Results from New Research
Three crossbreeding projects are currently under way with dairy cattle in the United States, while results from a fourth trial using data from commercial herds in California have been reported in recent scientific literature. There are additional efforts in other countries, some of which involve intensive grazing management programs. The domestic research referred to here is being conducted in typical U.S. confinement systems.
- Holstein-Jersey crosses versus. purebred Holsteins in Minnesota – oldest crosses have completed third lactation, but the only results are in abstract form as this is updated in June 2007.
- A “backcross” trial at Wisconsin, where over 160 Holsteins were bred to crossbred Holstein-Jersey bulls in AI – first calves were born in 2004 and initial performance results are now being analyzed.
- A designed trial comparing purebred Holsteins, Jerseys, and their reciprocal crosses in the Virginia Tech and Kentucky university herds. All calves in this trial have been born, but many are still in calf pens at this writing. Preliminary results reported here are early calf hood traits and a summary of yield data through May 2007. First calving dates for project animals were mid summer 2005 at Virginia Tech and mid winter 2006 for Kentucky.
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California Commercial Herd Results
Results reported in Tables 1, 2 and 3 are from the research reports of a study conducted by the University of Minnesota in cooperation with seven large commercial herds in California.
Table 1 shows production for purebred Holsteins and crosses of Normande (a French dairy breed), Montbeliarde (a French dairy breed), and Scandinavian Red bulls on purebred Holstein dams. Highest production was for purebred Holsteins, but milk yields from the Montbeliarde and Scandinavian Red crosses were close to Holstein, with higher components. Combined fat and protein volume (not shown in the table) for Scandinavian Red-Holstein crosses was not statistically lower than for purebred Holstein cows. These results show that some crossbred cows will produce yields similar to purebred Holsteins, particularly on a component basis. The closeness of performance for yield traits suggests that even small advantages in fitness and fertility will make crossbreds appealing to many commercial producers.
Table 1 also includes calving records for purebred and crossbred cows. Dystocia (calving difficulty) and stillbirths (calf mortality) were greatest for purebred Holstein mothers. Crosses to Montbeliarde and Scandinavian Red sires produced dams with significantly less dystocia and stillbirths than purebred Holstein dams. Normande-Holstein crosses did not differ from purebred Holsteins.
|Breed of Cow|
|No. Cows in Milk||380||245||494||328|
|No. of Calvings||676||262||370||264|
|% Calving Difficulty1||17.7||11.6*||7.2*||3.7*|
|*Crosses differed from Holsteins (P < 0.05). The paper reported volume of components, so component percentages were not tested for significance.
1Average dystocia and stillbirth rates are from first calvings when cows were bred to Montbeliarde, Brown Swiss, or Scandinavian Red bulls.
Table 2 shows calving difficulty and stillbirth results by breed of sire when used on first calf Holstein dams. Scandinavian Red bulls produce significantly less dystocia and stillbirths than Holstein sires, and Brown Swiss bulls produce less dystocia than Holsteins.
The advantages of easier calving for matings to Scandinavian Red bulls are clear from these results. Selection programs in the Scandinavian countries have emphasized reduction in dystocia and stillbirths for about 30 years. Many dairy producers across the United States are using Scandinavian Reds on Holstein heifers because of calving ease. All the calves by non-Holstein breeds would have the benefit of heterosis in survival.
We don’t have purebred Montbeliarde or Scandinavian Red cows to allow us to estimate heterosis in these calves. What we do know from this trial is that calves sired by Scandinavian Red bulls out of first calf Holsteins have significantly less calving difficulty than calves sired by Holsteins.
|Breed of Sire|
|Holstein||Montbeliarde||Brown Swiss||Scand. Red|
|No. of Calvings||371||158||209||855|
|% Calving Difficulty||16.4||11.6||12.5*||5.5*|
|*Different from Holsteins (P < 0.05).|
Table 3 includes survival and fertility data for purebred Holsteins and the three crossbred breed groups. Crossbreds were more likely to survive through 305 days of first lactation than were the purebred Holsteins. There were no statistically significant differences between the 4 breed groups for days open, but first service conception rate was significantly higher for crossbreds than for purebred Holsteins. The most fertile breed group was the Normande-Holstein cross, which, interestingly enough, was the lowest production breed combination in Table 1.
