Maternal Productivity of Tarentaise and Hereford Cattle
under Montana Range Conditions
Crossbred calves have generally shown greater preweaning growth than straightbred calves when both were raised on straightbred dams (Long, \1980; Lawlor et al., 1984), but few experiments have included Tarentaise, a moderate-framed breed noted for easy calving, hardiness, and maternal characteristics (Briggs and Briggs, 1980) . These data are from a long-term study of cow efficiency with different biological types of cows under range conditions. The present study was with foundation Hereford and Tarentaise cows raising Hereford, Tarentaise, and reciprocally crossed calves. The objectives were to compare preweaning growth of the calves, to compare milk production, reproduction, and size of the dams, and to determine the usefulness of the Tarentaise breed as a possible alternative in crossing to the British breeds.
Materials and Methods
There were 457 weaning records on calves raised on Hereford or Tarentaise dams at the Northern Agricultural Research Center near Havre. These foundation Hereford and Tarentaise dams were progeny of 30 Hereford and 20 Tarentaise sires. The 77 foundation Tarentaise were purchased or donated from 11 breeders in Montana, Oregon, Idaho, and Wyoming. They were obtained as heifers following weaning and were selected to represent herd average based primarily on their adjusted 205-d weight. The 85 foundation Herefords were selected at random from the grade Hereford herd at the research center. Foundation dams were mated to 17 Hereford and 16 Tarentaise sires selected to represent breed average for adjusted 365-d weight. All Hereford and Tarentaise sires were mated at random to both breeds of dam in a 2 x 2 design.
Breeding was by AI during a 45-day season starting the 1st week of June. Calves were born from early .March to late April and were weaned at 6 months of age during the first week of October. There was no creep feeding.
Supplemental feeding was practiced during the winter (late December to 1st week of May) with 20 Ibs. of alfalfa hay or its energy equivalent fed per day per cow before calving and increased to 30 Ibs. after calving. Cows were put on crested wheatgrass pasture the 1st week of May and then moved to a foothill bunchgrass type of summer pasture the last week of May. The summer pasture averaged 19 inches of annual precipitation and 4,000 ft altitude. Vegetation included rough fescue, Idaho fescue, and bluebunch wheatgrass with interspersed areas of ponderosa pine. Terrain varied from level to very steep areas and the .stocking rate was 2.7 acres per animal- unit-month.
Condition of cows and calves was visually scored from 1 to 9 (9 = very fat) by two technicians and then averaged. The weigh-suckle-weigh technique, as described by Williams et al. (1979) , was used to measure milk production.
Results and Discussion
Breed of dam was significant for calf weaning weight, weaning hip height, weaning condition score, and late milk production. Least-squares means for Hereford and Tarentaise dams are shown in Table 1. Tarentaise dams weaned heavier calves, taller calves, and calves with greater condition than Hereford dams. Tarentaise dams maintained their milk production into later lactation better than the Hereford dams.
Heterosis was important for calf growth and percentage heterosis was 3% for birth weight, 5% for weaning weight, 1% for weaning height, and 2% for condition score. None of the estimates of heterosis for milk production were significant, indicating that crossbred calves did not stimulate their dams to produce more milk.
Breed of dam was significant for cow weights at precalving, prebreeding, postbreeading, and weaning (but not for weight changes), cow condition score, cow weight:height ratio, and calf weight at weaning per unit of cow weight. Table 1 contains least-squares means for each breed of dam. Hereford dams were consistently about 100 Ib heavier during the year and had greater condition, but were only .6 cm taller than Tarentaise dams. Breed of dam was important for calf weaning weight per unit of cow weight at weaning and individual heterosis was 5.8%. Breed of dam differences were not significant for proportion calved, proportion weaned, or calf weaning weight per cow exposed to breeding.
Cow weights and heights indicate that Tarentaise cattle would work well in rotational crossbreeding systems with British breeds. In an environment that will support moderate levels of milk production and intermediate cow size, Tarentaise would cross particularly well with those British breeds with lower levels of milk production. Tarentaise crossed with other Continental breeds might be considered in situations where breeders want to maintain milk production at the Continental breed level but reduce cow size.
Briggs, H. M. and D. M. Briggs. 1980. Modern Breeds of Livestock (4th Ed.)
Macmillan Publishing Co., Inc., New York.
Lawlor, Jr., T. J., D. D. Kress, D. E. Doornbos, and D. C. Anderspn. 1984.
Performance of crosses among Hereford, Angus and Simmental cattle with different levels of Simmental breeding. I. Preweaning growth and survival. J. Anim. Sci. 58:1321.
Long, C. R. 1980. Crossbreeding for beef production: experimental results. J. Anim. Sci. 51:1197.
Williams, J. H., D. C. Anderson, and D. D. Kress. 1979. Milk production in Hereford cattle. I. Effects of separation interval on weigh-suckle-weigh milk production estimates. J. Anim. Sci. 49:1438. \
Table 1. Means for calf and cow traits by breed of
|Calf birth weight, Ib||90a||89a|
|Calf weaning weight, Ib||475a||519b|
|Calf weaning height, cm||109a||111b|
|Calf weaning condition score||5.5a||5.9b|
|Milk production Ib|
|Early (40 days)||20a||23a|
|Late (130 days)||14a||20b|
|Cow weights, Ib|
|Cow hip height, cm||131.1a||130.5b|
|Cow condition score||6.0a||4.9b|
|Cow weight:height ratio, Ib/cm||9.5a||8.6b|
|Calf wt:cow wt ratio||.39a||.47b|
|Calf wn wt:cow exposed, Ib||376a||400a|
a,b Means with different superscripts differ