Mineral Accretion During Prenatal Growth of Cattle

Published data on prenatal (fetal) growth in cattle have been limited primarily to birth weights or weights and linear measurements of fetuses at different stages of gestation. Others have provided data describing fetal growth in terms of weight, nitrogen, and energy. These and other data have provided insight into the rates of protein and energy accumulation by the fetus during development and serve as bases for the estimation of protein and energy requirements for fetal development. Objectives of the present study were to describe the patterns of calcium (Ca), phosphorous (P), sodium (Na), potassium (K), magnesium (Mg), iron (Fe), and zinc (Zn) accretion in bovine fetuses. and to estimate requirements of these minerals for pregnancy in cattle

Association, effects and validation of polymorphisms within the NCAPG - LCORL locus located on BTA6 with feed intake, gain, meat and carcass traits in beef cattle

<p>Abstract</p> <p>Background</p> <p>In a previously reported genome-wide association study based on a high-density bovine SNP genotyping array, 8 SNP were nominally associated (<it>P </it>≤ 0.003) with average daily gain (ADG) and 3 of these were also associated (<it>P </it>≤ 0.002) with average daily feed intake (ADFI) in a population of crossbred beef cattle. The SNP were clustered in a 570 kb region around 38 Mb on the draft sequence of bovine chromosome 6 (BTA6), an interval containing several positional and functional candidate genes including the bovine <it>LAP3, NCAPG</it>, and <it>LCORL </it>genes. The goal of the present study was to develop and examine additional markers in this region to optimize the ability to distinguish favorable alleles, with potential to identify functional variation.</p> <p>Results</p> <p>Animals from the original study were genotyped for 47 SNP within or near the gene boundaries of the three candidate genes. Sixteen markers in the <it>NCAPG-LCORL </it>locus displayed significant association with both ADFI and ADG even after stringent correction for multiple testing (P ≤ 005). These markers were evaluated for their effects on meat and carcass traits. The alleles associated with higher ADFI and ADG were also associated with higher hot carcass weight (HCW) and ribeye area (REA), and lower adjusted fat thickness (AFT). A reduced set of markers was genotyped on a separate, crossbred population including genetic contributions from 14 beef cattle breeds. Two of the markers located within the <it>LCORL </it>gene locus remained significant for ADG (P ≤ 0.04).</p> <p>Conclusions</p> <p>Several markers within the <it>NCAPG-LCORL </it>locus were significantly associated with feed intake and body weight gain phenotypes. These markers were also associated with HCW, REA and AFT suggesting that they are involved with lean growth and reduced fat deposition. Additionally, the two markers significant for ADG in the validation population of animals may be more robust for the prediction of ADG and possibly the correlated trait ADFI, across multiple breeds and populations of cattle.</p

Factors Influencing Fetal Growth and Birth Weight in Cattle

Fetal growth, as indicated by birth weight, has important influences on animal production. Birth weights lower than optimum are associated with reduced energy reserves, lowered thermoregulatory capability, and increased calf deaths at or near birth. In addition, low birth weights are related to low rates of growth after birth and decreased mature size. Conversely, birth weights greater than optimum are associated with greater calving difficulty. Primarily because of the increased calving difficulty, calf losses at birth and difficulties if rebreeding the cow are increased. Fetal growth, hence birth weight, is influenced by numerous factors including number of fetuses, sex, parity or age of the cow, breed of sire, breed of dam, heat or cold stress, and nutrition. The importance of these and other effectors of fetal growth vary. In general, however, birth weight of each fetus decreases with increased numbers of fetuses, is greater for males than for females, and increases with age or parity of the cow. Birth weights are decreased by heat or inadequate nutrition, and increased by cold. Both the sire and dam contribute to differences in genetic potential for growth, but it is evident that the dam exerts an influence beyond her contribution to fetal genotype. It is important to know what the factors are that affect fetal growth and their potential magnitude. In order to minimize adverse effects of factors influencing fetal growth, it is perhaps more important to understand how and why differences in fetal growth and birth weight occur. The following sections will summarize several experiments conducted to develop a better understanding of some of the major factors affecting fetal growth

