350 likes | 1.08k Vues
Dystocia. Outcomes. ID factors influencing dystocia Explain the ways in which dystocia might be avoided, controlled. Calf Losses by days at or following calving 1. % of Of all days losses Why? calf loss 1-3 61 % dystocia 68 % 4-6 31 accidents 6 7-9 38 scours 5
E N D
Outcomes • ID factors influencing dystocia • Explain the ways in which dystocia might be avoided, controlled
Calf Losses by days at or following calving1 % of Of all days losses Why? calf loss 1-3 61 %dystocia 68 % 4-6 31 accidents 6 7-9 38 scours 5 10-42 32 pneumonia 12 43-wn. 33 (other) 9 1Miles City Research, 14 yr. summary
Can improvement against dystocia be made? AGA Summary
Dystocia Q: What factors might cause dystocia? What factors can we manage in improve calving ease?
Birth weight Dam’s pelvic area Calf gender Gestation length Age, parity of dam Dam effect Breed effects Dam’s nutrition/condition Geographic region Exercise Endocrine effect 10 (well, ok . . 11) considerations . . .
Dystocia • Birthweight is a major cause of dystocia
Effect of BWT on CE in Simm-X Heifers (Meacham, VPI) Delivery Method Normal Hand Mechanical Birth Pull Pull Caesarean # females 68 34 16 2 % of total 56.7 28.3 13.3 1.7 Ave. BWT81 88 100 121
Genetic Parameters from AGA*: Can selection FOR CALVING EASE be effective? CE BW YW GL CE(m) CE .18 -.86 -.26 -.35 .59 BW .41 .37 .45 -.42 YWT .19 .07 -.05 GL .42 -.12 CE (m) .13 *AGA Sire Summary
Genetic Parameters of BWT (CSU) Trait h2 rg w/ BWT BWT .41 --- Wwt .32 .36 Ywt. .43 .29 189 mo. wt. .61 .69
Genetic Parameters from AGA*: Can selection against birthweight occur? CE BW YW GL CE(m) CE .18 -.86 -.26 -.35 .59 BW .41 .37 .45 -.42 YWT .19 .07 -.05 GL .42 -.12 CE (m) .13 *AGA Sire Summary
Can improvement for other traits occur simultaneously? AGA Summary
abnormal presentation gender of calf gestation length small pelvis calf effects (breed of sire, calf shape and ?) Interactions with birthweight . . .
Height:Dorsal pubic tubercle and sacrum Width:Widest points fr. Right and left shafts of ilium. Pelvic Area: Height X Width (cm.2)
Effect of BWT and Pelvic Area on CE in First Calf Heifers1 Calving Score Yrl. PA Calf Bwt. 1 (no assist) 151 cm2 72 lbs. 2 (minor assist) 145 77 3 (major assist) 141 82 4 (caesarean) 131 94 CSU data summary fr. BCH-2120. H. Ritchie and P. Anderson.
Ratio of pelvic area to birth weight predicts dystocia (r: ~.8)* Ratios of 2.1 before breeding required no assistance. 1.9 required calf puller. “Off the Hip” Trivia *NebGuide G88-895-A. 1991 * KSU C-705, 1989
“Off the Hip” Trivia (cont.) • h2: ~ .4 to .6 • rP: ~ .2 between PA and dystocia • rG : ~ .6 between bulls & heifers • bulls ave. smaller than heifers of same age, weight • 10 cm. increase in PA = 2 lbs. Bwt. And .02 decreasein CE score (Miles City, MT data)
Taylor, 1998 states that “ it is a questionable practice to include pelvic measurements in a female selection program. The end results don’t apparently justify the cost” Q: Why does Ruble still (effectively) use his tape system of predicting CE. Bottom Line . . .How does PA fit into CE management/breeding programs? Bottom Line of Pelvic Area . . .
Breed Effect on CE? Is there a “breed” of sire effect? • Note sire, dam effects (see handouts charts 1 and 2) • What about shape (chart 3)?
Effects of sire breed on calving difficulty and calf birth weight. Sire Calving BWT Breed Difficulty(%) (lbs.) H,A 2.9 79 Jersey 2.9 69 Gelbvieh 8.0 86 Limousin 9.4 86 Brahman 10.0 90 Chianina 11.8 89 Simmental 14.9 89 Charolais 18.4 91 Maine Anjou 20.4 91 MARC. Germ Plasm Eval Report.
Breed of Sire Effects?Old adage . . .More variation exists within a breed than between breeds . . . . • True or False? • Refer to MARC diagrams • Do all Jerseys weigh less than all Charolais? • Do all Simmental weigh more than all Angus?
Breed of Dam Effects? • Not consistent patternbut >Zebu influence = < BWT, dystocia • E.g. MARC: Brahman and Sahiwal F1 dams = 1 to 2% assistance; European breed F1’s = 7 to 17%
Effect of Gestation Length? Phenotypic correlation with dystocia HerefordAngus GL .10 .25Compare . . . BWT .54 .48 PA -.18 -.22 Cow wt. -.01 -.20 (Miles City data . . . )
Effect of Gestation Length? • + 1 day = .3 to .8 pounds birthweight . . • Any additional benefits to shorter gestation length (e.g. 280 versus 287 days)? Also . . . • h2 = .4 • rP of BWT and GL is .4,.and BWT with dystocia is ~.5. Therefore . . . Economic value yet to be concluded
Effect of dam age (KSU C-705). % Calving Difficulty Age MARC CSU 2 yr.* 54 30 3 yr. * 16 11 4 yr. 7 7 > 4 yr. 5 3 dam nutrition, condition? dam exercise (slight in extremes)? Geographical differences? Dam Effects on Dystocia? • * They also averaged 2.5 to 5 pound lighter calves!
Environmental Effects on Dystocia • Very little influence • Energy, protein not proven a factor • Exercise not a factor • Region, yearly differences within herd do exist • Care at calving reduces consequences of variation.
Calving Time Management . . when to give assistance? • Earlier assistance (at first show versus 2 to 3 hours of labor . . ) • 91 vs. 81 % rebreed rate • 75 vs. 60 % first service rate • Same (general) for cows and heifers • Bottom Line . . • Give 1 hour of intense labor • Insure feet visible and cervix fully dialated • Ensure correct position
Dystocia Management . . . Best management advice: 1. prevent dystocia genetically. • Hold birthweight! • Breed effects are significant, but variation w/in breed works 2. Manage first-timers carefully.
Genetic Effects on Reproduction Trait h2Trait h2 calving ease .15 age @ pub .40 BCS .40 BSE .10 Gest. Length .40 prim. abs .30 BWT .50 1st svc. concep. .25 % Calf Crop .10