Milk Production In Lactation Research Articles

Produção leiteira de vacas primíparas de acordo com o sexo da cria

Milk production in Brazil occupies the fourth position in the world ranking, with milk corresponding to one of the six essential products for Brazilian agriculture. The present study aimed to analyze the influence of the calf's sex at first calving on milk production (kg/milk/lactation) of cows. Using data from 43 bovine females, in which they were divided into two groups: Group I (male calving primiparous cows – MCPC) and Group II (female calving primiparous cows – FCPC). Subsequently, the data collected regarding milk production (kg of milk/lactation) were subjected to the normality test and analysis of variance, using the Tukey test. And the statistical analyses were performed using the public domain SISVAR 5.6 software. Dairy production of female calving primiparous cows (8,635.5) showed higher milk production (P < 0.05) than male calving primiparous cows (7,415.5), demonstrating in general aspects the existence of a positive effect of the sex of the calf in the milk production of primiparous cows. In conclusion, the sex of the calf creates an influence on milk production in the first lactation, where female calving primiparous cows tend to produce more milk.

Economically useful traits of cows received from different sires

When breeding Black-and-White holstinized cattle, the sperm of highly productive sires with high productivity potential of maternal ancestors, including Holstein breed, is used. Evaluation of sires by the quality of off spring is the most accurate method of determining the actual breeding value. The purpose of the work was to evaluate the economically useful traits of cows obtained from diff erent sires. The research was carried out in one of the breeding farms typical for the Sverdlovsk region for the breeding of Black-and-White cattle with a high proportion of blood in Holstein breed. The evaluation of three Holstein sires Zhadon 60044914, Onward 4512 and Plateau 62297905 on the quality of off spring was carried out by comparing the productivity of cows-daughters with their herdmates. It is established that when selecting sires for work in the herd, group selection of sires of the same type in terms of productive traits of maternal ancestors is used. This leads to almost equal milk yields for their daughters. There was also no signifi cant diff erence in milk quality indicators. When comparing the productivity of the cows-daughters of sires for the fi rst lactation with their herdmates, a certain diff erence was established, both in milk yield for 305 days of lactation, and in the mass fraction of fat and protein in milk. The cows-daughters of sire Onward 4512 turned out to be the best relative to herdmates in milk yield and mass fraction of fat in milk. The daughters of the sires Zhadon 60044914 and Plateau 62297905 had productivity lower than their herdmates by 315 and 127 kg, respectively. The daughters of the sire Plateau 62297905 surpassed their herdmates in terms of the mass fraction of fat and protein in milk. The level of profi tability of milk production for the highest lactation was 58,9–66,6 % and was higher in the group of cows–daughters of the sire Zhadon 60044914.

The Enhanced Milk Yield Effect of Early Lactation Increased Milking Frequency and Bovine Somatotropin Is Additive and Not Synergistic.

Dairy farm profitability depends on milk yield, so the dairy industry manages cows to improve their productivity. Both bovine somatotropin (bST) and early lactation increased milking frequency (IMF) and milk yield (MY) in dairy cows. The objective of this study was to evaluate the effects of mid-lactation bST administration on milk production in established lactation when combined with the milk yield carry-over effect from early lactation IMF. Thirteen multiparous Holstein cows were milked unilaterally for 20 days in early lactation. The left udder halves were milked twice daily (2X) and the right udder halves were milked four times daily (4X). Udder halves milked 4X produced 8.60 ± 1.40 kg more than 2X on the final day of IMF treatment. Cows were then returned to 2X milking for the remainder of lactation and sampled on alternate days from 74-94 days in milk (DIM). Bovine somatotropin was administered to all cows at 80 DIM. The 4X halves continued to make 2.66 ± 0.12 kg/d more milk than 2X through 94 DIM. Fat, protein, and lactose yields were significantly greater in the 4X halves compared to the 2X from 74-94 DIM. Overall milk yield increased by 2.71 kg/d with bST administration. However, there was no significant interaction between MF and bST administration. We can infer from these data that the mechanisms by which bST and IMF in early lactation increase milk yield are complementary due to their non-synergistic nature of enhancing MY.

