The effect of supplemental bioactive fatty acids on growth performance and immune function of milk-fed Holstein dairy calves during heat stress.

The present study aimed to evaluate the effects of different supplemental fat sources (soyabean oil (SBO) as a source of n-6 fatty acid (FA) and fish oil (FO) as a source of n-3 FA) in the starter feed of milk-fed dairy calves during the hot season. Forty Holstein calves (3 d of age; 39·67 kg of body weight; ten calves per group) were randomly assigned to the experimental treatments as follows: (1) starter feed supplemented with no fat source (CON), (2) starter feed supplemented with 3 % SBO (DM basis), (3) starter feed supplemented with 3 % FO (DM basis) and (4) starter feed supplemented with an equal mixture of SBO and FO (1·5 % each, DM basis). The milk feeding schedule was constant for treatments and all calves were weaned on day 65 of age. Results show that calves had greater starter intake, average daily gain and body length when fed SBO compared with the other treatments. However, feed efficiency was increased and inflammatory indicators (TNF-α, serum amyloid A and haptoglobin) concentrations were reduced in the calves fed FO compared with the other treatments. In summary, it was revealed that SBO rich in n-6 FA improved starter intake and growth performance, while FO rich in n-3 FA could improve the immune function of calves. Due to the current experimental condition, an equal mixture of SBO and FO (1·5 % each, DM basis) can be recommended to have an optimum growth performance and immune function while the calves are reared under the heat conditions.

Effects of dietary conjugated linoleic acid on metabolic status, BW and expression of genes related to lipid metabolism in adipose tissue of dairy cows during peripartum.

Conjugated linoleic acid (CLA) dietary supplementation reduces milk fat content and yield, but its effects on lipid metabolism and energy status remain controversial. The objective of this study was to investigate the effects of dietary CLA on adipose tissue (AT) mRNA abundance of genes related to lipid metabolism, plasma indicators of metabolic status, body condition score (BCS) and BW changes in dairy cows. Sixteen multiparous Holstein cows (3.2 ±â€¯1.4 lactations, 615 ±â€¯15 kg BW) were randomly assigned to treatments: 1) CLA; rumen-protected CLA (75 g/d) or 2) Control; equivalent amount of rumen inert fatty acid (FA) as the previous diet (78 g/d), from -20.2 ±â€¯3.2 (mean ±â€¯SEM) to 21d relative to calving (d 0). Subcutaneous AT was biopsied from the tail-head region at d 21 to determine the mRNA abundance of genes related to lipid metabolism. Blood samples were collected at -20.2 ±â€¯3.2, 0, 7, 14 and 21d relative to calving to determine plasma non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), insulin and glucose. Conjugated linoleic acid decreased milk fat yield and milk fat content by 15 and 16%, respectively. Cows fed CLA had lower plasma NEFA and BHBA and greater glucose and insulin concentrations (P < 0.05). Mean BCS at 21d postpartum was greater (P < 0.01; 2.89 vs 2.25), and BCS loss from the day of enrollment to 21d postpartum was reduced (P < 0.01; -0.13 vs -0.64) in the CLA group. The expression of acylcoenzyme A oxidase, carnitine palmitoyltransferase 1A, hormone-sensitive lipase, ß2 adrenergic receptor and acetyl-CoA carboxylase was downregulated by CLA supplementation, whereas the expression of sterol regulatory element binding protein, lipoprotein lipase and peroxisome proliferator-activated receptor gamma was upregulated (P < 0.01). In summary, CLA-supplemented cows showed signs of better metabolic status and less severe fat mobilization. Moreover, CLA increased mRNA abundance of genes related to lipogenesis and decreased mRNA abundance of genes related to FA oxidation and lipolysis in the AT of dairy cows during early lactation.

Effects of Flaxseed-rich Diet on Reproductive Performance in Estrous-synchronized Baluchi Ewes.

The purpose of this study was to compare the effects of using different levels of flaxseed in diets on the reproductive performance of estrous-synchronized Baluchi ewes (para 3). Diets contained either basal diet (control) or different levels of extruded flaxseed (2%, 5%, 7%, 10%, and 12%) and were fed from lambing to 60 days after lambing. The ewe estrus cycles were synchronized using controlled internal drug release (CIDR) for 14 days starting from day 16 of fat supplementation. The rams were introduced 24 h after CIDR removal. The ewes fed control diets had the highest mean dry matter intake (1,800&plusmn;35 g) which was declined with the increase of flaxseed levels. The experimental diets exerted no effects of urea concentration in blood plasma. However, plasma glucose concentration was lower (p &lt;0.05) in the ewes fed the control diet and 2% flaxseed, compared to those in other groups. Nonetheless, there was no difference among the ewes fed 5%, 7%, 10%, and 12% flaxseed in terms of plasma glucose concentrations (p &lt;0.05). The ewes fed 2% flaxseed had the highest level of plasma triglyceride concentration among other groups. In addition, the control group had the lowest level of plasma total cholesterol and low-density lipoproteins concentration in comparison to other groups (p &lt;0.05). However, plasma nonesterified fatty acids and &beta;-hydroxybutyrate concentrations were similar among the groups (P&gt;0.05). The mean interval between CIDR removal and the exhibition of estrus ranged from 30 to 40 h with the shortest interval being recorded in the ewes fed 12% flaxseed (p &lt;0.05). The control group had the lowest number of follicles on estrus day among other groups (p &lt;0.05). Furthermore, the ewes fed 10% and 12% flaxseed had the highest ovulation, pregnancy, and lambing rates, compared to other groups (p &lt;0.05). In conclusion, the findings revealed that feeding the ewes with 10% and 12% flaxseed resulted in the improvement of reproductive performance.

