Relationship of body condition score and blood urea and ammonia to pregnancy in Italian Mediterranean buffaloes

The relationship of body condition score (BCS) and blood urea and ammonia to pregnancy outcome was examined in Italian Mediterranean Buffalo cows mated by AI. The study was conducted on 150 buffaloes at 145 +/- 83 days in milk that were fed a diet comprising 14.8% crude protein, 0.9 milk forage units.kg-1 dry matter and a non-structural carbohydrate/crude protein ratio of 2.14. The stage of the oestrous cycle was synchronised by the Ovsynch-TAI programme and blood urea and ammonia levels were assessed on the day of AI. Energy corrected milk (ECM) production and BCS were recorded bi-weekly. The pregnancy risk was 46.7% and was slightly lower in buffaloes with BCS < 6.0 and BCS > 7.5. There were no significant differences in ECM, urea and ammonia between pregnant and non-pregnant buffaloes. However, pregnancy outcome was higher (P = 0.02) in buffaloes with blood urea < 6.83 mmol.L-1. The likelihood of pregnancy for buffaloes with low urea blood level was 2.6 greater than for high urea level and exposure to a high urea level lowered the probability of pregnancy by about 0.25. The findings indicate that buffaloes are similar to cattle and increased blood levels of urea are associated with reduced fertility when animals are mated by AI.     

Effects of progesterone presynchronization and eCG on pregnancy rates to GnRH-based, timed-AI in beef cattle

Three experiments were conducted to determine the effects of low-dose progesterone presynchronization and eCG on pregnancy rates to GnRH-based, timed-AI (TAI) in beef cattle (GnRH on Day 0, PGF_2α on Day 7, with GnRH and TAI on Day 9, 54-56 h after PGF_2α). Experiments 1 and 2 were 2 × 2 factorials with presynchronization (with or without a once-used CIDR; Days −15 to 0 in Experiment 1 and Days −7 to 0, with PGF_2α at insertion, in Experiment 2), and with or without 400 IU eCG on Day 7 in suckled cows. In Experiment 3, suckled cows and nulliparous heifers were either presynchronized with a twice-used CIDR (Days −5 to 0) and PGF_2α at insertion, or no treatment prior to insertion of a new CIDR (Days 0-7). Presynchronization increased (P < 0.05) ovulation rate to GnRH on Day 0 (75.0% vs 48.7%, 76.7% vs 55.0%, and 60.0% vs 36.1% for Experiments 1, 2, and 3, respectively), increased the diameter of the preovulatory follicle in Experiments 1 and 2, and increased the response to PGF_2α (regardless of parity) in Experiment 1 (P < 0.01), and in primiparous cows in Experiment 2 (P < 0.01). Effects of presynchronization on pregnancy rates (53.4% vs 54.1%, 57.7% vs 45.3%, and 54.3% vs 44.4% for Experiments 1, 2, and 3, respectively) were influenced by parity and eCG (P < 0.05). Treatment with eCG had no effect (P > 0.05) on the diameter of the preovulatory follicle (Experiment 1), or the response to PGF_2α (Experiments 1 and 2), but tended (P = 0.08) to improve pregnancy rates, especially in primiparous cows that were not presynchronized (P < 0.01). However, the effects of eCG and presynchronization were not additive.     

Evaluating recipient and embryo factors that affect pregnancy rates of embryo transfer in beef cattle