Heat stress of cattle from embryonic phase until culling

Heat stress becomes a serious problem in the livestock sector as it affects cows' performance negatively. The objective of this paper review is to investigate the effects of heat stress during the different phases of the life cycle of cows; embryos, calves, heifers, and cows. Heat stress during early maternal gestation affects the ability of embryos to develop increasing the risk of abortion and early embryonic death. Heat stress during late maternal gestation affects the performance of calves and heifers later in their life, as it reduces growth performance, conducts physiological changes, impaired immunity, changes the behavior, and reduces the length and intensity of the estrus in heifers with decreasing in milk production in the first lactation. On the level of cows, milk quality and production, meat quality, and the final body weight decrease under hot temperatures. Heat stress decreases the conception rate, alters follicle growth, and estrous symptoms. Hormones secretion and physiological changes because of the heat stress conduct to impair the immunity system, and in oxidative stress and death in some cases. Same as for calves and heifers a change in the behavior of cows was detected in order to decrease their temperature.

Genetic relationships between weight loss in early lactation and daily milk production throughout lactation in Holstein cows

After calving, high-yielding dairy cows mobilize body reserves for energy, sometimes to the detriment of health and fertility. This study aimed to estimate the genetic correlation between body weight loss until nadir and daily milk production (MY24) in first- (L1) and second-lactation (L2) Holstein cows. The data set included 859,020 MY24 records and 570,651 daily raw body weight (BWr) phenotypes from 3,989 L1 cows, and 665,361 MY24 records and 449,449 BWr phenotypes from 3,060 L2 cows, recorded on 36 French commercial farms equipped with milking robots that included an automatic weighing platform. To avoid any bias due to change in digestive content, BWr was adjusted for variations in feed intake, estimated from milk production and BWr. Adjusted body weight was denoted BW. The genetic parameters of BW and MY24 in L1 and L2 cows were estimated using a 4-trait random regression model. In this model, the random effects were fitted by second-order Legendre polynomials on a weekly basis from wk 1 to 44. Nadir of BW was found to be earlier than reported in the literature, at 29 d in milk, and BW loss from calving to nadir was also lower than generally assumed, close to 29 kg. To estimate genetic correlations between body weight loss and production, we defined BWL5 as the loss of weight between wk 1 and 5 after calving. Genetic correlations between BWL5 and MY24 ranged from -0.26 to 0.05 in L1 and from -0.11 to 0.10 in L2, according to days in milk. These moderate to low values suggest that it may be possible to select for milk production without increasing early body mobilization.

Influence of a temporary restriction of dietary protein in prepubertal ewe lambs on first lactation milk traits and response to a mammary gland inflammatory challenge

This study evaluated the influence of a temporary nutritional protein restriction (NPR) performed, under commercial conditions, in prepubertal female lambs on first lactation milk production traits and the inflammatory response triggered by an inflammatory challenge of the. From 40 Assaf female lambs, we defined a control group (Cn = 20), which received a standard diet for replacement lambs and the NPR group (n = 20), which received the same diet but without soybean meal between 3 and 5 months of age. About 150 days after lambing, 24 of these ewes (13 NPR, 11C) were subjected to an intramammary infusion of E. coli lipopolysaccharide (LPS). Our dynamic study identified indicator traits of local (SCC) and systemic (rectal Ta, IL-6, CXCL8, IL-10, IL-36RA, VEGF-A) response to the LPS challenge. The NPR did not show significant effects on milk production traits and did not affect the SCC and rectal Ta after the LPS challenge. However, the NPR had a significant influence on 8 of the 14 plasma biomarkers analysed, in all the cases with higher relative values in the C group. The effects observed on VEGF-A (involved in vasculogenesis during mammary gland development and vascular permeability) and IL-10 (a regulatory cytokine classically known by its anti-inflammatory action) are the most remarkable to explain the differences found between groups. Whereas further studies should be undertaken to confirm these results, our findings are of interest considering the current concern about the future world's demand for protein and the need for animal production systems to evolve toward sustainability.