Relationship between body condition score loss and mRNA of genes related to fatty acid metabolism and the endocannabinoid system in adipose tissue of periparturient cows.

The endocannabinoid system (ECS) controls feed intake and energy balance in nonruminants. Recent studies suggested that dietary management alters the expression of members of the ECS in the liver and endometrium of dairy cows. The aim of this study was to determine the relationship between body condition score (BCS) loss and the mRNA abundance of genes related to fatty acid metabolism and the ECS in the subcutaneous adipose tissue (AT) of dairy cows. The BCS was determined in multiparous (3.2 ± 0.5 lactations) Holstein cows at -21 and 42 days relative to calving (designated as d = 0). Cows were grouped into three categories according to BCS loss between both assessments as follows: (1) lost ≤0.25 unit (n = 8, low BCS loss (LBL)), (2) lost between 0.5 and 0.75 units (n = 8, moderate BCS loss (MBL)) and (3) lost ≥1 unit (n = 8, high BCS loss (HBL)). Concentrations of haptoglobin and non-esterified fatty acids (NEFAs) were determined in plasma. Real-time PCR was used to determine mRNA abundance of key genes related to fatty acid metabolism, inflammation and ECS in AT. Milk yield (kg/day) between week 2 and 6 post-calving was greater in the LBL group (49.4 ± 0.75) compared to MBL (47.9 ± 0.56) and HBL (47.4 ± 0.62) groups (P < 0.05). The overall mean plasma haptoglobin and NEFA concentrations were greater in MBL and HBL groups compared with the LBL group (P < 0.05). The mRNA abundance of TNF-α, Interleukin-6 (IL-6) and IL-1ß was greatest at 21 and 42 days post-calving in HBL, intermediate in MBL and lowest in LBL groups, respectively. Cows in the HBL group had the greatest AT gene expression for carnitine palmitoyltransferase 1A, hormone sensitive lipase and adipose triglyceride lipase at 21 and 42 days post-calving (P < 0.05). Overall, mRNA abundance for very long chain acyl-CoA dehydrogenase and peroxisome proliferator-activated receptor gamma, which are related to NEFA oxidation, were greater in MBL and HBL groups compared to the LBL group at 42 days post-calving. However, mRNA abundance of fatty acid amide hydrolase was lower at 21 and 42 days post-calving in HBL cows than in LBL cows (P < 0.05). In summary, results showed a positive association between increased degree of BCS loss, inflammation and activation of the ECS network in AT of dairy cows. Findings suggest that the ECS might play an important role in fatty acid metabolism, development of inflammation and cow's adaptation to onset of lactation.

Postpartum health disorders in lactating dairy cows and its associations with reproductive responses and pregnancy status after first timed-AI.

The objective was to evaluate the association between postpartum health disorders, reproductive responses and pregnancy status in lactating multiparous cyclic Holstein cows. Cows were retrospectively categorized as healthy (n = 70) or sick (n = 60) based on postpartum health records and serum metabolites. Sick cows were further categorized as having metabolic (MET; n = 35), infectious (INF; n = 15), or both diseases (MET/INF; n = 10). Blood samples were collected on d 7 and 14 after calving to determine serum concentrations non-esterified fatty acids (NEFA), ß-hydroxybutyrate (BHB) and aspartate aminotransferase (AST), on d 0 (TAI), 8, 16, 18 and 20 after TAI to determine concentrations of progesterone (P4; d 0, 8, 16, 18 and 20) and prostaglandin F metabolite (PGFM; d 16, 18 and 20) and interferon-stimulated gene-15 (ISG15; d 16) relative mRNA expression. Cyclicity was determined by transrectal ultrasonography 30 d postpartum and cows were subjected to a GnRH-based TAI protocol (to classify cows bearing a visible CL as cyclic). Prediction of pregnancy status on d 16 after TAI was determined by ISG15 mRNA gene expression relative to ß actin and following, pregnancy was diagnosed by transrectal ultrasonography at 32 and 60 d after TAI. An interaction (P = 0.04) between occurrence of disease and pregnancy status was detected for the expression of ISG15 in blood, with healthy pregnant healthy cows having the greatest relative expression of ISG15. Postpartum health disorders were associated with reduced concentration (P < 0.05) of serum P4 post TAI. However, serum P4 concentrations at TAI were greater (P = 0.01) in sick cows (0.65 ±â€¯0.09, 0.86 ±â€¯0.13 and 0.75 ±â€¯0.10 ng/mL for MET, INF and MET/INF cows, respectively) compared with that in healthy cows (0.24 ±â€¯0.10 ng/mL). Serum concentrations of PGFM after TAI was reduced in healthy cows, regardless of pregnancy status. Pregnancy status on d 16 after TAI predicted by ISG15 mRNA expression and P/AI on d 32 and 60 after TAI based on ultrasonography, were negatively affected (P < 0.05) by occurrence of health disorders. Similarly, pregnancy loss from d 16 to 32 and d 16 to 60 after TAI was greater (P < 0.05) in sick cows compared to that in healthy cows. However, neither P/AI nor pregnancy loss were associated to the category of postpartum health disorder. Cows affected by postpartum health disorders had overall reduced P4 and greater PGFM serum concentrations after TAI, which were associated with reduced pregnancy success and enhanced pregnancy loss. Collectively, our findings support the hypothesis of a carryover effect of disease on reproductive responses, embryo survival and maintenance of pregnancy in lactating dairy cows independent of the category of postpartum health disorder.

