A Breeding Objective is a statement or plan about how genetic progress will be achieved by the breeder. It calls for a long-term commitment on the part of the breeder, requiring several generations of cumulative results in order to truly realize genetic progress. At Lukefahr Ranch the breeding objective is: To maintain a breeding herd of polled, slick and light-colored STAR cattle of appropriate tropical genetics for the region and where selection is applied to promote high fertility and survival in a low input system. The herd is already polled, most are slick, but it will take a few more years before most cattle are light-colored. Slick and light-colored coats are simply inherited traits that relate to genetic adaptation to (sub)tropical environments. Of course, there are also the more important, so-called quantitative traits that are affected by many genes that relate to aspects of tropical adaptation. Traits include physiological maturity, high summer fertility, fattening ability on grass, grazing behavior, and maintenance of body condition.
This page will first address how selection is being applied to instill tropical genetic breeding into the herd to promote fertility and survival. And lastly how selection is being achieved for the three simple inherited traits: polled, slick, and white.
To restate, the breeding objective at Lukefahr Ranch is: To maintain a breeding herd of polled, slick and white-colored STAR cattle of appropriate genetics for the region and where selection is applied to promote high fertility and survival in a low input system. A simple strategy is to appropriately select for high fertility and survival. To a large extent, a goodly amount of progress has been realized by utilizing no doubt numerous genes for tropical adaptation already found in Senepol and Tuli breeds. These breeds combined with Red Angus have formed a composite that has fared well in south Texas since 2005, even over several years of exceptional drought. The following photo epitomizes this point.
Of relevance, a recent study performed by geneticists at University of Florida (Dikmen et al., 2018 in the Journal of Animal Science) reported that in hot climates at least 1/2 Brahman is needed in cows, whereas in severely hot climates the figure increases to 3/4 Brahman genetics. This study certainly demonstrates the emphasis on high levels heat tolerant genetics in hot climates. However, there are many issues in using Brahman-derived breeds or crosses, which is why Star cattle possess instead heat adapted, Bos taurus breeds (Senepol and Tuli). An earlier Florida study (Hammond et al., 1998 in the Journal of Animal Science) showed no statistical differences in average body temperatures between Senepol X Angus or Tuli X Angus 1-1/2 year-old heifers when compared to purebred Brahman heifers.
From a genetic adaptation perspective, the selective focus at Lukefahr Ranch is all about the cow. Heifer replacements are selected from cows that have records of sustained fertility and that have produced a good calf to weaning age, year after year. In addition, such cows have no issues with respect to poor health or reproductive issues (e.g., dystocia, lameness and bad udders) or poor dispositions or maternal instincts. The ideal cow, more likely than not, maintains excellent body condition throughout most of the year – a sure tell sign of adaptation. However, the cow focus is even more important when it comes to bull selection. Since STAR cattle are really a maternal breed composite (as opposed to a terminal sire breed), it is imperative that bulls are selected from the oldest, proven cows in the herd. This expression of functionality, referred to as “longevity”, is a composite trait that reflects several key components, in particular fertility and survival. Of relevance, in the Tuli breed it is very common to have cows over 20 years of age that have produced a calf every year – without any pampering. In 2006, I had the opportunity to visit several Tuli ranchers in South Africa. It was impressive to see first-hand so many highly productive herds of cattle managed in low input systems. Below is a photo of a 20 year-old cow (AJR 90-03) that produced 17 calves who was from one of the fine ranches visited. She was owned by Ms. Wilma Ackhurst (photo courtesy of Carmen Welz). This photo is revealing in the sense that the cow exemplifies the term functionality; she is well adapted to her environment and is not extreme in any way.
