Measures Of Reproductive Performance Research Articles

Growth characteristics, reproductive performance, and evaluation of their associative relationships in Brangus cattle managed in a Chihuahuan Desert production system1

Balancing growth and reproductive performance in beef cattle managed in desert environments is challenging. Our objectives were to 1) evaluate trends in growth and reproductive traits, and 2) assess associative relationships between growth characteristics and reproductive performance in a Brangus herd managed in a Chihuahuan Desert production system from 1972 to 2006. Data were from bull (n = 597) and heifer calves (n = 585; 1988 to 2006) and cows (n = 525; repeated records of cows, n = 2,611; 1972 to 2006). Variables describing the growth curve of each cow were estimated using a nonlinear logistic function (each cow needed 6 yr of data). Mixed-effect models and logistic regression were used to analyze trends across years in growth and reproductive traits (both continuous and categorical). For continuous traits of calves, a slight cubic response (P < 0.01) described the dynamics of birth weight, 205-d BW, and 365-d BW across years. For categorical traits of females, positive linear trends (P < 0.05) across years were observed in percent pregnant as yearlings, calved at 2 yr of age, and first-calf heifer rebreeding (slopes ranged from 0.007 to 0.014%/yr). Autumn cow BW increased gradually until 1997 (509 kg +/- 8.8) and then decreased gradually by 0.6 kg/yr, whereas pregnancy percentage decreased gradually until 1995 (78.4% +/- 1.0) and then increased slightly by 0.2%/yr. A quadratic effect best described the dynamics of these 2 variables across years (P < 0.01) as well as estimates describing the growth curve of each cow. Specifically, asymptotic BW and age increased (P < 0.05) from 1972 to 1983 and 1990, respectively. Asymptotic age then decreased by 27% from 1983 to 1996 (P < 0.05). The maturing rate index was negatively correlated with age at first calving and calving interval (r = -0.42 and -0.18, P < 0.01), which suggested that early-maturing cows had enhanced fertility in this environment and production system. In summary, minimal changes were observed in measures of growth in bulls and heifers in a Brangus herd managed in the Chihuahuan Desert. Opposing relationships were observed among measures of cow size and fertility; as growth curves shifted toward earlier maturity, measures of reproductive performance suggested that fertility improved.

Classification of reproductive performance of ten winegrape varieties

Background and Aims: Flowering and fruitset are principal determinants of grapevine yield. Poor fruitset is said to limit the yield of many varieties in most regions in Australia; however, there is a lack of knowledge of the reproductive performance of most varieties under Australian conditions. Methods and Results: The reproductive performance of Vitis vinifera winegrape varieties – Cabernet Sauvignon, Chardonnay, Merlot, Nebbiolo, Pinot Noir, Sangiovese, Sauvignon Blanc, Shiraz, Tempranillo, and Zinfandel – was studied in four consecutive growing seasons (commencing in 2004/05) across a range of climatic regions from cool (Adelaide Hills) to warm (Adelaide Plains). Measures of reproductive performance included flower number per inflorescence, fruitset (%), berry number per bunch, coulure index (CI), and millerandage index (MI). Principal component analysis and agglomerative hierarchical classification were used to group the varieties into three classes of reproductive performance. Conclusions: Certain varieties have a reputation of having ‘poor fruitset’ that has been inferred from relatively low berry number per bunch; however, for some of these varieties, it is ‘low flower number per inflorescence’ rather than ‘poor fruitset’ that is the cause of low berry number. Significance of the Study: An improved understanding of the reproductive performance of winegrape varieties has been achieved.

