Early Dry Period Research Articles

Effects of strain and season on incubation parameters of Nigerian local guinea fowls

The study was conducted to determine the effects of strain and season on incubation parameters of Nigerian local guinea fowls. A total of three thousand six hundred (3600) fertile eggs (400 eggs per strain in each of the three seasons; early rainy, late rainy and early dry) generated from 144 matured guinea fowls (120 guinea hens and 24 guinea cocks) were used to obtained the following parameters; number of eggs set (NOES), number of fertile eggs (NOFE), number of dead in shell (NODIS), number of eggs hatched (NOEH), fertility (%) and hatchability (%). Data generated for the study were subjected to multivariate analysis of variance (MANOVA) of SPSS 25 (2017) to determine the effects of season and strain on incubation parameters. The results of the study showed that Pearl strain had significantly higher (p<0.001) NOFE (320.00), NODIS (36.00), NOEH (274.89), fertility (80.00 %) and hatchability (85.91 %). Season wise, late rainy and early dry seasons had significantly higher (p<0.001) values on most incubation parameters observed. The interaction effect of strain and season on incubation parameters of guinea fowls was not significant, except on NOEH (p<0.001) where estimates obtained for Pearl at late rainy and early dry seasons had the highest values, while the least were observed in Lavender during early rainy, late rainy and early dry periods. In conclusion, Pearl strain of Nigerian local guinea fowl had the best results for incubation parameters during late rainy and early dry seasons than white and Lavender types.

Impact of dry-off and lyophilized Aloe arborescens supplementation on plasma metabolome of dairy cows

Positive effects have been observed as a result of Aloe arborescens supplementation in the dry-off phase in dairy cows. Metabolomic approaches can provide additional information about animal physiology. Thus, we characterized plasma metabolome around dry-off in 12 cows supplemented (AL) or not (CTR) with 10 g/d of lyophilized A. arborescens with an untargeted metabolomic approach. Overall, 1658 mass features were annotated. Regardless of treatment, multivariate statistics discriminated samples taken before and after dry-off. Overall, 490 metabolites were different between late lactation and early dry period, of which 237 were shared between AL and CTR. The most discriminant compounds (pentosidine and luteolin 7-O-glucoside) were related to the more fibrous diet. Pathway analysis indicated that pyrimidine and glycerophospholipid metabolisms were down-accumulated, suggesting reduced rumen microbial activity and liver load. Samples from AL were discriminated from CTR either the day of dry-off or 7 days after. At dry-off, aloin and emodin were the most discriminant metabolites, indicating that Aloe's bioactive compounds were absorbed. Seven days later, 534 compounds were different between groups, and emodin was among the most impacted. Pathway analysis highlighted that glycerophospholipid, pyrimidine, and folate metabolisms were affected. These results might indicate that Aloe has positive effects on liver function and a modulatory effect on rumen fermentation.

Correlations of whole blood heavy metals with serum immunological and oxidative markers during the early dry period and transition period of dairy cattle.

Immunological and oxidative alterations have been reported around calving in dairy cattle. In addition, the levels of heavy metals rise in the blood around parturition, which might affect body systems. Therefore, in this Research Communication we evaluate the changes in whole blood lead (Pb), arsenic (As), and cadmium (Cd) around calving, in comparison with the beginning of the dry period, and assess the correlations of these elements with immunological factors and oxidative markers. Samples were collected from 30 clinically healthy dairy cows in the early dry period (-6 w), one week before expected calving (-1 w), and one week postpartum (+1 w). The highest concentrations of Pb, As, and Cd were observed at -1 w and all the three elements decreased after parturition leading to significantly lower As and Cd, compared to -1 w (P < 0.05). The lowest levels of tumor necrosis factor-alpha, immunoglobulin G, interleukin 4, interleukin 10 and haptoglobin were found at -1 w simultaneous with the highest measures of the heavy metals, with tumor necrosis factor-alpha being significantly lower at this time (P < 0.05). At -6 w, As concentration was significantly (P < 0.05) correlated negatively (r = -0.366) and positively (r = 0.417) with total antioxidant capacity and malondialdehyde, respectively. Furthermore, at -1 w Pb and As had significant (P < 0.05) negative correlations with interferon gamma (r = -0.502) and interleukin 4 (r = -0.483), respectively. After parturition, Pb was observed to be negatively correlated with total antioxidant capacity (r = -0.538, P < 0.05). The observed results revealed that the alterations in immunological factors and antioxidant capacity around parturition were correlated with Pb and As levels.