There is an important lesson in this observation – high production and high fertility are hard to accomplish together. There is a genetic antagonism between these two traits, and some trade-offs are likely as we strive to improve fertility in high-producing dairy cows. Do we have to accept lower production to achieve acceptable fertility? Hopefully not, but we need to develop dairy cows that regain energy balance and retain enough body tissue reserves while making a lot of milk to breed back in a timely manner.
The California trial is the first to compare purebred Holsteins to crosses of some European dairy breeds. It gives us important new information but needs to be interpreted with some caution. The herds that participated made a considered decision to move away from purebred Holsteins. The crosses themselves were novel animals. Consequently, the Holsteins and crosses may have been treated somewhat differently than will be the case in herds that repeat such matings in the future. The results are based on several hundred animals, not many thousands of animals, such as are used to evaluate merit of U.S. pure breeds. Finally, the traits studied are those expressed relatively early in life. Some of the important questions about crossbred-purebred performance relate to performance in mature animals. We have more to learn about these European breeds under U.S. management conditions.
|No. of Cows||523||363||229||190|
|% Surviving to 305 Days||86||93*||92*||93*|
|No. Cows for Days Open||520||375||371||257|
|Average Days Open1||150||123*||131*||129*|
|No. of Cows for Conception Rate||536||379||375||261|
|First Service Conception Rate (%)||22||35*||31*||30|
|*Different from Holsteins (P < 0.05).
1First calf heifers that had a subsequent calving or had pregnancy status confirmed by a veterinarian: at least 250 DIM was required.
Holstein-Jersey Crosses at Kentucky and Virginia Tech
The Holstein-Jersey crossbreeding project at Virginia Tech and the University of Kentucky was started in 2002. First calves were born in 2003, and first calvings for project animals were in June 2005. Data on early calfhood performance were recently completed, but have not been summarized. Results below are from a preliminary analysis.
Table 4 compares the four breed groups in this project for birth weights and dystocia. No significant differences between calves born to the four breed groups were found for stillbirths, so those results are not shown. The breed of the sire appears first in breed group designations. Table 4 shows that birth weights differed for all four breed groups, with purebred Holsteins producing the largest calves, as expected. Jersey-sired calves out of Holstein dams were larger than Holstein-sired calves out of Jersey dams, suggesting an important effect of breed of dam on birth weights. Dystocia scores were highest for calves sired by Holstein bulls. Jersey dams had as much difficulty giving birth to Holstein-sired calves (the HJ group) as did Holstein dams (the HH group). Conversely, Holstein mothers were equally good “easy calvers” as the Jersey dams when Jersey bulls sired the calves they carried.
|Breed Group of Calf|
|Birth Weights (lb)||88a||65b||69c||50d|
|Dystocia (1 to 5 scale)||1.7a||1.6a||1.2b||1.2b|
1Stillbirth percentages did not differ by breed group of calf.
a, b, c, dMeans with different superscripts are statistically different (P < 0.05).
Analysis of Dystocia and Stillbirths Using Odds Ratios
Results using odds ratios are in Table 5. Holstein and Jersey genes for dystocia or stillbirths have one set of effects on the calf but a separate effect from the mother. These are called “additive” and “maternal” effects. A third effect, heterosis, results from combinations of genes from different breeds.
These separate genetic effects all work together to form the breed group means shown in Table 4. These effects can differ greatly in size and in the direction that they operate. It isn’t always easy to judge additive, maternal, and heterosis effects by looking at breed group means. Results for stillbirths were included in this analysis because the approach of examining additive, maternal, and heterosis effects showed differences between Holstein and Jersey gene sources. The stillbirth differences canceled out (differences were not significant) when we compared the four breed groups as we did for birth weight and dystocia in Table 4.