Assessing the Association of the Level of Milk Production with Reproductive Performance in Dairy Cattle

There is much debate about possible antagonism between high milk production and reproductive performance. This paper reviews methods of measuring reproductive performance and the association of the level of milk production with pregnancy rate at the herd and individual levels. The main question is whether fertility (the capacity for reproductive function and successful pregnancy) of dairy cows has in fact declined, as opposed to the success of management systems and people at meeting the metabolic, nutritional, housing, and social needs of increasingly productive animals but with no less inherent capacity to achieve and maintain pregnancy; and if fertility really has diminished, the extent to which this decline is caused by increased milk production. There is no doubt that production per cow has increased, but it is unclear how much of this increase can explain the apparent decrease in fertility. It is important to separate the biology of reproductive function from the effects of economically based management decisions about culling and continuation of breeding. Most traditionally-used measures of reproductive performance (calving interval, conception rate, non-return rate) are incomplete or severely biased outcome measures. Both herd and cow-level data should include as much information as possible on confounders of the relationship of production with reproduction. Population or herd-level data should not be used to make inferences about individual-level associations. Considering the quality of data and analytic methods in the published literature, it is not clear if there is any association between higher milk yield and the probability and timing of pregnancy, either among cows at various levels of production in a population at one time, or with increasing production over time.

Reproductive performance measures among Thoroughbred mares in central Kentucky, during the 2004 mating season

To improve efficiency at the farm level, a better understanding of how farm management factors impact reproductive performance is important. To assess reproductive efficiency and effectiveness among Thoroughbred mares in central Kentucky. A cohort of 1011 mares on 13 farms in central Kentucky was followed during the 2004 mating and 2005 foaling season. Information on farm level practices was collected via interviews with farm managers. Reproductive records were collected for each mare mated to obtain information on mare characteristics. The influence of mare age and status (maiden, foaling, barren) on Days 15 and 40 post mating pregnancy rates, foaling rates and total effective length of the mating season were assessed. The influence of stallion book size on reproductive performance measures was also examined. Per season pregnancy rates on Days 15 and 40 post mating and live foal rate were 92.1, 89.3 and 783%, respectively. Per cycle rates for the same time periods were 64.0, 583 and 50.8%. There were no significant associations between stallion book size and reproductive performance outcomes. The mean +/- s.d. interval from the beginning of the mating season to the last mating of the mare was 36.5 +/- 26.1 days. Mare age had a significant impact on efficiency of becoming pregnant, maintaining pregnancy and producing a live foal. Overall, fertility did not decrease among stallions with the largest book sizes. Total interval length of the mating season can be reduced if managers ensure maiden and barren mares are mated at the beginning of the season and foaling mares are mated at the earliest oestrus after acceptable uterine involution has been achieved. Measures identified in the study can be used by owners, farm managers and veterinarians to improve mare reproductive performance and identify parameters to assist with the implementation of effective culling practices.

Temporal variation in Adélie penguin diet at Béchervaise Island, east Antarctica and its relationship to reproductive performance

Diet, and in particular, food quality and quantity can influence the reproductive performance of marine predators. Also, the diet of specialist predators is often monitored in programmes that model and manage ecosystems. We examined the diet of Adelie penguins (Pygoscelis adeliae), an important consumer of Southern Ocean living resources, at Bechervaise Island, east Antarctica, during the chick-rearing periods for 11 years between 1991–1992 and 2002–2003. We also investigated the relationship between diet and annual reproductive performance. Substantial inter- and intra-annual variation in both meal mass and composition was evident: adults generally returned with larger food loads during the creche compared with the guard stages, and diet composition was dominated by two prey types, krill and fish, which combined contributed to >90% of the diet by mass in 7 out of 11 years. Females generally brought back meals dominated by krill; males generally consumed fish-dominated meals. However, both sexes returned with a high proportion of krill when annual mean meal mass was also high, suggesting that more food was available in high krill years. There was also evidence that years of high reproductive performance were positively correlated with years of both high meal and krill mass. We believe that our results indicate that there is significant long-term inter- and intra-annual variability in the amount of food available to Adelie penguins and that this was reflected in their diet and measures of reproductive performance. Coupled with the observation that penguins did not switch prey, this indicates that Adelie penguins from Bechervaise Island are dependent predators of krill. This contrasts with populations in other locations but supports the notion that Adelie penguins are an informative species to monitor the management of Southern Ocean marine living resources in this region.