Supplementation of chilling storage medium with glutathione protects rooster sperm quality.

This study was aimed to evaluate the effect of addition of reduced glutathione (GSH) to the extender on the rooster's semen quality parameters and fertility potential. Semen samples were diluted with Lake extender contained 0, 0.5, 1, 2, 4 and 8 mM GSH. Then, were chilled to 5 °C and stored for a period of 48 h. Sperm motion characteristics, viability, membrane integrity, lipid peroxidation, mitochondrial activity and fertility potential were evaluated. At the initiation of the experiment (0 h), GSH did not affect sperm parameters, while 2-4 mM GSH improved (P ≤ 0.05) quality indicators during storage periods. Moreover, the samples treated with 2-4 mM GSH have had a lower lipid peroxidation compared to other groups (P ≤ 0.05). Artificial insemination using the semen samples, which had been stored in groups treated with 2-4 mM GSH for a period of 24 h, led to greater (P ≤ 0.05) fertilizing potential compared to the control group.

Short- and long-term effects of postpartum oral bolus v. subcutaneous Ca supplements on blood metabolites and productivity of Holstein cows fed a prepartum anionic diet.

Little information is available regarding the calcium (Ca) dynamics and how its concentration is influenced following the Ca treatment (injection or bolus) after calving in dairy cows. To evaluate the short- and long-term effects of different sources of Ca supplement to animals fed anionic diets during the pre-partum period, 36 multiparous Holstein cows were randomly assigned to 1 of 3 treatments: (1) control group without Ca supplement (CON); (2) subcutaneous injection of 500 ml of 40% w/v Ca borogluconate immediately post-calving (SUB) and (3) oral supplement of Ca bolus containing 45 g Ca immediately and 24 h post-calving (BOL). Serum concentrations of Ca, P and Mg were measured. Serum concentration of Ca was affected by treatments at 48 h of post-calving (P < 0.01). The mean Ca at 6 h was greater in SUB compared to CON group (2.34 v. 2.01 mmol/l; P < 0.002). The lowest Ca concentration at 12 h was related to CON cows compared with BOL and SUB cows (1.90, 2.16 and 2.14 mmol/l, respectively; P < 0.02); a similar trend was observed 24 h post-calving (P < 0.02). Serum concentrations of P and Mg were not influenced by treatments. Yield of milk, milk protein and fat-corrected milk were lowest (P < 0.05) in SUB cows within 3 weeks of lactation in comparison with CON and BOL cows. However, milk yield and milk composition did not show any difference among treatments throughout the first 3 months post-calving. In general, under conditions of this experiment, Ca supplements to fresh cows as an oral bolus are recommended in comparison with subcutaneous injection.

Characterization and Pattern of Culling in Goats.

In order to describe the proportion and pattern of culling in commercial goatherds, this survey was carried out in an industrialized goatherd in Torbat-e-Jam, Iran, over a period of 18 years from 1996 to 2013. In total, the data of 3945 goats were used in this study. Finally, out of all samples, 499 (12%) goats were culled. The involuntary culling was performed mainly due to shortage disorders (3.8%), viral disorders (3.3%), microbial diseases (2.8%), and other disorders (2.1%). Sheep pox was the most important reason (64%) for culling due to viral disorders. Tick paralysis was the most common parasitic disease that contributed to culling and responsible for 88% of parasitic disorders. On the other hand, enterotoxemia accounted for 55% of microbial disorders is considered the most common cause of culling. The high proportion of culling due to shortage disorders, especially nutritional deficiencies should be considered the most important cause of culling. It requires precautionary measures and planning in order to reduce the aforementioned rate.

Effects of feeding a source of omega-3 fatty acid during the early postpartum period on the endocannabinoid system in the bovine endometrium.