Hydrological sustainability of in-pit reclaimed oil sands landforms under climate change

Development of robust reclamation designs would require understanding the relative effects of climate change on the water budget of reclaimed Athabasca oil sands landforms (Alberta, Canada). A surplus water budget is critical to sustain pit lakes and periodically freshen localized surface water ponds within the closure landscape. In this study, four hypothetical future climate scenarios were developed from statistically downscaled RCP2.6 and RCP8.5 climate projections and used in a hydrological model to investigate the potential effects of climate change on the water budget of an in-pit reclaimed oil sands mine landform. The four scenarios allowed the assessment of climate change effects for endpoints that bracket a range of future climate conditions on the water balance of the landform. Surface water and groundwater flow and chloride transport were simulated for the 2024–2100 period using daily climate forcing and the results were compared with equivalent responses under historical climate (1944–2020). The results suggest that the hydrological behavior under historical and RCP2.6 scenarios is similar. The climatic water deficit (potential evapotranspiration exceeding precipitation) will rise significantly under the RCP8.5 scenario. However, the modeling suggests that the water budget of the landform will not be too different from the early 21st century prolonged dry climate period. The chloride released from the landform under the different projected and historical climate scenarios also remained similar. Although evapotranspiration increases and leads to relatively drier conditions, a modest increase in precipitation helps maintain a surplus water budget in most years. The results demonstrate that incorporating future climate projections into water balance analyses is crucial to understand the potential reductions in runoff depths.

Identification of bacterial pathogens in dry bovine udder and their antimicrobial susceptibility

Mastitis is a multi-etiological production disease of dairy cows worldwide. The likelihood of developing clinical mastitis in subsequent calving is enhanced by intramammary infections with pathogens during the late dry and post-calving period. There is an increase in the occurrence of intramammary infections during early and late dry period. Thirty apparently healthy, pregnant cross-bred dairy cows were screened for the presence of contagious mastitis pathogens in the secretions taken after 48 h of cessation of milking. A total of 118 bacterial isolates were obtained from the secretions collected from 108 quarters, and identified using morphological and cultural characteristics. Among them, 50.8 per cent were coagulase negative Staphylococci (CNS), 16 per cent were coagulase positive Staphylococci (CPS) and 27.1 per cent were Streptococci isolates. Micrococci and E. coli constituted 2.5 per cent each and Klebsiella spp. formed 0.8 per cent of the total isolates obtained. The CNS isolates identified included 22 S. chromogens, 14 S. xylosus, 12 S. saprophyticus, six S. hominis and S. epidermidis each. Among the CPS isolated 11.8 per cent were S. aureus and 4.2 per cent were non-aureus coagulase positive Staphylococcus which included three S. hyicus and two S. pseudointermedius. Molecular confirmation of S. aureus, CNS isolates, St. agalactiae were done by targeting nuc, cns and 16SrRNA gene respectively. Identification of bacterial pathogens that are present during dry period can help in formulating an effective dry cow therapy. Antibiogram studies of the isolates obtained were done using in vitro antibiotic sensitivity testing method.

Influence of heat stress on cows during the dry and postpartum period

In the article, the authors presented information on the effect of heat stress on cows in the dry and postpartum periods. The study aims to study clinical and metabolic manifestations of heat stress in dry and fresh cows. The object of the study is cows of the early and late dry periods and new calves. The authors assessed the parameters of the microclimate of livestock premises, clinical examination of cattle, and blood sampling for hematological and biochemical studies. The authors also calculated the leukocyte index of intoxication, the shift index of blood leukocytes, and the lymphocytic index. Animals were found to have worsened general conditions, weakness, and reduced feed intake during the medical examination. An increase in body temperature (39.42±0.55 °C), tachypnea (86.45±8.04 resp.), and tachycardia (127.65±3.66 bpm) were also revealed. A hematological study revealed a decrease in the absolute number of lymphocytes and a shift in the indicators of the leukocyte formula. According to the results of the assessment of the lymphocytic index in cows during the dry period, the ratio of humoral and cellular immunity was balanced, and in new calves, an imbalance was observed. Biochemical screening of the blood serum of cows under conditions of heat stress showed significant changes in the metabolic profile against the background of a general decrease in feed intake. The content of total protein and globulins in the blood serum in the first days after calving was 68.36±3.48 (p≤0.01) and 35.36±3.89 g/l (p≤0.01), which is 16 .0 and 33.0% lower than in cows of the early dry period. Glucose and cholesterol levels progressively decreased after starting, reaching a minimum in the postpartum period (glucose - 3.14±0.59, total cholesterol - 2.18±0.55 mmol/l (p≤0.01)). The content of urea in the blood of animals increased significantly, reaching a maximum in the first days after calving - 7.44±1.48 mmol/l (p≤0.01). The authors also found an increase in the content of total bilirubin, aspartate aminotransferase, and creatine phosphokinase. Thus, heat stress leads to changes in the clinical and metabolic status of highly productive cows.

