Effects of Body Condition on Reproductive Performance of Range Beef Cows

Simnental-Angus crossbred cows were fed differing Levels of nutrition from December to May in each of 3 years to create a wide range in cow body condition or fleshiness at the beginning of the calving season (beginning mid-March) and when turned to summer pasture (early May) 1 month prior to the beginning of the breeding season (early June). Cows that were fleshier in March, May or June cycled earlier. Cows that were fleshier at the beginning of the breeding season calved earlier the following years. For cows that calved Late in the calving season, body condition prior to calving, in early May and at the beginning of the breeding season were all closely related to when they calved the following year. Cows that calved early in the calving season were able to withstand more nutritional stress, as body condition prior to calving and in May had less of an effect on calving interval than did body condition at the beginning of the breeding season

Relationships Between Body Condition Scores and Live Animal Measurements of Beef Cows

Records from 133 mature Simmental x Angus cows collected over a 3-year period were used to determine the relationships between body condition scores and other measurements of cow body condition. Positive correlations were found between condition scores and backfat, weight/height ratios and cow weight. Correcting weight/height ratios of pregnant cows for weight of the conceptus did not improve the correlations with condition score. Backfat measurements had limited use in describing body condition, since backfat wasnear zero for cows less than condition score 5. Equations using condition scores accurately predicted weight/height ratios

Effects of Cow Body Condition and Calving Date on Calf Performance

Records from 285 Charolais-sired calves out of 133 Simmental x Angus crossbred cows taken over 3 years were used to evaluate the influence of cow body condition at calving, condition score change following calving and calf birth date on calf performance. Calves nursing cows with higher condition scores in March had increased daily gains from birth until May. However, at weaning time average daily gain and weaning weights were similar regardless of cow condition at calving. Cows which maintained body condition or lost less than two condition scores from March to May weaned heavier calves than cows which lost two or more condition scores after calving. Calf growth rate from birth until 6 months of age was similar between calves born early and those born late in the calving season

Effects of Body Condition on Reproductive Performance of Range Beef Cows

Mature Simnnental x Angus crossbred cows were fed differing Levels of nutrition from December to May in each of 3 years to create a wide range in cow body condition or fleshiness at the beginning of the calving season (beginning mid-March) and when turned to summer pasture (early May)1 month prior to the beginning of a 60-day breeding season ( early June). Cows that were fleshier in March, May or June cycled earlier and conceived earlier. Being thin in May or June had a more detrimental effect on pregnancy rate for cows that calved late in the calving season. A condition score of 4 for early calving cows and 5 for late calving cows at calving and breeding were the minimum body condition for high reproductive performance

Methionine Addition to a Urea-Grain Supplement for Cows Grazing Dormant Winter Range

A 2-year grazing study involving 103 mature pregnant Simmental x Angus cows grazing dormant winter range was conducted to determine the effects of methionine addition to a urea-grain supplement on forage intake and digestibility and on cow performance. Four protein supplements designed to supply .8 1b crude protein per head daily were fed from mid-November to mid-February. Supplements contained (1) urea (CON), (2) urea plus methionine (MET), (3) urea plus sodium sulfate (SUL) and (4) soybean meal (SBM). Twice during the second winter (late November and late January), cows were administered controlled release chromic oxide boluses and fecal samples were collected to determine grass intake by the fecal output/indigestibility ratio technique. Organic matter intake (OMI) and digestibility (OMD) were higher in November than January. No differences in OM1 between supplemental treatments were detected. A treatment x grazing period interaction was detected for OMD. In late January and November, OMD was higher for cows fed SBM than cows fed supplements containing urea. In late January, OMD was lower for MET compared to SUL fed cows. Cows supplemented with MET gained less weight and body condition over each winter grazing period than SUL fed cows. Methionine addition to a urea-grain supplement did not improve digestibility or intake of range forage or cow weight gains

Effects of Body Condition on Reproductive Performance of Range Beef Cows

A 3 yr. 22 factorial study was conducted with 133 mature Simmental X Angus cows calving for 81 d beginning in mid-March to determine minimum cow body condition required for adequate reproductive performance of range beef cows. Two levels of early (early December to mid-February) and late (from calving date to early May) winter nutrition were imposed. Nutritional treatments produced total winter (December-May) weight changes ranging from -188 to -5 kg and wide cow body condition differences at calving and breeding. The breeding season lasted 60-70 d beginning June 5 each yr. Visual condition scores (CS 1-9, l=thin), weight to height ratios (WHR, kg/cm), and backfat measurements (mm) were determined monthly from December to July. Blood samples were collected 7-10 d apart in May, June and July for progesterone and in March and May for serum d-B-hydroxybutyrate (BHB) and urea nitrogen (SUN) determinations. Percentage of cows on low early and late winter nutrition that were cycling at the start of the breeding season was depressed (P\u3c .05} and calving interval for those cows was extended (P\u3c .05). Calf weight gains (calving to May) and 205 d adjusted weights were higher (P\u3c .05) as level of winter nutrition increased during the last 2 yr. of the study. Cows on early winter low energy treatment had higher (P\u3c .05) SUN levels in March. Within late winter treatments BHB levels were higher (P60 d postpartum at the start of the breeding season calving interval was decreased (

