Non-treated Cows Research Articles

Lactation performance, feed efficiency, and blood metabolites of dairy cows treated with recombinant bovine somatotropin: A systematic review and meta-analysis

A systematic review and meta-analysis were conducted to assess the impact of recombinant bovine somatotropin (rbST) on lactation performance, feed efficiency, and blood metabolites in dairy cows. In the systematic review, articles were selected based on the following criteria: (1) Data focusing on the influence of bovine somatotropin doses on milk production; (2) Submission of original data; (3) Articles published in journals; and (4) Articles in English or Portuguese. The analysis of variance was used with a completely randomized design and mixed models methodology. Polynomial regression was applied to significant fixed effects (rbST dose). The use of rbST resulted in increased milk yield and 4% fat-corrected milk yield, while fat, protein, and lactose contents remained unaffected. Dry matter and metabolizable energy intakes, as well as milk/feed efficiency, exhibited a linear increase, but body condition score (BCS) was negatively impacted. The administration of rbST led to higher blood concentrations of triglycerides and insulin. Cows treated with rbST showed a 23% increase in non-esterified fatty acid (NEFA) concentrations compared to non-treated cows. Additionally, growth factors IGF-1 and IGF-2 displayed a linear increase with rbST treatment. In summary, rbST administration increased milk yield and fat-corrected milk yield without affecting milk components. However, despite increasing intake, it resulted in BCS losses and alterations in blood parameters such as NEFA, IGF-1, and IGF-2.

Effects of the Immunocontraceptive Gonacon on Pregnancy in Brucella-Seropositive American bison (Bison bison).

The purpose of this study was to determine if the number of pregnancies in naturally infected Brucella abortus-positive bison (Bison bison) cows would be reduced over a period of 5 yr after one treatment with 3000 µg gonadotropin-releasing hormone immunocontraceptive (GonaCon) compared to a similar group of naturally infected B. abortus-positive bison cows not treated with GonaCon. In each of the 5 yr, GonaCon-treated cows produced fewer offspring in relation to number of cows than the nontreated cows. Fisher's Exact test comparing offspring produced during the first reproductive season showed a significant difference between the two groups (P=0.0028). Differences in number of calves produced in GonaCon-treated and control groups were also noted in remaining years, but statistics were not applied because of data constraints. These data indicate that one treatment with GonaCon in brucellosis-seropositive female bison reduced pregnancies over five reproductive years. Thus, immunocontraception could potentially be used to manage brucellosis in affected herds.

Eficácia da terapia antimicrobiana associada à vacinação na cura bacteriológica de mastite subclínica causada por Staphylococcus aureus em vacas em lactação

ABSTRACT: The objective of this study was to evaluate the efficacy of the antibiotic therapy associated with vaccination on the microbiological cure rate of subclinical mastitis caused by Staphylococcus aureus in lactating dairy cows. A total of five herds, from which 72 cows (120 mammary quarters - MQ) were diagnosed with S. aureus subclinical mastitis, were included in this study. Cows were randomly allocated to one of three treatment groups: a) Control (no treatment); b) ATB (antibiotic therapy); and c) ATB+VAC (antibiotic therapy plus vaccination against S. aureus). Intramammary treatment consisted of twice-daily infusion of ampicillin 75mg + cloxacillin 200mg, for 5 days. Parenteral treatment was done by injection of a single dose (7.5mg/kg) of enrofloxacin, on the first day of the treatment protocol. Vaccinated cows received three doses of a commercial vaccine 14 days before treatment (d-14), on the first day of treatment protocol (d1), and 14 days after the treatment protocol (d+14). Non-treated cows had a lower cure rate (0.06) than cows treated with ATB (0.84) and ATB+VAC (0.85). No difference in cure rate was observed between cows treated with ATB and ATB+VAC. On the other hand, vaccinated cows had lower somatic cell count (SCC) after 28 days of the treatment protocols (4.76 log10) than non-treated cows (5.37 log10). In conclusion, treatment with intramammary ampicillin and cloxacillin, associated with intramuscular enrofloxacin presented a high cure rate for SCM caused by S. aureus during lactation. The use of vaccination against S. aureus in association with antibiotic therapy did not increase the cure rate of MQ during lactation, but it was effective in reducing the SCC when compared to non-treated MQ. Although to ensure that the decrease of the SCC in ATB+VAC group was associated with the vaccination, the study should have included an additional group of only vaccinated cows, without antimicrobial therapy, with was not done in the present study, and therefore is one of the limitations of the experimental protocol used.