Effect of dietary protein level on nitrogen excretion in dry cows

Nitrogen (N) utilisation in dairy cattle is generally low and thereby results in potential downstream ammonia and nitrous oxide emissions as well as nitrate leaching. Despite this, only few studies have investigated N excretion in dry cows. The objective of the present study was to examine the effect of protein level in the diet on N excretion in dry cows and subsequently to develop a simple equation to predict N excretion based on nutrient intake parameters. In addition, the aim was to investigate whether a low diet crude protein (CP) concentration is sufficient to fulfil N requirements of dry cows. Twelve Danish Holstein dry cows were fed two total mixed ration (TMR) diets both containing grass-clover and maize silage, but with different ratios of rapeseed cake and dried sugar beet pulp to vary the concentration of CP, 111 and 135 g/kg of DM, respectively. Cows were randomly allocated to one of the two dietary treatments in a 2 × 2 Latin square design with six replications in early and late dry period, both lasting for two weeks. In both periods, the first eleven days were used as adaptation, while the last three days were used for sampling and recording. Feed and water intake were recorded daily, and blood, faeces and urine samples were collected and analysed for N, nutrients and other compounds. Faecal output of N was not affected by increased dietary CP level, whereas urinary N output increased with increased CP level in the diet, indicating that excess N is mainly excreted in urine. Thus, urinary N output appears to be strongly correlated with CP intake in dry cows. A dietary CP level of 111 g/kg of DM seems sufficient to meet N requirements of dry cows, underpinning the potential of reducing N excretion by dietary manipulation. Using the Lucas principle, equations predicting N excretion in faeces and urine, respectively, were established for dry cows based on dry matter intake (DMI) and N intake, and the equations were considered reliable proxies for N excretion in dairy cattle during the dry period.

Responses of a macrobenthic community to seasonal freshwater flow in a wet-dry tropical estuary

Wet-dry tropical estuaries are extreme environments driven by wet season rainfall and runoff events. The biota associated with these systems are highly adapted to large fluctuations in salinity. There are few examples globally where water extraction for human needs has not yet had a major impact on freshwater flow volumes and seasonal variability in these systems. Therefore, this study examined the importance of seasonally variable flow on intertidal macrobenthic (>0.5 mm mesh size) abundance and species composition in a pristine, wet-dry tropical estuary and nearshore environment. The focus was on intertidal mud- and sandflats where macrobenthos are known to be an important food source for endangered migratory shorebirds and fisheries species in the region. Macrobenthos on the intertidal flats were sampled on four occasions spanning the late-dry, late-flood, and early-dry periods across four years. Across all sites, total macrobenthic abundance was significantly lowest during the late-flood period, when the salinity was low, and highest in the late-dry season, under hypersaline conditions. In the muddy estuarine intertidal flats, the dominant macrobenthic group was polychaetes. In contrast, in the sandy nearshore intertidal flats, bivalves dominated in the late-dry and early-dry. However, during the late-flood, when salinities were at their lowest, the nearshore intertidal flats experienced almost complete loss of bivalves. Although flow had short-term negative effects on some species, it is clear that macrobenthos recruitment back into the intertidal flats had begun once the tide re-established in the early-dry. The differences in the flood response between polychaetes and bivalves likely reflects differences in their life history strategies, with the burrowing and swimming behaviour of polychaetes likely to be providing the ability to seek refuges during low salinity periods. Macrobenthic abundance was also correlated with benthic chlorophyll a concentrations, likely reflecting that both primary and secondary production is impacted by flow. This study suggests that macrobenthos abundance, and species dominance is driven by the seasonal changes in flow in this pristine system, demonstrating the important role of freshwater inputs.

Assessment of Some Inflammatory Cytokines and Immunologic Factors in Dairy Cows with Subclinical Ketosis

