-and-White dairy cattle and 3 ones in Ukrainian Red-and-White dairy breed, Elevation 1491007.65 – 4 sires in the array of Ukrainian Black-and-White dairy cattle and 3ones in Ukrainian Red-and-White dairy breed.Currently the sires of Chief 1427381.62 (7712-3,76-289,9-3,14-242,1), Starbuck 352790 (7857-3,87-295,4-3,07-241,2), Jocko Besne 694028588.94(6687-3,88-259,5-3,03-202,6), and Bell 1667366 bloodlines (61341-3,95-242,3-3,02-185,2) among sires of Ukrainian Black-and-White dairy cattle and the sires of Cavalier 1620273.72 (7285-3,98-289,9-3,08-224,4), Chief 1427381.62 (7522-3,76-282,8-3,00-225,7),Starbuck 392405 (7667-3,87-296,7-3,00-230,0), and Elevation 1491007.65 bloodlines (7544-3,80-286,7-3,5-230,0) among sires of Ukrainian Red-and-White dairy breed are classified to a highly productive and promising for breeding and wider use by productive qualities.After the first insemination the lowest proportion of fertilized cows is among offspring belonging to Chief 1427381 bloodline which is only 38 % among both breeds. However, the milk yield of breeding stock belonging to this bloodline is 7712 kg with 3.76 % fat content for Ukrainian Black-and-White dairy cows and 7522 kg of milk with 3.76 % fat content for Ukrainian Red-and-White dairy cows. Daughters belonging to Elevation1491007, Valiant 1650414, and Hanover 1629391 bloodlines with yields of 4566-5478 kg of milk per lactation had a part of fertilized cows, after the first insemination, at the level of 41-49 %. Fertilization after the first insemination above 50% was in daughters belonging to Cavalier 1620273.72 (52%), Starbuck 392405(50-55 %), Bell 1667366(56%) and Jocko Besne 694028588.94 bloodlines (64 %). The level of performance of these animals for milk yield ranged from 6134 kg to 7857 kg.Heritability coefficients of milk yield and duration of service period were low (0.118-0.289). A positive correlation can be explained by the fact that extension of service period (to a certain level) leads to growing number of milking days (duration of lactation) and defers a decrease in productivity of cows by physiological reasons, namely as a result of pregnancy. Low rates of heritability indicate little genetic diversity of traits and the significant influence of physiological and environmental factors in their formation.As Ukrainian Black-and-White and Ukrainian Red-and-White dairy breeds have a high proportion of heredity of Holstein breed which has genetically large fetus, there is need to study the characteristics of nature passing calving in cows of these breeds. Itis found the number of first-calf heifers which needed help was 52.4%. Animals calve alone in 47.6 % of all cases. Calving was without complications if the live weight of calves not exceeding 6-7% of mother’s weight. The cows calved without help of staff exceeded by 11.7% of the width of the pelvis in the buttocks, 7.5 % of the width of the ilium, and 7.1 % of its oblique length compared with animals of same age.

Challenges and Opportunities of Artificial Insemination on Dairy Cattle in Ethiopia

2021 ◽  
Vol 1 (2) ◽  
pp. 47-54
Author(s):  
Mohammed Yousuf
Keyword(s):  
Dairy Cattle ◽  
Milk Production ◽  
Artificial Insemination ◽  
Genetic Improvement ◽  
Dairy Industry ◽  
Dairy Farmers ◽  
Local Breed ◽  
Cattle Breeds ◽  
Challenges And Opportunities

Artificial insemination is very important for genetic improvement, especially in dairy cattle breeds. It has problems in meeting the needs of some producers, not its opportunities. The objective of this study was the challenge and opportunity of artificial insemination on dairy cattle in the case of Sayo district, west Wollega Zone, Ethiopia. The problem of not using Artificial insemination is not limited to the region, and there are also dairy farmers in our district who have not practiced the service due to various challenges. In addition, most of the Artificial insemination services reported by the dairy industry have failed, rather than bull services. However, although there are few attempts to quantify opportunities, constraints, and why producers do not use artificial insemination services in other regions, researchers have not disclosed well-documented data on the challenges and opportunities of artificial insemination services in the Sayo region. The Result is Artificial insemination has played an important role in increasing milk production in the study area because the crossbreed that got good traits from exotic breeds gave high milk than local breed.

