BLAD genotypes and cow production traits in Hungarian Holsteins (1999)

Introduction Bovine Leukocyte Adhesion Deficiency (BLAD) is a recessive autosomal inherited disease in Holstein–Friesian cattle. BLAD is caused by a deficiency in a Mac‐1 (CD11b/CD18) leukocyte‐surface glycoprotein involved in the defence mechanism against infections. A granulocytopathic syndrome was described in Holstein cattle ( Hagemoser et al . 1983 ; Nagahata et al . 1987 ; Takahashi et al . 1987 ), and Kehrli et al . (1990) later demonstrated that this disease was equivalent to BLAD. BLAD is genetically identical and phenotypically similar to the human LAD ( Springer et al . 1984 ), and to the condition identified in Irish Setters ( Renshaw &amp; ; Daves 1979 ) . Until now BLAD has been identified in the Holstein–Friesian breed only in the United States of America (US) and in other countries importing Holstein cattle. In BLAD‐affected calves (homozygotes) there is a defect in the surface of the neutrophile granulocytes, where neutrophile migration through the vascular endothelium into the extravascular tissue cannot occur. The neutrophiles of these calves are unable to reach the inflammatoric sites. BLAD is lethal for the affected (homozygote) calves. These calves would probably be the first ones to die if a disease outbreak occurred on a given dairy farm. It is also possible that affected calves might die as a result of disease caused by normal flora. The majority of BLAD calves die before reaching 1 year of age. Some animals may live past 2 years of age but are severely stunted in growth and suffer from various infectious conditions. To detect BLAD carriers a polymerase chain reaction (PCR)‐restriction fragment length polymorphism (RFLP) test was introduced by Shuster et al . (1992) , and the test was later improved among others by Tajima et al . (1993) , Batt et al . (1994) , Mirck et al . (1995) , Tammen et al . (1996) and Zsolnai &amp; Fésüs (1996) . Due to the wide use of BLAD heterozygote US Holstein–Friesian top AI breeding bulls in many countries having black and white and Holstein–Friesian population, quite a high incidence of carriers has been reported ( Takahashi et al . 1987 ; Tajima et al . 1993 ; Jørgensen et al . 1993 ; Grzybowski et al . 1994 ; Duesmann 1994 ; Lüpsik et al . 1995 ; Kirilenko &amp; Glazko 1995 ; Boichard et al . 1995 ; Kostetskij et al . 1966 ; Poli et al . 1996 ; Yakovlev et al . 1996 ; Tammen et al . 1996 ; Powell et al . 1996 ; Fésüs &amp; ;, –; Anton 1997 ) . Since some breeders supposed that the reason for the spread of the BLAD defect was the better production of the carrier animals, in 1991 the Holstein Association of America implemented a BLAD control programme and many countries took similar measures as well. The majority of the few studies which have been carried out so far do not support the above hypothesis and have not demonstrated any positive effect of the BLAD gene on production traits. Jørgensen &amp; Madsen (1994) studied the effect of the BLAD genotypes on some performance test data (weight at day 42 and at 336, daily gain, feed utilization and ultrasonic muscle area) in Danish Holsteins. Non carrier (TL) bulls showed a better feed utilization of 0.07 SFU/kg gain than BLAD‐carriers (BL). All other contrasts between carriers and non carriers were not significant. InFrance, Boichard et al . 1995 ) tested the putative association between the BLAD gene and five productive traits, milking ease, as well as 15 type traits, with a granddaughter design involving 620 AI bulbs. No significant association was detected. It was concluded that the recent spreading of the BLAD mutation cannot be explained by a linkage with a quantitative trait locus (QTL) for a selected trait. The daughters of 153 BL‐type Hungarian Holstein–Friesian bulls produced significantly more milk, milk fat and milk protein than the daughters of TL bulls ( Dohy et al . 1996 ). In a study with US Holsteins Powell et al . (1996) observed a negative effect on some selected production traits in BLAD carriers and concluded that selection against BLAD would not negatively influence herd production level. In another Hungarian study Jánosa &amp; Dohy (1997) when analysing the progeny‐testing data of 107 Hungarian and 153 Dutch Holstein–Friesian bulls compared the INET values of the BL and TL groups and some significant advantages for the BL group were demonstrated. In their recent study with Danish Friesian bulls Jørgensen (1997) found that carriers of BLAD had poorer feed utilization than non carriers and tended to grow more slowly. In this paper some selected production traits of Hungarian Holstein–Friesian BL and TL type bull rearing cows are compared. Materials and methods Between May 1993 and September 1997 a total of 236 AI bulls, 720 breeding bull rearing cows and 266 young breeding bull candidates were BLAD‐typed. The cows originated from 21 herds. All tested animals belonged to the Holstein–Friesian breed. The effect of the cows’ BLAD status on the following production traits was estimated: age at first, second and third calving; calving interval; number of milking days in lactation, milk (kg), milk fat (%), milk fat (kg), milk protein (%), milk protein (kg); milk production (kg), milk fat (%), milk fat (kg), milk protein (%) and milk protein (kg) in 305 day lactation. All production trait data were obtained from the authorities responsible for collection and processing data for breeding‐value estimations in registered herds. DNA for the PCR‐RFLP BLAD typing was extracted from whole blood samples, occasionally from frozen semen in the case of some bulls. The primers described by Shuster et al . (1992) were used in the early stage of the studies, and later those published by Schwerin et al . (1994) . Details of the typing method were given elsewhere ( Fésüs &amp; Zsolnai 1995 ). Later an improved and simplified method allowing