A total of sixteen Holstein dairy cows (35 ±â€¯1.1 kg/d of milk yield) were randomly assigned to consider the effects of feeding omega-3 sources on endometrial endocannabinoids system (ECS) genes expression to understand the effect mechanism of omega-3 on reproductive performances during the early postpartum period to evaluate to what extent can be intervened in reproduction, e.g. via nutrition to improve fertility. Experimental diets were 1) either protected palm oil (control) or 2) extruded linseed (linseed). Cows (n = 16) were fed from calving date to 70 days in milk (DIM). There was no difference between groups (mean ±â€¯S.E.M.) in parity (3.0 ±â€¯1.00) or body condition score (BCS) at calving day (3.1 ±â€¯0.25). At 30 DIM, the ovulatory cycles of cows were synchronized using two injections of prostaglandin F2α (PGF2α) with a 14-day interval. On day 15 of synchronized estrous cycle (d0 = ovulation) uterine endometrial biopsies were collected to evaluate the expression of genes related to ECS (endocannabinoid receptor (CNR2), N-acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N-acylethanolamine acid amidase (NAAA), monoglyceride lipase (MGLL)) and PGF2α. Results showed that dry matter intake and milk yield were not affected by diets. Uterine endometrial NAAA (7.69 fold), and MGLL (1.96 fold) genes expression were greater (P < 0.05) in cows fed linseed compared with control ones. The messenger RNA (mRNA) levels of CNR-2 (4.26 fold), and NAPEPLD (20.0 fold) were decreased (P < 0.05) in animals fed linseed compared to control cows. The expression of mRNA for the FAAH was not influenced by the diets. First service conception rate was greater in cows fed linseed compared to control cows (75 vs. 25%). Pregnancy loss within 32-60 day after artificial insemination (AI) was lower in cows fed linseed compared to control cows (0 vs. 100%). In conclusion these data demonstrated that positive effect of omega-3 on reproduction may act through a mechanism involving the ECS. However, more studies to be undertaken to confirm these results.

Endocannabinoids as endometrial inflammatory markers in lactating Holstein cows.

The objective of this study was to consider endocannabinoid system as inflammatory markers in bovine endometrium to better understand the role of this system in regulating many of the functions that are related to inflammatory condition. At day 26 post-partum, fourteen cows were divided into two groups depending on the inflammatory condition: 1- subclinical endometritis (n = 7, with purulent or mucopurulent uterine discharge detectable in the vagina) and 2- healthy (n = 7, No (muco)) purulent discharge. Blood samples were collected at 26 and 30 days relative to calving to determine plasma tumour necrosis factor (TNF) and lipopolysaccharide-binding protein (LBP) concentrations; moreover, uterine biopsy was carried out on day 26 post-partum to measure mRNA abundance of TNF, interleukin-1B (IL1B), interleukin-6 (IL-6), C-X-C motif chemokine ligand 8 (CXCL8), endocannabinoid receptor (CNR2), N-acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N-acylethanolamine acid amidase (NAAA) and monoglyceride lipase (MGLL) by real-time PCR. Results showed mean plasma concentrations of TNF and LBP were lower in healthy cows compared to subclinical endometritis cows (p < .05). Relative mRNA expression for NAAA and FAAH was decreased (p < .05), and relative mRNA expression for CNR2 and NAPEPLD increased in cows with subclinical endometritis compared to healthy cows. In conclusion, relative mRNA expression of TNF, IL1B and CXCL8 and plasma concentration of LBP increased during inflammatory condition along with decreased endocannabinoids hydrolyzing enzyme (NAAA and FAAH), increased enzymes that synthesize endocannabinoids (NAPEPLD) and relative gene expression of the endocannabinoid receptor; together, these contribute to increased endocannabinoids levels during inflammation. Overall, we provide evidence that endocannabinoid system is altered in endometrium tissue during inflammation through increased mRNA expression of CNR2 and synthesis enzyme and decreased mRNA expression of hydrolyzing enzymes interfere with pro-cytokine production and signalling, which may interfere with the onset and progression of inflammation.

Effect of oral calcium bolus administration on milk production, concentrations of minerals and metabolites in serum, early-lactation health status, and reproductive performance of Holstein dairy cows.

AIMS: To determine the effects of oral Ca bolus administration in the early postpartum period of cows on milk yield and composition, blood metabolites, early-lactation health status, and reproductive performance. METHODS: Multiparous Holstein dry cows (n=66) with a mean parity of 3.1 (SD 0.35) were fed a diet with a positive dietary cation-anion difference (DCAD) prior to calving. They were randomly assigned to receive no treatment (Control; n=33) or two oral Ca boluses (n=33, 45 g of Ca per bolus); one was administered immediately after calving (Day 0) and the second 24 hours (±30 minutes) later. Blood samples were collected at calving, and on Days 2 and 7 to determine concentrations in serum of Ca, P, Mg, glucose, non-esterified fatty acids (NEFA), and ß-hydroxybutyric acid (BHBA). Milk yield was recorded daily and milk composition was determined weekly from calving until 28 day postpartum. Health and outcomes were determined during the first 30 days postpartum and reproductive outcomes to 180 days postpartum. RESULTS: Mean milk yields and composition over the first month of lactation were similar between cows in the two treatment groups (p>0.1). Mean concentrations of Ca in serum were not different between treatment groups on Day 0, but were higher on Day 2 for cows that received oral Ca boluses (1.77 (SE 0.07)) compared with Control cows (1.54 (SE 0.08)) (p=0.04). Concentrations in serum of P, Mg, glucose, NEFA and ΒHBA did not differ between treatment groups on any day of measurement. Fewer cows that received oral Ca were diagnosed with hypocalcaemia (total concentrations of Ca in serum <1.5 mmol/L) by Day 2 (2/33; 6%) compared with Control cows (12/33; 36%) (p=0.01). There was no difference in the prevalence of other health outcomes between treatment groups. The proportion of cows conceiving to first insemination was greater in cows that received an oral Ca bolus (19/29; 65%) than Control cows (12/29; 41%) (p=0.01). CONCLUSIONS: Oral Ca bolus administration increased concentrations of Ca in serum on Day 2 postpartum, and increased first service conception rates, in cows fed a diet with a positive DCAD prior to calving compared to cows that received no oral Ca bolus supplementation. Because of the small number of cows used in this study, further studies in large-scale dairy farms should be carried out to confirm these findings.

