University Research Herd Research Articles

PSIII-14 The Effects of Co-Twin Sex on Fitness Traits in Young Meat Goat Does

Abstract This study examined if co-twin status influenced reproductive and health traits in meat goat does. Herd records of does identified as twin-born between 2003-2022 in the Tennessee State University Research herd were evaluated for fitness traits as two and three-year-olds. Twin category (TC) was classified as female co-twin (n = 188; FT) or male co-twin (n = 194; MT). Study does were the crossbred or purebred daughters of Kiko, Myotonic, Spanish, and South African (Boer and Savanna) sire breeds. Traits analyzed were birth weight (BWT), weaning weight ratio (WWR), doe breeding body weight (DWT), fecal egg count (FEC), packed cell volume (PCV), kidding rate (KR), weaning rate (WR), and survival rate (SR) using MIXED and GLIMMIX models of SAS. Birth weight revealed doe sire breed (P < 0.0001) and twin category (P = 0.002) were significant. Study does born with a FT were heavier (2.68 ± 0.06 vs. 2.53 ± 0.06 kg) than does born with MT. South African breeds were heavier (P < 0.0001) than all three breeds, while the Myotonic was lighter (P < 0.0001) than all three breeds. Weaning weight ratio revealed the interaction of TC with doe sire breed (P = 0.05) was significant. The interaction showed that FT Spanish does had a greater (P = 0.01) WWR than MT Spanish does (103.90 ± 2.86 vs. 91.69 ± 2.94). Sire breed (P < 0.0001) and doe age (P < 0.0001) were significant for doe breeding weights but not twin category (P = 0.47). Twin category was significant (P = 0.01) for breeding FEC; does with FT had decreased counts (2.53 ± 0.12 vs 2.34 ± 0.12 eggs/g) than does with a MT. Doe age and TC were not significant for breeding PCV while sire breed (P = 0.01) was significant. Doe age, litter size born, and TC were not significant for kidding FEC and PCV. Doe sire breed was significant (P = 0.003) for kidding FEC. The interaction of TC and litter size weaned was significant for weaning FEC (P = 0.01) and weaning PCV (P = 0.04). The nature of the interaction was within TC class for litter size differences. Doe age (P = 0.008) and sire breed (P < 0.0001) were significant for weaning FEC whereas TC was not significant (P = 0.47). Sire breed (P = 0.86) and TC (P = 0.71) were not significant for SR. Sire breed (P < 0.0001) was significant for KR and WR but not TC (P = 0.29 and P = 0.13). Based on the findings of this study, sex of co-twin had limited influence for the traits tested. Sire breed and doe age had more impact on the traits tested.

Ultrasound-assisted injection of the centrodistal joint in the horse.

Injection of the centrodistal (CD) joint in the horse is a commonly performed procedure for both diagnostic and therapeutic purposes. This procedure can be technically challenging, and while radiographic guidance has been previously used, ultrasound localised injection of the CD joint has not been described. The purpose of this study was to explore the feasibility of using ultrasound localisation to increase the accuracy of CD joint injection. Experimental method assessment. One operator performed the ultrasound and injection of 24 CD joints in 12 sedated horses. The joints were injected with iohexol (2ml), sterile saline (1.5ml) and amikacin (0.5ml). Dorsoplantar and dorsomedial plantarolateral radiographic projections were obtained immediately after injection to evaluate the presence of contrast material in the CD joint. The CD joint was successfully injected in 17/24 joints, representing a 70.8% accuracy. The horses used in this study were from the University research herd, and not clinical cases. One investigator performed all the ultrasonography and CD joint injections. The use of ultrasound localisation could improve success of CD joint injection as well as improve the learning curve of less experienced practitioners learning this procedure.

Effect of rumen-protected B vitamins and choline supplementation on health, production, and reproduction in transition dairy cows

