Crossbreeding trials in California

Dairy producers should not consider crossbreeding to be genetic improvement – it is not! Continuous use of progeny-tested and highly-ranked A.I. sires is the key to genetic improvement. Some dairy producers have viewed crossbreeding as a justification to turn to natural service bulls rather than A.I. That would be an unfortunate consequence of the new interest in crossbreeding.

CIRCUMSTANCES HAVE CHANGED

Interest in crossbreeding is perhaps at an all-time high among commercial dairy producers internationally. Over the past 50 years, North American Holsteins have steadily increased as a percentage of the national dairy herd in most countries. Generally speaking, however, circumstances have changed regarding the historical superiority of pure Holsteins compared to crossbreds. Economically, milk pricing in most markets has placed greater emphasis on the solids in milk rather than the fluid carrier, which gives the Holstein breed less of a competitive advantage compared to other breeds. Biologically, the reproductive decline of Holsteins, on both an observed and a genetic basis, has been clearly documented in most countries of the world. Furthermore, postpartum complications of Holsteins have become more pronounced in recent years in most environments. All dairy breeds in the world likely have fewer problems than the Holstein breed for the direct and maternal effects of calving difficulty. Frequently, Holstein cows have become too large for optimum longevity in many facilities, because they have difficulty fitting in stalls that are inadequate in size. The combined effect of these factors is fewer calvings during the lifetimes of pure Holstein cows at this time than in the past.

Inbreeding

The global Holstein population is becoming more inbred over time. As expected, relationships continue to mount within the Holstein breed because of highly effective selection programs. As relationships between individuals rise, it becomes more and more likely that bulls and cows that are mated to one other will be closely related. Most consequences of inbreeding are masked and not readily noticeable. Inbreeding robs dairy producers of income by increasing stillbirths, hampering growth rates of heifers, reducing cow fertility, and reducing disease resistance. A major negative consequence of inbreeding should be reduced cow fertility, because highly inbred embryos are more likely to be nonviable and sloughed.

Table 1 has the relationship in 2005 of individual sires of high impact to the USA Holstein population. These relationships were estimated by USDA with a base year of 1960, so relationships prior to that year were ignored. Two bulls born in the 1960s – Elevation and Chief – together make up about 30% of the Holstein breed today. All of the other bulls in Table 1 are descendants of at least one of these two stalwarts of the breed. Blackstar is a relatively "young" ancestor with a birth year of 1983, yet he already has a relationship of 15.8% to the Holstein breed. Many of Blackstar's sons (Emory, Juror, Lord Lily, Duster, Patron) and grandsons (Mtoto, Tugolo, Outside) have begun to have their impact on the breed. Historically, no bull has surpassed 16% relationship to the Holstein breed, but Blackstar should be the first bull to do so. Globally, the “narrowing of the genetic base” is almost as severe as in the USA, because North American Holstein genetics have replaced native breeding stock internationally.

Table 1. Relationships of individual sires to the Holstein breed in the USA.

Sire Pedigree Birth year Relationship (%)
Blackstar Traces twice to Elevation and twice to Chief    1983 15.8
Elevation     1965 15.2
Chief     1962 14.8
Emory Son of Blackstar and dam is sired by a double grandson of Chief   1989 14.2
Valiant   Son of Chief 1973 13.6
Mark Son of Chief   1978 13.2
Starbuck Son of Elevation   1979 12.2

Four Holstein bulls (Blackstar, Rudolph, Manfred, and Elton) currently dominate the pedigrees of sires and dams of progeny-test young bulls entering A.I., because their descendants tend to rank highly for cow fertility and survival. Elton’s relationship to the breed in 2005 is 11.6%, but will likely increase substantially through his sons (Durham and Convincer) and especially his grandsons (O-Man, BW Marshall, Addison, Jesther, and Machoman).

Table 2 has the average inbreeding of Holstein females in the USA from milk recording by birth year. The estimates are conservative, because many cows lack parts of their pedigree and because pedigrees go back to only 1960. Knowledge of relationships prior to 1960 suggests that 2% should be added to all current estimates of inbreeding with the 1960 base for pedigrees.

Table 2. Average inbreeding of Holstein females in the USA.