Application of P4 rapid test and exogenous source of progesterone in prevention of early embryonic death in dairy cows

Abstract. The objectives of this study were: 1) to determine the percent of cows with low P4 at Day 7-8 post-AI; 2) to treat the animal with low progesterone for 14 days with a P4-releasing intravaginal device (PRID DELTA); 3) to analyze the influence of P4 exogenous supplementation on pregnancy rate in treated and non-treated cows and 4) to create a protocol using “P4 Rapid” test allowing increased pregnancy rate under farm conditions. For this purpose, the current study has been conducted on 155 repeat breeding Holstein cows (<3 artificially inseminated – AI) with prolonged estrus cycle (<26 days). At day 7 and 8 post-AI, the milk progesterone levels were measured (P4 Rapid test). The cows with low P4 (n=104 or 67%) were divided into two groups each n=52. In Group I the progesterone devices were inserted for two weeks and control Group II without progesterone devices. At days 40 and 50 post artificial insemination (AI) all animals (n=104) were submitted to ultrasound pregnancy detection. Pregnancy was registered in 27 animals (51.9%) for Group 1, and in 16 cows (30.7%) for Group II. P4 Rapid is a quick, easy and practically applicable test to measure milk progesterone levels in dairy farms. The method is highly accurate and detects animals with low or high P4 at Day 7-8 after insemination. It also allows identification of conditions such as ovarian cysts, ovarian hypofunction and distinguishing of cycling and non-cycling cows. The combination of P4 measurement by P4 Rapid test and treatment with exogenous P4 to increase circulating concentrations in the first few days after conception can prevent embryo death and improve reproductive efficiency in dairy cattle.

Influence of Season of Calving, Parity and Flunixin Meglumine Administration on Conception Rate in Repeat Breeder Egyptian Baladi Cows and their Crosses

This work was conducted to evaluate the effect of season of calving, parity and treatment with Flunixin Meglumine (NSAID) on conception rate in repeat breeder Egyptian Baladi cows and their crosses (Baladi x Friesian). Season of calving was divided into two season cold season (from November to April) and hot season (May to October). A total of 120 cows (n= 60 Baladi cows, n= 60 crossbred cows) were used in the study. 30 Baladi cows were taken and another crossbred was calved during the cold season and was divided into four groups of each group consisting of 15 cows. A total of 30 Baladi cows were also taken and another crossbred was calved during the hot season. It was divided into four groups, each consisting of 15 cows. Fifteen Baladi cows and another crossbred Flunixin Meglumine were treated (1.1 mg / kg BW intramuscular) at fourteenth day from mating in both cold and hot seasons and the other group was as control. The main results showed that the overall average conception rate in Baladi cows was 43.3% higher than that of crossbred cows (30%). Conception rate was higher in Baladi cows calved during the cold season (46.7%) than in cows calved during the hot season (40%). Conception rate of crossbred cows calved during the season was 33.3% higher than those born during the hot season (26.7%). Conception rate in cows in the fourth parity was higher in both Baladi and crossbred cows (83.3 and 50%) respectively compared to the second and third parity. Administration with Flunixin Meglumine resulted in an increase in conception rate of 13.3% in both Baladi and crossbred cows. Concentration of P4 was higher during the first three weeks of conception in the treated Flunixin Meglumine cows than in non-treated cows in both Baladi and crossbred cows. The current study showed the negative effect of the hot season on the rate of conception in cows raised under the conditions of the hot zones, as well as the positive effect of treatment with Flunixin Meglumine on the conception rate in cows. Conception rate was higher during the 4th parity in Baladi and their crosses. The current study recommends the synchronization of estrous in cows to arrange the births to be during the cold season to avoid the problems of the hot season, especially in southern Egypt, as well as treated with Flunixin Meglumine on the fourteenth day of mating in cows. Future studies on the treatment of Flunixin Meglumine in cows.

Placental Iodothyronine Deiodinases Expression in Pregnant Cows Exposed to Propylthiouracil (Ptu) and Thyroid Axis Activity of their Calves

Abstract The aim of our study was to investigate if the thyroid axis of newborn calves is affected by prenatal application of propylthyouracil (PTU). The study included 20 late pregnant Holstein cows. One group (n=10) was treated with PTU (4 mg/kg of BW daily) from day 20 before expected calving until the day of calving. The other group (n=10) was non-treated. Placental samples of dams were obtained for measuring mRNA expression of iodothyronine deiodinases type I (D1), type II (D2) and type III (D3). After parturition calves were separated from the dams and included in the study. Blood samples were taken daily from each calf starting on the day of birth until day 7 of age. Blood T3, T4 and TSH concentrations were measured. PCR analysis of the placental tissue revealed an abundance of all three types of placental deiodinases in non-treated cows, and a significant elevation of mRNA levels for all three types of deiodinases after PTU treatment. Calves that originated from dams treated with PTU had significantly lower T3 and T4 and significantly higher TSH concentrations compared to non-treated calves during the first 2 days of life. Starting from day 4 until day 6 of life the opposite effect was observed meaning that calves prenatally exposed to PTU had significantly higher T3 and T4 and slightly lower TSH. Our study, for the first time, provides information related to iodothyronine deiodinases mRNA expression in bovine placenta, and confirm that PTU treatment of pregnant dams provokes depression of thyroid function in newborns during the first days of life.