The statistical procedure used estimates the “odds ratio” that Holstein genes in the calf (additive gene effects) would lead to more (>1.0) or less (<1.0) calving difficulty (or stillbirths) than Jersey genes. The design of the study allowed comparison of the odds that Holstein genes in the dam (maternal effects) would increase likelihood of difficulty giving birth (or to stillbirths) versus. Jersey genes in the dam. Finally, odds ratios were evaluated for the joint effects of pairs of genes (heterosis) either crossbred combinations (HJ or JH) versus the average of purebred combinations (HH or JJ). Table 5 below shows the outcome of that analysis.
Holstein calves are 34.9 times as likely to experience dystocia at birth as Jersey calves. However, contrary to what some may believe, Holstein maternal genes are only 30% as likely to cause dystocia or stillbirths as Jersey maternal genes. However, negative additive effects of Holstein genes more than offset the maternal advantage. Dairy farmers will certainly have fewer overall dystocia problems by adding Jersey genes to a crossbreeding program than by adding Holstein genes. There is no difference between crossbred gene combinations (heterosis) or the average purebred gene combinations for either dystocia or stillbirths when using Holsteins and Jerseys in the crossbreeding system. Holstein and Jersey breed differences in incidence of stillbirths are much less than differences in dystocia. These results are still preliminary, as about 25% of the births in this project are yet to be recorded, including a number of births of Jersey calves.
|Gene Effect||Odds Ratio for Holstein vs. Jersey Genes|
1Odds ratio greater than 1.0 indicates a greater probability of dystocia or stillbirths from Holstein genes than from Jersey genes.
2Heterosis was not significant. Crossbred calves were equally likely to experience dystocia or stillbirths as purebred calves.
|Trait||40 HH cows||27 HJ cows||23 JH cows||16 JJ cows|
|Age at Calving, Months*||24.6||24.0||23.7||25.0|
|305d Actual Milk, lb||21579||18935**||20419||15244**|
|305d Actual Fat, lb||806||863||806||703**|
|305d Actual Protein, lb||645||643||643||500**|
|Peak Milk, lb||81||78||76||55**|
|Summit Milk, lb||74||68||70||53**|
|*Based on 122 cows that have freshened.
**Different from Holsteins (P < 0.05).
No statistical differences were found in age at first freshening between breed groups. All 122 cows that have freshened for the first time were used in this comparison, but 16 of these have not been in milk long enough to contribute to the other traits in the table. The table does not include any mature equivalent (ME) averages because there are no age adjustment factors for crossbreds. You will see ME values associated with crossbred records, but they are calculated from purebred age adjustment factors.
Thus far, HJ and JJ groups are producing significantly less than purebred Holsteins, but there is no significant difference between the JH and HH group for actual milk yield. Differences between Holsteins and crosses for fat and protein are not statistically different. Peaks and summit yields are numerically higher for Holsteins than crossbreds, but they are not significantly higher. Jerseys do not produce as much as Holsteins for any of the traits in Table 6. They are also significantly lower in production of milk, fat, and protein than the crossbreds. Only 16 purebred Jerseys are in Table 6, and half of these are sired by the poorest of the four foundation Jersey bulls for Net Merit. Unfortunately, the highest Net Merit Jersey bull has yet to contribute a daughter to the purebred Jersey group, but he has contributed to the JH group. The project will produce more data in coming months, and conclusions should wait for a more complete story.
Minnesota Holstein-Jersey Results
Minnesota has summarized first lactation yields in a preliminary analysis. Holsteins produced significantly more milk and protein than did JH crosses in first lactation. Fat yield, however, was not different for the two groups. The JH crosses had significantly less udder clearance, which makes sense because of reduced body size. Front teat placement and teat length did not differ from Holsteins. Days open averaged 136 d for JH crosses compared to 159 d for Holsteins and a higher percentage of crossbreds calved a second time (87% versus 77%). There was no indication that the fitness traits were significantly different between the two groups. All of the trials in progress will struggle to show statistically significant differences between breed groups for lowly heritable traits such as fertility. Performance needs to be measured on larger numbers of animals than can be maintained in university research herds to demonstrate such differences.