Bearing in mind this simple selection strategy that focuses on the cow, there are a few additional criteria that are considered each year when matings are planned at Lukefahr Ranch. To illustrate, in planning matings for the next year the calf must have at least a 50% blend of Senepol and Tuli genetics (less than 50% Red Angus). Involving nearly 10 years of observations and detailed records, cows with higher than 50% Red Angus genetics have generally not fared well (e.g., lower body condition, heavier body eights, and higher milk production). Using genetic software programs, if a mating shows the potential calf has 50% or more Red Angus influence other matings are projected until this figure is reduced.
In 2012 a purebred and registered Red Angus bull with genes for small calves at birth and low energy maintenance was purchased. The bull’s daughters that were over 50% Red Angus have generally been borderline insofar as heat adaption and productivity is concerned. (In the past 10 years there have been a few exceptional cows with as high as 50% Red Angus influence that were adaptable and productive, but these cows were more the exception than the rule.) Below is a photo taken during the summer of 2017 of a 4 year-old cow that is 62.5% Red Angus and 37.5% Senepol, as well as the purebred Red Angus sire at 2 years of age (right). Concerning the cow, even with the inheritance of the slick gene and some heterosis (not to mention the availability of green grass), 62.5% Red Angus appears to be too much for this adverse environment. The optimum range for Red Angus-influenced cows is likely between only 25 and 37.5% when combined with 62.5% or more tropical genetics – along with the slick gene and a goodly amount of heterosis. In contrast, the first photo at the top of this page shows a tan-colored cow with a light-colored calf. This cow is only 28.1% Red Angus. Even bulls that are 50% Red Angus (or other British or European breeds) and 50% tropical or African breed influenced – when bred to Angus cows – will produce daughters that are 75% Angus. In hot subtropical environments, 25% tropical genetics in the cow is clearly not enough to promote heat tolerance and/or tropical adaptation ability. In addition, such bulls should be referred to as an F1, not a composite animal. A composite refers to a selected and intra-breeding population which originated from an F1 cross or crosses. Besides Star cattle, breeds such as Beefmaster, Brangus, and Santa Gertrudis are all composite breeds; they all originated from an F1 cross or crosses. The F1 and subsequent generations of animals and were then selected for several to many generations to develop a new breed with the desired combination of genes from the original breeds. The main feature is one of simplicity: composites are bred together like purebreds but perform well – more like a good crossbred.
In addition, since calves are a composite, matings are also planned so that heterosis is not less than 50% (Hetero column) and inbreeding (Inbreed column) is not more than 15%. Bear in mind that the STAR composite is not fully crossbred like an F1 cross that expresses 100% potential heterosis or hybrid vigor. Genetic software programs have been used to make these useful calculations. As stated elsewhere at this website, crossbred and composite-bred cattle express important hybrid vigor, which further enhances genetic adaptation beyond the high level of breed complementarity (akin to icing on the cake). Often times several reassigned planned matings have to be made to finally meet the above described parameters. Below is a table showing three STAR bulls and a sample of cow mate cohorts that were destined for matings in summer 2015. The table was developed from a spreadsheet using Excel.
In the summary section (bottom right) are simple statistics: average, minimum, and maximum for this sample of nine total matings. These statistics confirm that the above described parameters are met. In addition, the probability of each mating producing aslick or light-colored (yellow or white) calf is also calculated as shown in the last two columns. Considering all the matings planned for 2015, it is predicted that, on average, for every three calves born that two will be slick, and that for every five calves born that three will be light-colored, some even white. Only polled, slick, and light-colored calves will be selected from the best, most adapted cows.
The following figure illustrates genetic trends for Star cattle born from 1999 to present. For each trait (birth weight, weaning weight, and milk), line plots are based on data points with each value being the average breeding value (2X EPD) for all calves born that year. The plots for birth and weaning weights show a clear downward trend, while no trend has occurred for milk. There are likely several plausible reasons to explain the trends. First, there have been no selective efforts to increase milk production. They key is to develop cattle that are adaptable to the region without pampering such as feed supplements. But mostly for the past few years there was a more intense focus on use of bulls (AI and natural composite sires) with large negative birth weight EPDs. More specifically, for Red Angus a change was made through the purchase of PCC R2R Simon in 2012. This bull had a markedly negative birth weight EPD, among other desirable trait performance values. For Senepol, two AI sires (Blondie and WC 950K) known as “heifer bulls” by the breed association have been used since 2012. And for Tuli there was continued use of Honey Bear who consistently sired light calves at birth.