Post-calving administration of uterine stimulants does not improve reproductive performance in dairy cows

The aim of this study was to evaluate the effects of administration of oxytocin, in combination with dinoprost or ergometrin, after parturition on the occurrence of clinical endometritis and subsequent reproductive performance in dairy cows. The cows, without retained foetal membranes, were assigned to one of three groups. No treatment was performed in the control group (Group C, n = 229). However, intramuscular administrations of oxytocin (30 IU) on Days 1 and 2 post partum, in combination with dinoprost (25 mg, Group D, = 123) or ergometrin (15 mg, Group E, n = 130) administered on Day 7 post partum, were performed in experimental groups. Vaginal discharge score (VDS, 1-5), uterine content score (UCS, 1-3) on Day14 to 21 post partum, number of treatment interventions (TI), proportion of non-treated cows (NT) because of endometritis, calving to first insemi - nation interval (CI), first insemination conception rate (CR), and proportion of pregnant cows by Day 150 post partum (PC), were compared among groups. There was no significant difference among groups for any parameter. Average values were 2.08, 2.24 and 2.06 (VDS); 1.49, 1.51 and 1.45 (UCS); 0.86, 0.93 and 0.74 (TI); 59.4, 54.2 and 54.7% (NT); 73.9 ± 15.2, 75.4 ± 17 and 74.2 ± 17 days (CI); 41.4, 38.9 and 44.3% (CR); and 75.4, 77.7 and 80.5% (PC) for Groups C, D and E, respectively. There was no significant benefit of preventive administration of oxy - tocin, in combination with dinoprost or ergometrin, after parturition on reproductive performance in dairy cows.

Oestrus synchronisation in postpartum dairy cows using repetitive prostaglandin doses: Comparison between D-cloprostenol and dinoprost.

This trial evaluated the reproductive performance in an early routine oestrus induction programme using two different PGF2α preparations in dairy cattle. D-cloprostenol sodium (n = 192; Group A) or dinoprost (n = 187; Group B) was administered between days 35 and 42 post partum. Also, a group of non-treated cows (n = 135; Group C) was included as control. Pedometers were used to detect oestrus, and also secondary oestrous signs and vaginal mucus quality were assessed prior to artificial insemination (AI). When oestrus was not detected for 14 days after PGF2α administration, the treatment was repeated, up to a maximum of three times. There were no differences between the study groups in oestrus detection (A = 73.48%, B = 73.01%, C = 79.26%; P = 0.428), good mucus quality (A = 96.45%, B = 91.30%, C = 93.45%; P = 0.203) and the presence of mounting lesions (A = 98.58, B = 94.93%, C = 98.13; P = 0.414). First-service pregnancy rates were 19.78%, 15.64% and 32.03% in Groups A, B and C, respectively (P = 0.003). There were no inter-group differences for the interval from parturition to first AI. However, a significantly shorter interval from parturition to conception (92.17 days, 99.45 days, 118.93 days; P = 0.002) and significantly less services per conception (2.12, 2.18, 2.66; P = 0.003) were observed in Groups A and B in comparison with Group C. The use of PGF2α resulted in better fertility in a repetitive, routine postpartum programme, although no differences between Dcloprostenol and dinoprost were detected.

Effect of repeated eCG treatments and ovum pick-up on ovarian response and oocyte recovery during early pregnancy in suckling beef cows

This study was designed to evaluate in suckling early pregnant beef cows with and without eCG-pre-stimulation: (i) the influence of day gestation (from 40 to 101 days) and the consecutive eCG treatments on the follicular growth induced by means of ultrasound-guided transvaginal follicle ablation (FA; all follicles≥5mm) and the number and quality oocytes recovered by ovum pick-up (OPU) and (ii) the possible effects of repeated hormonal stimulation and FA/OPU on pregnancy outcome. Twelve suckling early pregnant Angus cows (40 days post fixed-time artificial insemination) were randomly assigned to each of two groups (n=6group−1). Group 1 treatments included: FA (Day 0), eCG (1600IU; Day 1) and OPU (Day 5). Group 2: as cited Group 1 with no eCG treatment. In both groups, OPU was repeated five times (Days 45, 59, 73, 87 and 101 of gestation). The numbers (mean±SEM) of class II (5–9mm; 4.3±0.9) and class III (≥10mm; 2.5±0.4) follicles visualized per cow per OPU session in eCG-treated cows were greater (P<0.05) than for non-treated cows (0.9±0.1 and 0.9±0.1, respectively). In contrast, the number (mean±SEM) of class I (<5mm) follicles per cow per OPU session was lower for cows with eCG treatment (2.8±0.4) than for non-treated cows (5.7±0.5). The mean number of aspirated follicles was not significantly different (P<0.05) between eCG-treated cows and non-treated cows at 45 and 59 days of pregnancy. However, the mean number of aspirated follicles was greater (P=0.03) in eCG-treated cows than non-treated cows from 73 day of pregnancy onwards. The numbers (mean±SEM) of recovered oocytes and viable oocytes/cow/session were greater (P<0.05) for eCG-treated cows (2.2±0.2 and 1.6±0.4, respectively) than for non-treated cows (1.0±0.2 and 0.9±0.2, respectively). No donor pregnancies were lost either during or following OPU procedure. We can conclude that (1) eCG-treated pregnant suckled cows can be a source of oocytes for IVF at least to 100 days of gestation and (2) repeated FA/eCG treatment/OPU procedures did not affect the pregnancy outcome.