Performance of Backcrosses to Holstein in Wisconsin
Wisconsin has reported differences in type traits between the 75% Holstein and purebred Holstein cows in a preliminary analysis. The JH crosses were shorter and stronger than Holstein contemporaries, with lower dairy form scores, steeper foot angle, and more slope to narrower rumps. Udder traits were not different between the two groups, except for closer front teat placement in the crosses. More dystocia and higher stillbirth incidence was reported among Holstein sired calves born to the three-quarter cross dams. The narrow rumps of the crossbred dams seemed to contribute to problems when giving birth to seven-eighths Holstein calves. Some dairy producers have Holstein-Jersey crossbred sires to reduce calf size and dystocia. These results suggest that there is a price to pay for that practice if the three-fourth Holstein crosses are bred back to Holstein sires. These are also lowly heritable traits where large numbers of observations are needed to declare differences significant by statistical tests. The results are preliminary; many more calves are to be born to first lactation dams of this particular cross.
Crossbreeding Systems in the United States
It is easy to decide to crossbreed some or even all of the cows in a purebred herd. The challenge is to adopt a system that can be sustained for the long-term good of the dairy business. Producers should make the decision to use crossbreeding based on economics of their dairy business, as their cows are their most important production asset.
Crossbreeding can produce an advantage for a straight-bred Holstein herd if that herd receives payments for protein in their milk check. Almost every cross likely to be considered by U.S. producers would increase protein percentage in milk, but a corresponding reduction in volume of milk produced may offset the gain. If a herd sells milk into a market that does NOT pay for protein – as is the case in Virginia and much of the southeastern United States– then there is one less reason to consider crossbreeding.
Benefits of crossbreeding come from two important sources. The first, and likely most important, is the strength that a second breed may bring in traits that are weak in an existing pure breed. An example would be using Jersey genes to reduce the size of individual cows in a purebred Holstein herd. Not every producer considers Holsteins to be too large, but some do. Breeds used in crossbreeding programs should complement each other. Holsteins improve milk volume in all dairy crosses. Jerseys will improve calving ease and milk components in all crosses likely to be considered by commercial producers. Swedish (more specifically, Scandinavian) Reds show important advantages in dystocia and stillbirths in the California trails reported earlier. Results on breed differences in fertility are not yet clear enough to report with any confidence, but as a breed, Jerseys are more fertile than Holsteins.
The second advantage from crossbreeding is the bonus of heterosis for certain traits. Dairy producers, by and large, aren’t very familiar with heterosis, but they have become accustomed to the opposite genetic effect of heterosis – inbreeding depression. Inbreeding occurs when related animals are mated. The offspring tends to have homozygous (the same) gene combinations at various point in its DNA because both mother and father inherited the same gene from some common ancestor – they were related, right?
Homozygous gene combinations (two genes of the same type) are generally “bad.” Why? Suppose that gene “A” is good, while an alternate form of the same gene, “a,” is bad. Natural selection tends to eliminate “a” – except when “A” is dominant to it, and animals with Aa gene combinations are equally fit to animals with “AA” combinations. In that case, and it isn’t all that infrequent, the “a” gene “hides in the heterozygote,” and isn’t eliminated by natural selection. Under inbreeding, the Aa animals tend to mate with each other more often than with “outcross” matings, producing 25% “aa” offspring in the process. All of those “aa” combinations throughout an inbred animal’s DNA cause inbreeding depression.
Crossbreeding eliminates mating of related animals, at least if the two breeds involved are really different. That means that crossbred offspring have NONE of the inbreeding depression that their parents or other members of the two pure breeds have. Heterosis differs for every combination of breeds. We shouldn’t expect the same heterosis for Holstein-Jersey crosses as for Swedish Red–Montbeliarde crosses. Heterosis differs for every trait and is largest for those traits that are most affected by inbreeding depression. In general, those are the fitness and fertility traits.
Optimal economic performance of dairy cows is a function of yield and fitness and fertility traits over their lifetimes. Crossbreeding systems capitalize on both breed additive merit and heterosis with the expectation that the lifetime performance will be superior to a pure breeding system. A research project in Canada conducted from 1972 until 1986 with Holstein and Ayrshire pure lines examined lifetime performance, finding heterosis of 16.5 to 20.6% for lifetime performance traits, with some crossbred groups statistically equal to Holsteins for lifetime yields. Prediction of lifetime performance of animals produced under pure breeding versus. crossbreeding systems requires estimates of breed additive merit for all traits and of heterosis for the various breed combinations involved. Research under way will provide data from current dairy cattle populations to generate those estimates.