The objectives of this experiment were to determine the effects of corpus luteum characteristics, progesterone concentration, donor-recipient synchrony, embryo quality, type, and developmental stage on pregnancy rates after embryo transfer. We synchronized 763 potential recipients for estrus using one of two synchronization protocols: two doses of PGF2alpha (25 mg i.m.) given 11 d apart (Location 1); and, a single norgestomet implant for 7 d with one dose of PGF2alpha (25 mg i.m.) 24 h before implant removal (Location 2). At embryo transfer, ovaries were examined by rectal palpation and ultrasonography. Of the 526 recipients presented for embryo transfer, 122 received a fresh embryo and 326 received a frozen embryo. Pregnancy rates were greater (P < 0.05) with fresh embryos (83%) than frozen-thawed embryos (69%). Pregnancy rates were not affected by embryo grade, embryo stage, donor-recipient synchrony, or the palpated integrity of the CL. Corpus luteum diameter and luteal tissue volume increased as days post-estrus for the recipients increased. However, pregnancy rates did not differ among recipients receiving embryos 6.5 to 8.5 days after estrus (P > 0.1). There was a significant, positive simple correlation between CL diameter or luteal tissue volume and plasma progesterone concentration (r = 0.15, P < 0.01 and r = 0.18, P < 0.01, respectively). There were no significant differences in mean CL diameter, luteal volume or plasma progesterone concentration among recipients that did or did not become pregnant after embryo transfer. We conclude that suitability of a potential embryo transfer recipient is determined by observed estrus and a palpable corpus luteum, regardless of size or quality.     

Relationships between administration of GnRH, body condition score and fertility in Holstein dairy cattle

The objective of this study was to determine the effect of GnRH treatment in dairy cows differing in body condition score. A total of 2437 primiparous and multiparous cows was allocated randomly to receive either GnRH (100 mug) or placebo at the post partum exam (25 to 35 d) and at the first breeding. Complete records were available from 1906 cows: Group 1 (n = 535) placebo and placebo; Group 2 (n = 489) GnRH and placebo; Group 3 (n = 438) placebo and GnRH; and Group 4 (n = 444) GnRH and GnRH. The change of body condition score during early lactation was determined on a 1 to 5 scale (1 = emaciated to 5 = obese). Cows with a high body condition score (>/=3.0) at the first breeding had 8.8 fewer days to first service and 6.4 fewer days open but more services per conception (0.16) than cows with low body condition score (<3.0). Conception rate improved when GnRH was administered at the first breeding to cows with a body condition score of <3.0 at the first breeding regardless of parity. The administration of GnRH at the post partum exam decreased the conception rate in first lactation cows but was beneficial for cows in second and greater lactations. Thus the efficacy of GnRH may not be consistent in all parities and body condition groups.     

GnRH treatment at artificial insemination in beef cattle fails to increase plasma progesterone concentrations or pregnancy rates

Treatment with GnRH at the onset of standing estrus increased pregnancy percentages and circulating concentrations of progesterone in repeat breeder dairy cows. The objective of this study was to determine the effect of treatment with GnRH at AI on concentrations of progesterone and conception rates in beef cattle that exhibited estrus. Two hundred ninety-three heifers at four locations were synchronized with the Select Synch plus CIDR protocol (given GnRH and a CIDR was placed into the vagina, and 7 d later, given PGF_2α and CIDR removed; n = 253) or the 14-19 melengestrol acetate (MGA) protocol (MGA fed at 0.5 mg/head/d for 14 d, with PGF_2α 19 d after MGA withdrawal n = 40) and AI was done after detection of estrus. At Location 1, blood samples were collected on Day 2, 4, 6, 10, 15, and 18 after AI (Day 0 = AI). Two hundred and fifty postpartum cows at two locations were synchronized with the Select Synch plus CIDR protocol, and AI was performed after detection of estrus. At AI, cattle were alternately assigned to one of two treatments: (1) treatment with GnRH (100 μg) at AI (n = 127 heifers and n = 108 cows); or (2) non-treated control (n = 120 heifers and n = 119 cows). Concentrations of progesterone tended to be greater in control heifers compared to GnRH-treated heifers on Days 6 (P = 0.08), 10 (P = 0.07), and 15 (P = 0.11). Overall conception rates were 68% and 66% for GnRH treated and control, respectively, and were not different between treatments (P = 0.72). In summary, treatment with GnRH at time of AI had no influence on conception rates in cattle that had exhibited estrus.     