Florfenicol concentrations in milk of lactating cows postreated by intramuscular or intramammary routes

Objetivo. Determinar la concentración de florfenicol en leche bovina después del tratamiento intramuscular o intramamario, para establecer el tiempo de retiro, la eficacia terapéutica, y su influencia sobre la producción láctea. Materiales y métodos. Se seleccionaron doce vacas Holstein en lactancia de la hacienda de Universidad de Antioquia (Colombia). Se asignaron al azar al grupo control (n=6) o al grupo florfenicol (n=6), al cual se le administró 20 mg/kg de florfenicol por vía intramamaria e intramuscular con 15 días de diferencia entre tratamientos. Resultados. La Tmax y Cmax para la vía intramuscular fueron 6 horas y 2.86 mg/L respectivamente. La Tmax y Cmax para la vía intramamaria, fueron estimados como 0 hora y aproximadamente 20000 mg/L respectivamente por extrapolación de la línea de regresión. La fase de eliminación del florfenicol en leche, tuvo una vida media de eliminación (t½) promedio de 19.8 horas y 4.9 horas para la vía intramuscular e intramamaria respectivamente. Cuando la concentración inhibitoria minima (C.I.M) del florfenicol para Stahphylococcus aureus, fue usada como el valor de referencia, la eficacia terapéutica sólo se alcanzó por la vía intramamaria. No existió diferencia estadística significativa entre las producciones lácteas de las vacas tratadas y no tratadas. Conclusiones. De acuerdo con estos resultados, el tiempo de retiro postratamiento no debe ser menor de 3 días para la administración intramamaria y al menos 7 días para la administración intramuscular. La eficacia terapéutica sólo se alcanzó por la vía intramamaria. Además no existió diferencia estadística significativa en la producción láctea de las vacas tratadas con respecto a las no tratadas.

Efficacy of enrofloxacin in the treatment of naturally occurring acute clinical Escherichia coli mastitis

The efficacy of the combination of systemic enrofloxacin (5mg/kg twice with a 24-h interval, first dose i.v., second dose s.c.) and the nonsteroidal antiinflammatory agent ketoprofen (3mg/kg i.m. or 4mg/kg per os daily for 1 to 3 d) treatment was compared with antiinflammatory treatment only in dairy cows with naturally occurring acute clinical Escherichia coli mastitis. A total of 132 cows with acute clinical mastitis and with confirmed growth of E. coli in a pretreatment milk sample were randomly allocated to 1 of 2 treatment groups. Response to treatment was evaluated clinically and by bacteriological culturing and determination of N-acetyl-β-d-glucosaminidase (NAGase) activity on d 2 and 21 posttreatment. Enrofloxacin treatment did not increase bacteriological (90.5% of treated vs. 86.8% of nontreated cured) or clinical cure (46.7% of treated vs. 57.1% of nontreated cured), cow survival (95.3% of treated vs. 92.7% of nontreated), or quarter milk production assessed 21 d posttreatment (21.8 vs. 29.3% return to preinfection level for nontreated cows), nor did it decrease mammary gland tissue damage estimated using determination of milk NAGase activity (24.0±0.3 vs. 18.3±1.3 pmol of 4-methylumbelliferone per min per μL for nontreated cows). Treatment did not influence the number of study cows remaining in the herd after 6 mo (71.9% of treated vs. 80.6% of nontreated). The only significant effects of enrofloxacin were enhancing the bacteriological cure (odds ratio=3.32 for treated cows) and decreasing the clinical cure (odds ratio=0.05 for treated cows) on d 2 posttreatment. Our results did not support the use of enrofloxacin to treat acute clinical E. coli mastitis.

17 EFFECT OF A PROGESTERONE INTRAVAGINAL DEVICE ON PREGNANCY RATE IN CROSSBREED DAIRY COWS UNDER TROPICAL CONDITIONS

The objectives of these experiments were to evaluate the effect of intravaginal progesterone device on crossbreed Holstein × Carora on pregnancy rate under 2 conditions: cycling and noncycling cows. The first experiment was conducted on 135 noncycling cows (45 ± 3 days postpartum) divided in 2 groups. The first group was treated with a timed AI procedure using a progesterone device for 9 days with an eCG injection on Day 6 and estradiol benzoate after progesterone device removal followed by AI 48 h later. The second group was not treated and they were checked until they came in heat and were inseminated. The second experiment was performed on 123 cycling cows and they were divided in 2 groups. The first group was submitted to a time AI treatment similar to that in experiment 1, and the second group was not treated and they were inseminated upon heat detection. Pregnancy rate on Day 120 postpartum was recorded and pregnancy rate was compared among the different proportion of Holstein (H) × Carora (C) crossbreed cows. For the first experiment, differences (P &lt; 0.05) were observed between ¾ Carora ¼ Holstein (46.15%) compared with the other crossbreed groups (10% 7/8 H 1/8 C, 21.42% 5/8 H 3/8 C, 29.16% ½ H ½ C). In the second experiment, differences (P &lt; 0.05) were observed between ¾ Carora ¼ Holstein (57.14%) compared with the other crossbreed groups (6.66% 7/8 H 1/8 C, 30.76% 5/8 H 3/8 C, 33.33% ½ H ½ C). For the variable pregnancy rate at 120 days postpartum, significant differences (P &lt; 0.05) were observed in cycling cows (39.2%) treated with the progesterone device v. nontreated cows (21%). In noncycling cows, there were no differences between treated and nontreated cows. In conclusion, the use of progesterone device did not improve pregnancy rate in the noncycling cows, which could be related to the negative energy balance that cows undergo during the first part of gestation. However, the use of the progesterone device in cycling cows did improve the pregnancy rate compared with nontreated, cycling cows. We demonstrated that this dairy farm has a serious problem in detecting estrous, which was help by use of the progesterone device and timed AI. Also, the Carora blood included in dairy animals help them to perform better under tropical conditions and they can became pregnant much faster than animals with a high level of Holstein blood.