Trends in calving ages and calving intervals for Iranian Holsteins in Fars province, southern Iran

To determine trends in calving ages and calving interval as measures of reproductive performance in Iranian Holsteins in Fars province, southern Iran during 2000-2005. Data about birth dates and previous calving dates for cows which calved between 21 March 2004 to 20 March 2005 were retrieved from the database of the Agricultural Jihad Organization of the province. Overall, calving records for 1134 cows from 12 herds during 2000-2005 were included in the statistical models. Mean calving interval was 435 days in 2000 and declined significantly to 389 days during the study period (P < 0.001). Age at first calving decreased significantly from 30 months in 2000 to 26 months in 2005 (P < 0.001). The corresponding measures for age at second calving were 44 and 41 months, respectively (P = 0.003). Cows which calved during warm months had significantly (P < 0.001) higher calving interval (420 days) compared with calving in cold months (411 days). No significant effect for parity on calving interval was observed in this study. Reproductive performance revealed relatively positive trend in the Iranian Holsteins in Fars province. This could be attributed to better management and nutrition practices during this period and also to the fact that large genetic trend for milk which has been observed in countries with decreasing reproductive performance has not occurred in these herds yet.

Number of Calves Produced at Specified Age as a Measure of Reproductive Performance in Beef Cattle under Artificially-Inseminated Breeding Scheme

Reproductive abilities in beef cattle herds are receiving increased attention due to recent rises in production costs. To achieve more efficient management, a measure ot fertility, namely the number ot calves produced at K yr of age (NCP k ), was developed and its genetic parameters were estimated from Japanese Black cows by restricted maximum likelihood procedures. The k examined were distributed from 2 to 10 yr of age and NCP 2 averaged 1.077 calves over 43,536 cows. The averages increased by approximately 0.9 calf with each additional 1 yr increment in k. Heritabilities of NCP k were estimated to be low ranging from 0.083 to 0.162, which seemingly suggested a difficulty of genetic improvement. However, large genetic variation and high accuracy were observed in predicted breeding values of NCP k . For example, the breeding values of NCP 7 were predicted between -0.303 and +0.213 with average accuracy of 0.607 for cows with observations. Genetic correlations among different k were generally high and positive (0.474 to 0.995). The analyses showed that at least NCP 4 was required to maintain the genetic correlations of 0.8 or higher with subsequent NCP k . Also NCP 5 maintained the genetic correlations of 0.9 or higher with subsequent NCP k . The results suggested some possibilities for NCP k to be a selection criterion considering its genetic variation, high accuracy and consistency with subsequent performance.

Individual quality and reproductive effort mirrored in white wing plumage in both sexes of south polar skuas

It is well established that female choice may lead to sexual selection on quality-revealing ornaments in males. However, in many species, both sexes display conspicuous characters, which may reflect individual quality and condition. We examined the correlations between measures of individual condition, reproductive performance and variation in size and whiteness of white wing patches in both sexes of the south polar skua (Catharacta maccormicki). Females with a whiter patch had a lower mean clutch size and higher survival, and males with whiter patches had higher immune responses against the injected immunogen tetanus. Birds with a larger white patch, on the other hand, had a higher mass loss, and females with large white patches laid larger eggs and had reduced survival probability. Thus, variation in 2 measured aspects of the wing patches in the south polar skua seems to mirror a gradient of reproductive investment strategies; from 1) reduced reproductive investment, better immune defense, and higher survival in birds with more intensely white wing patches to 2) high reproductive investment but survival costs in birds with larger patches.