Inflammatory status and its relationships with different patterns of postpartum luteal activity and reproductive performance in early lactating Holstein cows.

This study was undertaken to determine the effect of inflammatory status on different patterns of postpartum luteal activity and reproductive performance of Holstein cows during early lactation. The cows (n = 75) averaged 3.4 ±â€¯1.2 (mean ±â€¯SEM) in parity and 3.1 ±â€¯0.2 (mean ±â€¯SEM) in body condition score at calving. Transrectal ultrasonography was performed twice weekly from day 10-60 postpartum to consider ovarian dynamics. Plasma concentrations of progesterone (P4) and estradiol (E2) were measured twice weekly and plasma levels of tumor necrosis factor alpha (TNF-α) and lipopolysacchride binding protein (LBP) were measured weekly (week 3-6 postpartum). Based on plasma P4 and E2 results, 34 (45.3%) cows had normal luteal activity (NLA), whereas 19 (25.3%), 12 (16.0%), 7 (9.3%) and 3 (4.0%) cows had prolonged luteal phase (PLP), delayed first ovulation (DO), anovulation (AO) and short luteal phase (SLP), respectively. Plasma TNF-α and LBP concentrations were affected by postpartum luteal activity (NLA, SLP and PLP), ovulatory status (DO and AO) and number of weeks postpartum (P < .05). These concentrations were greater in cows with PLP (P < .05) as compared to NLA cows, and in cows that had delayed ovulation or anovulation compared to ovulated cows (P < .05). Cows with PLP had greater open days and lower conception rate as compared to NLA cows (P < .05). Healthy cows had a larger CL and greater plasma estradiol and progesterone concentrations at first and second cycle postpartum compared to inflamed cows and followed it with greater fertility (P < .05). In conclusion, inflammatory statuses were different in high-producing dairy cows showing PLP, AO and DO in comparison with the postpartum normal luteal activity (NLA) cows that influenced reproduction outcomes.

Evaluation of shortened timed-AI protocols for resynchronization of ovulation in multiparous Holstein dairy cows.

The objective was to compare three shortened protocols for timed-AI (TAI) on ovarian responses, pregnancy per AI (P/AI) and pregnancy loss after resynchronization of ovulation in multiparous Holstein cows. Cows (n = 370), at one location, were randomly assigned at non-pregnancy diagnosis (approximately 32 d after AI) to one of three ovulation resynchronization protocols. Cows in the OS group received a 5-d Ovsynch [100 µg GnRH on Day 1, 500 µg cloprostenol (PGF) on Days 6 and 7, GnRH on Day 8.5 and TAI on Day 9 (16 h after second GnRH)]. Cows in the OS + P4 (progesterone) group received a 5-d Ovsynch as described for OS group plus an intravaginal device (Cue-Mate), containing 1.56 g of progesterone (P4), between Days 1 and 6. Cows in the J-synch group received a Cue-Mate and 2.5 mg of estradiol benzoate (EB) on Day 0, PGF and Cue-Mate removal on Day 6, another PGF on Day 7, and 100 µg of GnRH on Day 8.5, with TAI on Day 9. Ovarian response and pregnancy status at 32 and 60 d after the resynchronization TAI were determined by transrectal ultrasonography. Blood samples were collected at first PGF treatment and at TAI from a subset of 40 cows per group to determine P4 concentrations. Percentage of cows with CL at initiation of the protocol did not differ (P > 0.05) among resynchronization groups. Plasma P4 concentrations at first PGF treatment were greater (P < 0.01) in cows that received a Cue-Mate (OS + P4 and J-synch) compared to OS cows. Luteal regression was greater (P < 0.01) for J-synch (88.6%) compared with OS (76.9%) and OS + P4 (78.8%). More (P < 0.01) cows in the OS + P4 and J-synch groups had their estrous cycle synchronized and were pregnant at 32 d after TAI (48.7 and 34.7%, 67.8 and 48.0%, and 72.4 and 50.0% for OS, OS + P4 and J-synch, respectively). However, more cows subjected to J-synch remained pregnant at 60 d after TAI and, hence, had fewer (P < 0.05) pregnancy losses (19.2, 18.8 and 5.0% for OS, OS + P4 and J-synch, respectively). In summary, cows resynchronized with either OS + P4 or J-synch had greater P4 concentrations at first PGF treatment and a greater response to treatments compared to cows subjected to OS. Although OS + P4 and J-synch resynchronization protocols resulted in increased P/AI at 32 d, pregnancy losses were significantly reduced in cows subjected to the J-synch protocol.