Altered cytokine profile and weakened immunity along with clinical or subclinical ketosis (SCK) are among the remarkable challenges around parturition. Therefore, the present study aimed to compare some inflammatory cytokines and immunologic factors between two groups of healthy and SCK cows. Serum specimens were collected from 30 clinically healthy dairy cows on the early dry period (EDP), one week before expected calving (-1w), and one week postpartum (+1w). The animals were divided into the two groups of healthy (N=20) and SCK (N=10) based on serum β-hydroxybutyrate cut-off of 1.2 mmol/L on +1w. The concentrations of immunoglobulin G (IgG), interleukin-4 (IL-4), IL-10, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and haptoglobin (Hp) were measured by enzyme-linked immunosorbent assay. The data were statistically analyzed by mixed analysis of variance and independent samples t-test using the SPSS software. The findings demonstrated that the overall levels of IL-4 (P=0.033), IL-10 (P=0.049), TNF-α (P=0.028), and Hp (P=0.018) were significantly higher in the SCK group than the control group. Furthermore, the interaction of time × SCK had a significant influence on IL-4 (P=0.028) and Hp (P=0.022) levels. It was revealed that IL-4 (P=0.008), IL-10 (P=0.009), TNF-α (P=0.01), and Hp (P=0.002) were all significantly higher in the SCK group than the control group on +1w. In conclusion, SCK in dairy cattle might have a relationship with immunologic and inflammatory changes around calving.

Comparative Body Condition and Haemato-biochemical Profile of Tellicherry Does during Pregnancy, Lactation and Dry Period

Background: The aim of the study is to provide a complete picture of dynamics of body condition and selected hemato-biochemical parameters of Telicherry does during pregnancy, lactation and dry period.Methods: Blood samples were collected from 40 Tellicherry does ageing around 2-2½ years fortnightly during early pregnancy (1-3 months), late pregnancy (3-5 months), early lactation, mid lactation, late lactation and dry period. Haematological parameters such as haemoglobin (Hb), packed cell volume (PCV), red blood cells count (RBC) and white blood cells count (WBC) were analyzed. Biochemical parameters such as lactate dehydrogenase (LDH), blood urea nitrogen (BUN), total protein (TP), glucose, triglyceride, aspartate transaminase (AST), calcium (Ca), phosphorus (P), sodium (Na) and potassium (K) were estimated.Result: Significant reduction in body weight and condition was observed during early lactation followed by gradual increase during mid and late lactation. The levels of Hb, PCV, RBC (P less than 0.01) found to be elevated throughout pregnancy while WBC, BUN and total protein values were higher during late pregnancy and late lactation. However, LDH levels (P less than 0.01) were higher during both pregnancy and lactation. The serum levels of glucose and triglyceride were lowest during early lactation and highest during early pregnancy and dry period. Reduction in Ca and P (P less than 0.01) levels were observed throughout lactation. AST, Na and K levels remained unaffected during all the physiological status.

Body condition loss during the dry period: Insights from feeding behavior studies

Body condition change during the dry period (ΔBCS) has been associated with a myriad of transition cow diseases. We used data from 3 studies to assess the relationship between ΔBCS, feeding behavior, and body condition score (BCS) at dry-off. We also studied the mediation effect that dry matter intake (DMI) has on ΔBCS and the association between dry period feeding time and DMI. A total of 100 parous cows were enrolled in 3 studies to investigate differences in dry period diet on behavior, health, and performance pre- and postcalving. Body weight was measured and BCS was assessed by the same trained observer after dry-off and 1 wk from calving date. The ΔBCS was calculated by subtracting the BCS at calving minus the BCS at dry-off. The BCS at dry-off was categorized as overconditioned (≥3.5) or not overconditioned (<3.5); no cows had a BCS <2.75. Feeding behavior data were collected using electronic feed bins. Parity at dry-off (median = 2; min = 1, max = 6) and 305-d milk production (mean = 10,235 kg, SD = 1,625 kg) from the previous lactation were considered. Data sets were split into 2 time periods: d -56 to -22 (early) and -21 to 0 (late) in relation to calving. Selected feeding behaviors (DMI, DMI as a percentage of body weight, and feeding time) were used to evaluate the associations between each feeding behavior and BCS at dry-off in each period using mixed linear regression models. Each model included the following covariates: parity, previous 305-d milk yield, and trial treatment. Experimental day was included as random slope, and cow was included as random intercept. A mediation analysis was used to evaluate the potential causal direct effect of BCS at dry-off on ΔBCS and the potential indirect effect mediated by differences in DMI. The BCS at dry-off was associated with changes in feeding behavior, such that overconditioned cows had lesser daily DMI and feeding time during the early and late dry periods compared with not overconditioned animals. We also noted an effect of previous 305-d milk yield on DMI; cows that produced more milk had greater DMI throughout the dry period. The ΔBCS was only partially mediated by DMI, and BCS at dry-off still had a direct effect on ΔBCS. This result indicated that mechanisms other than DMI were associated with BCS loss during the dry period. Feeding time correlated weakly and moderately with DMI during the early and late dry periods, respectively. To conclude, strategies to improve intake during the dry period should take dry-off BCS into account or, preferably, efforts should be made to minimize the number of overconditioned cows at the end of lactation.