There is a strong positive genetic correlation between birth and weaning weights. So if progress occurs due to selection for one trait, genetic response also occurs for the other correlated trait(s), which in this case was decreased weights for both growth traits. Yet another possible reason was due to the culling of cows that had positive birth and(or) weaning weight EPDs. At the bottom of the figure are linear equations for each trait. For birth weight the change was about 0.20 pounds lower average birth weight per year, while for weaning weight the change was about 1.0 pound lower average weaning weight per year. In total, birth weight EPD has declined by about 4 pounds while weaning weight has declined by about 15 pounds since 1999. Further, there is also a positive genetic correlation between weaning and mature weights. A related breeding focus has been for cattle that are more moderate in mature size in terms of body frame and weight and consequently are more efficient in feed and(or) land utilization. So smaller cattle at maturity would be expected, on average, to produce calves with lighter weaning as well as birth weights. The photo below the figure is a 2 year-old cow with her 7 month-old calf and pregnant with her next calf. She weighs no more than 900 pounds and her calf’s 205-day adjusted weaning weight was 477.7 pounds, so the cow yielded over 50% of her own body weight.
POLLED VS. HORNS
Since African genetics is utilized in STAR cattle, aside from the conventional inheritance of polled versus horns as found in European cattle, there is an additional gene pair that is referred to as the African horn locus. First, “Locus” is defined as the specific location where a gene is located on a chromosome. In cattle of European descent, polled is a dominant trait. And because there is complete dominance, a calf with only one polled gene will be polled. Instead, it takes two copies of the horn gene (one from each parent) to produce a horned calf. This is because horns is a recessive trait.
Below is a table called a Punnett Square that shows how polled versus horns is inherited from parents that are both polled but that carry the horned recessive gene (Pp). Both parents are called heterozygotes since they carry two different genes (P – polled, p – horns):
The above example is well understood among cattle breeders. In such a mating, one would expect, on average, three calves polled to every one calf horned that are produced.The STAR cattle herd is based on breeds that are primarily polled so all cattle are presumed to be PP genetically.
However, in terms of African genetics the situation of polled versus horns inheritance is quite different. It involves the condition known as sex-influenced inheritance. Specifically, it is at this locus that horns is the dominant trait. Heterozygous bulls have horns but heterozygous cows are polled! This is due to the influence of testosterone in males. Several years ago, this phenomenon first become apparent in bull calves that were sired by Senepol bulls and out of Tuli X Red Angus cows. Later, this would occur in some bull calves that were Red Angus sired and out of STAR cows.
The Tuli breed possesses genes for polled and horns at the African horn locus (a different chromosomal location than the P locus). A small percentage of animals are horned so this gene has a low frequency. Below is a photo of LR Charlie. He was sired by Nocona (Senepol) and his dam who was polled was Tuli X Red Angus. It is presumed that his genotype at the European horn locus was PP. There are still other genes that affect the size and shape of the horns. The two following tables show the nature of inheritance at the African horn locus involving the mating of a heterozygous bull (horned) to a heterozygous cow (polled):
Interestingly, the results are opposite for bull and heifer calves due again to the sex-influenced nature or dependency of the expression of the African horn gene. From a practical breeding standpoint, polled STAR bulls should not produce horned heifer or bull calves if mated to polled cows. Even so, horned STAR bulls should not produce horned heifer calves; however, half of their sons would be expected to have horns. Only polled STAR bulls are now used on Lukefahr Ranch. It would be useful if a DNA test was available to identify heifers being considered as selection candidates. Heifers that carry the African horn gene (being inherited from their dams) would be culled. Dams that are carriers have a 50% chance of producing a calf that does not inherit this gene.