Type 2 abomasal ulceration in cattle and buffalo: energy and lipid metabolic status, clinico-biochemical parameters, treatment, and prognostic indicators

Twenty nine animals (22 cattle and 7 buffaloes) having type 2 abomasal ulcer (AU2) were studied in this prospective investigation, along with a control group (n = 20). Signalment, history, clinical signs, and laboratory alterations were determined. Blood, rumen fluid, abomasal fluid, and fecal samples were collected at the time of presentation. Depressed behavior, anorexia, dehydration, melena, sparse feces, and mushy rumen with substantially reduced or nonexistent motility, tachycardia, and tachypnea were common clinical findings. Colic was observed in 58% of animals. While the neutrophil count was significantly greater, the mean of lymphocytes, hemoglobin, erythrocyte count, and hematocrit were all lower (p < 0.05) than the corresponding control values. In comparison to the control values, the levels of BHBA, NEFA, lactate, bilirubin, BUN, creatinine, LDH, CK, GGT, ALP, and AST were significantly higher but levels of proteins, cholesterol, Na, K, Cl, and calcium were lower (p < 0.05). In comparison to the control values, the other hemato-biochemical parameters did not differ substantially (p < 0.05). The rumen and abomasal pH were within the reference range while rumen chloride concentration was increased in majority of animals. Higher percentage (p < 0.05) of non-survivors showed left shift and toxic alterations in neutrophils than the survivors. As compared to the survivors, the non-survivors had higher (p < 0.05) BHBA, triglycerides, total bilirubin, AST, ALP, LDH, and lactate, and lower (p < 0.05) fibrinogen and calcium. The response to medical treatment was fair, long time survival rate was good, and there was no recurrence. The follow-up period was 28months. After treatment, both the current and the subsequent lactation's milk production were unaffected.

Observational study on dry period length and its associations with milk production, culling risk, and fertility in Italian dairy farms

From an initial data set involving 84,189 lactations, this research evaluated the relationship between dry period length (DPL) and milk production, culling risk, and fertility. The data set included a total of 48,297 multiparous cow lactation records, with a calving event occurring in 2019 and 2020, belonging to 62 Italian herds with at least 150 cows. The DPL was classified into 5 categories (<40, 40-49, 50-60, 61-70, and >70 d) and these categories were used to establish the association between DPL and the outcome variables. All data obtained were assessed with simple and multiple linear regressions and Cox proportional hazard models. Cumulative milk production at 60 d in milk (DIM) was the highest in DPL categories of 61 to 70 d (2,480.29 kg/cow) and 50 to 60 d (2,474.39 kg/cow), and the lowest in <40 d (2,281.29 kg/cow). Similarly, DPL categories 61 to 70 d (10,830.94. kg/cow) and 50 to 60 d (10,817.48 kg/cow) had the highest 305-d milk production, whereas the <40 d (10,200.96 kg/cow) had the lowest one. The groups with a DPL of 40 to 49 d and >70 d had slightly, but significant, lower milk production both as cumulative 60 DIM and predicted 305-d milk production. Culling risk had a curvilinear behavior, with DPL <40 d and DPL >70 d showing significantly higher odds for culling during the first 60 DIM compared with DPL of 50 to 60 d [relative risk (RR): 1.53; RR: 1.46]. Within the same comparison, DPL of 61 to 70 d also had a slightly higher risk for culling (RR: 1.13). The DPL was associated also with fertility, with DPL of 40 to 49 d and 50 to 60 d having the greatest odds for pregnancy within the first 200 DIM. The DPL of <40, 61 to 70, and >70 d were negatively associated with fertility and showed pregnancy risks of 0.87, 0.95, and 0.94, respectively. This paper reinforces the importance of DPL as we demonstrated its association with milk production, culling, and fertility. Despite being attractive for high production dairy cows, very short dry periods are at the same time also associated with higher culling risk, lower milk production and fertility. Long DPL is detrimental, especially regarding culling and fertility. In summary, reducing variability in DPL and avoiding extremes by improving reproductive performance, maximizing late lactation milk production and making wise decisions on dry-off timing, may lead to better performances and lower early culling under Italian dairy conditions.

A randomized controlled trial assessing the effect of intermittent and abrupt cessation of milking to end lactation on the well-being and intramammary infection risk of dairy cows