Birth year   Inbreeding (%)
1994 3.5
1996 3.9
1998 4.2
2000 4.5
2002 4.8
2004 5.0

Inbreeding is increasing at a constant rate of 0.1% per year for USA Holsteins, and heifers born in 2004 had an average inbreeding of 5.0%. The recommendation for commercial milk production is that inbreeding shouldn’t surpass 6.25%. With an average of 5.0%, many individual Holstein matings surpass the 6.25% threshold. What does the 6.25% mean? Cows have two genes at every location on their chromosomes – one from each parent. The inbreeding coefficient measures the percentage of those two genes (on all chromosomes) that are identical because they trace to the same ancestor. As the inbreeding % goes up, the likelihood of doubling up on genetic recessives (most of them of minor consequence) becomes greater.

Most dairy producers are probably unaware that individual cows in their herd have inbreeding % higher than what is recommended. With increased relationships among Holsteins, inspection of pedigrees is essential when mating individual bulls to individual cows. The corrective mating programs offered by A.I. organizations can assist to avoid the mating of A.I. sires with cows that will result in unacceptable inbreeding. However, pedigrees of cows must be provided for the mating programs, and the mating programs must go deeply into pedigrees to pick up bulls like Elevation and Chief, which often appear many, many times in the pedigrees of current bulls and cows. A major hurdle for avoiding inbreeding by pedigree inspection is misidentification of sires of cows, which was recently estimated to be at least 25% of cows in the USA.

CROSSBREEDING

Concerns about inbreeding can be eliminated by crossbreeding. The effects of crossbreeding are the exact opposite of the effects of inbreeding. At each location on pairs of chromosomes, the two genes are much less likely to be identical with crossbreeding than with same-breed matings. Therefore, genetic recessives of both major and minor consequence are not expressed. Old research has indicated that hybrid vigor from crossbreeding is greatest for traits related to fertility, health, and survival. Currently, routine crossbreeding of Holsteins and Jerseys in New Zealand has resulted in phenomenal increases in survival of crossbreds compared to purebreds.

Crossbreeding should be of the most benefit when environments are limited and when dairy producers are unable or resistant to keep reliable records on parentage of cows in their herds. New research is underway to help uncover the potential value of crossbreeding for commercial milk production. However, the commercial pig, beef cattle, and sheep production have relied on crossbreeding to improve reproduction, growth, and disease resistance for about half a century.

Background

The decline in fertility and survival of pure Holsteins led the managers of seven large dairies in California to mate Holstein heifers and cows with imported semen of the Normande and Montbeliarde breeds from France, as well as the Swedish Red (SRB) and Norwegian Red (NRF) breeds. The Swedish Red and Norwegian Red breeds share similar ancestry and exchange sires of sons; therefore, the two breeds were collectively regarded as “Scandinavian Red” for this study. However, Finnish Ayrshire and Danish Red are two additional Scandinavian Red breeds. Crossbred cows began calving in June 2002, and all early crossbreds in the seven California dairies were Normande-Holstein. Some cows in the seven dairies continued to be pure Holstein, which permitted comparison of pure Holsteins and crossbreds.

Production

Crossbreds and pure Holsteins that calved for the first time from June 2002 to January 2005 were studied for production. Sires of all cows were A.I. sires, and all Holstein sires had NAAB-assigned sire codes. Furthermore, the Holstein maternal grandsires of all cows (both purebred and crossbred) were likewise required to be A.I. sires with NAAB-assigned sire codes. Therefore, cows were removed from the study that had natural service or unidentified Holstein sires or Holstein maternal grandsires.

Actual production (milk, fat, and protein) for 305-day lactations was calculated with the Best Prediction technique used by USDA for national genetic evaluation in the USA. Best Prediction was applied separately to each of the seven dairies and used herd-specific lactation curves rather than breed-specific lactation curves to calculate 305-day actual production. Adjustment was made for age at calving and milking frequency (test days with 3X were adjusted to 2X), and records less than 305 days in length were projected to 305 days. Herdyear-season of calving (4-month seasons) and genetic level of each cow’s Holstein maternal grandsire were included in a statistical analysis of 305-day actual production of cows. Table 3 provides the number of cows analyzed for production and number of sires of the cows by breed group.

Table 3. Number of cows and sires of cows analyzed for production.

