B.A. Sandelin

Fatty acid and sensory characteristics of beef from three biological types of cattle grazing cool-season forages supplemented with soyhulls

Over two consecutive years, the effects of allocating divergent biological types of cattle (n=107) to fescue pasture without supplementation, or fescue or orchardgrass pasture with soyhull supplementation on chemical, fatty acid and sensory characteristics were investigated. Cattle from the two supplemented treatments produced beef that had increased (P<0.05) percentage lipid and decreased (P<0.05) polyunsaturated and n-3 fatty acids compared to the control. However, the n-6 to n-3 ratio was still less than four in beef from the supplemented cattle. Additionally, supplementation did not decrease (P>0.05) the CLA present in the longissimus, which can commonly occur when forage-fed cattle are supplemented concentrates. Although supplementation did not impact (P>0.05) Warner-Bratzler shear force or tenderness, supplementation of soyhulls reduced (P<0.05) the grassy flavor intensity of rib steaks when compared to the control. Biological type did not have a significant influence on most traits analyzed in this study. These results suggest that supplementation of soyhulls to cattle grazing forage can reduce grassy flavor intensity without decreasing CLA proportions, but can reduce the n-3 fatty acid proportions present in the longissimus.

Carcass and beef color characteristics of three biological types of cattle grazing cool-season forages supplemented with soyhulls

Soyhull supplementation to divergent biological types of cattle on forage-based systems was studied to determine the impact on carcass and color characteristics. Weaned calves (n=107) biologically classified as large-, medium-, or small-framed and intermediate rate of maturing were allocated to three cool-season grazing systems consisting of either orchardgrass pasture or fescue pasture, each with soyhull supplementation, or fescue pasture with no supplementation as a control. Supplementing cattle with soyhulls allowed for heavier (P<0.05) live and carcass weights, larger (P<0.05) longissimus muscle area, increased (P<0.05) backfat, kidney, pelvic and heart fat (KPH), and yield grades, and improved (P<0.05) marbling scores and quality grades. Utilizing cattle biologically classified as large- or medium-framed allowed for heavier (P<0.05) carcass weights without reducing (P<0.05) marbling scores or quality grades when compared to small-framed cattle. Instrumental color analysis of lean and adipose tissue revealed improved (P<0.05) lightness (L (∗)) in lean color for supplemented carcasses as compared to the control. There were no differences (P<0.05) between dietary treatments for L (∗), a (∗) or b (∗) values of adipose tissue. These results indicate that supplementing forage-grazing cattle with soyhulls can improve carcass merit, and utilizing large- or medium-framed cattle can allow for increased carcass weights without decreasing carcass quality.

Use of Ultrasound to Identify Brangus Cattle with Superior Intramuscular Fat and Other Carcass Traits

Abstract The objectives of this research were 1) to determine the effects of sire on the expression of intramuscular fat and 2) to determine the relationship of intramuscular fat with selected performance traits. Purebred Brangus cattle (n = 1,215) were subjected to real-time ultrasound evaluation of body composition; traits recorded were the 12th-13th rib subcutaneous fat thickness ( FT ), longissimus area ( LA ), and percentage intramuscular fat ( IMF ). Performance data provided by the International Brangus Breeder’s Association ( IBBA ) included birth BW ( BBW ; n = 323), weaning BW ( WBW ; n = 328), yearling BW ( YBW ; n = 1,087), and scrotal circumference ( SC ; n = 329). Data were analyzed to determine genetic relationships with the animal model using multiple trait restricted maximum likelihood ( MTDFREML ) procedures. Contemporary group was included in the model as a fixed effect, and age (in days) was included as a covariate. Analyses of covariant models were examined to determine the relative importance of sire and carcass traits to IMF. Genetic correlations of IMF with LA, FT, and YBW were –0.25, 0.36, and 0.31, respectively. Sire, FT, and LA were significant (P QG ), ultrasonically determined IMF may be considered in selecting seedstock for increased QG.

Postpartum Maternal Behavior Score in Six Breed Groups of Beef Cattle over Twenty-Five Years

The objective of this study was to determine the effects of fixed sources of variation on postpartum maternal behavior score (MBS) in six breed groups of beef cows. Postpartum MBS were determined on 5070 births representing the progeny of 142 sires and 145 maternal grandsires used in purebred herds of the University of Arkansas Agricultural Experiment Station over a 25-yr period. Breed groups included Angus (n = 2073), Charolais (n = 549), Hereford (n = 722), Heritage Angus (n = 445), Polled Hereford (n = 981), and Red Poll (n = 300). Within 24 h of birth, a MBS was assigned as the handler obtained calf birth BW and body condition of each calf. Postpartum MBS were 1) very aggressive, 2) very attentive, 3) indifferent, and 4) apathetic. Variation in MBS across breeds was partitioned using a repeated measures model that included terms for an overall mean, year, breed, within breed, age of dam, sex of calf, body condition of calf, sire of calf, and maternal grandsire of calf. Across breed, important sources of variation (P<0.01) in MBS were year, age of dam, body condition of calf at birth, breed, sire within breed, and sire of dam within breed. Dams giving birth to calves in thin body condition had greater (P<0.01) mean MBS than dams giving birth to calves in average or fat body condition (2.34 vs 2.24 vs 2.19), respectively. These results suggest MBS is influenced by several sources of variation, which should be considered when evaluating maternal behavior in selection programs.