Relationship between body condition of American alligators and water depth in the Everglades, Florida

Feeding opportunities of American alligators (Alligator mississippiensis) in freshwater wetlands in south Florida are closely linked to hydrologic conditions. In the Everglades, seasonally and annually fluctuating surface water levels affect populations of aquatic organisms that alligators consume. Since prey becomes more concentrated when water depth decreases, we hypothesized an inverse relationship between body condition and water depth in the Everglades. On average, condition of adult alligators in the dry season was significantly higher than in the wet season, but this was not the case for juveniles/subadults. The correlation between body condition and measured water depth at capture locations was weak; however, there was a significant negative correlation between the condition and predicted water depth prior to capture for all animals except for spring juveniles/subadults which had a weak positive condition–water depth relationship. Overall, a relatively strong inverse correlation occurred at 10–49 days prior to the capture day, suggesting that current body condition of alligators may depend on feeding opportunities during that period. Fitted regression of body condition on water depth (mean depth of 10 days when condition-water depth correlation was greatest) resulted in a significantly negative slope, except for spring adult females and spring juveniles/subadults for which slopes were not significantly different from zero. Our results imply that water management practices may be critical for alligators in the Everglades since water depth can affect animal condition in a relatively short period of time.     

Urea space and body condition score to predict body composition of meat goats

Yearling Boer × Spanish goat wethers (40) were used to develop and compare body composition prediction equations for mature meat goats based on urea space (US) and body condition score (BCS). Before the experiment, one-half of the animals were managed to have high BW and BCS (1–5, with 1 being extremely thin and 5 very fat) and the others were managed to have low BW and BCS. During the 24-week experiment, initially fat wethers were fed to lose BW and BCS and initially thin wethers were fed to increase BW and BCS. BCS, US, and whole body chemical composition were determined after 0, 12, and 24 weeks. Mean, minimum, and maximum values were 42.1 (S.E. = 1.12), 24.5, and 59.0 kg for shrunk BW; 3.0 (S.E. = 0.11), 1.5, and 4.0 for BCS; 61.3 (S.E. = 1.01), 53.7, and 76.5% for water; 20.2 (S.E. = 1.11), 4.7, and 29.7% for fat; 15.6 (S.E. = 0.19), 13.3, and 18.1% for protein; and 2.9 (S.E. = 0.062), 2.2, and 3.7% for ash, respectively. For water, fat, and ash concentrations and mass, simplest equations explaining greatest variability (with independent variables of US, BCS, and (or) shrunk BW) based on BCS accounted for more variation than ones based on US, although in some cases differences were not large (i.e., water and ash concentrations and mass). Neither US nor BCS explained variability in protein concentration. Equations to predict protein mass based on shrunk BW and US or BCS were nearly identical in R² and the root mean square error. A 1 unit change in BCS corresponded to change in full BW of 8.9 kg (full BW (kg) = 17.902 + (8.9087 × BCS); R² = 0.653), fat concentration of 7.54% (%fat = −5.076 + (7.5361 × BCS); R² = 0.612), and energy concentration of 3.01 MJ/kg (energy (MJ/kg) = 0.971 + (3.0059 × BCS); R² = 0.615). In summary, BCS may be used as or more effectively to predict body composition of meat goats than US. The primary determinant of BCS, within the range of BCS observed in this experiment, was body fat content.     

Recombination locations and rates in beef cattle assessed from parent-offspring pairs

Background

Recombination events tend to occur in hotspots and vary in number among individuals. The presence of recombination influences the accuracy of haplotype phasing and the imputation of missing genotypes. Genes that influence genome-wide recombination rate have been discovered in mammals, yeast, and plants. Our aim was to investigate the influence of recombination on haplotype phasing, locate recombination hotspots, scan the genome for Quantitative Trait Loci (QTL) and identify candidate genes that influence recombination, and quantify the impact of recombination on the accuracy of genotype imputation in beef cattle.

Methods

2775 Angus and 1485 Limousin parent-verified sire/offspring pairs were genotyped with the Illumina BovineSNP50 chip. Haplotype phasing was performed with DAGPHASE and BEAGLE using UMD3.1 assembly SNP (single nucleotide polymorphism) coordinates. Recombination events were detected by comparing the two reconstructed chromosomal haplotypes inherited by each offspring with those of their sires. Expected crossover probabilities were estimated assuming no interference and a binomial distribution for the frequency of crossovers. The BayesB approach for genome-wide association analysis implemented in the GenSel software was used to identify genomic regions harboring QTL with large effects on recombination. BEAGLE was used to impute Angus genotypes from a 7K subset to the 50K chip.