438 REPEATED ULTRASOUND-GUIDED FOLLICULAR ASPIRATION IN PREGNANT SUCKLED BEEF COWS PRETREATED WITH OR WITHOUT eCG

In vivo oocyte recovery during the first trimester of pregnancy may be an alternative method of obtaining gametes for IVM/IVF/IVC from genetically valuable females. This study was conducted to evaluate i) the influence of the day of gestation on the follicular growth and number and quality of oocytes recovered by ovum pick-up (OPU) in pregnant suckled beef cows with or without eCG pre-stimulation, and ii) the possible effects on pregnancy outcome. Twelve pregnant suckled Angus cows (40 days after FTAI) were randomly assigned to 2 groups (n = 6/group). Group 1 treatment included: Day 0 = dominant follicle ablation (DFA) to synchronize the emergence of a new follicular wave, Day 1 = eCG treatment (2,000 IU, i.m. Syntex, Argentina) and Day 5 = OPU (follicles &gt;3 mm were aspirated). Group 2: as for Group 1 with no eCG treatment. In both groups, OPU was repeated 5 times (Days 45, 59, 73, 87, and 101 of gestation) and ovarian follicles were classified into 3classes according to diameter (class I, &lt;5 mm; class II, 5-9 mm; and class III, ≥10 mm). The collected COCs were categorized in 4 categories (I to IV) on the basis of both cumulus cells and appearance of oocyte cytoplasm. Categories I + II were considered as viable. Data were analyzed by PROC MIXED (SAS Institute, Cary, NC, USA). There was a significant treatment by follicular class interaction (P &lt; 0.001). The numbers (mean ± SEM) of class II (4.3 ± 0.9) and III (2.5 ± 0.4) follicles/cow/session observed in eCG-treated cows were greater than for nontreated cows (0.9 ± 0.1 and 0.9 ± 0.1, respectively). In contrast, the number (mean ± SEM) of class I follicles/cow/session was lower for cows with eCG treatment (2.8 ± 0.4) than for nontreated cows (5.7 ± 0.5). A significant treatment by day of gestation interaction for aspirated follicles was observed (P = 0.03). The numbers (mean ± SEM) of recovered oocytes and viable oocytes/cow/session were greater (P &lt; 0.05) for eCG-treated cows (2.2 ± 0.2 and 1.6 ± 0.4 respectively) than for nontreated cows (1.0 ± 0.2 and 0.9 ± 0.2, respectively). No donor pregnancies were lost either during or following OPU procedure. The overall efficiency of OPU procedure is shown in Table 1. We can conclude that (1) eCG-treated pregnant suckled cows can be a source of oocytes for IVF to at least 100 days of gestation and (2) repeated DFA/eCG treatment/OPU procedures did not affect the pregnancy outcome. Table 1.Overall efficiency of repeated DFA/eCG treatment/OPU procedures in pregnant suckled cows

Transvaginal follicular aspiration and embryo development in superstimulated early postpartum beef cows and subsequent fertility after artificial insemination