Crossbreeding programs should be designed to capitalize on both breed additive merit and heterosis. The most critical decision is the choice of breeds to use in a program. For a long-term crossbreeding program, three breeds probably make the most sense. The most likely candidate breeds are Ayrshire, Holstein, Jersey, Brown Swiss, Normande, Montbeliarde, and Swedish Red.
The first breed choice for producers is already made by existing cows, though crossbred progeny may become part of a rotational crossing program that does not include the original maternal breed. The second breed of preference is the one used to produce the first cross – the F1s. The third breed of preference is the breed to use on the F1s. Resulting three-breed crosses would be bred back to the foundation breed unless the chosen program excludes that breed and incorporates a fourth breed.
Three breed rotational systems maintain 86% of the hybrid vigor in the F1. Two breed systems maintain 67% of F1 hybrid vigor because they produce more “pure-breed” gene combinations in offspring than three-breed rotations. All rotational systems create herds with overlapping generations and multiple breed combinations. The same breed of service sire is used on females of each generation throughout their lives. Semen inventories of each breed in a system would be necessary, but pedigree considerations for inbreeding avoidance would not likely be an issue.
Some producers won’t find a third breed that interests them. They may not be interested in the complexity of a three-breed system, though the difficulties could be overcome by appropriately colored ear tags that identified the breed of service sire to use. Two-breed rotational systems may suit these producers best, or they may simply choose to use a second breed, such as Jerseys, as a mate for Holstein heifers to reduce dystocia and keep some higher component cows in the herd to improve bulk tank component percentages.
Regardless of the crossing system used, service sires should be chosen for their genetic merit within their own breed. There is no justification to just use a bull of a different breed. If a producer is going to use genetics from a second or third breed, he should use the best genetics that he can justify economically. One of the objectives in the Virginia Tech–Kentucky crossbreeding project is to show that genetic merit of the sire of a crossbred calf matters. The project used purebred foundation sires of different genetic merit – from an elite bull down to below average proven bulls – to form breed groups. As performance data become available, we will examine relationships between sire merit and performance of purebred and crossbred daughters.
The Bottom Line for Crossbreed Programs
- Make a long-term business evaluation before starting a crossbreeding program.
- Choose the breeds carefully and with a purpose. Look for “breed complimentarity” to match strengths to weaknesses.
- Maintain hybrid vigor where possible through three-breed rotational crossbreeding systems.
- Use the best proven AI bulls possible. Selection matters in both purebred and crossbred systems.
Heins, B.J., L.B. Hansen, and A.J. Seykora. 2006. Production of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red. J. Dairy Sci. 89:2799-2804.
Heins, B.J., L.B. Hansen, and A.J. Seykora. 2006. Calving difficulty and stillbirths of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red. J. Dairy Sci. 89:2805-2810.
Heins, B.J., L.B. Hansen, and A.J. Seykora. 2006. Fertility and survival of pure Holsteins versus crossbreds of Holstein with Normande, Montbeliarde, and Scandinavian Red. J. Dairy Sci. 89:4944-4951.
Cassell, B., A. McAllister, R. Nebel, S. Franklin, K. Getzewich, J. Ware, J. Cornwell, and R. Pearson. 2005. Birth weights, mortality, and dystocia in Holsteins, Jerseys, and their reciprocal crosses in the Virginia Tech and Kentucky crossbreeding project. J. Dairy Sci. (Suppl. 1):92.
Cassell, B.G., K.M. Olson, and A.J. McAllister. 2007. Comparison of yield in Holsteins, Jerseys, and reciprocal crosses in the Virginia Polytechnic Institute and State University – Kentucky crossbreeding trail. J. Dairy Sci. 90(Suppl.1):597.
Bennet Cassell, Virginia Polytechnic Institute and State University (Virginia Tech)
Jack McAllister, University of Kentucky