Modifications of the G6G timed-AI protocol improved pregnancy per AI and reduced pregnancy loss in lactating dairy cows.

In dairy cows, subjected to a G6G protocol, objectives were to determine effects of (1) extending the interval from prostaglandin F2α (PGF2α) to gonadotropin-releasing hormone (GnRH) during presynchronization; and (2) adding a second PGF2α treatment before artificial insemination (AI), on ovarian response, plasma progesterone (P4) concentrations and pregnancy per AI (P/AI). In a 2×2 factorial design, lactating cows were randomly assigned to one of four timed AI (TAI) protocols: (1) G6G (n=149), one injection of PGF2α, GnRH 2 days later and a 7-day Ovsynch (GnRH, 7 days, PGF2α, 56 h, GnRH, 16 h, TAI) was initiated 6 days later; (2) G6GP (n=144), an additional PGF2α treatment (24 h after the first) during Ovsynch of the G6G protocol; (3) MG6G, one injection of PGF2α, GnRH 4 days later before initiation of the G6G protocol; and (4) MG6GP, an additional PGF2α treatment (24 h after the first) during Ovsynch of the MG6G protocol. Blood samples were collected (subset of 200 cows) at first GnRH and PGF2α of the Ovsynch, and at TAI to measure P4. Ultrasound examinations were performed in a subset of 406 cows to evaluate ovarian response at various times of Ovsynch, and in all cattle to determine pregnancy status at 32 and 60 days after TAI. Extending the interval by 2 days between PGF2α and GnRH during presynchronization increased (P<0.01) ovulatory response to first GnRH of Ovsynch, circulating P4 during Ovsynch, and P/AI at 32 and 60 days after TAI. Adding a second PGF2α treatment before AI increased the proportion of cows with luteal regression (P=0.04), improved P/AI at 60 days after TAI (P=0.05), and reduced pregnancy loss between 30 and 60 days after TAI (P=0.04). In summary, extending the interval from PGF2α to GnRH during presynchronization increased response to first GnRH of Ovsynch and P4 concentrations during Ovsynch, whereas adding a second PGF2α treatment before AI enhanced luteal regression. Both modifications of the G6G protocol improved fertility in lactating dairy cows.

Dietary conjugated linoleic acid supplementation alters the expression of genes involved in the endocannabinoid system in the bovine endometrium and increases plasma progesterone concentrations.

Endocannabinoids are derived from phospholipids and reduce fertility by interfering with implantation. Identification of changes in the expression of genes of the endocannabinoid system as a result of dietary inclusion of conjugated linoleic acid (CLA) is critical to the advancement of our understanding of the nutritional regulation of uterine function. An experiment was conducted on transition cows to evaluate the expression of key endocannabinoid genes in bovine endometrium in response to dietary supplementation with CLA. A total of 16 cows were randomly assigned to two treatments: (1) control (75 g/day palm oil) and (2) CLA (75 g/day CLA) from 21 days prepartum to Day 42 postpartum. Cows underwent uterine biopsy on days 21 and 42 postpartum. The abundance of mRNA encoding endocannabinoid receptor (CNR2), N-acyl phosphatidylethanolamine phospholipase D (NAPEPLD), fatty acid amide hydrolase (FAAH), N-acylethanolamine acid amidase (NAAA), and monoglyceride lipase (MGLL) was measured by real-time PCR. Results reported that relative levels of mRNA encoding CNR2 and NAPEPLD were decreased (P < 0.05) compared with control cows between Days 21 and 42 postpartum. Relative levels of mRNA coding for NAAA and MGLL were not different (P > 0.05) in the same situation. Mean plasma progesterone concentrations were higher in CLA-fed cows compared with control cows at Day 42 postpartum (3.51 and 1.42 ng/mL, respectively, P < 0.05). In conclusion, we suggest that the beneficial effects of a diet enriched with CLA are the result of a decrease in relative gene expression of the endocannabinoid receptor (CNR2) and enzymes that synthesize fatty acid amides (NAPEPLD) and of an increase in the expression of PTGS2 that in turn can oxidate endocannabinoids and consequently resulted in increased plasma progesterone concentrations during early lactation.

Administration of prostaglandin F2α 14 d before initiating a G6G or a G7G timed artificial insemination protocol increased circulating progesterone prior to artificial insemination and reduced pregnancy loss in multiparous Holstein cows.