scholarly journals SELECTION OF THE SITUATION IN SEEF «OLEKSANDRIVSKE» FOR BREEDING UKRAINIAN RED-AND-WHITE DAIRY CATTLE AND UKRAINIAN BLACK-AND-WHITE DAIRY CATTLE AND ITS IMPROVING

2018 ◽  
Vol 51 ◽  
pp. 69-73 ◽  
Author(s):  
G. S. Kovalenko ◽  
S. V. Priyma ◽  
G. A. Holysa ◽  
A. V. Tuchyk ◽  
L. V. Marchuk ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Fat Content ◽  
Breeding Value ◽  
Body Structure ◽  
Point Scale ◽  
Black And White ◽  
Dairy Breed

Created Ukrainian Red-and-White Dairy and Ukrainian Black-and-White Dairy cattle have a desirable level of reproductive and productive qualities.  These breeds are competing successfully with animals of the European selection, so comparative study of pedigree and productive qualities of animals at one of the farms has practical value. The studies were conducted in the herd of “Oleksandrivske” SE RF at the animals of Ukrainian Red-and-White Dairy and Ukrainian Black-and-White Dairy breeds of Vinnytsia region. The animals of both breeds were kept under the same technological conditions in housing for livestock. It was taken into account milk production (milk yield, fat content in milk and milk fat) for 305 days of lactation. Expert evaluation of the exterior of first-calf heifers has been conducted for 2015-2016. Assessment of type of body structure of cows was conducted on 100-point scale. Fatness of cows was determined on 5-point scale. The analysis of genealogies of 37 bulls which had progeny in the herd was conducted by breeding index, discharge of breeding values and milk production of ancestors. Milk production of the animals of the herd was more than 6000 kg of milk for 305 days of lactation. Comparing milk yields, it was found that the animals of Ukrainian Black-and-White Dairy breed dominated Ukrainian Red-and-White Dairy cows of the same age. It is noteworthy that biological feature of cows to increasing milk yield with each subsequent lactation is positive. Thus, the Ukrainian Black-and-White Dairy cows after the second calving in comparison with the first calving increased milk yield by 380 kg and the animals after the third calving and older comparatively with the second one – by 425 kg more. Also the Ukrainian Red-and-White Dairy cows increased milk yield, respectively, by 348 and 358 kg. The average body measurements of the first-calf heifers were inferior by targeted parameters of Ukrainian Red-and-White Dairy and Ukrainian Black-and-White Dairy cattle from -0.3 cm (girth of metacarpus) to -7.8cm (height in the sacrum) in most cases.  The total number of points for type of body structure was 87.9 at the animals of Ukrainian Black-and-White Dairy cattle and, respectively, 87.0 at the Ukrainian Red-and-White Dairy cows; it corresponds to the assessment "very good". This indicates the high estimation of individual parts of the exterior. The cows of the herd had the required fatness. The average of this trait at animals of Ukrainian Black-and-White Dairy breed was 3.0 points and at the cows of Ukrainian Red-and-White Dairy cattle was respectively 3.4 points. The genealogical structure of the current herd of “Oleksandrivske” SERF consists of two female contingents. The animals of Ukrainian Black-and-White Dairy cattle were derived from 18 bulls belonging to 8 bloodlines. Most of animals belong to R.O.R.Elevation 1491007 bloodline – 45.4%, H.H.Starbuck 352790 and P.F.A.Chief 1427381 bloodlines – 14.4%. Qualitative characteristic of bulls used for the female livestock of the herd, shows that in the vast majority they are valuable breeding bulls. However, it should be noted that there are progeny derived from bulls with low breeding value in the herd. Thus, bull Matrix Red 136549448 had SI-7 and H- and Trubadur 343643346 had SI-50 and H-. The use of bulls for female livestock of the herd with low breeding value is unacceptable for further breeding work. Expectation of improving the breeding traits in progeny from such fathers is unlikely. It is planned to accelerate the reproduction of valuable genotypes and increase the rate of genetic progress at the herd using embryos transplantation this year. Donors of embryos will be their own breeding resources. Using this method will make it possible to exclude from the selection process animals with exterior defects and low-yielding cows. The considered aspects of selective breeding work indicate prospects of using Ukrainian Red-and-White Dairy and Ukrainian Black-and-White Dairy cattle. This applies particularly to increase of milk yield to 8000 kg and more per lactation. Bulls which will be used for breeding stock should have high rates of breeding values (SI +1000 and P4 and more). Especially it applies such features as fat content in milk and some exterior defects.