SLICK HAIR COAT
A very short hair coat as observed in the Senepol breed is due to the dominant “Slick” gene. There is complete dominance in both sexes, meaning that only one slick gene is needed for either a bull or heifer calf to be born with a slick coat. Experiments carried out by scientists at the University of Florida revealed that Senepol cattle had similar body temperatures in summers as purebred Brahman cattle. Another study reported that dairy cattle that were slick compared to normal hairy cattle produced more milk. It is amazing what a difference one gene can make as shown in the next two photos of a hairy heifer and a slick heifer (both are Red Angus-sired and by Star dams).
However, besides a slick hair coat there may well be other heat tolerant factors involved. For example, the numerous vertical skin folds on the body (especially in the neck area), increases total body surface area, which is important in dissipating heat – as exemplified in the photo below of a STAR bull calf:
To briefly digress, because breeding season at Lukefahr Ranch is in the dog days of summer (July-August) – so that calves are born mostly in May – it is critical that cattle have high summer fertility levels. It is well known that black color absorbs heat (ultraviolet radiation) which can render an animal infertile. While black calves generally sell for higher prices than non-black colored calves, a business should strive to sell more calves as a reflection of more cows that became pregnant from fertile bulls, Calving in May best ensures that cows have more nutritious grass to graze while rearing their calves .
A Punnett Square for the inheritance of the slick gene is shown below involving the mating of slick heterozygous parents:
In the first photo above of the horned bull it is evident that he is also slick. The photo below is of a slick cow-calf pair. The STAR cow was sired by a purebred Tuli bull (ss) but her dam who was 1/2 Senepol and 1/2 Red Angus was also a slick heterozygote (Ss). The calf inherited the slick gene (a 50:50 chance) from its dam. Its sire was a purebred Red Angus bull (ss). When mated to hairy cows, it is expected that half of his calves will be slick and half will be hairy. That was a free Genetics 101 lesson.
One word of caution, however, is that feeder and stocker calves that are slick may be discounted at auction barns when sold to feedlots in northern states because it may be felt that they need a normal hairy coat to stay warm in winter. For years now, Lukefahr Ranch has sold feeders to local grass finisher operations where there have been no problems reported. To date, slick STAR cattle have performed well in winters in Missouri, New Mexico, Oklahoma, and South Carolina. They do grow a winter coat even though it is somewhat shorter than coats of hairy cattle.
A scientific report published in Nature Communications in 2014 involved the mapping and sequencing of the slick gene (link to article: NC 2014). The methods used were validated from DNA analysis performed using hair samples taken from many STAR cattle. This was an international collaborative study that involved several genetic labs and the company GeneSeek. The slick gene is located on chromosome 20. Another interesting result was that slick cattle do not have more sweat glands under the skin. Rather, the glands are more responsive to environmental cues that cause higher sweating ability. The interest in this work relates to breeding cattle that can better cope in the future in an environment involving global climate change. Slick calves produced from matings of heterozygous parents at Lukefahr Ranch are now being DNA tested to determine those that are SS versus Ss. Ideally, only SS calves will be selected as replacements. Confirmed SS parents when mated will breed true by producing only SS slick calves, and there is no further need for DNA testing. In 2017, I published an article that showed a major and positive effect of the slick gene on weaning weight performance (link to article: Slick gene effect). In a recent analysis that included data from 2005 through 2016, slick compared to hairy calves were, on average, 35 pounds heavier for 205-day adjusted weaning weight. This is a dramatic effect of a single gene!