Results

DAGPHASE was superior to BEAGLE in haplotype phasing, which indicates that linkage information from relatives can improve its accuracy. The estimated genetic length of the 29 bovine autosomes was 3097 cM, with a genome-wide recombination distance averaging 1.23 cM/Mb. 427 and 348 windows containing recombination hotspots were detected in Angus and Limousin, respectively, of which 166 were in common. Several significant SNPs and candidate genes, which influence genome-wide recombination were localized in QTL regions detected in the two breeds. High-recombination rates hinder the accuracy of haplotype phasing and genotype imputation.

Conclusions

Small population sizes, inadequate half-sib family sizes, recombination, gene conversion, genotyping errors, and map errors reduce the accuracy of haplotype phasing and genotype imputation. Candidate regions associated with recombination were identified in both breeds. Recombination analysis may improve the accuracy of haplotype phasing and genotype imputation from low- to high-density SNP panels.     

Effect of monensin, energy level, and cow body condition on pregnancy rate in nonlactating beef cows

One hundred eighty-two nonlactating cycling Brahman crossbred and Angus cows were used to study the effects of monensin, cow body condition and supplemental energy level on pregnancy rate. The cows were classified as being in either moderate or poor body condition at the start of the experiment and were fed either 9 or 18 Mcal of supplemental metabolizable energy/head/day with or without 125 mg of monensin in the ration. Feeding commenced 21 days prior to and throughout a 45-day breeding season. In the monensin treated group ruminal propionic acid levels (molar %) were increased (P<.01) while acetic and butyric acid levels were lowered (P<.05) regardless of supplemental energy intake. Pregnancy rate, pregnancy rate at first service, and the percentage of conceptions per estrus were increased (P<.05) when cows were fed 18 Mcal of supplemental energy per head per day. Neither cow body condition nor addition of monensin to the diet had an effect on the preceding reproductive endpoints. Cows in poor body condition and receiving 18 Mcal of supplemental energy per head per day had increased (P<.05) reproductive performance as evidenced by an increase in the pregnancy rate, pregnancy rate at first service, and percentage of conceptions per estrus when compared to the other groups.     

The effects of crossbreeding with Norwegian Red dairy cattle on common postpartum diseases,fertility and body condition score

Norwegian Red bulls, selected in Norway, have been used for crossbreeding with Israeli Holstein on commercial farms. The aim of this project was to investigate Norwegian Red×Israeli Holstein (NRX) performance to see how the daughters perform in a different environment than the one their sires were selected in. This was done by comparing health and fertility of NRX with their Israeli Holstein (HO) counterparts. The data consisted of 71 911 HO records and 10 595 NRX records from 33 855 cows in 23 Israeli dairy herds. Calving events took place between 2006 and 2016. Five postpartum disorders (mean frequency in HO v. NRX, %) recorded by veterinarians were analyzed: anestrus (37.4 v. 41.2), metritis (40.1 v. 28.6), ketosis (11.9 v. 7.1), lameness (7.1 v. 3.1) and retained placenta (6.2 v. 4.0). The incidence of abortions was also analyzed; HO had a mean frequency of 9.9% and NRX 8.2%. These traits were defined as binary traits, with ‘1’ indicating that the disorder was present and a treatment took place at least once, or ‘0’ if the cow did not show signs of that disorder. Days open (i.e. the number of days from calving to conception), body condition score (BCS) recorded on a 1 to 5 scale and changes in BCS from calving to peak lactation were also analyzed. A logistic model was used for the health traits, while days open and BCS were analyzed with linear models. The model included breed group, herd-year of calving, birth year and parity as fixed effects. There was a significantly higher risk (odds ratio for HO v. NRX in parentheses) of ketosis (1.46), metritis (1.78), lameness (2.07), retained placenta (1.41) and abortion (1.13) in HO compared with NRX. Israeli Holstein heifers and cows in parity 3 to 6 had fewer cases of anestrus than NRX but no differences were found between the groups in parities 1 and 2. Body condition score was higher for NRX than HO and there was less change in BCS from calving to peak lactation in NRX compared with HO. Likewise, NRX had fewer days open than HO. Results indicate that crossbreeding can produce cows with better fertility that are less susceptible to postpartum disorders.     