The objectives of this study were to determine the effect of PGF2α treatment 14 d before the initiation of a G6G or G7G (PGF2α, 2 d, GnRH, 6 or 7 d, Ovsynch) protocol on ovarian response, synchronization protocol on ovarian response, progesterone (P4) concentration, pregnancy per AI (P/AI), and pregnancy loss in multiparous Holstein cows. Cows (3.6±1.1 lactations and yielding >30kg/d of milk) were randomly assigned to 1 of 4 timed artificial insemination (TAI) protocols: 1) G6G (n=240), one injection of PGF2α, GnRH 2 d later and a 7-d Ovsynch protocol (GnRH, 7 d, PGF2α, 56 h, GnRH 16 h TAI) was initiated 6 d later; 2) PG6G (n=250), PGF2α 14 d before the initiation of the G6G protocol; 3) G7G (n=200), one injection of PGF2α, GnRH 2 d later, and a 7-d Ovsynch protocol initiated 7 d later; and (4) PG7G (n=200), a PGF2α injection 14 d before the initiation of the G7G protocol. Blood samples from a subset of 269 cows were collected at the times of first and second GnRH, and PGF2α of the Ovsynch protocol to measure P4. Ultrasound examinations were performed to evaluate ovarian response to GnRH and PGF2α of Ovsynch, and to determine pregnancy status at 32 and 60 d after TAI. The proportion of cows with high (≥1ng/mL) P4 at first GnRH of Ovsynch was greater for PG6G and PG7G compared with G6G and G7G groups (combined 79.7 vs. 59.3%). In addition, mean (±SEM) plasma P4 concentration (ng/mL) at PGF2α of Ovsynch was also greater in PG6G (6.5±0.2) and PG7G (6.7±0.3) compared with G6G (5.1±0.2) and G7G (5.0±0.2). Cows given PGF2α 14 d before initiating a G6G or a G7G TAI (PG6G and PG7G) tended to have a greater P/AI at 32 d compared with those cows not receiving PGF2α (G6G and G7G). However, P/AI at 60 d was greater in cows subjected to PG6G and PG7G protocols (31.1 vs. 39.2%), with a lower pregnancy loss between 32 and 60 d (11.65 vs. 19.7%). In summary, administration of PGF2α 14 d before initiating a G6G or a G7G TAI protocol increased P4 concentrations before artificial insemination and late embryonic/early fetal survival in multiparous Holstein cows.

The endometrial expression of prostaglandin cascade components in lactating dairy cows fed different polyunsaturated fatty acids.

Feeding n-6 polyunsaturated fatty acids (PUFA) increases the endometrial percentages of linoleic and arachidonic acids (AA), enhances the synthesis of prostaglandin F2α (PGF2α), and improves uterine health. In contrary, the n-3 PUFA, eicosapentaenoic acid, and docosahexaenoic acid may play pivotal roles by suppressing the synthesis of uterine PGF2α, a component being centrally involved in the control of the bovine estrous cycle and in early embryo survival. The objectives of the present study were to determine the effect of feeding a diet enriched in either α-linolenic acid (n-3) or linolenic acid (n-6) on the uterine expression of genes related to prostaglandin cascade and uterine release of PGF2α (measured as 13, 14-dihydro-15-keto PGF2α [PGFM]). From calving to 60 days in milk, cows (n = 24) were fed isonitrogenous, isocaloric, and isolipidic diets that differed in the ratio of n-3/n-6 PUFA. Treatments including palm oil ([PLM]; saturated FA, n = 8), soybean whole roast ([SOY]; n-6, n = 8), and linseed extruded ([LIN]; n-3, n = 8). At 30 days in milk, the ovulatory cycles of cows were synchronized using 2 injections of PGF2α with a 14-day interval. On day 15 postovulation, cows were injected with oxytocin and blood samples were collected to monitor the uterine release of PGF2α (measured as PGFM) and uterine endometrial biopsies were prepared to evaluate the expression of genes related to prostaglandin cascade (prostaglandin F synthase [PGFS], prostaglandin E synthase [PGES], prostaglandin endoperoxide synthase-2 [PGHS-2]), phospholipase A2 (PLA2), peroxisome proliferator-activated receptors [PPAR]). Results showed that uterine endometrial PPAR-δ genes were higher in cows fed LIN (3.17-fold) compared with cows fed PLM or SOY (P < 0.05). The messenger RNA (mRNA) level of PGES in the LIN group was threefold as high as those found in SOY and PLM diets (P < 0.05). The mean relative gene expression of PLA2 and PGFS was increased in animals fed the SOY diet (2.4- and 1.7-fold, respectively) compared with LIN and PLM diets (P < 0.05). The expression of mRNA for the PGHS-2, PPAR-α, and PPAR-γ was not influenced by the diet effect. Dietary inclusion of soy FAs was associated with an increase in the PGFM concentration, possibly through an increase in the expression of genes involved in prostaglandin cascade. The uterine concentration of PGFM, however, was decreased in cows fed diets containing n-3 FAs.

Effect of linseed feeding on blood metabolites, incidence of cystic follicles, and productive and reproductive performance in fresh Holstein dairy cows.