WHITE COLOR DILUTION
In addition to my own observations, several published scientific studies support my view that lighter colored cattle have lower body temperatures, attract fewer flies, spend more time grazing, among other advantages. The classic example is reference to cattle breeds in India (e.g., Brahman, Nellore, and Krishna) which tend to be very light colored. Other breeds like the Gyr and Sahiwal are light red-colored. However, there are other critical anatomical and physiological adaptations besides color that are likely even more important, such as increased body surface area and increased sweating rates which enhance processes of thermoregulation – the animal’s ability to control its own body temperature. Below is a photo taken from a distance one hot afternoon during the summer. Several light-colored cows were out grazing while the red ones were in the shade. I have made this same observation many times.
In remote south Texas, it is commonly observed in summers that black cattle, even with Bos indicus (Brahman) influence, seek shade and ponds in morning hours and avoid daytime grazing (see next photo), not to mention being covered with flies. However, the main problem is low fertility in summers, which again is the ideal time to breed. This results in a missed opportunity to work with Nature to develop a genetically adaptable herd and, for example, largely avoid unnecessary costs such as feed supplements.
As reported in the American Red Angus magazine, an ongoing adaptation study at Mississippi State University is comparing performance of red and black colored cattle. Interestingly, during the summer some of the black colored cattle had body surface temperature recordings of 130 degrees Fahrenheit! In addition, over a 10 month period, developing heifers that were red gained, on average, 36 pounds compared to black heifers that lost 106 pounds. Another interesting observation is that there were 71% fewer horn flies on red compared to black heifers.
That said, in all fields of science, including genetics, there are always certain exceptions to the general rule. Black Mashona cattle (a breed closely related to Tuli, also from SE Africa) have the ability to produce a thick, oily sweat that enables the animal to produce a sheen coat luster that reflects more solar radiation than that of a common black colored animal. Sometimes at a distance and at a certain angle, such black animals that secrete copious amounts of sweat even appear white! Below is a photo (courtesy of Johann Zietsman) of such a fine animal.
However, it will remain to be seen whether, for example, a crossbred from a Mashona X Black Angus will exemplify this same unique ability of producing a thick, oily sweat, as well as having a high level of immunity against tick-borne diseases. It would be more simple just not to breed black animals.
The Tuli breed possesses two genes for dilution of color: white and dun, which are found at separate loci (chromosome locations). The basic colors of Tuli cattle are red, yellow and white, although the dun gene can further dilute red and yellow colors. A few years ago, I published a paper on the inheritance of coat colors in Tuli cattle which describes the inheritance of these genes (link to article: Color Article). Basically, all Tuli cattle have the same background color of being red and homozygous (ee). (In contrast, the E gene is for black color, which is completely dominant to the recessive e gene.) Red Angus and Senepol cattle also share the same ee genotype. Next is a photo of purebred Tuli heifers from a fine South African herd in which all three colors are expressed (courtesy of Carmen Welz).
A dilution gene, W, is located at a separate locus (known as the PMEL locus). If one white dilution gene has been inherited, the animal is yellow, two and the animal is white. This is a case of no dominance (also called co-dominance) because otherwise the heterozygous animal would be white instead of yellow. In addition, because the red and white genes are from different loci and they interact by working together (eeWw – dilution of red to produce yellow color), this is a condition called epistasis. This genetic condition is similar to the inheritance of Palomino color in horses, which likewise involves red (sorrel) horses that possess one dilution gene found at a different locus. A similar example in cattle is a yellow calf that results from mating a Charolais bull to a red Hereford cow. However, the white gene in the Tuli breed may not be the same mutation as the white gene in Charolais. Moreover, white Tuli cattle typically have dark pigmented hides, eyelids, muzzles, and hooves, unlike Charolais cattle that have pink skin. Below is a photo of red, yellow, and white STAR calves:
The chart below illustrates how color is inherited in Tuli and STAR cattle:
Parental genotypes appear in rows and columns. In the yellow body of the chart is the predicted outcome of the offspring from all possible matings. Simply, parents that are both red with no dilution genes (eeww) will only produce red calves. The same is true for white parents producing only white calves (eeWW). A red x white mating will produce only yellow calves (eeWw). A red x yellow mating produces these same two colors as does a yellow x white mating produces these same two colors. However, a yellow x yellow mating will produce all three colors: red, yellow, and white in a 1:2:1 ratio.