Associations between body condition score, locomotion score, and sensor-based time budgets of dairy cattle during the dry period and early lactation

Lameness, one of the most important disorders in the dairy industry, is related to postpartum diseases and has an effect on dairy cow welfare, leading to changes in cows' daily behavioral variables. This study quantified the effect of lameness on the daily time budget of dairy cows in the transition period. In total, 784 multiparous dairy cows from 8 commercial Dutch dairy farms were visually scored on their locomotion (score of 1-5) and body condition (score of 1-5). Each cow was scored in the early and late dry period as well as in wk 4 and 8 postpartum. Cows with locomotion scores 1 and 2 were grouped together as nonlame, cows with score 3 were considered moderately lame, and cows with scores 4 and 5 were grouped together as severely lame. Cows were equipped with 2 types of sensors that measured behavioral parameters. The leg sensor provided number of steps, number of stand-ups (moving from lying to standing), lying time, number of lying bouts, and lying bout length. The neck sensor provided eating time, number of eating bouts, eating bout length, rumination time, number of rumination bouts, and rumination bout length. Sensor data for each behavioral parameter were averaged between 2 d before and 2 d after locomotion scoring. The percentage of nonlame cows decreased from 63% in the early dry period to 46% at 8 wk in lactation; this decrease was more severe for cows with higher parity. Cows that calved in autumn had the highest odds for lameness. Body condition score loss of >0.75 point in early lactation was associated with lameness in wk 4 postpartum. Moderately lame cows had a reduction of daily eating time of around 20 min, whereas severely lame cows had a reduction of almost 40 min. Similarly, moderately and severely lame dry cows showed a reduction of 200 steps/d, and severely lame cows in lactation showed a reduction of 600 steps/d. Daily lying time increased by 26 min and lying bout length increased by 8 min in severely lame cows compared with nonlame cows. These results indicate a high prevalence of lameness on Dutch dairy farms, with an increase in higher locomotion scores from the dry period into early lactation. Time budgets for multiparous dairy cows differed between the dry period and the lactating period, with a higher locomotion score (increased lameness) having an effect on cows' complete behavioral profile. Body condition score loss in early lactation was associated with poor locomotion postpartum, whereas lameness resulted in less eating time in the dry period and early lactation, creating a harmful cycle.

Effects of THI changes on milk production and composition of three dairy cattle farms in Mugello from 2010 to 2018: a preliminary study

Submitted 2020-07-03 | Accepted 2020-09-09 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.167-173 Global warming is already affecting several areas and a further increase of 1.5°C is expected by 2050. Dairy cattle are particularly sensitive to high temperature. So, the aim of this study was to examine the effect of temperature-humidity index (THI) on milk traits, considering changes of climatic parameters in the different seasons from 2010 to 2018. The study was conducted in 3 farms located in a hilly-mountainous area of Tuscany, the Mugello, situated from 220 to 450 m above sea level. Data on average daily milk yield and composition were monthly collected in the 3 farms from 2010 to 2018, while climatic parameters were recorded by a climatic station located in the area of the farms. As regards the climatic parameters, no significant variations have been observed in the last decade. 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Influence of mixed-liganding complexes of Zinc, Manganese and Cobalt in feeding highly productive cows in the early dry period for their dairy productivity in the first 100 days of lactation and reproductive functions

A number of scientific publications on the influence of microelements on the vital activity of cows, the level of milk productivity and reproductive function are analyzed. The article presents the results of research on the study of different levels of mixed-ligand complexes of Zinc, Manganese and Cobalt in the feeding of cows in the dry season for their future milk productivity and reproductive functions. The research was carried out in the conditions of “Terezine”, Bila Tserkva district, Kyiv region, on highly productive cows of the Ukrainian black-spotted dairy breed. It was found that the elimination of Zinc, Manganese and Cobalt deficiency in the diets of cows in the dry season due to different doses of their mixed-ligand complexes had a positive effect on further milk productivity. In terms of gross milk yield of natural milk for milk of 4 % fat content, the difference in this indicator between the cows of the 2nd experimental group and control was 195.9 kg, or 5.52 % (P &lt; 0.01), the 3rd experimental – 220.4 kg, or 6.21 % (P &lt; 0.001), the 4th experimental – 242.0 kg, or 6.82 % (P &lt; 0.001) and the 5th experimental group and control – 116.3 kg, or 3.28 %. Different concentrations of mixed-ligand complexes of the studied micronutrients in the diets of dry and lactating cows differently affected their reproductive functions. One fertile insemination of each cow in the 1st control group required 2.8 inseminations, in the 2nd, 3rd, 4th and 5th experimental groups – 2.1; 1.9; 1.7 and 2.3 fertilization, which is 75.0 according to the control; 67.9; 60.7 and 82.1 %. Lower levels of Zinc, Manganese and Cobalt led to positive dynamics in the physiological state of cows, stimulated their hunting and provided normal conditions for the processes of fertilization and embryo development in cows. The best effect on the milk productivity of cows and their reproductive functions had the following levels of trace elements in 1 kg of SR feed, mg: Zinc – 30; Manganese – 30; Cobalt – 0.38; Selenium – 0.3; Copper – 9 and Iodine – 0.7. This concentration of trace elements was achieved due to their mixed-ligand complexes, and Copper – its sulfate, Iodine – potassium iodide, and Selenium – selenium Suplex.