The objectives were to compare the effects of an intermittent milking schedule with a thrice daily milking schedule during the final week of lactation on the well-being, udder health, milk production, and risk of culling of dairy cows. We hypothesized that cows subjected to an intermittent milking schedule would experience less udder engorgement and pain, lower concentrations of fecal glucocorticoid metabolites (11,17-dioxoandrostanes; 11,17-DOA concentration) after dry-off, lower risk of an intramammary infection during the dry period, higher milk production and lower somatic cell count in the subsequent lactation, and lower culling risk compared with herd mates milked 3 times daily and dried off by abrupt cessation. In a randomized controlled field study, Holstein cows (n = 398) with a thrice daily milking schedule were assigned to treatment and control groups. The treatment consisted of an intermittent milking schedule for 7 d before dry-off (gradual cessation of milking, GRAD). Gradual-cessation cows were milked once daily until the day of dry-off, whereas cows in the control group (abrupt cessation of milking, APT) were milked 3 times daily until the day of dry-off. Udder firmness and pain responses of the udder 3 d after dry-off, as well as the percentage change in fecal 11,17-DOA concentration (3 d after dry-off compared with the dry-off day), were used to assess the well-being of the animals. Compared with cows in the GRAD group, the odds [95% confidence interval (CI)] of udder firmness were 1.55 (0.99-2.42) for cows in the APT group, and the odds of a pain response were 1.48 (0.89-2.44) for cows in the APT group. The least squares means (95% CI) of the percentage change in 11,17-DOA concentration were 129.3% (111.1-150.4) for the APT group and 113.6% (97.5-132.4) for the GRAD group. Quarter-level culture results from the periods before dry-off and after calving were compared, to assess the likelihoods of microbiological cure and new infection. Cows in the APT group had lower odds of a new intramammary infection in the dry period [odds ratio, 95% CI: 0.63 (0.37-1.05)], whereas we observed no meaningful differences in the microbiological cure likelihood among groups. The least squares means (95% CI) for somatic cell counts (log10-transformed) were 4.9 (4.8-5.0) in the APT group and 4.9 (4.8-5.0) in the GRAD group. The odds (95% CI) of clinical mastitis in the first 30 d postcalving were 1.32 (0.53-3.30) in the APT group compared with the GRAD group. We observed no meaningful differences in milk production at the first test date postcalving or the culling risk among groups. We conclude that the gradual-cessation protocol tested herein failed to significantly improve animal well-being, udder health, milk production, and survival in the tested study cohort. However, the observed differences in udder firmness, as well as the numerical differences in udder pain and the percentage change in fecal 11,17-DOA concentrations suggest that this line of research may be useful. Future research is needed to develop drying-off strategies that are appropriate for lowering milk production at the end of the lactation and improve animal well-being without compromising udder health.

Influence of Heat Stress on Milk Production in Fraternal Twins

The aim of this study was the evaluation of heat stress in milk production in dairy cows (daily milk yield; milk production in 1st lactation). The comparison was performed between fraternal twins (full sisters), produced on the same farm and same parity. One of the twins produced in a hot period whereas her sister produced in a cooler period. Also, there can be differences in milk production between fraternal twins. Therefore, a second group of fraternal twins was also created that produced without heat stress. Databases of fraternal twins were analysed using PROC GLM analysis of Statistica&#174; with selected effects. In conclusion, a negative effect of heat stress on milk production was found. There was an obvious tendency (in some cases insignificant) for worse milk production during heat stress in both the daily milk yield during hot days and in 1st lactation started in the hot season. Fat content (in %) was also lower in the hot period but differences were insignificant. On the other hand, there was found very low differences in milk production (and milk components) between fraternal twins produced in season without heat stress.

Efeitos de um hepatoprotetor e diferentes fontes de energia na dieta sobre a composição do leite e a partição dos nutrientes em vacas lactantes

ABSTRACT The present study aimed at assessing the effects of hepatoprotective agents in diets that contain sources of energy on milk production, milk composition, and nutrient partition in lactating cows. Sixteen Holstein x Gir crossbred mid-lactation cows with an average body weight of 553 ± 85 kg were used in this study. These animals were allocated in a 4x4 Latin square design. A 2x2 factorial arrangement was employed in this feeding experiment. In each treatment, cows received diets with or without a hepatoprotective agent and variable in ground corn grain or citrus pulp as energy sources. Evaluated parameters included nutrient intake and digestibility, milk production, milk composition, energy balance, and nitrogen balance. Performance and nutrient balance variables were assessed and no interaction was observed between the hepatoprotective compounds and the dietary sources of energy. Dry matter intake, milk production and net energy for lactation were higher in corn as an energy source whereas milk fat content was higher in citrus pulp diets. There was a reduction in protein and casein contents in the milk of cows that was supplemented with an hepatoprotective agent. In this study, the hepatoprotective agent improved nitrogen balance in dairy cows. The use of the hepatoprotective compounds in the diet of these lactating cows in confinement reduced the milk protein fraction and favored a higher nitrogen balance in these animals. Retention of nitrogen compounds in the metabolism of lactating cows under confinement is influenced by hepatoprotective agents.