DUN COLOR DILUTION
The dun gene (dn) appears to be recessive, although in some cases all it takes is one dun gene to express itself. Like the white gene it too dilutes or washes out color by decreasing the concentration of color pigments. However, an exception is that in white cattle the dun gene is incapable of further diluted color because there is none (likewise, genes for white spotting or a white face could not be expressed). Therefore, the dun gene can only work on red and yellow colors. In red cattle, it is sometimes difficult to discern if the animal possesses a dun gene because the color is so dark. However, this is more evident in calves that are yellow (eeWw) and that have inherited one or two dun genes. They are usually mouse-brown in color as newborns (left photos below). Later, they become very light in color even by weaning age (corresponding right photos of the same animals below).
Two Tuli bulls used at Lukefahr Ranch – Honey Bear and his son Buddy – were both yellow but they also possessed the dun gene, the latter of which was infused into the STAR herd. The last photo is of Honey Bear’s sire, Kikame, who was also a yellow dun.
The photo shown below is of a STAR bull (LR 12-2009 – a son of Buddy) that is slick and very light colored (due to the addition of modifier genes, described later). He is described as a yellow-dun. The dun gene dilutes color pigments in a yellow coat such that color appears grey, similar to that of grey Brahman cattle. Interestingly, his muzzle, eyelids, hooves, and hide are dark due to this dun gene. In this region, Charolais bulls suffer from sun and wind burn because of their pink-colored skin.
In other words, the combined effects of W and dn in yellow cattle may produce a very light grey color, which is another example of epistasis. In addition to this is the action of what are called minor or modifying genes – a set of genes that literally tweak color (darkening or lightening, akin to a contrast switch). According to the pioneer breeder, Jan Bonsma, lighter colors are preferred from a genetic adaptation standpoint. Below is a slideshow of several STAR cattle that are all light yellow duns (eeWwdn_), but each animal inherited a dun gene(s) and a set of modifier genes that caused further color dilution or lightening.
In contrast, the next photo shows a yellow-dun calf that inherited a set of modifier genes that darkened yellow color.
In spring 2014, the first white calf was born at Lukefahr ranch. Both of his parents were yellow so there was a 25% chance that they could produce a white calf. LR “Blanco” also has a slick hair coat. A DNA test revealed that he is heterozygous for the slick gene (Ss). Like his sire, he appears to have a small set of scurs. His breed composition is 9/16 Tuli, 1/4 Senepol, and 3/16 Red Angus, which represents over 50% African genetics. This summer (2014) he will be used for breeding at 14-15 months of age. Because he is homozygous for the white gene (WW), it is predicted that all his calves will be light colored: yellow and white, while half will be slick. Blanco also displays a dark pigmented hide, eyelids, muzzle, and hooves, which is another important adaptive trait that will prevent sunburn effects and pinkeye. Because both of his parents were yellow and very light-shaded, it is likely too that he carries the dun gene, which will lighten up his yellow-colored calves.
In the next couple of years, the few hairy cows and those that are red will be replaced by daughters that are slick and light colored. Only bulls that are homozygous slick (DNA tested) and white will be selected. If you have read and understood the genetic lessons presented in this webpage, the ideal genotype is PPaaSSeeWW in terms of the simply inherited traits that are desired that have been subjected to selection. A population of cattle that all inherit this ideal genotype will breed true. However, since the STAR population is not a closed herd, improved genetics will be periodically re-introduced (via AI) by using unrelated slick Senepol and white or yellow Tuli bulls from outstanding lines.
So what is your breeding objective?