Relationship between plasma progesterone concentrations and pregnancy rates in cattle receiving either fresh or previously frozen embryos

Blood samples were collected for the measurement of progesterone concentrations from 320 Holstein-Friesian heifers on Days 7 and 21 post-estrus. All animals were the recipients of either a fresh or previously frozen embryo on Day 7 and were palpated for pregnancy on Day 60 post-estrus. At the time of transer, progesterone levels were highly variable and were not strongly related to subsequent pregnancy status. There was a tendency for lower pregnancy rates in heifers receiving fresh embryos if progesterone levels were less than 1 ng/ml (33 vs 64% overall), and for previously frozen embryos when progesterone concentrations were less than 3 ng/ml (34 vs 44% overall). Progesterone concentrations were not related to subjective evaluation of corpus luteum quality by palpation per rectum. No heifers which maintained pregnancy had progesterone levels less than 1 ng/ml on Day 21. Only 41% of 247 heifers receiving either fresh or previously frozen embryos that were not pregnant on Day 60 had progesterone concentrations less than 1 ng/ml on Day 21. These data suggest that many recipients that do not maintain a pregnancy will experience an extended estrous cycle after transfer.     

Relationship of pregnancy rate to peripheral concentrations of progesterone and estradiol in beef cows

The relationship between pregnancy rate and concentrations of progesterone (P(4)) and estradiol-17beta (E(2)) in serum was examined in inseminated beef cows. Jugular blood was collected twice daily on Days 4 through 7 and Days 14 through 17 after estrus to establish patterns of secretion of P(4) and E(2). Pregnancy rate was determined by palpation per rectum at 45 d. Mean concentrations of each hormone, ratio of E(2):P(4) and regressions of hormone on day were the variables measured for each of the 2 periods. Cows were classified into low (n=26), medium (n=50) and high (n=26) groups for each variable. The relationship of pregnancy rate to each variable was tested using Chi-square analyses. Pregnancy rates to the first service decreased linearly as relative mean concentrations of E(2) increased on Days 14 through 17 (P<0.05) but were not affected by any of the other hormonal variables studied during either period. Pregnancy rates to the second service were not related to concentrations of P(4) or E(2) during the luteal phase before mating (Days 14 through 17). The effects of pregnancy on concentrations of E(2) and P(4) also were tested. On Days 14 through 17, P(4) increased slightly in pregnant cows and declined slightly in nonpregnant cows (P<0.05), but pregnancy did not affect E(2) during either period or P(4) on Days 4 through 7. In summary, pregnancy rate to the first service decreased significantly as concentrations of E(2) increased on Days 14 through 17.     

Short communication: Differences in genetic merit for visually-assessed body condition score materialises as phenotypic differences in tactile-based body condition score in commercial dairy cows

Body condition score (BCS) is a known risk factor for cow health and well-being. Many different BCS scales and systems for assessment exist;while the scales used for assessing BCS vary, differences in how BCS is assessed (i.e., visual versus visual plus tactile) and the extent of training and experience of the assessor (i.e., professional linear classifiers versus producers) also contributes to the underlying variability. Registered dairy cows globally are routinely assessed for linear type traits which describe biological extremes in the morphological attributes; BCS and a correlated trait angularity are within this suite of traits assessed. These linear-type data are used to generate estimates of genetic merit (predicted transmitting ability), but how these estimates manifest themselves as phenotypic differences when assessed by producers on commercial multiparous cows has never been quantified. To evaluate this, 58 440 phenotypic BCS records from 48 823 lactations in 38 608 cows were used. Associations were undertaken using linear mixed models relating phenotypic BCS to genetic merit after accounting for nuisance factors. Differences in genetic merit for either BCS or angularity (assessed visually by professionals on a 1 to 9 scale just once during lactation in primiparous registered cows) translated to phenotypic difference in BCS (assessed by producers using both tactile and visual assessment on a 1 to 5 scale across lactation in commercial dairy cows). The partial correlation between test phenotypic BCS and genetic merit for either BCS or angularity was 0.13 and  0.10, respectively. Based on the model coefficients estimated in the present study, the mean expected difference in phenotypic BCS on a 1 to 5 scale between the top and bottom 10% on genetic merit for BCS or angularity was 0.28 and 0.31 units, respectively. Results from the present study clearly provide confidence that genetic merit for BCS or angularity based on a single visual assessment in primiparous cows is useful to breed for cows of better body condition, irrespective of stage of lactation or parity.     