Breed Cows Sires
Holstein 380 69
Normande-Holstein 245 24
Montebeliarde-Holstein 493 23
Scandinavian Red-Holstein 328 13

Results for 305-day actual production of first lactations are in Table 4. Fat (kg) plus protein (kg) was used to gauge the overall production of the pure Holsteins versus crossbreds. The Scandinavian Red-Holstein crossbreds (-.2%) were not significantly different from the pure Holsteins for fat (kg) plus protein (kg); however, the Montbeliarde-Holstein crossbreds (- 3.8%) and the Normande-Holstein crossbreds (-8.6%) were significantly lower than pure Holsteins for fat (kg) plus protein (kg). Pure Holsteins had significantly higher milk (kg) and protein (kg) than all crossbred groups, but pure Holsteins were not significantly different than Scandinavian Red-Holstein crossbreds for fat (kg). The Montbeliarde-Holstein and the Scandinavian Red-Holstein crossbreds were not significantly different from one another for any production trait.

Table 4. Actual 305-day production (2X milking) for first lactation.

  Holstein Normande-Holstein Montbeliarde-Holstein Scandinavian Red-Holstein
Milk (kg) 9757a 8530b 9161c 9281c
Fat (kg) 346.2a 319.0b 333.8c 340.0a,c
Protein (kg) 305.3a 276.7b 293.0c 297.3c
Fat (kg) + Protein (kg)  651.4a 595.7b 626.8c 637.3a,c
% of Holstein   -8.6% -3.8% -2.2%

a,b,c Different letters of superscripts indicate significant differences (p<.05)

Importantly, no adjustment was made to production for differences in days open (pregnancy status) of cows. It has been documented that cows with very short days open are penalized for 305-day production, and cows with long days open or do not become pregnant have inflated 305-day production. Production and reproduction must both be included, along with other important traits, in indexes to determine total economic merit of cows.

Averages of somatic cell score (as an indicator of mastitis) during first lactation were uniformly low compared to the entire USA, and crossbred groups did not differ significantly from pure Holsteins, with averages of 2.5 for Normande-Holstein crossbreds, 2.4 for pure Holsteins, 2.3 for Montbeliarde-Holstein crossbreds, and 2.2 for Scandinavian Red-Holstein crossbreds.
All cows in the study were sired by A.I. sires, and the seven California dairies historically used high-ranking Holstein A.I. sires. The weighted averages for estimated breeding value (May 2005) of the sires of the 380 pure Holstein cows in this study were +513 kg milk, +12 kg fat, +16 kg protein, which were relative to the USA’s updated step-wise genetic base for 2005. Also, of the 328 Scandinavian Red-Holstein crossbreds, 180 were sired by nine Norwegian Red bulls and 148 were sired by four Swedish Red bulls. The Swedish Red-sired crossbreds had a non-significant advantage over the Norwegian Red-sired crossbreds of 206 kg milk, 3 kg fat, and 3 kg protein, with no difference for somatic cell score.

Calving Difficulty and Stillbirths

Calving difficulty was measured on a 1 to 5 scale, with 1 representing a quick and easy birth without assistance and 5 representing an extremely difficult birth that required a mechanical puller. Scores of 1 to 3 were combined and regarded as no calving difficulty, and scores of 4 and 5 were combined and represented calving difficulty. Stillbirths were recorded as alive or dead within 24 hours of birth. Calving difficulty and stillbirth are traits of both the sire and the dam.

Breed of sire

To analyze effects of breed of sire, dams of calves were separated into first calving versus 2nd to 5th calving. Adjustments were made for sex of calf and herd-year-season (3-month seasons) of calving. Across breeds of sire for first-calf heifers, calving difficulty averaged 15.5% for bull calves and 7.3% for heifer calves, and stillbirth rates were 18.8% for bull calves and 5.6% for heifer calves. Clearly, the bulk of calving difficulty and stillbirth was for bull calves. Table 5 provides the number of births, calving difficulty rate, and stillbirth rate by breed of sire for first-calf pure Holstein dams. Inadequate numbers prevented the evaluation of Normande sires. Scandinavian Red sires had significantly less calving difficulty and stillbirth than Holstein sires when dams of calves were first-calf pure Holsteins.

Table 5. Calving difficulty and stillbirths for breed of sire for first-calf pure Holstein dams.