Age-specific reproduction and survival of individually marked Wood Thrushes,Hylocichla mustelina

Several nonexclusive, sometimes contradictory, hypotheses have been employed to explain age-related changes in reproduction and survival among vertebrates. We evaluated these hypotheses with observations collected from a 31-year study of individually marked Wood Thrushes (Hylocichla mustelina). Age-specific fledgling production, survival probabilities, and derived life table columns are presented here. Additionally, we report "genetic value," or the number of young remaining to be recruited into the breeding population by individuals of age x. Controlling for age of mate, the presence of some individuals in multiple years, and the effect of year of breeding, reproduction and survival peaked in middle-aged birds of each sex and declined later in life for the oldest individuals. We could not exclude the selection hypothesis (removal of inferior individuals) as an explanation for improved female reproduction until middle age. The age at last reproduction was a significant determinant of age-related reproductive success, indicating a disappearance of low-quality individuals. Yearling females that did not successfully reproduce had greater within-season emigration than all other age classes of each sex, regardless of the reproductive success of other classes. For males, we favored the constraint hypothesis (improved reproduction with experience) to explain greater reproductive output with increasing age until at least middle age. For each sex, the age of the mate independently influenced all measures of reproductive performance, but there was generally a linear or quadratic, rather than interactive, effect of the mate's age on reproduction. For both sexes, hypotheses of age-related reproduction were only partially supported because of effects of senescence, or a decline in reproductive output or survival probabilities with increasing age. Senescence may confound attempts to examine or apply general hypotheses of age-related reproduction that assume a monotonic relationship between age and reproduction or survival.

Age-related reproductive performance in the parental burying beetle, Nicrophorus orbicollis

Age-related improvements in reproductive performance have been explained by the selection, constraint, and restraint hypotheses (increased performance related to greater effort and a declining residual reproductive value). Using a laboratory population of the burying beetle, Nicrophorus orbicollis, 6 measures of performance were assessed. Consideration of the selection and constraint hypotheses was minimized by reducing mortality to near zero and comparing reproductive outcomes of equal-sized females with equivalent mating and breeding experience. Young and old females were provided a resource for breeding (mouse carcass) and were confronted by a potentially infanticidal intruder (young or old) after offspring were present in the nest. Younger females were more likely to experience a brood failure and were slower to oviposit eggs. Younger intruding females also were less likely to usurp a carcass from a resident female. Age, however, did not affect any measure of reproductive performance once a female had a brood. There were no differences between young and old females in the number and mass of offspring in original or replacement broods, or in the probability of successfully defending offspring against an intruder. In a follow-up experiment with smaller carcasses, there was, again, no significant difference in the ability of young and old females to defend their brood. In N. orbicollis, the reproductive restraint observed in younger females appears to inhibit the initiation but not the continuance of reproduction. The usefulness of the residual reproductive, targeted reproductive effort and the maturational limits hypotheses to explain age-related variation in reproductive performance are discussed. Key words: aging, burying beetle, contest behavior, indirect effects, maternal effects, Nicrophorus, parental care, reproductive effort, senescence. [Behav Ecol]

Small and large wetland fragments are equally suited breeding sites for a ground-nesting passerine

Large habitat fragments are generally thought to host more species and to offer more diverse and/or better quality habitats than small fragments. However, the importance of small fragments for population dynamics in general and for reproductive performance in particular is highly controversial. Using an information-theoretic approach, we examined reproductive performance and probability of local recruitment of color-banded reed buntings Emberiza schoeniclus in relation to the size of 18 wetland fragments in northeastern Switzerland over 4 years. We also investigated if reproductive performance and recruitment probability were density-dependent. None of the four measures of reproductive performance (laying date, nest failure probability, fledgling production per territory, fledgling condition) nor recruitment probability were found to be related to wetland fragment size. In terms of fledgling production, however, fragment size interacted with year, indicating that small fragments were better reproductive grounds in some years than large fragments. Reproductive performance and recruitment probability were not density-dependent. Our results suggest that small fragments are equally suited as breeding grounds for the reed bunting as large fragments and should therefore be managed to provide a habitat for this and other specialists occurring in the same habitat. Moreover, large fragments may represent sinks in specific years because a substantial percentage of all breeding pairs in our study area breed in large fragments, and reproductive failure in these fragments due to the regularly occurring floods may have a much stronger impact on regional population dynamics than comparable events in small fragments.