Comparison of prepartum low-energy or high-energy diets with a 2-diet far-off and close-up strategy for multiparous and primiparous cows

Previous research demonstrated that nutrition during the far-off (early) dry period may be as important to transition success as nutrition during the close-up dry period. Our objectives were to determine if a low-energy, high-fiber diet fed throughout the dry period improved metabolic status and production of dairy cows compared with a higher-energy diet or a 2-diet system, and to compare responses of cows and heifers to those diets. Holstein cows (n = 25 with 10 primiparous per treatment) were assigned to each of 3 diets at 60 d before expected calving. Treatment LO [40.5% wheat straw; 5.6 MJ of net energy for lactation (NEL)/kg of DM] was designed to meet but not exceed National Research Council recommendations for ad libitum intake from dry-off until calving. Treatment HI was a high-energy diet (6.7 MJ of NEL/kg of DM) fed for ad libitum intake from dry-off until calving. For the LO+HI treatment, the LO diet was fed ad libitum from dry-off until 21 d before expected calving, followed by the HI diet until parturition. After parturition all cows were fed a lactation diet (7.0 MJ of NEL/kg of DM) through 63 d postpartum. Dry matter intake and body weight were greater for HI cows prepartum, but not postpartum. When LO+HI cows were switched to the HI diet, their dry matter intake increased to match that of HI cows. Cows fed HI had greater gain of body condition before calving but lost more postpartum. Energy balance postpartum was higher for LO cows than for HI cows. Milk production, protein content, and protein yield did not differ among diets. Milk fat content and yield were highest for HI cows, lowest for LO, and intermediate for LO+HI cows. The HI cows had lower serum nonesterified fatty acids prepartum than either LO or LO+HI, but greater concentrations postpartum. Serum β-hydroxybutyrate did not differ prepartum, but was greater for HI than for LO or LO+HI postpartum. Serum glucose and insulin were lower for LO than HI and LO+HI prepartum; insulin was lower for LO and HI than for LO+HI postpartum. The LO cows had lower liver total lipid concentration postpartum than the HI cows and LO+HI cows. Primiparous cows generally responded to diets the same as multiparous cows. The LO+HI feeding strategy provided no benefit over the LO diet. Moreover, the high-energy diet, even when fed for only 19 d before calving in the LO+HI group, resulted in increased serum β-hydroxybutyrate and liver total lipid concentrations compared with LO.

Effect of heat stress during the early and late dry period on mammary gland development of Holstein dairy cattle

Dry period heat stress impairs subsequent milk yield. Our objective was to evaluate the effect of heat stress or cooling during the early and late dry period on mammary gland gene expression and microstructure. Cows were dried off ∼45 d before expected parturition and randomly assigned to 1 of 2 treatments: heat stress (HT, n = 39) or cooling (CL, n = 39) during the first 21 d of the dry period. On d 22, cows were switched or remained on HT and CL and this yielded 4 treatments: heat stress during the entire dry period (HTHT, n = 18); cooling during the entire dry period (CLCL, n = 20); HT for the first 21 d dry, then CL until calving (HTCL, n = 21); or CL for the first 21 d dry, then HT until calving (CLHT, n = 19). Data were analyzed in 2 periods: first 21 d dry (early dry period) and from 22 d until calving (late dry period) and analyzed using PROC MIXED or GLM in SAS (SAS Institute Inc., Cary, NC). Mammary biopsies (5-8 cows/treatment) were collected at -3, 3, 7, 14, and 25 d relative to dry-off to evaluate mammary gland gene expression and histology [i.e., cellular apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling) and proliferation (Ki67)]. Mammary alveoli number and connective tissue were visualized by hematoxylin and eosin and Mason's trichrome staining, respectively. During the early dry period, CL upregulated expression of CASP3, IGF1R, HSP90, HSF1, BECN1, ATG3, ATG5, and PRLR-LF relative to HT. However, in the late dry period, CLHT treatment upregulated expression of CASP3, CASP8, HSP70, HSP90, PRLR-LF, STAT5, CSN2, and ATG3 relative to CLCL. During the early dry period, cows exposed to HT had reduced mammary and stroma cell apoptosis and proliferation relative to CL. In addition to these findings, cows exposed to HT had lower connective tissue 3 d after dry-off relative to CL. However, in the late dry period, HTHT cows had higher connective tissue relative to CLCL. Also, in the early dry period, cows exposed to HT had greater alveoli number relative to CL, and HT decreased expression of genes related to autophagy and apoptosis in the early dry period, consistent with a delay in involution with HT. Thus, cows exposed to HT have extended involution with delayed apoptosis and autophagy signaling. Also, HT compromises mammary gland cell proliferation and leads to higher connective tissue later in the dry period. These results provide evidence that heat stress impairs overall mammary gland turnover during the dry period, which then affects secretory activity and productivity in the next lactation.