Breed of sire Number of births Calving difficulty(%) Stillbirth(%)
Holstein 371 16.0a 15.7a
Montebeliarde 158 12.0a 13.2a,b
Brown Swiss 224 11.9a,b 12.0a,b
Scandinavian Red 1,016 5.5b 7.9b

a,b Different letters of superscripts indicate significant differences (p<.05)

Table 6 has number of births, calving difficulty rate, and stillbirth rate for pure Holstein cows calving for the 2nd to 5th time. Cows calving for the 2nd to 5th time had less calving difficulty and fewer stillbirths than first-calf heifers. However, bull calves again were more of a problem than heifer calves, with almost twice the rate of calving difficulty (7.9% versus 4.4%) and twice the rate of stillbirth (8.4% versus 4.3%). Again, calves sired by Scandinavian Red sires had significantly less calving difficulty than Holstein-sired calves. Furthermore, significantly more Holstein-sired calves were stillborn than calves sired by bulls of other breeds.

Table 6. Calving difficulty and stillbirths for breed of sire when pure Holstein dams calved for the 2nd to 5th time.

Breed of sire Number of births Calving difficulty(%) Stillbirth(%)
Holstein 1.241 7.7a,b 11.8a
Normande 327 9.1b 6.5b
Montebeliarde 2.385 5.7a 4.4b
Brown Swiss 527 5.4a,c 4.9b
Scandinavian Red 516 2.6c 4.2b

 a,b,c Different letters of superscripts indicate significant differences (p<.05)

All non-Holstein breeds of sire had (for first-calf heifers) or tended to have (for 2nd to 5th lactation cows) fewer stillbirths than Holstein sires. Dams of all calves for the breed of sire analysis were pure Holsteins, so calves sired by Holstein sires were purebreds, whereas calves sired by bulls from the other breeds were crossbreds. Therefore, inbreeding probably caused the much higher stillbirth rates for Holstein-sired calves, perhaps due to lethal genetic recessives that have not yet been uncovered.

Breed of dam

To estimate differences in breed group of dam for calving difficulty and stillbirths, breeds of sire were limited to Brown Swiss, Montbeliarde, and Scandinavian Red, because numbers of births by sires of other breeds were small and were not well distributed across breed group of dam. Therefore, all births analyzed for effect of breed of dam were for crossbred calves. Adjustments were made for breed of sire, sex of calf, and herd-year-season of calving. Cows calving for the first time were analyzed separately. Across breed group of dam, calving difficulty rates were 11.4% for bull calves and 4.2% for heifer calves, and stillbirth rates were 13.6% for bull calves and 2.2% for heifer calves for cows calving the first time. Table 7 has number of births, calving difficulty rate, and stillbirth rate for 2,301 first births of cows.

Table 7. Calving difficulty and stillbirths for breed group of dam at first calving.

Breed of sire Number of births Calving difficulty(%) Stillbirth(%)
Holstein 1.398 9.3a 11.8a
Normande-Holstein 269 9.2a,b 7.8a,b
Montebeliarde-Holstein 370 8.1a,b 7.1a,b
Scandinavian Red-Holstein 264 4.7b 4.9b

a,b Different letters of superscripts indicate significant differences (p<.05)

Scandinavian Red-Holstein crossbreds (4.7%) had significantly less calving difficulty than pure Holsteins (9.3%) at first calving. Stillbirth rates tended to follow the averages for calving difficulty respective to breed group of dam, and Scandinavian Red-Holstein dams had a significantly lower stillbirth rate than pure Holstein dams at first calving.

Normande x Holstein 1-11 305d Milk, 286 Fat, 261 Protein Normande X Holstein Grand Champin - 2004 Minnesota State Fair
Montbeliarde x Holstein 1-11 305d 9163 Milk, 304 Fat, 267 Protein Montbeliarde x Holstein 2-3 305d 12,025 Milk, 469 Fat, 342 Protein
Swedish Red x Holstein 1-11 305d 10,102 Milk, 337 Fat, 316 Protein Swedish Red x Holstein 1-10 305d 10,773 Milk, 340 Fat, 321 Protein

Survival

First-lactation cows that calved from June 2002 to October 2004 in the seven California dairies were compared for survival to 30 days, 150 days, and 305 days postpartum. Survival rates were adjusted for herd-year of calving. Table 8 has the survival rates for 692 pure Holsteins and 1,554 crossbreds. Pure Holsteins left these dairies sooner than crossbreds, with 86% of pure Holsteins surviving 305 days postpartum compared to 92% to 93% of crossbreds.

Reason for disposal was recorded, and 1.7% of pure Holsteins died by 30 days postpartum. Death rate grew for pure Holsteins to 3.1% by 305 days postpartum, and this was more than double the death rate of any of the three crossbred groups. However, all of these death rates are probably low based on death rates that have reported for other dairies in California.