This study was done to investigate the effect of feeding linseed on blood metabolites, incidence of cystic follicles, resumption of postpartum ovarian cyclicity, pregnancy rate, milk production, and composition in fresh Holstein dairy cows. A total of 399 dairy cows were assigned randomly to 2 diets. Diets contained either protected palm oil (CON) or extruded linseed (LIN) and were fed from calving to d 40 postpartum. Ovaries of each cow were examined on d 10, 20, 30, and 40 after parturition (parturition=d 0) by transrectal ultrasonography to determine follicular development, ovarian disorders, and cyclicity. Blood samples were collected at 14-d intervals for 6 wk starting on the day of parturition to determine plasma concentrations of glucose, ß-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and blood urea N (BUN). Results showed plasma glucose concentration was affected by the diets and was greater in the LIN treatment, but BHBA, NEFA, and BUN concentrations were similar among treatments. Dietary treatments had no significant effect on milk production and composition except milk fat percentage that significantly decreased in cows fed LIN (3.55%) compared with those fed with CON (4.17%). Plasma progesterone concentrations were greater in LIN treatment than CON treatment (1.31±0.09 vs. 0.87±0.09) at early postpartum. The resumption of cyclicity and onset of estrus were influenced by treatments and reduced by 7 d in LIN treatment compared with CON treatment. Cows fed diets enriched in LIN fatty acids had a lesser incidence of cystic follicles. Treatments did not differ significantly in terms of the number of days open, number of services per pregnancy, and pregnancy rate. In conclusion, feeding linseed immediately after parturition decreased milk fat and incidence of cystic follicles, increased progesterone concentrations early postpartum, and caused earlier resumption of cyclicity but did not affect pregnancy rate.

Double-Ovsynch, compared with presynch with or without GnRH, improves fertility in heat-stressed lactating dairy cows.

The objective was to compare 3 timed artificial insemination (TAI) protocols in lactating dairy cows during heat stress. Multiparous Holstein cows yielding (mean ± SEM) 29.4 ± 0.3 kg of milk/d randomly were assigned to 1 of 3 TAI protocols at 34 ± 5.1 days in milk: 1) double-Ovsynch (DO; n = 486): the cows received GnRH-7d-2α-3d-GnRH and Ovsynch56 (GnRH-7d-PGF2α-56h-GnRH-16h-AI) was initiated 7 days later; 2) Presynch-GnRH-Ovsynch (PGO; n = 453): the cows received PGF2α-14d-PGF2α-2d-GnRH and Ovsynch56 was initiated 7 days later; and 3) presynch-Ovsynch (PO; n = 435): the cows received PGF2α-14d-PGF2α and Ovsynch56 was initiated 12 days later. The ovulatory response to the first GnRH of Ovsynch56 was higher in DO (65.0%) compared to PGO (53.2%) and PO (45.5%). Luteolytic response to PGF2α of Ovsynch was similar among TAI protocols (90.1%, 87.1%, and 86.2% for DO, PGO, and PO, respectively). Synchronization rate was greater in DO (86.2%) than in PGO (78.1%) and PO (72.1%) protocols. Irrespective of the TAI protocol, cows that ovulated in response to first GnRH had greater response to PGF2α (92.7 vs. 77.1%). Mean (±SEM) diameter (mm) of ovulatory follicle at TAI was larger in DO (16.1 ± 0.3) than PGO (15.6 ± 0.21) and PO (15.2 ± 0.12). Cows subjected to DO had greater P/AI at 32 days and at 60 days after TAI (26.6 and 24.4%) compared with those in PGO (21.4 and 20.0%) and PO (17.2 and 15.9%). However, TAI protocol had no significant effect on the incidence of pregnancy loss (6.1%, 6.6%, and 7.4% for DO, GO, and PO, respectively). In summary, cows in the DO protocol had a greater ovulation rate to the first GnRH and a greater synchronization rate, larger ovulatory follicles and greater P/AI. Of the 3 protocols used, DO yield the best reproductive performance in heat-stressed, lactating dairy cows.

Starting Ovsynch protocol on day 6 of first postpartum estrous cycle increased fertility in dairy cows by affecting ovarian response during heat stress.

The objective was to compare fertility in cows using an Ovsynch protocol starting on day 6 of first postpartum estrous cycle with an Ovsynch protocol initiated at random stages of the estrous cycle during heat stress (temperature-humidity index (THI)=77-83). Cows (n=459) at the beginning of the lactation period were randomly assigned to time-of-ovulation synchronization treatments: (1) control, Ovsynch (first GnRH treatment, PGF2α treatment 7 days later, second GnRH treatment 56 h later, and TAI 16 h later), initiated at random stages of the estrous cycle (40 ± 2 days postpartum, n=224) and (2) Ovsynch initiated on day 6 of first postpartum estrous cycle (estrus=day 0) based on detection of the first estrus after day 30 postpartum (O6, 35 ± 2 postpartum, n=235). Statistical analyses were conducted using SAS. The percentage of cows responding to the initial GnRH injection using the Ovsynch protocol was greater with the O6 treatment compared to the control treatment (60.4% compared with 52.6%). The percentage of cows having a corpus luteum (CL) on the day of the PGF2α injection was not different among treatments (control=87.0% and O6=90.2%, respectively). Also more cows in the O6 treatment group responded to the second GnRH injection of the Ovsynch protocol compared with control treatments (82.5% compared with 75.8%). Treatment affected the percentage of cows diagnosed pregnant at 32 ± 0.7 days and 60 ± 3 days after the resynchronized timing of AI but pregnancy losses (5.3% compared with 6.8%) did not differ between treatment groups. It is concluded that initiating the Ovsynch protocol 6 days after estrus during the first 40 days postpartum resulted in a greater pregnancy rate at the synchronized estrus and increased fertility compared with control cows during heat stress.