Treatment of Acute Puerperal Metritis with Flunixin Meglumine in Addition to Antibiotic Treatment

The objective of this field trial was to evaluate effects of a single administration of 2.2mg/kg of body weight (BW) of flunixin meglumine (FM) in addition to a systemic antibiotic treatment in cows with acute puerperal metritis (APM). Outcome variables tested were proportion of cows with a fever, prevalence of chronic endometritis 18 to 22 and 32 to 35 d in milk (DIM), and reproductive performance measures in the current lactation. In addition, serum concentrations of haptoglobin and fibrinogen were analyzed. Daily milk yield within 6 d after the first treatment was recorded. Cows were examined 4 to 5 DIM by rectal palpation and vaginoscopy, and rectal temperature was measured. Fetid vulvar discharge and a body temperature ≥39.5°C were signs of APM. Cows with APM were treated in the reference group with 1.0mg/kg of BW of ceftiofur on 3 to 5 consecutive days (CEF, n=119). In the study group, cows received the same antibiotic treatment as in CEF and 2.2mg/kg of BW of FM on treatment d 1 (CEF + FM, n=119). Blood samples were collected 4, 6, and 10 DIM and analyzed for concentrations of haptoglobin and fibrinogen. A group of cows without APM remained untreated and served as controls (n=9). There were no significant differences between CEF and CEF + FM in the proportion of cows with fever 1 d after the first treatment (33.6 vs. 46.2%), milk yield per milking 10 DIM (7.5±0.3 vs. 7.6±0.3kg in primiparous, 9.6±0.4 vs. 10.6±0.4kg in multiparous cows), prevalence of chronic endometritis 32 to 35 DIM (64.3 vs. 52.2%), and in reproductive performance (31.5 vs. 34.3% conception to first AI, 58.0 vs. 54.6% pregnancy rate, 107.8±36.9 vs. 101.6±41.4 d open). Compared with the control, CEF and CEF + FM had significantly greater concentrations of haptoglobin (1.1±0.28 vs. 1.9±0.06 and 1.8±0.07mg/mL at 4 DIM; 0.3±0.15 vs. 1.1±0.06 and 1.2±0.07mg/mL at 10 DIM) and fibrinogen (2.2±0.17 vs. 3.9±0.14 and 3.7±0.13g/L at 4 DIM; 1.9±0.1 vs. 2.6±0.1 and 3.0±0.13g/L, respectively, at 10 DIM) on all test days. The additional treatment with FM had no effect on these acute phase proteins. In conclusion, the single administration of 2.2mg/kg of BW of FM in addition to a systemic antibiotic treatment of cows having APM did not result in beneficial effects on clinical cure, milk yield within 6 d after the first treatment, or reproductive performance.

Heritability of reproductive traits and genetic correlations with growth in the black tiger prawn Penaeus monodon reared in tanks

Captive-reared broodstock of the black tiger prawn ( Penaeus monodon) have exhibited poor reproductive performance limiting attempts to domesticate this species. The potential for improved reproductive performance was assessed by determining heritabilities of four measures of reproductive performance, their genetic correlations with each other and with growth rate and weight at age. Heritability estimates ( h 2 ± S.E.) obtained from √ (days to spawn), √ (egg number), √ (nauplii number) and arcsin√ (proportion hatched) were 0.47 ± 0.15, 0.41 ± 0.18, 0.27 ± 0.16, and 0.18 ± 0.16, respectively. Estimates of genetic correlations between reproductive traits and weight at age, or growth rate were less than 0.5 except for √ (egg number) and weight at 54 weeks (0.93 ± 0.19) and √ (egg number) and 16–54-week growth (0.63 ± 0.29).

Seabird predation by great skuas Stercorarius skua– intra‐specific competition for food?