This study was conducted to investigate in early postpartum suckled beef cows with and without FSH pre-stimulation: (i) the influence of the postpartum period on the number and quality of oocytes recovered by ovum pick-up (OPU), (ii) the overall efficiency of the OPU/IVP embryos from days 30 to 80 postpartum and (iii) if repeated OPU negatively affect fertility following a fixed-time artificial insemination protocol. After parturition suckled Angus cows ( n = 30) were divided in three groups ( n = 10 group −1). All cows were anestrous at the commencement of experimental treatments (30.0 ± 3.2 days postpartum, mean ± SD; range 25–34 days). Group 1 treatments included: dominant follicle ablation (DFA), FSH treatment and OPU procedure 5 days after DFA. A total of 9 mg FSH (Ovagen™) was administered s.c. once a day over 2 days at equal doses (4.5 + 4.5 mg). For fertility test the cows received an intravaginal progesterone treatment from Days 78 to 86 postpartum and were fixed-time artificially inseminated (FTAI) at 56 and 72 h after device removal. Group 2: as cited for Group 1 with no FSH treatment. In both groups, OPU was repeated four times (Days 35, 49, 63 and 77 postpartum) and the collected oocytes classified as viable were in vitro matured, fertilized and presumptive embryos cultured for 8 days. Group 3 (Control FTAI): cows that had not previously aspirations were FTAI as Groups 1 and 2. Pregnancy was diagnosed by means ultrasonography 39 days after FTAI. The numbers (mean ± SEM) of follicles visible and aspirated at the time of OPU in FSH-treated cows were greater ( P < 0.05) than in non-treated cows (10.6 ± 0.6 and 8.4 ± 0.4 vs. 8.0 ± 0.5 and 4.6 ± 0.3, respectively). Following FSH treatment, the number (mean ± SEM) of recovered oocytes per cow per OPU session and percentage of viable oocytes were greater in the treated ( P < 0.05) than in non-treated animals (3.0 ± 0.1 and 39.5% vs. 1.5 ± 0.1 and 30.0%). The cleavage and embryo development rates were similar ( P > 0.05) for both groups (14.8 and 6.4% vs. 16.6 and 5.5%). After FTAI the pregnancy rates were not different ( P > 0.05) among groups (70, 60 and 90% for Groups 1, 2 and 3, respectively). We can conclude that (1) FSH-treated suckled postpartum cows can be a source of oocytes for in vitro fertilization and (2) repeated DFA/OPU applied during postpartum period did not affect the subsequent fertility following FTAI.

Production response of multiparous Holstein cows treated with bovine somatotropin and fed diets enriched with n-3 or n-6 fatty acids

Multiparous cows (n=59) were blocked by expected calving date and previous milk yield and assigned randomly to treatments to determine the effects of bovine somatotropin (bST; Posilac, Monsanto Animal Agricultural Group, St. Louis, MO) and source of dietary fat on production responses. Diets were provided from calving and included whole, high-oil sunflower seeds [SS; 10% of dietary dry matter (DM); n-6:n-3 ratio of 4.6] as a source of linoleic acid (18:2) or a mixture of Alifet-High Energy and Alifet-Repro (AF; Alifet USA, Cincinnati, OH; 3.5 and 1.5% of dietary DM, respectively; n-6/n-3 ratio of 2.6) as a source of protected n-3 fatty acids. Diets contained 181 versus 188g of crude protein and 183 versus 186g of acid detergent fiber/kg of DM and 1.54 versus 1.66 Mcal of net energy for lactation at the actual DM intake for SS versus AF, respectively. Cows received 0 or 500mg of bST every 10 d from 12 to 70 d in milk (DIM) and at 14-d intervals through 280 DIM. The 2×2 factorial combination of diet (SS or AF) with or without bST administration resulted in treatments designated as SSY, SSN, AFY, and AFN, respectively. Data were analyzed as repeated measures using mixed model procedures to determine the effects of diet, bST, and their interactions. Yield of 3.5% fat-corrected milk was not altered by diet, but was increased by 4.0±1.9 kg/d from 12 to 70 DIM and by 5.1±1.2 kg/d from 12 to 280 DIM by bST. Treatment did not affect DM intake or energy balance (EB) nadir. There was an interaction of bST and diet on EB because AF decreased the impact of bST on overall EB and allowed AFY cows to reach a positive EB earlier than SSY cows. Gross feed efficiency adjusted for body weight change was greater for bST-treated cows (1.03 vs. 1.15±0.03kg of fat-corrected milk/Mcal of net energy for lactation). Circulating insulin-like growth factor-I concentrations were increased by bST (85 vs. 125±8 ng/mL). Body weight, body condition score, and backfat thickness were reduced by bST, but differences between treated and nontreated cows did not differ by 280 DIM. Results indicate cows responded to bST administration in early lactation, but the magnitude of the response was greater after 70 DIM. Source of dietary fat had a minimal effect on most production measurements, but relative to SS, AF decreased the impact of bST on overall EB. Results support the premise that bST administration prolongs the delay in postpartum tissue replenishment.

Effects of standing estrus and supplemental estradiol on changes in uterine pH during a fixed-time artificial insemination protocol1