Effects of feeding fodder beet or kale in winter to dams and their heifer offspring on the heifer growth and production

Context Fodder beet (FB) is a widely used winter feed in New Zealand’s southern regions due to its high yield, consistent quality, and environmental benefits. However, FB is low in crude protein, phosphorus and fibre, and a survey showed that many dairy farmers were concerned that feeding FB may have negative impacts on lifetime performance. Aim To determine whether winter feeding FB or kale (Ka) to dairy cows, and then their heifer offspring at 1 and 2 years old, affects the heifer performance from birth until the end of their first lactation. Methods In June–August 2017, pregnant dairy cows were fed FB or kale over winter and then 140 of the resultant heifer offspring were divided into four treatment groups at 9–11 months old according to their dam’s winter diet and offered either FB or kale, with pasture baleage. The groups were as follows (dam crop–heifer crop): FB–FB, FB–Ka, Ka–FB, Ka–Ka. The heifers’ subsequent performance (growth, stature, milk production, and reproduction) was measured to the end of their first lactation (May 2020), and blood mineral status was monitored from May 2018 to May 2019. This observational study has its limitations, but is useful for generating hypotheses to test in more controlled research. Key results Heifers grazing FB in winter (June–August) 2018 had lower blood plasma urea and phosphate concentrations than did heifers grazing kale, despite similar dietary crude protein contents. Treatments had no effect on milk production. However, the heifer liveweights were affected and there was an indication of poorer reproductive performance. The FB–FB heifer treatment group had a lower average liveweight than the FB–Ka heifers from 1 to 2.8 years old. Conclusions Although no impact on milk production for the first lactation was observed, the key results suggest possible negative impacts of feeding heifers FB during winter, particularly if their dam also wintered on FB. Implications The combined effects of FB dam and heifer winter diets on lifetime productivity warrant further investigation to help develop sustainable FB feeding systems. When feeding FB, we recommend that farmers test their crops and supplements to ensure that sufficient nutrition, in particular protein and phosphorus are provided.

Digestive and metabolic efficiency of energy and nitrogen during lactation and the dry period in dairy cows.

The objective of this study was to characterize total-tract nutrient digestibility, energy balance, and N balance in the critical dietary and metabolic transitions of the lactation cycle. Twelve dairy cows were housed in tiestalls from 10 wk before to 16 wk after parturition. After 2 wk of adaptation to the facility and diet, digestibility of organic matter (OM), neutral detergent fiber (NDF), starch, and N were measured, and energy and N balances determined at weekly intervals by total collection of feces, urine, and milk over 48 h. Cows were individually fed ad libitum a grass silage- and corn silage-based total mixed ration during lactation and a corn silage- and barley straw-based total mixed ration during the dry period. Effects of stage of lactation were evaluated by clustering week in 5 groups: late lactation (wk -8 to -7), dry period (wk -6 to -1), and 3 early lactation periods (wk 1 to 5, wk 6 to 10, and wk 11 to 16). In lactation, apparent total-tract digestibility of OM, NDF, and starch was lowest in the first 5 wk of lactation. From wk 2 to 16 after parturition, apparent nutrient digestibility of all nutrients increased linearly, but with a negative quadratic component for dry matter, OM, and NDF, to levels comparable to those reported in last 2 wk of the previous lactation. However, differences in digestibility across lactation stage were moderate, illustrated by the difference between OM digestibility in late lactation (last 2 wk, 74.8%) and early lactation (first 5 wk, 72.5%). Cows were in negative energy balance for the first 8 wk after calving, and in negative N balance for the first 4 wk after calving. Based on energy and N balance, we predicted that 36.5 kg of body fat and 3.5 kg of body protein were gained in the last 8 wk before calving, and that 47.5 kg of body fat and 7.6 kg of body protein were mobilized in the first weeks of lactation. These predicted changes in body mass, both the gain before calving and loss after calving, were greater by 37% and 10%, respectively, than fluctuations in measured body weight (corrected for predicted gut fill and fetus weights). At wk 1 and 2 postpartum, body N loss corresponded to 25 and 29%, respectively, of total N excretion in milk, and body energy loss corresponded to 64% and 44%, respectively, of the energy exported to milk, illustrating the important contribution of N and energy from body stores to milk production in early lactation. Metabolic N efficiency, measured as total N output (milk and body) over digestible N input (from diet and body), averaged 54.4% in the last 2 wk of lactation, increased to 65.9% 2 wk after calving, and decreased linearly as lactation advanced to 61.9% by wk 16. Short (48 h) but weekly repetition of total collection of feces and urine appears to be a suitable approach to evaluate temporal changes in nutrient digestibility, energy balance, and N balance across lactation and the dry period.