Competition for food is widely cited as an important cost of coloniality among birds and much of the evidence in support of this hypothesis comes from studies of colonial piscivorous seabirds. However, for generalist seabirds able to switch between different prey types, the role of food availability in relation to colony size is unclear. Here we investigate patterns of the consumption of seabird prey in relation to colony size in a generalist seabird, the great skua Stercorarius skua, in Shetland, UK. At the population level skuas feed mainly on sandeels Ammodytes marinus and fishery discards, but respond to declines in fish availability to facultatively prey on other seabirds. By comparing the consumption of seabirds among seven different sized colonies, including one colony with artificially reduced numbers of skuas (Fair Isle), we investigate whether consumption of seabird prey is influenced by skua population size, while simultaneously measuring seabird prey availability. Data from five years also enables us to investigate the influence of annual variation in environmental conditions on seabird consumption. Using measures of body condition and reproductive performance we investigate the consequences of living in different sized colonies, which may provide insight into ultimate costs of nesting at high population density. Skua diets varied among colonies and the proportion of seabird prey in the diet was inversely related to skua colony size, despite similar per capita numbers of seabirds across colonies. At the colony where their numbers were artificially suppressed, skuas consumed a greater proportion of seabirds per capita. Highly significant year effects in seabird predation were observed but the pattern among colonies remained consistent over time. Two measures of adult body condition (pectoral muscle index and mean corpuscular volume) revealed that adult great skuas were in poorer condition at the largest colony (Foula), but reproductive performance did not alter significantly among colonies. This study provides evidence that intra‐specific competition among skuas may limit opportunities for obtaining seabird prey, which may be particularly important during periods of poor availability of sandeels and fishery discards, and has implications for assessing the impact of skuas on seabird populations.

Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows

Relationships between genetic merit for milk production and animal parameters and various parameters of reproductive performance were examined using multilevel binary response analysis in a study of 19 dairy herds for three successive years, representing approximately 2500 cows per year. The proportion of cows intended for rebreeding that were back in-calf again within 100 days of calving (ICR-100) and the proportion of cows that reappeared again with 365 (RR-365) and 400 days (RR-400) of a previous calving were considered in addition to the traditional measures of reproductive performance. Each 100-kg increase in genetic merit for milk yield was associated with an increased interval to first service (IFS) and calving index (CI) of 1.4 ( P < 0.001) and 1.8 days ( P < 0.001), respectively, a 0.5% increase ( P < 0.05) in calving rate to first insemination (CR-1) and 0.8% increase in RR-400. Each £10 increase in £PIN (the economically weighted yield selection index used in the UK that takes account of butterfat and protein yields) was associated with an increased IFS and CI of 1.5 ( P < 0.001) and 3.0 days ( P < 0.001), respectively. Cows with increased genetic merit for milk yield and £PIN were more likely to re-calve (RR-overall; P < 0.001). Each 1000-kg increase in 305-day milk yield was associated with an increased IFS and CI of 3.2 ( P < 0.001) and 7.8 days ( P < 0.001), respectively, and a 13.6 ( P < 0.001), 22.4 ( P < 0.001), 19.9 ( P < 0.001) and 19.0% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. A 10-kg increase in maximum yield was associated with a 6.6-day increase in CI ( P < 0.001) and a 14.9 ( P < 0.001), 18.3 ( P < 0.001), 9.6 ( P < 0.05) and 14.2% ( P < 0.001) decrease in CR-1, ICR-100, RR-365 and RR-400, respectively. Fertility performance was also associated with season of calving, lactation number and dystocia score. Level of production had a larger effect on fertility performance than genetic merit for milk production suggesting that infertility at an individual cow level is more likely to be associated with increased production and an inability to meet the nutritional requirements of the cow.