The objectives were to determine the effects of a rumen-protected blend of B vitamins and choline (RPBC) on the incidence of health disorders, milk yield, and reproduction in early lactation and the effects on gene expression and liver fat infiltration. A randomized controlled trial in 3 commercial dairy herds (n = 1,346 cows with group as the experimental unit; experiment 1) and a university research herd (n = 50 cows with cow as the experimental unit; experiment 2) evaluated the use of 100 g/cow per d of commercially available proprietary RPBC supplement (Transition VB, Jefo, St. Hyacinthe, Quebec, Canada), or a placebo, fed 3 wk before to 3 wk after calving. In experiment 2 liver biopsies were taken at 4 and 14 ± 1 d in milk to measure triacylglycerol concentrations and expression of 28 genes selected to represent relevant aspects of liver metabolism. Treatment effects were assessed using multivariable mixed logistic regression models for binary health and reproductive outcomes; linear regression models for milk yield, dry matter intake, and liver outcomes; and survival analysis for time insemination and pregnancy. In experiment 1, treatment did not have an effect on the incidence of hyperketonemia (blood β-hydroxybutyrate ≥ 1.2 mmol/L; cumulative incidence to 3 wk postpartum of 28 to 30%), clinical health disorders, or udder edema. The prevalence of anovulation at 8 wk postpartum was 11% in the treatment group and 23% in the control but did not differ statistically given group-level randomization. Pregnancy at first insemination (33 and 35%) and median time to pregnancy to 200 d in milk (96 and 97 d) were not different between treatment and control, respectively. No difference was observed between treatment groups in milk yield or components through the first 3 Dairy Herd Improvement Association test days (44 kg/d in both groups, accounting for parity and components). In experiment 2, there were no differences between treatment groups in feed intake. Mean blood β-hydroxybutyrate was lower at wk 3 in RPBC (0.6 vs. 0.9 ± 0.12 mmol/L) with no difference between treatments for mean blood concentrations of fatty acids (wk -1 or 1) and β-hydroxybutyrate at wk 1 or 2. The gene for acyl-CoA oxidase 1 (ACOX1) had lower mRNA abundance in RPBC with no difference between treatments for the other genes, but the expression of half of the genes assessed differed with days in milk. Liver triacylglycerol was lower in primiparous cows at 4 d in milk in RPBC (2.0 vs. 4.4 ± 1.2%) but not at 14 d in milk (2.2 vs. 3.2 ± 0.97%) with no treatment effect in multiparous cows (4.6 ± 0.8%). Accounting for parity, days in milk, fat and protein percentages, repeated test days, and a random effect of cow, no significant difference was observed between treatments in milk yield across the first 3 Dairy Herd Improvement Association tests (41.2 ± 1.3 in RPBC vs. 38.0 ± 1.4 kg/d in control). Under the diet and management conditions of the field study including low prevalence of clinical health disorders, in experiment 1 we did not detect a benefit of RPBC, but in experiment 2 liver fat content decreased in primiparous cows.

Best prediction of yields for long lactations

Lactation records of any reasonable length now can be processed with the selection index method known as best prediction (BP). Previous prediction programs were limited to the 305-d standard used since 1935. Best prediction was implemented in 1998 to calculate lactation records in USDA genetic evaluations, replacing the test interval method used since 1969 to calculate lactation records. Best prediction is more complex but also more accurate, particularly when testing is less frequent. Programs were reorganized to output better graphics, give users simpler access to options, and provide additional output, such as BP of daily yields. Test-day data for 6 breeds were extracted from the national dairy database, and lactation lengths were required to be ≥500 d (Ayrshire, Milking Shorthorn) or ≥800 d (all others). Average yield and SD at any day in milk (DIM) were estimated by fitting 3-parameter Wood's curves (milk, fat, protein) and 4-parameter exponential functions (somatic cell score) to means and SD of 15- (≤300 DIM) and 30-d (>300 DIM) intervals. Correlations among TD yields were estimated using an autoregressive matrix to account for biological changes and an identity matrix to model daily measurement error. Autoregressive parameters (r) were estimated separately for first (r=0.998) and later parities (r=0.995). These r values were slightly larger than previous estimates due to the inclusion of the identity matrix. Correlations between traits were modified so that correlations between somatic cell score and other traits may be nonzero. The new lactation curves and correlation functions were validated by extracting TD data from the national database, estimating 305-d yields using the original and new programs, and correlating those results. Daily BP of yield were validated using daily milk weights from on-farm meters in university research herds. Correlations ranged from 0.900 to 0.988 for 305-d milk yield. High correlations ranged from 0.844 to 0.988 for daily yields, although correlations were as low as 0.015 on d 1 of lactation, which may be due to calving-related disorders that are not accounted for by BP. Correlations between 305-d yield calculated using 50-d intervals from 50 to 250 DIM and 305-yield calculated using all TD to 500 DIM increased as TD data accumulated. Many cows can profitably produce for >305 DIM, and the revised program provides a flexible tool to model these records.