Cows that exhibit estrus within 24 h of fixed-time AI have elevated concentrations of estradiol and greater pregnancy rates compared with cows not in estrus. Our objective was to determine whether estradiol, estrus, or both had an effect on uterine pH during a fixed-time AI protocol. Beef cows were treated with the CO-Synch protocol (100 mircog of GnRH on d -9; 25 mg of PGF(2alpha) on d -2; and 100 mircog of GnRH on d 0). One-half of the cows received an injection of estradiol cypionate (ECP; 1 mg) 12 h after PGF(2alpha). Cows detected in standing estrus within 24 h of the second GnRH injection were considered to be in standing estrus. Uterine pH was determined in all animals 12, 24, and 48 h after the PGF(2alpha) injection. For Exp. 1, pH was also determined 72 and 96 h after the PGF(2alpha) injection; in Exp. 2, pH was also determined at 54, 60, 66, 72, 78, 84, 90, and 96 h after the PGF(2alpha) injection or until ovulation. A treatment x time interaction (P < 0.01) influenced concentrations of estradiol. All cows had similar (P > 0.15) concentrations of estradiol at the time of ECP administration, but after ECP treatment all cows treated with ECP and control cows that exhibited estrus had greater (P < 0.01) concentrations of estradiol compared with nontreated cows that did not exhibit estrus. In all animals, estradiol diminished 48 h after the PGF(2alpha) (time of the second GnRH injection), but ECP-treated cows, regardless of estrus, had elevated (P < 0.02) concentrations of estradiol compared with control cows. There was a treatment x time interaction (P < 0.001) on uterine pH. All cows had similar uterine pH (P > 0.19) 24 h after the PGF(2alpha) injection. Control cows that did not exhibit estrus had a greater uterine pH compared with control cows that exhibited estrus (P < 0.01) and ECP cows that exhibited estrus (P = 0.05) 48 h after the PGF(2alpha) injection (7.0 +/- 0.1 vs. 6.7 +/- 0.1 and 6.8 +/- 0.1, respectively). Estradiol cypionate-treated cows not exhibiting estrus were intermediate (6.8 +/- 0.1; P > 0.05). All cows had similar uterine pH 72 h after the PGF(2alpha) injection through ovulation (P > 0.06). In summary, uterine pH was similar among all animals that exhibited estrus, regardless of treatment with ECP.

Detection of Anovulation by Heatmount Detectors and Transrectal Ultrasonography Before Treatment with Progesterone in a Timed Insemination Protocol

Our objective was to determine the accuracy of identifying noncycling lactating dairy cows before the application of a timed artificial insemination (AI) protocol [with or without progesterone supplementation via a controlled internal drug-release (CIDR) insert and 2 different timings of AI] by using heatmount detectors and a single ovarian ultrasound examination. At 6 locations in the Midwest, 1,072 cows were enrolled in a Presynch protocol (2 injections of PGF2α 14 d apart), with the second injection administered 14 d before initiating the Ovsynch protocol (injection of GnRH 7 d before and 48h after PGF2α injection, with timed AI at 0 or 24h after the second GnRH injection). Heatmount detectors were applied to cows just before the first Presynch injection, assessed 14 d later at the second Presynch injection (replaced when activated or missing), and reassessed at initiation of the Ovsynch protocol. Ovaries were examined for the presence of a corpus luteum (CL) by ultrasound before the initiation of treatment. Treatments were assigned to cows based on the presence or absence of a CL detected by ultrasound: 1) no CL + no CIDR; 2) no CL + CIDR insert for 7 d; and 3) CL present. Further, alternate cows within the 3 treatments were assigned to be inseminated concurrent with the second GnRH injection of Ovsynch (0h) or 24h later. Pregnancy was diagnosed at 33 and 61 d after the second GnRH injection. By using low (<1 ng/mL) concentrations of progesterone in serum as the standard for noncycling status, heatmount detectors were activated on a large percentage of noncycling cows (>60%), whereas the single ultrasound examination incorrectly classified noncycling cows only 21% of the time. Conversely, cycling cows (progesterone ≥1 ng/mL) were correctly identified 70 to 78% of the time by heatmount detectors, but 85 to 92% were correctly identified by ultrasound. Overall accuracy of heatmount detectors and ultrasound was 71 and 84%, respectively. Application of progesterone to cows without a CL at the time of the first injection of GnRH reduced the incidence of ovulation but increased the proportions of pregnancies per AI at d 33 or 61 compared with nontreated cows without a CL at the onset of the Ovsynch protocol. Percentages of cows pregnant and pregnancy survival did not differ for cows having a CL before treatment compared with those not having a CL and treated with progesterone. Compared with no response, when a follicle ovulated in response to the first GnRH injection, percentage of cows becoming pregnant after the timed AI increased from 33.3 to 41.6%. Timing of AI at 0 or 24h after the second GnRH injection did not alter pregnancies per AI, but cows having luteal activity before treatment had improved pregnancies per AI compared with noncycling cows. We conclude that identifying noncycling cows by ultrasound was more accurate than by heatmount detectors. Subsequent progesterone treatment of previously cycling cows not having a CL at the onset of Ovsynch increased the proportion of pregnant cows, equal to that of cows having a CL but not treated with progesterone.

Ovarian function in Nelore (Bos taurus indicus) cows after post-ovulation hormonal treatments