Identification of candidate genes for milk production traits by RNA sequencing on bovine liver at different lactation stages

BackgroundRNA-sequencing was performed to explore the bovine liver transcriptomes of Holstein cows to detect potential functional genes related to lactation and milk composition traits in dairy cattle. The bovine transcriptomes of the nine liver samples from three Holstein cows during dry period (50-d prepartum), early lactation (10-d postpartum), and peak of lactation (60-d postpartum) were sequenced using the Illumina HiSeq 2500 platform.ResultsA total of 204, 147 and 81 differentially expressed genes (DEGs, p < 0.05, false discovery rate q < 0.05) were detected in early lactation vs. dry period, peak of lactation vs. dry period, and peak of lactation vs. early lactation comparison groups, respectively. Gene ontology and KEGG pathway analysis showed that these DEGs were significantly enriched in specific biological processes related to metabolic and biosynthetic and signaling pathways of PPAR, AMPK and p53 (p < 0.05). Ten genes were identified as promising candidates affecting milk yield, milk protein and fat traits in dairy cattle by using an integrated analysis of differential gene expression, previously reported quantitative trait loci (QTL), data from genome-wide association studies (GWAS), and biological function information. These genes were APOC2, PPP1R3B, PKLR, ODC1, DUSP1, LMNA, GALE, ANGPTL4, LPIN1 and CDKN1A.ConclusionThis study explored the complexity of the liver transcriptome across three lactation periods in dairy cattle by performing RNA sequencing. Integrated analysis of DEGs and reported QTL and GWAS data allowed us to find ten key candidate genes influencing milk production traits.

Associations between postpartum diseases and milk yield and changes in body condition between drying off and parturition of dairy cows in Argentina

ABSTRACT Aims: To assess the change in body condition score (BCS) during the early and late dry periods and its association with postpartum diseases and milk yield in grazing dairy cows from central Argentina. Methods: BCS assessments during the dry period, and cow health and milk production records up to 90 days in milk (DIM), were collated for cows from 28 farms at monthly visits between 2007 and 2008. Cows were categorised into four groups; those in Group 1 (n=7,067) maintained or gained BCS during the early and late dry periods; Group 2 (n=2,615) maintained or gained BCS during the early dry period and lost BCS during the late dry period; Group 3 (n=1,989) lost BCS during the early dry period and maintained or gained BCS during the late dry period; and Group 4 (n=5,144) lost BCS during the early and late dry periods. Results: Cows in Group 1 had reduced odds of having retained fetal membranes (RFM), metritis, and clinical mastitis up to 90 DIM than cows in Group 2 (p<0.001), but the odds of disease were similar to cows in Group 3. The odds of having RFM or clinical mastitis tended to be lower in cows in Group 1 than cows in Group 4 (p=0.08). The odds of cows being culled or dying during the first 90 DIM were lower for cows in Group 1 than for those in Groups 2, 3, and 4 (p≤0.05). Mean accumulated milk yield up to 90 DIM was higher in cows in Group 1 than Group 2 and Group 4 (p<0.001), but was similar to that of cows in Group 3 (p=0.28). Conclusions and clinical relevance: Cows that lost BCS during the late dry period had increased odds of being diagnosed with several postpartum diseases and had decreased milk yield compared to cows that maintained or gained BCS during the entire dry period. Loss of BCS during any stage of the dry period was also associated with increased incidence of culling or death during the first 90 DIM. These results should raise awareness among dairy cattle producers of the importance of properly managing cow body condition during the dry period, especially during the late dry period.

Experimental Staphylococcus aureus Mastitis Infection Model by Teat Dipping in Bacterial Culture Suspension in Dairy Cows.