COMPARATIVE DESCRIPTION OF MILK PRODUCTIVITY OF COWS UKRAINIAN RED-AND-WHITE DAIRY CATTLE AND UKRAINIAN BLACK-AND-WHITE DAIRY CATTLE AND HOLSTEIN BREEDS IN SERF «OLEKSANDRIVSKE»

2016 ◽  
Vol 52 ◽  
pp. 6-12 ◽  
Author(s):  
M. V. Gladiy ◽  
G. S. Kovalenko ◽  
S. V. Priyma ◽  
G. A. Holyosa ◽  
A. V. Tuchyk ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Milk Yield ◽  
Fat Content ◽  
Holstein Cows ◽  
Milk Productivity ◽  
Black And White ◽  
The Third ◽  
Fat Yield ◽  
Selection Of

The main goal of dairy breeds selection should be improving breeding and productive qualities of animals under modern conditions. The majority of farms, using native breeds to produce milk, has created optimal conditions for keeping and feeding, selection and matching, growing of replacements etc. Further improvement of created native dairy breeds for economically useful traits occurs at total use of purebred Holstein bulls (semen) of foreign selection. In order to realistically assess milk productivity (milk yield, fat content in milk and fat yield) of Ukrainian Black-and-White and Red-and-White Dairy cows should be conducted a comparative analysis of Holstein cows under the same conditions of feeding and keeping. It was established that Ukrainian Red-and-White Dairy cows were characterized by the highest milk yields for 305 days of all lactations, taken into account, the among three investigated breeds. Their milk yield during the first lactation was 5933 kg of milk, during the second – 6393 kg, the third – 6391 kg and during higher lactation – 6650 kg. Ukrainian Black-and-White Dairy cows were second by milk yield (except for the second lactation), during the first lactation – 5932 kg of milk, the third – 6462 kg and higher – 6541 kg, and Holstein cows were third, during the first lactation – 5794 kg of milk, the second – 6381 kg, the third – 6335 kg and higher – 6469 kg. The fat content was almost the same and varied within 3.49-3.58% in milk of Ukrainian Red-and-White Dairy cattle, 3.50-3.60% in milk of Ukrainian Black-and-White Dairy cattle and 3.50-3.56% in Holsteins’ milk. The difference between the breeds was within 0.01-0.04%. All the investigated breeds had predominance in fat yield for three lactations over standards of these breeds: Ukrainian Red-and-White Dairy cows from 75.1 to 93.4 kg, Ukrainian Black-and-White Dairy cows – 75.1-89.0 kg respectively and Holstein cows – 41.9-60.2 kg. It was found different level of positive correlation between milk yield and fat yield in all the cases and high correlation (r = 0.604-0.921, P < 0.001) in five cases (41.7%) Negative correlation coefficients indicate that selection of animals to higher milk yield in the herd will decrease the second trait – fat content in milk. Positive and highly significant correlation between milk yield and fat yield indicates that selection of cows in the herd to higher milk yields will increase fat yield. It was revealed that bulls were among the factors impacted the milk productivity (milk yield, fat content, fat yield) of three investigated breeds. So, the force (η²x) of father’s impact on milk yield was15.4-47.9%, fat content – 22.0-43.4% and fat yield – 14.9-47.7% taking into account a lactation and a breed. The force of lines impact (η²x) was second; it was on milk yield 6.1-24.5%, fat content – 4.1-17.1 and fat yield – 5.8-23.5%. The force of breeds impact (η²x) was last; it was on milk yield 0.3-2.9%, fat content – 0.2-0.3% and fat yield – 0.6-2.7%. So, the comparative studies of milk productivity of Ukrainian Red-and-White and Black-and-White Dairy cattle with Holsteins indicate that under similar conditions of feeding and keeping, these native breeds can compete with Holstein cattle. The milk yield for 305 days of higher lactation was 6650 kg of milk in Ukrainian Red-and-White Dairy cows, 6541 kg in Ukrainian Black-and-White Dairy cows and 6469 kg in Holsteins. It was found the inverse correlation r = -0.025-0.316 between milk yield and fat content in milk in most cases. Selection and matching of animals in the herd should be carried out simultaneously on these traits. It was found positive repeatability of milk yields between the first and second, the third and higher lactations (rs = 0.036-0.741), indicating the reliability of forecasting increase in milk productivity during the next lactations in all herd. Bulls have the greatest impact (η²x) on milk productivity among the factors taken into account: milk yield – 15.4-47.9%, fat content in milk – 22.0-43.4% and fat yield – 14.9-47.7%.