Maternal recognition of pregnancy in the cow requires successful signaling by the conceptus to block luteolysis. Conceptus growth and function depend on an optimal uterine environment, regulated by luteal progesterone. The objective of this study was to test strategies to optimize luteal function, as well as prevent a dominant follicle from initiating luteolysis. Nelore (Bos taurus indicus) beef cows (n=40) were submitted to a GnRH/PGF(2alpha)/GnRH protocol. Cows that ovulated from a dominant ovarian follicle (ovulation=Day 0) were allocated to receive: no additional treatment (G(C); n=7); 3000IU of hCG on Day 5 (G(hCG); n=5); 5mg of estradiol-17beta on Day 12 (G(E2); n=6); or 3000IU of hCG on Day 5 and 5mg of estradiol-17beta on Day 12 (G(hCG/E2); n=5). Ultrasonographic imaging of the ovaries, assessment of plasma progesterone concentration, and detection of estrus were done daily from Day 5 to the day of subsequent ovulation. Treatment with hCG induced an accessory CL, increased CL volume, and plasma progesterone concentration throughout the luteal phase (P<0.01). Estradiol-17beta induced atresia and recruitment of a new wave of follicular growth; it eliminated a potentially estrogen-active, growing ovarian follicle within the critical period for maternal recognition of pregnancy, but it also hastened luteolysis (Days 16 or 17 vs. Days 18 or 19 in non-treated cows). In conclusion, the approaches tested enhanced luteal function (hCG) and altered ovarian follicular dynamics (estradiol-17beta), but were unable to extend the life-span of the CL in Nelore cows.

Risk factors for isolation ofStaphylococcus aureusorStreptococcus dysgalactiaefrom milk culture obtained approximately 6 days post calving

Milk culture results at approximately 6 d post calving were assessed in a 2-year retrospective single-cohort study in 178 Norwegian herds. A combined teat dipping and selective antibiotic therapy trial was performed in these herds where cows with composite milk somatic cell count (CMSCC) >100,000 cells/ml before drying-off (geometric mean of the last three CMSCC test-days) and isolation of Staphylococcus aureus or Streptococcus dysgalactiae were selected for either short-acting lactation antibiotic treatment or long-acting dry cow antibiotic treatment. Milk culture results at approximately 6 d post-calving were available from 437 treated cows and 3061 non-treated cows before drying-off and separate multivariable logistic regression models were ran for these two groups. Risk factors associated with isolation of Staph. aureus 6 d post calving for non-treated cows were CMSCC >400,000 cells/ml before drying-off v. <400,000 cells/ml (Odd ratio (OR) = 2.4) and clinical mastitis (CM) in the previous lactation v . non-treated (OR=1.5). Risk factors associated with Staph. aureus 6 d post calving for treated cows was a CMS > 200,000 cells/ml before drying-off v. <200,000 cells/ml (OR=2.3) and CM in the previous lactation verus non-treated (OR=1.7). For non-treated cows it was 1.7 times more likely to isolate Str. dysgalactiae 6 d post-calving if the CMSCC was > 50,000 cells/ml compared with <50,000 cells/ml. For treated cows it was 3.7-5.8-times more likely to isolate Str. dysgalactiae 6 d post calving if given short-acting lactation formula at quarter level compared with long-acting dry cow formula used at cow level. Regular use of iodine post-milking teat disinfection (PMTD) did not influence the isolation of Staph. aureus 6 d post calvin, but it was less likely to isolate Str. dysgalactiae 6 d post calving if iodine PMTD was used regularly rather than irregularly. The external teat sealant had no effect on either of the two bacteria. This study indicates that the CMSCC limit for sampling cows before drying-off can be reduced to 50,000 cells/ml in herds with a Str. dysgalactiae problem. Iodine PMTD should also be recommended in these herds. Cows with a CMSCC > 400,000 cells/ml prior to drying-off should receive long-acting dry cow formula irrespective of the milk result.

Effect of Post Insemination Progesterone Supplement on Pregnancy Rates of Repeat Breeder Friesian Cows

Fifty repeat breeder (RB) Friesian cows were allocated to five groups of 10 cows each, to determine the effect of progesterone (P4) supplement on P4 concentrations and pregnancy rates during the periods of corpus luteum (CL) formation and development between days 2-7 and 7-12 following a spontaneous or PGF 2α -induced estrus. Cows were artificially inseminated during PGF 2α -induced (PGF-P4-d2 and PGF-P4-d7 groups) or spontaneous (S-P4-d2, S-P4-d7, and control groups) estrus. Progesterone-releasing intravaginal device (PRID) devoid of estrogen capsule were inserted either on d 2 (PGF-P4-d2 and S-P4-d2 groups) or d 7 (PGF-P4-d7 and S-P4-d7 groups) post-insemination and left in place for 5 days. Control cows did not receive any treatment. Blood samples were collected for progesterone analysis from all cows once daily for 4 days starting on the day of estrus (d 0) and once every 3 days thereafter until d 22. Progesterone treatment by day interaction accounted for higher plasma P4 in treated than non-treated control cows. Progesterone concentrations differed significantly (p<0.05) during metestrus (d 2 to d 7) but not during diestrus (d 7 to d 12). PGF 2α treatment, lactation number, service number or their interactions did not affect progesterone concentrations and pregnancy rates. Therefore, cows were grouped according to the day of P4 supplement irrespective of the PGF 2α treatment. Progesterone supplement on d 7 but not d 2 significantly increased (p<0.03) pregnancy rates in repeat breeding cows with four or more previous services but not in cows in their third service. In conclusion, post-insemination P4 supplement to repeat breeding cows with four or more previous services improved pregnancy rates and should be advocated when no specific reason for infertility is diagnosed. Further studies with larger numbers of repeat breeding cows under field conditions are needed to ascertain the findings of this study.