Variation in the Percentage of Female Births over Time in Five Breeds of Registered Beef Cattle1

Breed and sire effects on the percentage of female births over time in five breeds of registered beef cattle were studied. Breed groups were managed separately, and matings were performed by artificial insemination and natural service. The percentage of female births was included in the study for sires that were used for at least 2 yr and sired at least seven progeny. Progeny of 48 Angus, 7 Charolais, 19 Horned Hereford, 17 Polled Hereford, and five Red Poll sires were used in the study. The numbers of birth years by breed were 33, 21, 31, 31, and 15 for Angus, Charolais, Horned Hereford, Polled Hereford and Red Poll, respectively. Variances for breed and sire were partitioned for percentage female births using a nested random effects analysis of variance. Breed effects for percentage of female births were 0.46% of total variance. Sire effects accounted for 0.27% of total variance. Means for percentage female births by breed were 50 ± 1% for Angus, 47 ± 3% for Charolais, 48 ± 2% for Horned Hereford, 52 ± 2% for Polled Hereford, and 49 ± 5% for Red Poll. Although sire variance was minimal, there were some sires that consistently produced a greater or lesser number of females over time. These results suggest that more research is needed to determine the factors that influence sex ratio in cattle due to its economic importance to the industry.

Seasonal Weight Changes and Prepartum Weight:Height Ratio in Angus and Brahman Cows Grazing Common Bermudagrass or Endophyte-Infected Tall Fescue

Abstract Cow weights, hip heights, and reproductive data on 82 Angus and 78 Brahman cows grazing common bermudagrass or endophyte-infected tall fescue forage systems were used to evaluate relationships of breed, forage system, and reproductive status to seasonal weight changes and prepartum body condition. Cow BW gains were computed for winter, spring, and summer for each of these seasons before the calving season the next year. Weight:height ratios (kg/cm) were computed from BW and hip height data taken in February of each year of the study to estimate body condition before calving and breeding. Thus, BW gain and condition data corresponded to seasons before the subsequent calf crop. Cows in each breed-forage system subclass were classified into four groups based on all possible combinations of previous and subsequent year calving data. Winter BW gain was not associated with pregnancy in the following breeding season (P>0.57). Spring BW gain in open heifers or cows did not affect subsequent pregnancy, but Angus cows that calved in consecutive spring seasons had greater spring BW changes compared with contemporaries that calved but did not rebreed (P 0.31) Increased summer ADG during the breeding season was a useful indicator of subsequent calving rates in primiparous heifers and in cows that had calved the previous spring (P 0.84). Consequently, these data indicate that a suitable predictor of subsequent reproduction in spring-calving cows is summer BW change.

Growth, Luteal Activity, and Pregnancy Rates of Three Breed Types of Dairy Heifers in a Forage-Based Development Program

Growth, luteal activity, and pregnancy rates were evaluated in 89 dairy heifers raised as contemporaries. Breed types were Holstein (H, n = 35), Jersey x H (JH, n = 30), and Brown Swiss x H (BSH, n = 24); they ranged in age from 129 to 205 d at the beginning of the trial. Heifers grazed pasture and received grain supplementation to ensure 0.9 kg of daily BW gain. Hip height, chest depth, and BW were obtained monthly; BCS was recorded at ca. 14 mo of age. At ca. 12 mo of age, two blood samples for each heifer were collected (10 d apart) by jugular vein puncture for progesterone assay. Heifers were considered cycling if progesterone concentrations were > 1 ng/ mL in either of the two serum samples. Heifers were bred artificially (AI) on a synchronized estrus starting at 14 mo of age, and pregnancy status was determined ultrasonically 60 d after breeding. The BSH and H had similar (P>0.05) weights and hip heights; whereas JH were lighter and shorter (P 0.05) occurred for depth of chest and mean BCS. Estrus occurrence by 12 mo of age was greater (P<0.05) for JH (90%) than for BSH (75%) and lowest (P<0.05) for H (47%). Pregnancy rates did not differ (BSH = 96%, JH = 87%, H = 77%). These data suggest that genetic effects of crossbreeding influence early growth and cyclicity at 12 mo of age for replacement dairy heifers. Forage-based development of dairy heifers may be a suitable option to concentrate feeding for dairy producers in Arkansas and the Southern Region.