An association analysis between PRL genotype and milk production traits in Italian Mediterranean river buffalo

2017 ◽  
Vol 84 (4) ◽  
pp. 430-433 ◽  
Author(s):  
Jun Li ◽  
Aixin Liang ◽  
Zipeng Li ◽  
Chao Du ◽  
Guohua Hua ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Milk Fat ◽  
Fat Content ◽  
Phenotypic Variance ◽  
River Buffalo ◽  
Production Traits ◽  
Milk Production Traits ◽  
Exon 2 ◽  
Mediterranean River

This Research Communication describes the association between genetic variation within the prolactin (PRL) gene and the milk production traits of Italian Mediterranean river buffalo (Bufala mediterranea Italiana). High resolution melting (HRM) techniques were developed for genotyping 465 buffaloes. The association of genetic polymorphism with milk production traits was performed and subsequently the effects of parity and calving season were evaluated. Single nucleotide polymorphisms (SNPs) were identified at exons 2 and 5 and at introns 1 and 2. All the SNPs were in Hardy–Weinberg equilibrium, and statistical analysis showed that the polymorphism of intron1 was significantly (P < 0·05) associated with milk yield, milk protein content and peak milk yield. The average contribution of the intron1 genotype (r2intron1) to total phenotypic variance in milk production traits was 0·09, and the TT genotype showed lower values than CC and CT genotypes. A nonsynonymous SNP was identified in exon 2, which resulted in an amino acid change from arginine to cysteine. Moreover, the polymorphism of exon 2 was associated significantly with milk fat content (P < 0·05), and the buffaloes with TT genotype showed higher total fat content than the buffaloes with CT genotype. These findings provide evidence that polymorphisms of the buffalo PRL gene are associated with milk production traits and PRL can be used as a candidate gene for marker-assisted selection in Italian Mediterranean river buffalo breeding.

Comparison of milk production, mastitis, lameness and days to conception of Brown Swiss, Holstein and Holstein cross Brown Swiss dairy cattle

2006 ◽  
Vol 2006 ◽  
pp. 86-86
Author(s):  
G Wellwood ◽  
J K Margerison
Keyword(s):  
Dairy Cattle ◽  
Somatic Cell ◽  
Milk Production ◽  
Milk Yield ◽  
Complex Disease ◽  
Economic Loss ◽  
Brown Swiss ◽  
Somatic Cell Counts ◽  
Cell Counts ◽  
Holstein Friesian

Mastitis is a complex disease causing inflammation of the udder, which has been estimated to cost the dairy farmer between £40-£117/cow per year (Stott et al., 2002). Economic loss occurs as a result of discarded milk, reduced milk yield and milk quality, increased vet costs and an increase in replacement costs. The objective of this study was to examine the effect of breed on the incidence of mastitis and somatic cell counts and milk production capabilities of Holstein Friesian, Brown Swiss and Brown Swiss crossbred cows.

scholarly journals THE FACTORS AFFECTING MILK YIELD IN DIARY FARMING IN GREATER GUWAHATI REGION OF ASSAM

2021 ◽  
Vol 9 (08) ◽  
pp. 723-728
Author(s):  
Heman Sarmah ◽  
◽  
Jnanashree Borah ◽  
Tirthankar Sarma ◽  
◽  
...  
Keyword(s):  
Regression Analysis ◽  
Dairy Cattle ◽  
Milk Production ◽  
Milk Yield ◽  
Policy Maker ◽  
Production Cost ◽  
Relative Importance ◽  
Factors Affecting ◽  
Micro Level ◽  
Farming Households

The production of milk is conceived of several factors and a very multifarious process. The knowledge of relative importance of the resource inputs influencing in milk production is essential for the dairy farmer for introducing desirable change in his operation at micro level and for the policy maker for formulating plans for improvements in dairy cattle productivity based on sound economic principles at the macro level (Rao, 1985).The income level of the dairy household is determined by the production of milk they produce at their farms. Generally, the income of the dairy household increases when the milk production cost decreases or when the milk production increases .For this it is essential to study the factors which directly or indirectly effect the milk production. Household samples have been selected both from the municipal wards of Guwahati Municipal Corporation area. Out of 672 dairy farming households, 201 household have been selected for the survey. Regression analysis has been used for the study of factors affecting milk production in greater Guwahati region of Assam.