Growth, reproductive performance, and manganese status of heifers fed varying concentrations of manganese1,2

An experiment was conducted to examine the effects of dietary Mn on growth, reproductive performance, and Mn status of beef heifers. Eighty Angus (n = 40) and Simmental (n = 40) heifers, averaging 249 kg, were stratified by BW within a breed and randomly assigned to 1 of 4 treatments providing 0 (control), 10, 30, or 50 mg of supplemental Mn/kg of DM from MnSO(4). Heifers were individually fed a diet containing cottonseed hulls, corn gluten feed, citrus pulp, and ground corn, and the control diet contained 15.8 mg of Mn/kg of DM by analysis. Average daily gain, DMI, and G:F for the 196-d period were not affected by Mn supplementation. Control heifers had reduced (P = 0.04) liver Mn when contrasted with the 3 levels of supplemental Mn. Serum cholesterol was greater (P = 0.001) in Angus compared with Simmental heifers over the course of the 196-d experiment but was not affected by treatment. Dietary Mn did not significantly affect measures of reproductive performance. Results of this study indicate that 15.8 mg of Mn/kg of diet DM should be adequate for growth, onset of estrus, and conception of beef heifers.

Dietary exposure of mink (Mustela vison) to fish from the Housatonic River, Berkshire County, Massachusetts, USA: Effects on reproduction, kit growth, and survival

We evaluated the effects of feeding farm-raised mink (Mustela vison) diets containing polychlorinated biphenyl (PCB)-contaminated fish from the Housatonic River (HR; Berkshire County, MA, USA) on adult reproductive performance and kit growth and survival. Diets contained 0.22-3.54% HR fish, providing 0.34-3.7 microg total PCBs (TPCB)/g feed wet wt (3.5-68.5 pg toxic equivalence [TEQ]/g). Female mink were fed diets before breeding through weaning of kits. Twelve kits from each treatment were maintained on their respective diets for an additional 180 d. Dietary PCBs had no effect on the number of offspring produced, gestation period, or other measures of adult reproductive performance. Mink kits exposed to 3.7 microg TPCB/g feed (68.5 pg TEQ/ g) in utero and during lactation had reduced survivability between three and six weeks of age. The lethal concentrations to 10 and 20% of the population (LC10 and LC20, respectively) were estimated to be 0.231 and 0.984 microg TPCB/g feed, respectively. Because inclusion of PCB-contaminated fish that composed approximately 1% of the diet would reduce mink kit survival by 20% or more, it is likely that consumption of up to 30-fold that quantity of HR fish, as could be expected for wild mink, would have an adverse effect on wild mink populations.

Strategies to Improve the Therapy of Retained Fetal Membranes in Dairy Cows

In this field trial, a protocol for the treatment of retained fetal membranes (RFM) without any intrauterine therapy was compared with 3 protocols based on the intrauterine use of antibiotic pills (AP), the manual removal (MR) of the fetal membranes, or the combination of both (PR). The study was conducted on 5 commercial dairy farms in Germany. Cows with RFM for at least 24h after calving were assigned to 1 of 4 treatment groups. Cows of all groups with a rectal temperature≥39.5°C received a systemic antibiotic treatment with ceftiofur (1mg/kg per d) for 3 to 5 consecutive days. In case of continued fever after 5 treatments, cows received a different antibiotic as an escape therapy. In the reference group (REF; n=131), cows did not receive any additional treatment. All cows in group AP (n=119) received intrauterine treatment with antibiotic pills consisting of 1,000mg of ampicillin and 1,000mg of cloxacillin for 3 consecutive days. In group MR (n=121), an attempt was made to remove the fetal membranes manually, but uterine pills were not administered. In group PR (n=130), an attempt was made to remove the fetal membranes manually and all cows received a local antibiotic treatment as in group AP. All cows received 2 doses of 25mg of PGF2α: one dose between 18 and 24 d and another between 32 and 38 d postpartum. Statistical analyses were performed using binary logistic regression models and survival analyses with group REF as reference. Of all animals, 79.8% had a body temperature of≥39.5°C at least once within 10 d postpartum and were treated with ceftiofur. Occurrence of fever within 10 d postpartum was significantly lower in groups AP and PR compared with reference group REF, but was not different between groups MR and REF. Risk of receiving an escape therapy in case of fever after 5 treatments with ceftiofur did not differ among groups. Reproductive performance measures did not differ significantly between group REF and any of the comparison groups. Compared with a treatment protocol based only on systemic treatment with antibiotics for cows with a fever, neither intrauterine antibiotics nor manual removal of fetal membranes alone or in combination reduced proportions of cows needing an escape therapy nor did those treatments improve reproductive measures in the current lactation. Systemic treatment alone based on elevated rectal temperature was effective and reduced use of antibiotics compared with therapies that included intrauterine antibiotics.