Transferable embryo recovery rates following different insemination schedules in superovulated beef cattle

The objective of this study was to evaluate the transferable embryo recovery rates from superovulated donor cattle after different artificial insemination (AI) schedules. Sixty mixed-breed crossbred females were administered follicle stimulating hormone (FSH) and prostaglandin F(2)alpha (PGF(2)alpha) to induce a superovulatory response. At standing estrus, donor females were randomly allotted to one of five treatment groups for AI. Donors were inseminated with two units of high-quality or low-quality frozen semen at 12, 24, 36, or 48 h after the onset of estrus in treatment Groups I, II, III, and IV, respectively, or inseminated with two units at 12, 24, 36, and 48 h (eight units/donor) in control Group V. Donor females inseminated once at either 12 or 24 h after the onset of estrus did not differ from donors inseminated in Group V in overall fertilization and transferable embryo recovery rates. The highest fertilization rate (89.5%) and transferable embryo recovery rate (74.9%) per donor resulted when AI was performed with high-quality semen at 24 h after the onset of estrus. These findings indicate that repeated insemination of superovulated beef cattle is not necessary to attain optimal fertilization rates and production of transferable quality embryos in beef cattle.     

Effect of a single growth hormone (rbST) treatment at breeding on conception rates and pregnancy retention in dairy and beef cattle

Initiation of long-term treatment with rbST (Posilac, Monsanto, St. Louis, MO) coincident with first insemination increased pregnancy rates in dairy cattle, but neither the efficacy of using only the initial injection, nor its effects on retention of pregnancy are known. Lactating dairy cows, dairy heifers, and lactating beef cows were assigned at random to treatment (rbST) or control. Dairy cows, dairy heifers, and beef cows received 500 mg rbST (n = 48, 35, 137 inseminations, respectively) at artificial insemination or were left untreated (n = 62, 33, 130 inseminations, respectively). Pregnancy was diagnosed by ultrasonography at 28-36 days. Treatment with rbST at insemination improved conception rates in dairy cows (60.4% versus 40.3%; P < 0.05), but not in dairy heifers or beef cows. Conception rates did not differ in dairy cows at < or =100 days in milk (DIM), but were improved in cows treated with rbST after 100 DIM (64.3% versus 25.8%; P < 0.05). Retention of pregnancy to approximately 60 days and sizes of CL, diameter of follicles > or =5 mm, and crown-rump lengths of embryos were not affected by treatment. The second objective was to examine the effects of rbST at insemination on birth weight and post-natal calf growth in beef cows. However, birth and weaning weights of beef calves were not affected by treatment. In conclusion, a single treatment with rbST at insemination increased conception rates in dairy cows, specifically in those >100 DIM.     

Selection on innate immunity and body condition in Florida scrub-jays throughout an epidemic

Opportunities to investigate selection in free-living species during a naturally occurring epidemic are rare; however, we assessed innate immunocompetence in Florida scrub-jays before the population suffered the greatest over-winter mortality in 20 years of study. Propitiously, three months prior to the epidemic, we had sampled a number of male breeders to evaluate a suite of physiological measures that are commonly used to estimate the overall health-state of an individual. There was a significant, positive selection gradient for both Escherichia coli bacterial killing capability and body condition, suggesting that directional selection had occurred upon each of these traits during the disease epidemic.