Cows enrolled in a pilot randomized clinical trial evaluating pegbovigrastim administered to dairy cows at dry-off had reduced incidence of intramammary infection.

The objective of this pilot study was to determine if an alternative dosing schedule of pegbovigrastim (PEG; Imrestor; Elanco Animal Health) affects mammary gland health, rear udder width, or milk production of healthy dairy cows. 20 pregnant late-lactation Holstein cows in November 2019 through April 2020. Cows were randomly assigned to receive subcutaneous injections with either 15 mg of PEG (PEG group; n = 10) or a sham injection with saline (0.9% NaCl) solution (control group; 10) administered 7 days before dry-off and at dry-off. Quarter milk samples were collected for bacterial culture and somatic cells before and after dry-off and after calving. Mammary gland width was assessed before and after dry-off. Daily milk yields were evaluated after calving. The incidence of intramammary infection was 5 times greater for quarters of cows in the control group than for quarters of cows that received PEG. The effect of treatment on somatic cell count was not significant, but the effects of period and a treatment-by-period interaction were identified. Treatment did not significantly affect milk production in the subsequent lactation, but the effects of period and an interaction of treatment by period were identified. Rear udder width after dry-off was not significantly affected by treatment, but an effect of period was identified. In this pilot study, cows treated with PEG using an alternative dosing schedule had reduced incidence of intramammary infection and an interaction of treatment by sampling period was observed for milk yield. These results suggest that further studies with larger numbers of cows are warranted.

Influence of Rumen Protected Fat Supplementation on Nutrient Intake and Feed Conversion Efficiency in Buffaloes

This study was carried out to assess the effects of supplementation of bypass fat for one month prepartum and three months postpartum on nutrient intake and feed conversion efficiency for milk production in buffaloes. Advanced pregnant buffaloes (n=32, 2-3 parity) were selected at farmers’ doorstep, and were divided into two equal groups, each of 16 animals, on the basis of previous lactation milk production and fat %. Animals in T1 group (n=16, control) received farmers’ feeding schedule, and those in T2 group were additionally supplemented with bypass fat @ 100 g/head/d during prepartum and 20 g/kg of milk yield during early lactation. Average daily DM and DCP intake did not differ significantly in control and treatment group, whereas average daily TDN intake was found significantly higher in treatment group during postpartum phase. Whole milk yield (kg/head/d) of buffaloes in T2 group was significantly (P&lt;0.05) higher than T1 (5.43±0.07 vs. 4.50+0.04). Feed conversion efficiency (kg intake/kg whole milk) of DM (2.40±0.04 vs. 1.99±0.02), DCP (133.50±1.84 vs. 111.56±01.20) and TDN (1.53±0.02 vs. 1.31±0.01) was superior (P&lt;0.05) in bypass fat group, and similar was the trend for 6% FCM yield. Daily feed cost (Rs. 101.66±0.45 vs. 92.98±0.64) and average realizable receipt from sale of milk (Rs. 231.12±1.46 vs. 165.88±1.39/head) were higher (p&lt;0.05) in T2 group over control. The findings indicated that the bypass fat supplement @ 100 g/head/day one month before parturition and 20 g/kg milk yield during early lactation to buffaloes was economically advantageous in terms of increased milk yield and better feed conversion efficiency.

Effect of heat stress amelioration during dry period on biological responses, proinflammatory cytokines and milk production in subsequent lactation of Surti buffaloes