Genetic variation and responses in reproductive performance of sows in lines selected for growth rate under restricted feeding

AbstractThe objective of this study was to examine genetic changes in reproduction traits in sows (total number born (TNB), number born alive (NBA), average piglet birth weight (ABW) and number of piglets weaned (NW), body weight prior to mating (MW), gestation length (GL) and daily food intake during lactation (DFI)) in lines of Large White pigs divergently selected over 4 years for high and low post-weaning growth rate on a restricted ration. Heritabilities and repeatabilities of the reproduction traits were also determined. The analyses were carried out on 913 litter records using average information-restricted maximum likelihood method applied to single trait animal models. Estimates of heritability for most traits were small, except for ABW (0·33) and MW (0·35). Estimates of repeatability were slightly higher than those of heritability for TNB, NBA and NW, but they were almost identical for ABW, MW, GL and DFI. After 4 years of selection, the high growth line sows had significantly heavier body weight prior to mating and produced significantly more piglets born alive with heavier average birth weight than the low line sows. There were, however, no statistical differences between the selected lines in TNB or NW. The lower food intake of high relative to low line sows during lactation was not significant, indicating that daily food intake differences found between grower pigs in the high and low lines (2·71 v. 2·76 kg/day, s.e.d. 0·024) on ad libitum feeding were not fully expressed in lactating sows. It is concluded that selection for growth rate on the restricted ration resulted in beneficial effects on important measures of reproductive performance of thea sows.

Investigation into the effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group housed sows (2006)

A total of 208 sows and 288 gilts (PIC Line C29) were used to determine the influence of feeding frequency (2 versus 6 times per day) in gestation on performance and welfare measurements. The experiment was conducted on a commercial sow farm in northeast Kansas that typically housed gestating sows and gilts in pens. Treatments consisted of feeding similar amounts of feed to each sow or gilt over 2 (07:00 and 15:30) or 6 meals per day (07:00, 07:30, 08:00, 15:30, 16:00, and 16:30 hours). There were 8 sows or 12 gilts in each pen. Gilts and sows were moved to pens after breeding. In gestating sows, there were no differences (P>0.10) between treatments in ADG, backfat change, or variation in body weight. There was a trend (P<0.08) for sows fed twice a day to farrow more total number born, but number born alive or other measures of reproductive performance were not different (P>0.10) among treatments. Sows fed 6 times a day had increased vocalization during the morning (P<0.07) and afternoon (P<0.01) feeding periods, compared with sows fed twice a day, but sows fed twice a day had more skin (P<0.01) and vulva (P<0.04) lesions, as well as a small, but significant, increase in feet/leg (P<0.01) and hoof (P<0.02) problems. In this commercial facility, the standard management protocol required moving gilts to a different gestation facility. On d 42, two pens of gilts with similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. From d 0 to 42, gilts fed 6 times a day had greater ADG (P<0.07) and d-42 backfat (P<0.09). After movement to the larger groups from d 42 to farrowing, ADG was similar (P > 0.10) for gilts fed 2 or 6 times per day. Gilts fed twice a day had less weight variation at both d 42 (P<0.04) and at farrowing (P<0.10). In gilts, there were no differences (P>0.10) for reproductive performance, skin and vulva lesions, and leg/feet and hoof scores. In conclusion, there were few growth, farrowing, or aggression differences among gilts fed either 2 or 6 times per day. This suggests that either feeding method is suitable for group-housed gilts. Among sows, different feeding frequency resulted in few growth or farrowing-performance differences. Feeding 6 times per day did result in a small, but significant, reduction in skin and vulva lesions and structural-problem scores, while increasing vocalization.