Effect of Breed and Postweaning Rate of Gain on Onset of Puberty and Productive Performance of Heifers

Age at puberty is an important production trait in beef cattle where heifers are bred to calve at 2 years of age, especially when a restricted breeding season is used. It is not only important that heifers breed and conceive, but, for maximum efficiency, they should breed and conceive early in the breeding season. Thus, age at puberty may be an important selection trait for identifying breeds most suited for efficient utilization of feed resources. Several researchers have demonstrated large differences among breed or breed cross in age at puberty of heifers. Other researchers have demonstrated that undernutrition may result in increased age at puberty, subnormal conception rate, and underdeveloped udders. Overfeeding, however,may result in weak heat symptoms, subnormal conception rate, high embryonic mortality, decreased mammary gland development, and decreased milk production. Thus, proper nutrition during the developmental period may have both short and long term effects on heifer productivity. The purposes of the present study were to describe the effects of breed and postweaning growth rate on the onset of puberty, milk production, and productivity of heifers

Energy Utilization by Hereford and Simmental Males and Females

Observed growth of cattle during the postweaning period reflects the genetic potential for growth as modified by the environment. Various breeds or breed crosses of cattle have been characterized for postweaning liveweight gain under ad libitum feeding conditions. Previous results showed calves by Simmental males had greater rates of postweaning gain than those sired by Hereford males. Simmental-sired steers were more efficient during a weight-constant interval, of equal efficiency during a time-constant interval and less efficient to a fat-constant end point than Hereford-sired steers. Differences among breeds in efficiencies of energy utilization for maintenance and gain have been reported. Similarly, differences among sexes (or sex condition) in growth rate and carcass characteristics have been documented. Efficiencies of energy utilization for maintenance and gain of castrate males have been reported to be similar to those of females. However, other results have suggested that intact males had higher maintenance requirements than castrate males. This paper describes the accretion of total empty body weight, water, fat, protein, and energy by Hereford and Simmental males and females in response to differing rates of metabolic energy (ME) intake. Estimates of breed and sex effects on ME requirements for maintenance and efficiencies of utilization of ME for maintenance and gain are reported

Energy Requirements for Maintenance of Beef Cattle Differing in Genetic Potential for Mature Size and Milk Production

Relative differences in expected performance for breed crosses of cattle are provided elsewhere in this report; see Characterization of Breeds Representing Diverse Biological Types. This information may be utilized by beef cattle producers to identify breed types for possible use in their beef cattle enterprises. In conjunction with information descriptive of production characteristics, variation in energy requirements among the breed types needs to be considered. Using general relationships between production potential and energy requirements, producers may identify the beef cattle breeds that would perform optimally in their respective production environments. Energy (either harvested by the animal or provided via supplementation) is used by animals to sustain life of the individual (maintenance) and for product formation (growth, gestation, and lactation). The energy available for metabolism by animals is referred to as metabolizable energy (ME). The information presented within this report demonstrates variation among breed crosses in energy requirements for animal production and documents variation in energy requirements for maintenance during specified periods of production

Influence of Biological Types on Energy Requirements

Since the introduction of new germ plasm resources into the U.S. beginning in the early 1960\u27s, the influence of biological types on various aspects of beef production have been evaluated extensively. Traits studied include preweaning calf performance, postweaning growth and feed efficiency, carcass characteristics, puberty and other reproductive characteristics, and milk production, to name a few. In general, however, most of the research efforts have concentrated on the areas involving the growing animal and/or its carcass characteristics. That is, output characteristics of the various biological types of cattle have been of primary interest to researchers. Much less effort has been expended to quantify the impact various biological types of cattle may have on input components of beef production. There has been, in particular, a dearth of information regarding the influence of biological type on the feed requirements of mature cows, even though various researchers have noted that the feed required to replenish and maintain the cow herd constitutes a major portion (65 to 75%) of the feed resources required for beef production. Differences among biological types in the feed required to maintain the cow herd may have a substantial impact on the efficiency of beef production. Thus, in this report, we will attempt to summarize our data relative to the effect of biological type on feed energy requirements of mature cows