Present study was conducted on 12 dry Surti buffaloes to assess the effect of heat stress amelioration during dry period on their biological responses and milk production in subsequent lactation. Buffaloes were divided into control (n=6) and treatment (n=6) groups. Treatment buffaloes were housed only during their dry period in shed having wall-mounted fans, roof whitewashed with microfine lime powder and open paddock covered with 75% green net. At -8, -3, +1 and +3 weeks of calving, blood collection and recording of observations (physiological, skin thermography and BCS) were done. Milk composition and daily milk yield were recorded at every 2 weeks up to 11 weeks of lactation, respectively. Shed modification was successful in lowereing air temperature and THI indicating thermal comfort for treatment buffaloes as also revealed by lower temperatures of rectum, tympanic membrane, surface like forehead, eye, udder, coronet and lower respiration rate. Treatment group maintained significantly higher BCS, glucose, total protein, GSH, TAS, in vitro lymphocyte proliferation, neutrophil phagocytic activity and lower levels of urea, creatinine, NEFA, BHBA, SOD, MDA, cortisol, TNF-α, IL-1β, IL-6 and HSP70. These results are indicative of minimum negative energy balance, stress and higher immune response. Milk yield and fat were higher in treatment group. Providing thermal comfort to buffaloes in dry period helped in abating the negative effects of heat stress not only during dry period but also during subsequent lactation along with improved milk yield.

Associations between putative risk factors and poor colostrum yield in Holstein Friesian cattle

When dairy cows produce little or no colostrum, calves are likely to suffer from failure of passive transfer (FPT). Volume of colostrum produced by the dam may be affected by: nutrition; environmental conditions; time from calving to milking; parity; dry period length; calving difficulty; calf weight; calf sex; calf viability; cow BCS / body weight; milk production in previous lactation and dam health. While risk factors for poor IgG concentration in colostrum have been extensively studied, there is little published literature on low colostrum yields and associated risk factors. The aim of this observational study was to identify risk factors for poor colostrum yield in dairy cows and to quantify the effect of variation in those variables that the farmer can directly control (length of dry period, and close-up transition period nutrition) using inverse probability modelling. 439 animals from a single Scottish dairy farm were used as a convenience sample. First milking colostrum yield was measured by farmers using a graduated bucket. For each animal, risk factor data and meteorological data from the nearest weather were obtained. Decreased colostrum yield was associated with increasing daily temperature range, while increasing UV index, lactation number and number of days dry increased colostrum yield. Marginal effect models revealed that for each additional day of dry period, colostrum yield increased. Higher UV indices the month before calving were positively associated with colostrum yield, particularly in primiparous cows, and higher temperatures in the months before calving were positively associated with colostrum yield in all cows.

Effects of concentrate supplementation and genotype on milk production and nitrogen utilisation efficiency in late-lactation, spring-calving grazing dairy cows

The study objectives were to evaluate the effects of (1) concentrate supplementation (CS), (2) cow genotype, and (3) a potential interaction between CS and cow genotype on milk production, dry matter (DM) intake (DMI) and cow nitrogen (N) utilisation efficiency (NUE) in late lactation (+208 ± 14.1 days in milk), spring-calving grazing dairy cows. The experiment was a complete randomised block design with a 2 × 2 factorial arrangement of treatments and was conducted over a 52-day period. There were two feeding strategies (pasture-only (PO) and pasture + 2.7 kg DM CS) and two genotype groups [lower milk genotype (LM; milk kg PTA = -48 ± 59.9, fat kg PTA = +7 ± 4.7 and protein kg PTA = +3 ± 3.2) and higher milk genotype (HM; milk kg PTA = +190 ± 109.7, fat kg PTA = +12 ± 5.7 and protein kg PTA = +9 ± 3.6)]. Cows in their respective genotype group were randomly assigned to one of two feeding strategies, resulting in four treatment groups (n = 12). Cows grazed full time and were allocated 17 kg DM pasture/cow per d. No interactions were observed for any parameters measured. Cows offered CS had increased daily yields of fat + protein (+0.18 kg), lactose (+0.13 kg) and ECM (+2.46 kg) compared to cows offered PO. The HM cows had increased yields of daily fat + protein (+0.13 kg) and lactose (+0.1 kg) compared to the LM cows. Cows offered CS had decreased daily protein (-0.14%) but increased lactose (+0.08%) concentration compared to cows offered PO. The HM cows had decreased daily fat (-0.2%), protein (-0.16%) and casein (-0.07%) concentration compared to the LM cows. Cows offered CS had a reduced daily pasture DMI (-1.41 kg) but an increased daily total DMI (+1.29 kg) and feed N intake (+0.085 kg) compared to cows offered PO. Cows offered CS had decreased NUE (-0.1%) compared to cows offered PO. In conclusion, offering cows 2.7 kg DM CS per day improved milk production in late lactation but resulted in a poorer NUE. The poorer NUE was due to no difference in milk N output and an increase in the partitioning of feed N to urine. The HM cows had an increased milk response to CS with respect to milk fat + protein kg compared to the MR obtained from LM cows.