Yield Losses Associated with Clinical Mastitis Occurring in Different Weeks of Lactation

The effects of the first lactational incidence of clinical mastitis (CM) on milk, fat, and protein production were studied in the Swedish Red and Swedish Holstein breeds. The data consisted of 38,535 weekly production records from 1,192 lactations (506 cows), sampled from 1987 to 2004 in one of the university's research herds. Daily yields were analyzed using a repeated-measures mixed model with an interaction between mastitis index and lactational stage, breed, parity, reproductive status, year-season of calving, and various indices for other disorders as independent variables. The indices were used to distinguish between cows with and without the studied diagnoses, as well as to indicate time (test day) in relation to day of diagnosis. Inclusion of the interaction made it possible to study the effects of CM occurring in different weeks of lactation. Primiparous and multiparous cows were analyzed separately, and the yields of nonmastitic cows were used as a reference for the production level in healthy cows. Lactational (305-d) yield losses were extrapolated from the daily estimates. High milk yield was predisposing to CM. Daily milk yield started to decline 2 to 4 wk before diagnosis. On the day of clinical onset, the milk yield of mastitic cows was reduced by 1 to 8kg. After a case of CM, milk yield was suppressed throughout lactation. The magnitude of the yield losses was determined by the week of lactation at clinical onset. The greatest losses occurred when primiparous cows developed CM in wk 6, whereas multiparous cows experienced the greatest losses when diseased in wk 3. The 305-d milk, fat, and protein production in mastitic primiparous cows were reduced by 0 to 9, 0 to 8, and 0 to 7%, respectively. The corresponding reductions in mastitic multiparous cows were 0 to 11, 0 to 12, and 0 to 11%, respectively.

Impacts on conceptus survival in a commercial swine herd.

An estimated 30 to 40% of potential piglets are lost before farrowing in U.S. or European pig breeds. Because these studies were conducted in limited numbers of university research herds, we decided to characterize the timing, pattern, and extent of conceptus loss in a commercial swine herd in Iowa (Pig Improvement Company; Camborough Line). Sows (parities 2 to 14) were slaughtered on d 25 (n = 83), 36 (n = 78), or 44 (n = 83) of gestation. These days coincide with periods before, during, and after uterine capacity becomes limiting to conceptus survival. At slaughter, numbers of corpora lutea (CL) and uterine horn length were determined, and conceptuses were removed and evaluated. Uterine horn length and CL number did not differ among these days of gestation, averaging 217 cm and 26.6 CL, respectively. In contrast, numbers of conceptuses decreased (P < 0.05) from 15.8 on d 25 to 12.9 on d 36, then remained relatively constant through d 44 (12.1). Thus, conceptus survival averaged 60.2% on d 25, 50.1% on d 36, and 46.3% on d 44, based on numbers of CL present. There was a positive correlation (P < 0.001; r = 0.50) between numbers of viable conceptuses on d 25 and ovulation rate, but this association was completely lost by d 36 (P > 0.10) when uterine capacity becomes limiting. In agreement with this premise, uterine horn length and conceptus number were not associated on d 25 but exhibited positive correlations (P < 0.05) on d 36 (r = 0.36) and d 44 (r = 0.40). On all 3 d examined, the numbers of viable conceptuses were not associated with fetal weight but were negatively correlated (P < 0.05) with placental weight. Compared with the commonly reported values for ovulation rate and percentage conceptus loss in university research herds, values from these production animals were extremely high. Data suggest that throughout this period, larger litters were associated with conceptuses exhibiting small placentae. These data lend support to the concept that increased placental efficiency (fetal weight/placental weight) may contribute to increased litter size in the pig.

Relationships Among Type Scores and Changes in Yield from First to Second Lactation

Changes between first and second lactation yields of days open adjusted milk and 3.7% FCM were correlated with classification traits. Yields within first and second lactation were corrected for herd-season, calving month within season, and age at calving. Classification scores during first lactation were available on 1341 cows appraised between 1971 and 1982 by Holstein Association of America classifiers in five North Carolina Department of Agriculture herds and a North Carolina State University research herd. All classification traits except final score were categorical. Final score, general appearance, dairy character, body capacity, mammary system, stature, rear udder, fore udder, and feet and legs were treated as continuous. Classification traits were adjusted for herd-year, age, and months in milk. First lactation milk was added as a covariate in selected analyses. Body capacity, dairy character, mammary system, back, rump, rear udder, and udder support each had significant effects on change in yield. Mammary system and final score showed a significant linear relationship with change in yield for at least one model. Dairy character and fore udder significantly predicted change in 3.7% FCM when first lactation milk was not in the model.