Table 8. Survival rates during first lactation.

Breed Number 30 days(%) 150 days (%)  305 days (%) 
Holstein  692  95a  91a  86a
Normande-Holstein  465  98b  96b  93b
Montbeliarde-Holstein  655  98b  96b  92b
Scandinavian red-Holstein 434  98b  96b  93b

a,b Different letters of superscripts indicate significant differences (p<.05)

Also, Normande-Holstein crossbreds (n = 118) were compared to pure Holsteins (n = 283) for percentage of cows that calved a second time within 20 months of first calving. Only 66% of pure Holsteins calved again within 20 months; however, 82% of Normande-Holstein crossbreds had a second calf within 20 months of first calving. Economically, this 16% difference is huge.

Fertility

Fertility of the pure Holsteins and crossbreds was measured as actual days open for cows that had a subsequent calving or had pregnancy status confirmed by a veterinarian. To be included in the analysis, cows were required to have at least 250 days in milk, which meant the pure Holsteins were a more highly-selected group compared to the crossbreds, because a smallerp ercentage of pure Holsteins than crossbreds survived to 250 days postpartum. Cows with more than 250 days open had days open set to 250. Adjustment was made for herd-year of calving.

The distribution of days open for cows indicated 38% of the pure Holsteins had 35 to 99 days open versus 52% of the Normande-Holstein crossbreds, 43% of the Montbeliarde-Holstein crossbreds, and 44% of the Scandinavian Red-Holstein crossbreds. On the other hand, 21% of the pure Holsteins had at least 250 days open versus only 14% of the Normande-Holstein and theS candinavian Red-Holstein crossbreds.

The 520 pure Holsteins had average days open of 150 days (Table 9) during first lactation, and all of the crossbred groups had significantly fewer days open than the pure Holsteins. The 375 Normande-Holstein crossbreds had average days open of 123, which was a difference of 27 days from the pure Holsteins. An advantage of this magnitude for fertility, coupled with the 16% advantage for survival to second calving, should compensate to a great extent, economically, for the 8.6% lower production of Normande-Holstein crossbreds compared to pure Holsteins.

Table 9. Days open during first lactation with a maximum of 250 days.

Breed Number of cows Number of sires Days open
Holstein 520 76 150a
Normande-Holstein 375 24 123b
Montbeliarde-Holstein 371 22 131b
Scandinavian red-Holstein 257 10 129b

a,b Different letters of superscripts indicate significant differences (p<.05)

First service conception rate was 22% for pure Holsteins compared to 35% for the Normande-Holstein crossbreds, 31% for the Montbeliarde-Holstein crossbreds, and 30% for the Scandinavian Red-Holstein crossbreds. All three crossbred groups had significantly higher first service conception rates than the pure Holsteins.

RECOMMENDATIONS

Dairy producers should not consider crossbreeding to be genetic improvement – it is not! Continuous use of progeny-tested and highly-ranked A.I. sires is the key to genetic improvement. Some dairy producers have viewed crossbreeding as a justification to turn to natural service bulls rather than A.I. That would be an unfortunate consequence of the new interest in crossbreeding.

Hybrid vigor is a bonus that dairy producers can expect on top of the positive effects of individual genes obtained by using top A.I. sires within breed. The bonus from hybrid vigor should be at least 5% for production and at least 10% for fertility, health, and survival of dairy cows. Therefore, the impact of hybrid vigor on profit could be substantial for commercial milk production. However, some dairy producers might need to get beyond the notion that level of milk production is the only measure of profitability of dairy cows.

Research on crossbreeding has been initiated at many of the major agricultural universities in the USA and around the world. However, the rate of increase in inbreeding of Holsteins (+0.1% per year in the USA) might make crossbreeding almost essential at some point in time in the future for commercial milk production globally.

Crossbreeding systems should make use of three breeds. The use of two breeds limits the long-term impact of hybrid vigor. The use of four breeds limits the contribution of any single breed of especially high merit to herd composition and makes the mating system more complex. Individual dairy managers should carefully choose the three breeds that seem optimum for conditions that are unique to their dairy operation (facilities, climate, nutritional regime, reproductive status, and overall level of management).

Three-breed cross in California
Sire: Swedish Red – Dam: Holstein x Jersey
2-00 305d 12,347 kg milk, 372 kg fat, 365 kg protein

Authors