Early life indicators of first lactation milk yield and the effect of treatment for bovine respiratory disease on survivability and risk of pregnancy in Holstein dairy cattle

The primary objective of this study was to evaluate the long-term effects of variables that could be measured early in life on first lactation milk production. The secondary objective was to evaluate the long-term effects of treatment for bovine respiratory disease (BRD), within the first 120 days of life, on survivability to 850 days and reproductive success. Data from Holstein heifer calves was collected from 1 October, 2015–31 January, 2020 and included milk consumption (MC; n = 10,431), bodyweight (BW; n = 9,825), average daily gain (ADG; n = 6,194), heifer conception age (n = 10,112), and 305-day first lactation milk production (305 M; n = 5,823), and treatment records for BRD (n = 12,485). Calves were fed pasteurized whole milk through an automated calf feeding system for 60 days (range, 48 – 126 days), with a 30% crude protein (CP) and 5% crude fat enhancer added at 20 g/L milk. Calves were weighed at birth, weaning, and several other times prior to 2 years of age. Daily BW were predicted for individual animals using a third order orthogonal polynomial to model individual BW regressions. Daily BW predictions were used to calculate ADG and BW predictions on specific days of interest.Season born, ADG (0–400 days), milk production potential, and heifer conception age had a significant impact on 305-day first lactation milk production (all P ≤ 0.05; r2 = 0.31). A retrospective cohort study was conducted utilizing data collected from a commercial farm with cohorts defined by BRD status. Calves treated for BRD from 61 to 120 days old had a significantly lower chance of survival to 850 days of age than animals not treated for BRD. Additionally, calves treated for BRD from 61 to 120 days old had reduced risk of pregnancy. The results show the impact of early life on future milk production, survivability, and pregnancy risk on a commercial dairy herd.

Supplementing Ruminally Protected Lysine, Methionine, or Combination Improved Milk Production in Transition Dairy Cows.

The objectives of this study were to evaluate the effects of dietary supplementation of ruminally protected lysine (RPL), or methionine (RPM), and their combination (RPML) on the production efficiency of transition cows. A total of 120 pre-partum multiparous Holstein cows were assigned to four treatments based on previous lactation milk production, days (d) of pregnancy, lactation, and body condition score (BCS). Cows were fed a basal diet [pre-calving: 1.53 Mcal/kg dry matter (DM) and post-calving: 1.70 Mcal/kg DM] with or without supplemental ruminally protected amino acids (RPAA). Treatments were the basal diets without supplemental amino acids (CONTROL, n = 30), with supplemental methionine (RPM, pre-calving at 0.16% of DM and post-calving at 0.12% of DM, n = 30), with supplemental lysine (RPL, pre-calving at 0.33% of DM and post-calving at 0.24% DM, n = 30), and the combination (RPML, pre-calving at 0.16% RPM + 0.33% RPL of DM and post-calving at 0.12% RPM + 0.24 % RPL DM, n = 30). The dietary content of lysine was balanced to be within 6.157.2% metabolizable protein (MP)–lysine and that of methionine was balanced within 2.1–2.35% MP-methionine. Dry matter intake (DMI) was measured daily. Milk samples were taken on d 7, 14, and 21 days relative to calving (DRC), and milk yields were measured daily. Blood samples were taken on d −21, −14, −7 before expected calving and d 0, 7, 14, and 21 DRC. Data were analyzed using SAS software. There were significant Trt × time interactions (P < 0.01) for DMI pre- and post-calving period. The CON cows had lower DMI than RPM, RPL, and RPML, both pre-calving (P < 0.01) and post-calving periods (P < 0.01). Energy-corrected milk (P < 0.01), milk fat (P < 0.01), protein (P = 0.02), and lactose (P < 0.01) percentage levels were greater for RPM, RPL, and RPML cows compared to CON. Supplementing RPAA assisted in maintaining BCS post-calving than CON (P < 0.01). Blood concentrations of β-hydroxybutyrate decreased with RPM or RPL or the combination pre-calving (P < 0.01) and tended to decrease post-calving (P = 0.10). These results demonstrated that feeding RPL and RPM improved DMI and milk production efficiency, maintained BCS, and reduced β-hydroxybutyrate concentrations of transition cows.