Evaluation of Controlled Release Chromic Oxide Boluses and Alkaline Hydrogen Peroxide Lignin as Markers to Determine Intake of Cows Fed Mature Prairie Hay

A digestion trial involving 8 mature cows fed mature prairie hay ad libitum was conducted to determine the validity of controlled release chromic oxide (Cr) and alkaline hydrogen peroxide lignin (APL) as markers for prediction of forage intake by the fecal output (F0)/indigestibility ratio technique. Seven days after oral administration of Cr boluses, total FO was collected daily, weighed and sampled. Rectal fecal grab samples were collected at 10:00 a.m. each day and at 4-hour intervals on day 4 of collections. Mean fecal Cr output based on total fecal collections was 1,662 mg Cr/day compared to a manufacturer\u27s suggested value of 1,505 mg Cr/day. Based on forage and fecal APL levels, mean fecal APL recovery was 95.9%. Increasing the number of days that grab samples were composited raised R2 values between actual FO and dry matter digestibility (DMD) and those predicted using fecal Cr and APL concentration (R = .56, .70, .77, .79 and .82; .27, .55, -61, .67 and .70 for 1- to 5-day composites for FO and DMD, respectively). With samples composited over the entire 5-day collection period, predicted FO, (DMD) and dry matter intake (DMI) were similar (paired t-test) to actual values. Fecal grab samples and total fecal collection samples, composited over 5 days, provided a similar relationship (R = .71) between actual and predicted DMI. Fecal Cr and APL concentrations were not affected by sampling time of day. Results from this study indicate that grab samples collected once daily and composited over 5 consecutive days can be used to predict FO when controlled release chromic oxide boluses are used. While accuracy of DMD estimations was not as high as that of FO, APL was nearly 100% recoverable and resulted in reliable predictions of DMD and DMI

Effect of Methionine, Leucine and Isovaleric Acid on In Vitro Digestibility of Corn Stover

Two-stage in vitro fermentation was used to evaluate the amino acids methionine and leucine and a branched chain volatile fatty acid, isovaleric acid, as potential additives to a grain-urea supplement for cattle consuming corn stover. Dry matter and fiber digestibility were higher for the husks and leaves than the stalk portion of the corn plant. Providing urea as a source of nitrogen improved dry matter and fiber digestibility. There were no improvements in digestibility or fermentation rate with addition of the amino acids or volatile fatty acid evaluate

Evaluation of Controlled Release Chromic Oxide Boluses and Alkaline Peroxide Lignin as Marker Methods to Determine Forage Intake of Grazing Ruminants

Twenty Hampshire ram lambs used in a digestibility trial were administered controlled release chromic oxide intraruminal boluses to evaluate chromic oxide and alkaline peroxide lignin in combination as potential markers for determining intake of ruminants grazing dormant winter range. Lambs were fed ad libitum mature prairie grass hay and provided .1 Ib crude protein from one of four supplements. The ability to predict fecal output using chromic oxide boluses and diet digestibility using alkaline peroxide lignin were not affected by supplemental treatments. Chromic oxide concentration in the feces was not affected by the time of sampling. The amount of chromium oxide excreted averaged 224 mg/day and was not affected by treatment. The amount of lignin consumed that was recovered in the feces was 97.8 + 11.6%. Predicted fecal output was closely related to actual values (R2 = 33, C.V. = 8.4%). Predicted digestibility and dry matter intake were similar to actual values (P = .77 and .90, respectively). Controlled release chromic oxide boluses and alkaline peroxide lignin procedures may be used to predict dry matter intake of ruminants grazing mature forages

Effects of Amino Acid and Branched-Chain Volatile Fatty Acid Additions on in Vitro Fermentation of Dormant Range Grasses

Two-stage in vitro fermentation was used to screen five amino acids and three branched-chain volatile fatty acids as potential additions to a grain urea supplement for cows grazing dormant winter range. Urea addition alone increased dry matter and fiber digestibility of dormant cool season grasses. Methionine addition improved fiber digestibility and rate of fermentation of cool season grasses over urea alone. Compared to urea addition, the branched-chain volatile fatty acids did not increase dry matter or fiber disappearance or improve rate of fermentation of dormant range grasses. None of the buffer additions tested or urea increased digestibility of the dormant warm season grasses. This preliminary laboratory study indicates that methionine offers the greatest potential for addition to a grain urea supplement to increase utilization of dormant range grasses