Follicular Hormonal Changes and Oocyte Quality in Heifers That Exhibited an LH Surge, no LH Surge, or in Which the LH Surge Was Suppressed With Progestin

The mechanisms that control follicular development, oocyte maturation and ovulation, are complex and poorly understood in farm animals. Superovulation via gonadotrophin stimulation of the ovaries provides a model to study follicular development and ovulation and the endocrine interactions at the follicle level. This study focused on the importance of luteinizing hormone (LH) in follicular development, hormonal secretion, and ovulation. The objectives of this study were to describe differences in follicular development, hormonal secretion, and oocyte quality in superovulated heifers that exhibited a normal LH surge, no LH surge, and in which the LH surge was suppressed with a progestin implant

Conversion Efficiency Through Weaning of Nine Breeds of Cattle

Beef cattle production entails the conversion of plant resources not normally considered as part of the food chain for humans into a food resource that partially fulfills human dietary needs. Traditionally, the beef industry has been segregated into production components, each having its own marketing endpoint. The cow/calf component of the industry produces progeny for introduction into the food chain conversion process. Energy and protein requirements of the commercial cow herd should be fulfilled as much as possible through direct harvest of forages by the animals. Within the U.S., a wide range of forage production environments exist. Commercial producers have the flexibility to identify breeds or breed crosses to be used as producing females and to identify sire breed or breed crosses to mate with these cows. Previous research at U.S. Meat Animal Research Center has demonstrated variation among and within breeds for traits affecting weight of calf produced at weaning. Cows representative of breeds with greater genetic potential for growth and lactation yield have been shown to produce calves that are heavier at weaning. Additional research at U.S. Meat Animal Research Center has documented a positive relationship between genetic potential for production and energy requirement to maintain body weight of the cow. Differences in energy required to sustain the producing female suggest that breeds or breed crosses can be identified that are more effective in the conversion of forage resources into amarketable product. Earlier work conducted at U.S. Meat Animal Research Center indicated that breed crosses more moderate in growth potential and lactation yield, were more effective in preweaning weight production of calves. The objective of the study was to determine if differences exist among breeds of beef cattle in the efficiency of converting food energy to weight of calf at weaning

Energy Expenditures of Mature Cows During the Production Cycle

The cow uses about 65% of the feed energy used in the production of beef cattle. Of that, about 74% is used for maintenance of the maternal body, 18% for lactation and 8% for pregnancy in the mature, producing beef cow. The growing- finishing animal uses about 35% of the total feed energy used for beef production. In the growing-finishing animal, maintenance costs may vary from 30 to 100% of the total feed energy consumed, with the lower proportion being at high intakes and rates of gain. Typically, in feedlot cattle this value ranges from 30 to 40%, whereas in cattle growing more slowly, such as stocker cattle, maintenance costs represent about 50 to 70% of the total. As a result, energy expenditures for maintenance are relevant to all phases of beef production, but are generally of greater importance in the cow herd. Numerous breeds of cattle are currently available to beef cattle producers. Large differences among breeds for important traits such as mature size, growth rate, body composition, and milk production have been well documented. To effect improvements in efficiency, both required feed input and product output need critical examination. Differences among breeds or genotypes have also been observed with regard to energy requirements and/or efficiency of energy utilization for maintenance and weight or energy gain. Some of the research efforts at U.S. Meat Animal Research Center in this regard were summarized in the previous Beef Research Progress Report (Ferrell and Jenkins, 1988). Those studies indicated that, in general, there appears to be a positive association between genetic potential for productivity and maintenance requirements. Stated another way, there is an antagonistic relationship between potential productivity and feed requirements for maintenance. Further understanding of relationships between utilization of feed energy and productive potential is needed in order to select appropriate genotypes for given production environments. The objective of the present study was to evaluate the relationship of animal energy expenditures to feed available in diverse genotypes