Feeding dams a high-fat diet prepartum didn't improve calf response to short-term cold stress or cool 50° F. ambient temperatures at calving.
The studies at Virginia Polytechnic Institute and State University found that feeding high-fat diets may improve resistance of neonatal calves to extremely cold calving conditions. But, reduced time to standing and increased serum immunoglobulin concentrations were the only positive calf responses observed.
Under mild spring calving conditions, feeding high-fat diets prepartum may have limited positive effects on neonatal calf survival. Therefore, inclusion of high-fat supplements may be warranted only when feed costs aren't increased.
The scientists also concluded calves from dams fed high-fat diets containing safflower or whole cottonseed respond similarly to cold stress, but these responses may not be consistent with greater cold resistance. In addition, high-fat dietary supplementation of late-gestation cows may only be beneficial during calving seasons with prolonged cold weather.
J. Anim. Sci. April 2003. 81:885-894
Wyoming researchers found establishment-year cutting method had a significant effect on alfalfa stand count after five years of production.
The researchers also found that the use of non-dormant alfalfa mixtures didn't increase establishment-year yields. However, the use of mixtures did adversely impact yields the fourth and fifth year after establishment.
The studies also examined the effect of first-year cutting frequency on stand longevity and long-term productivity.
Increased harvest frequency during the establishment year did not adversely affect stand productivity at the beginning of the second production year. However, total alfalfa forage yield the second year was higher in plots not harvested or harvested once compared to those harvested two and three times the first year.
The researchers say it's interesting that one, two and three cuttings during the establishment year impacted yield the following year, but didn't reduce production three, four or five years following the establishment year.
During establishment year, the three-cutting system yielded more than six tons of alfalfa/irrigated acre — more than the one- and two-cutting systems.
The researchers also say the two-cutting system was superior in yield to the one-cutting system.
University of Wyoming Forage Research Demonstration Reports compiled by David W. Koch, UW Ag Experiment Station.
Spring calving cows grazing dormant native range were used to determine the effect of two different sources of degradable intake protein (DIP) supplementation in the winter. Conducted at the University of Nebraska, treatments included:
supplement containing urea as a source of non-protein nitrogen,
corn gluten feed (CGF) as a source of true protein, and
Microbial protein (MCP) synthesis estimated from urinary excretion of allantoin was greater for cows receiving urea than CGF or no supplement. A crude protein content of 7.5% in forage was sufficient to meet microbial requirements for nitrogen or amino acids.
When DIP is adequate, supplying energy enhances MCP synthesis. Synthesis of microbial protein increased as amount of digestible organic matter consumed increased, but efficiency of microbial protein synthesis did not change and averaged 8.5% of digestible organic matter intake.
2003 Beef Report Summaries, Jim Gosey, Extension beef specialist, University of Nebraska.
How does age of dam affect the maternal performance of daughters from high- and low-milk EPD sires?
Researchers at the University of Georgia and Mississippi State University mated Angus bulls selected for either high- or low-milk EPD but similar growth EPD to Angus cows at random. Daughters were bred to calve at two years of age and annually until six years of age. Milk yield was measured four times during lactation to estimate 12-hour milk yield. Milk was collected for analysis of the percentage of fat and protein.
Daughters of sires with high-milk EPD produced more milk at each age and weaned heavier calves than daughters of sires with low-milk EPD. These results confirm the value of milk EPD for improvement of weaning weights in beef cattle and also validate age of dam effects on milk yield and the associated effects on weaning weights.
J. Anim. Sci. Aug. 2003. 81:1693-1699
The use of net feed intake (NFI) to improve feed efficiency, and an examination of the relationships between NFI and performance traits in growing cattle are the focus of research at Texas A&M University.
Researchers also want to determine if observed differences in NFI were associated with differences in ultrasound measures of carcass composition, and identify physiological measures that are predictive of NFI.
Historically, the beef industry hasn't attempted to select cattle for improved feed efficiency for two reasons:
the difficulty and expense of measuring feed intake in cattle and
the traditional measure of feed efficiency (feed-to-gain ratio) is inversely related genetically to growth and size.
NFI is a new feed efficiency trait that quantifies genetic variation in feed intake beyond that related to differences in growth and body weight. An animal with a negative NFI is more efficient because it eats less feed then expected, whereas a positive-NFI animal is less efficient because it eats more feed then expected.
Individual feed intake of growing steers and bulls were measured using electronic gate feeders, and NFI determined as actual intake minus expected intake from multiple linear regression analysis. Performance traits and ultrasound measures of carcass composition were measured and blood samples collected to measure various metabolites and hormones.
Net feed intake was not correlated with body weight or average daily gain (ADG) but was positively correlated with feed intake and feed conversion ratio (FCR). In the first study, steers identified as having low NFI (more efficient) had similar body weights and ADG, but ate 17% less feed and had 19% lower FCR compared to steers with high NFI (less efficient). The high NFI steers had greater back fat thickness, but similar ribeye areas compared to low NFI steers, suggesting that low NFI steers were slightly leaner.
These results demonstrate that NFI is an alternative measure of feed efficiency that may provide opportunities to identify more efficient cattle independent of growth traits, and it should be investigated further for increasing U.S. beef cattle production efficiency.
From “Current Research Project Updates,” Texas A&M University. http://animalscience.tamu.edu/ansc/beef/research.html
To submit items for “Research Roundup,” e-mail [email protected] or fax to 952/851-4601.