Simple SummaryUdder infection by bacteria such as Staphylococcus aureus cause economic losses to dairy production. An effective vaccine is required to control S. aureus mastitis. To develop an effective vaccine, a good experimental infection model is required. Infusion of bacteria into the udder can overwhelm the host because it bypasses physical barriers and defense mechanisms in the teat canal. The objective of this study was to develop Staphylococcus aureus mastitis challenge model that mimics natural infection. Eight Holstein dairy cows within 1st to 3rd parity at early non-milking period were randomly divided into experimental (n = 5) and control (n = 3) groups. All teats of experimental cows were challenged by dipping into S. aureus culture suspension, whereas those of control cows were dipped into phosphate-buffered saline. Bacteria in the mammary secretion was determined by bacteriological culture. The antibody titer in blood was tested by enzyme-linked immunosorbent assay (ELISA). Other analyses, which include somatic cell count, rectal body temperature, inflammatory changes in mammary secretion, and gland tissues, were assessed. Results showed that three and one of five experimental cows developed subclinical and clinical mastitis, respectively. The remaining cow was infected with Staphylococcus chromogenes. In conclusion, experimental S. aureus mastitis can be induced by teat dipping in the bacterial culture. Mastitis is inflammation of mammary glands usually caused by bacteria such as Staphylococcus aureus. Dairy cows are susceptible to mastitis during early dry and transition periods. Effective vaccine is needed during these periods. One of the limitations to develop an effective vaccine against S. aureus is the absence of good infection model. Intramammary infusion (IMIF) with S. aureus has been used as an infection model to test vaccine efficacy. IMIF is reliable in causing mastitis, but it bypasses physical barriers, non-specific natural defenses, and immunity in the teat canal. IMIF also transfers a large number of bacteria into the intramammary area at once. The objective of this study was to develop S. aureus IMIF model that mimics natural infection. Eight Holstein dairy cows were randomly divided into two groups of experimental (n = 5) and control (n = 3) cows. All teats of experimental cows were dipped in S. aureus culture suspension, whereas that of control cows were dipped in phosphate-buffered saline. Results showed that four of five cows were infected with challenge strain by day 3 of the challenge. The remaining cow was infected with Staphylococcus chromogenes. In conclusion, an experimental S. aureus intramammary infection can be induced by teat dipping into bacterial suspension.

Effects of far-off and close-up transition cow feeding on uterine health, postpartum anestrous interval, and reproductive outcomes in pasture-based dairy cows

BackgroundIn seasonal, pasture-based, dairy production systems, cows must recover from calving and become pregnant within two to 3 months. To achieve this, the uterus must involute and ovulation must occur and continue at regular intervals. As these processes are affected by the cows’ nutritional or metabolic status post-calving, the objective of this study was to evaluate the effect of cow feeding strategies on uterine health, the length of postpartum anestrous interval, and reproductive outcomes. The treatments consisted of two feeding strategies during late-lactation and early dry period (far-off period; starting 4-month pre-calving) and three close-up dry period feeding regimes (1-month pre-calving) in a 2 × 3 factorial arrangement. We randomly assigned 150 cows to one of two far-off treatments. During late lactation, the herds (n = 75 cows per herd) were either control-fed (Controlfed) or over-fed (Overfed) to achieve a low or high body condition score (4-month pre-calving; BCS; ~ 4.25 and ~ 4.75; 10-point scale) at cessation of lactation. Within each of these treatments, three feeding levels were applied during the close-up period (1-month pre-calving): ~ 65% (Feed65), ~ 90% (Feed90), or ~ 120% (Feed120) of metabolizable energy (ME) intakes relative to pre-calving requirements.ResultsUterine health improved (i.e. polymorphonucleated (PMN) cells declined) with increased feeding during the close-up period for cows in the Overfed group. The reverse was evident for the Controlfed group with the greatest PMN at the highest intakes during the close-up period. The postpartum anoestrous interval (PPAI) was shorter in cows from the Overfed group when moderately fed (Feed90) during the close-up period; in comparison, the PPAI was shorter in the Controlfed group, when those cows were overfed in the close-up period (Feed120). The cows in the Overfed treatment had greater conception and pregnancy rates if cows had moderate dry matter intakes (Feed90) during the close-up period; these reproductive variables were less under excessive feed intakes (Feed120); yet, close-up dry matter intake had little effect on conception and pregnancy rates for the Controlfed group.ConclusionsThe far-off feeding strategies increased early reproductive outcomes at 3 weeks of mating. Additionally, the interaction between far-off and close-up feeding strategies resulted in high six-week pregnancy rate with a slight restriction during the close-up period but only in the far-off Overfed group. Thus, our hypothesis is supported under these conditions.