Heritabilities of Teat Traits and their Relationships with Milk Yield, Somatic Cell Count, and Percent Two-Minute Milk

Two teats on one side of the udder of 898 Holstein cows were scored on a continuous scale for shape, orientation, and pigmentation. Corresponding teat ends were scored for shape, lesions, pigmentation, and orifice location. Teat lengths and diameters, udder height, and distances between teats were measured on the same day. Cows were from six herds owned by the North Carolina Department of Agriculture and two North Carolina State University research herds. Repeatabilities from 98 cows rescored 6 mo after initial scoring were: .54, teat shape; .76,teat-end shape;.98, teat pigmentation; .98, orifice pigmentation, and .32, lesion score. Heritabilities based on 72 paternal half-sister groups were: .38, teat shape; . 5 5, teat-end shape;, 55, teat pigmentation; .40, orifice pigmentation; .24,lesion score; .19, orifice location. Those for four traits of teat orientation averaged .18. Corresponding heritabilities from 200 cow-dam pairs were .37, .67, .55, .30, .22, and .48.Teat-end shape was related to somatic cell count and percent 2-min milk. Somatic cell counts were influenced by udder height, teat-end shape, percent 2-min milk, lesion score, and teat diameter. Teat shape, length, diameter, pigmentation, and orientation did not have large effects on economically important traits.

Profitability in Daughters of High Versus Average Holstein Sires Selected for Milk Yield of Daughters

Data from 778 cows with 2,461 lactations through three generations of selection at the Iowa State University research herd were used to study differences between daughters of sires selected for high and breed-average Predicted Difference Milk. A profitability function, income minus expense, was calculated for each cow. A fixed, linear model was used to describe lifetime profitability. Daughters of high Predicted Difference Milk sires had 49% higher semen costs, 1% higher reproductive health costs, less than 1% fewer breedings, and less than 1% more reproductive examinations. They had 9% more respiratory costs, 6% more digestive costs, and 8% more skin and skeletal costs. Daughters of high Predicted Difference Milk sires produced 16% more milk, had 26% more mammary costs, and 42% more discarded milk costs. Disregarding breeding costs, they had 21% higher total health costs. Including breeding costs, total health costs were 32% higher. With 9% increased feed costs, they netted 18% more lifetime profit and 18% more profit per day of life. Use of a mixed model, which adjusted for fixed effects and included cows as random variables, showed daughters of high Predicted Difference Milk sires to have 12.5% more milk and 15.5% more profit per lactation. Number of breedings and reproductive examinations increased in later lactations and also in later generations as milk production increased in the daughters of high Predicted Difference Milk sires.

Genetic and phenotypic parameters estimated from Nebraska specific-pathogen-free swine field records.

Records collected during 1971 through 1979 from 101,606 hogs raised in 18 Nebraska Specific Pathogen Free herds were analyzed. Traits considered were backfat at 100 kg (BF), weight at 140 d of age (WT) and, in some analyses, number of live pigs/litter at birth (NBA). The phenotypic correlation of BF and WT, averaged across herds, was -.07. The correlations between BF and NBA and between WT and NBA were .04 and -.05, respectively. Average phenotypic standard deviations for BF, WT and NBA were 2.6 mm, 8.8 kg and 2.0 pigs. Estimates of the heritability of BF and WT were lower than most estimates reported from university research herds. Within breed, herd and sex estimates of heritability ranged from -.22 and .51 (unweighted mean = .16 +/- .025) for BF and ranged from -.28 to .49 (mean = .16 +/- .016) for WT. Estimates of the genetic correlation between BF and WT were extremely variable (mean = -.62 +/- 14.3, range = -9.42 to 1.30) among breed-herd-sex subclasses.

Teat Dip Comparisons

Two University research herds with 189 cows were divided for a teat dip comparison with half of each herd using 4% chlorine and the other half 1% iodine. After 6 months the dips used in each half were switched. Teat dipping and routine dry period treatment lowered the infection from 22 to 16% of the quarters during the one year study. Efficacy of the two products differed slightly in the two herds; however, for the total trial 59 new pathogenic infections occurred in both the chlorine- and iodine dipped groups.