Value for milk production of artificially dried forages as cobs and pellets

1972 ◽  
Vol 14 (1) ◽  
pp. 69-75 ◽  
Author(s):  
J. A. Milne ◽  
E. F. Thomson ◽  
R. C. Campling
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Live Weight ◽  
Fat Content ◽  
Significant Positive Effect ◽  
Significant Difference ◽  
Four Levels ◽  
Milk Solids ◽  
Positive Effect ◽  
Basal Ration

SUMMARYTwo experiments were conducted to compare the milk-producing value of dried forages in the form of cobs and pellets as replacements for a standard dairy concentrate. Four levels (0·33, 0·44, 0·55 and 0·66 kg/kg milk) of dried forage or standard dairy concentrate were offered in addition to a basal ration of 6 kg hay and 2 kg standard dairy concentrate. In both experiments the rate of eating by the cows of cobs was significantly slower (P<0·05) than that of pellets. No significant difference was found between the cobs and pellets in either experiment in their value for milk production. In Experiment 2 the standard dairy concentrate had a non-significantly higher (P>0·05) milk-producing value than the dried lucerne. Level of feeding had a significant positive effect on the milk yield (P< 0·001) of cows offered the dried grass and lucerne and on the milk solids- not-fat content (P<0·05) and live weight (P<0·01) of cows offered the dried grass, lucerne and standard dairy concentrate.

Effect of first 60-day cumulative milk yield on days open in Holstein dairy cows in Iran

2007 ◽  
Vol 2007 ◽  
pp. 148-148
Author(s):  
A. Heravi Moussavi ◽  
M. Danesh Mesgaran ◽  
T. Vafa
Keyword(s):  
Dairy Cattle ◽  
Dairy Cows ◽  
Milk Production ◽  
Milk Yield ◽  
Dairy Farm ◽  
Reproductive Efficiency ◽  
Root Cause ◽  
Principal Factors ◽  
Days Open ◽  
Holstein Dairy Cows

Reproduction and milk production are the principal factors that are influencing dairy farm profitability. The dairy industry in Iran has changed dramatically in the last decade. The shift toward more productive cows and larger herds in Iran is associated with a decrease reproductive efficiency (Heravi Moussavi et al., 2004). Increased knowledge about the principal causes of reduced fertility is essential. The root cause of the declining fertility is probably a combination of a variety of physiological and management factors that have an additive effect on reproductive efficiency. Dairy cattle are inseminated and pregnancy is established while dairy cows are lactating. Based on the analyses of large datasets, there is clearly an antagonistic relationship between milk production and reproduction in dairy cattle (Lucy, 2001). It was shown that the hazard ratio for cumulative first 60-day milk yield and conception in high producer cows was 8 percent less than the others and also high milk yield was a risk factor for several reproductive disorders (Grohn and Rajala-Schultz, 2000). The objective of this study was to evaluate the effect of first 60-day cumulative milk yield on days open in Iranian Holstein dairy cows.

Influence of Genetic Merit on Fertility Traits of Dairy Cattle on Commercial Farms

2002 ◽  
Vol 2002 ◽  
pp. 126-126
Author(s):  
H.C.F. Wicks ◽  
J.D. Leaver
Keyword(s):  
Dairy Cattle ◽  
Milk Production ◽  
Milk Yield ◽  
Body Condition Score ◽  
Potential Yield ◽  
Genetic Merit ◽  
Condition Score ◽  
Actual Yield ◽  
High Level ◽  
Daily Milk Yield

The selection of dairy cattle for high milk production is thought to be linked to increased problems with fertility. Most research has concentrated on the influence of actual yields rather than the effect of genetic merit on fertility. It has also been reported that by maintaining a high level of herd management the reproductive efficiency problems associated with high milk production can be removed (Nebel and Gilliard, 1993). The current work estimated the influence of genetic merit (defined as PIN95), 90-day daily milk yield, deviation from herd mean 305-day milk yield and body condition score on fertility, in an attempt to assess whether actual yield has more effect than potential yield as indicated by genetic merit.

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