Lactation Number Research Articles

84 Puerto Rican Slick-Haired Holstein Cattle Exhibit Enhanced Mammary Gland Hemodynamics Compared with Their Wild-Type Haired Counterparts

Abstract A mutation of the prolactin receptor gene (PRLR) results in cattle with short and sleek hair coat and superior thermoregulatory capacity when exposed to heat stress conditions. This mutation, which is present in Puerto Rican Holstein cattle (SLICK) results in decreased vaginal temperatures and increased milk yield (MY) compared with wild-type haired Holstein cattle (WT) under tropical conditions. The superior performance of SLICK Holstein cows has been considered multifactorial in nature and physiological differences between genotypes still need to be elucidated. Thereby, the objective was to compare the mammary gland hemodynamics and udder skin temperature between SLICK (n = 7) and WT (n = 7) Holstein cows during the summer as possible contributors to such physiological differences. Animals were selected for differences in MY (23.77±1.24 vs.19.74±1.24 kg, SLICK vs. WT, respectively; P = 0.041) and stratified by body weight (BW), lactation number, and days in milk (DIM). At 160±3 DIM, left and right pudendoepigastric arteries were assessed transrectally via Doppler ultrasonography and the udder skin temperature was determined using a thermal camera. Data were analyzed by one-way ANOVA using the MIXED procedure of SAS with resistance index (RI), pulsatility index (PI), diameter, total mammary blood flow (MBF), MBF relative to BW, and udder skin temperature as dependent variables and hair coat as the independent variable. The CORR procedure of SAS was used to determine the correlation between MY and MBF. Statistical significance was declared at P ≤ 0.05 and tendencies were established at 0.05 ≤ P ≤ 0.10. The RI was less (P = 0.045) in SLICK Holsteins (0.56 ± 0.02) than WT (0.64 ± 0.02). The PI tended (P = 0.0589) to be less in SLICK Holsteins (0.94±0.07) compared with WT (1.15 ± 0.07). The average diameter of the left and right pudendoepigastric arteries was greater in the SLICK animals compared with WT (1.31 ± 0.07 vs..08±0.07 cm, respectively; P = 0.038). Total MBF was increased in SLICK cattle compared with WT (9.03 ± 1.11 vs. 5.14 ± 1.11 L/min; P = 0.0291). There was a tendency (P = 0.0577) for the MBF relative to BW to be greater in the SLICK Holsteins compared with the WT (16.75 ± 2.14 vs.0.38 ± 2.14 mL/min*kg). No differences were observed in udder skin temperature between SLICK and WT Holsteins (P ≥ 0.05). Lastly, a tendency for a positive correlation between MY and MBF was observed (r = 0.51, P = 0.066). In the current study, SLICK Holsteins had enhanced blood supply to the mammary gland which is indicative of greater amount of oxygen and nutrients available for milk synthesis. Therefore, the gene introgression of the PRLR mutation to a dairy herd may result in animals with superior physiological performance during heat stress conditions preventing economical losses in the dairy industry.

87 Milk Yield, Vaginal Temperature, and Solar Radiation Exposure in Slick and Wild Type-Haired Puerto Rican Holstein Cows

Abstract As heat stress limits dairy cattle performance in the tropics, selection for heat resistant cattle has been proposed as a possible alternative for these countries. Such cattle should be able to regulate their body temperature efficiently so grazing activity is not compromised by environmental conditions. This is particularly important for Puerto Rico’s dairy industry, which depends on grazing as the principal or unique source of dietary fiber. Even though Puerto Rican slick-haired dairy cattle (SLICK) have been associated with superior thermoregulation, empirical data about their capacity to withstand greater solar radiation exposure while maintaining lower body temperature is scarce. The current study aimed to compare the vaginal temperature, solar radiation exposure, and milk yield between SLICK and wild type-haired (WT) cows. Evaluated groups were balanced for lactation number (P = 0.8101) and days in milk (DIM: P = 0.9619). Eight SLICK (2.00 ± 0.33 lactations and 160.33 ± 11.39 DIM) and 8 WT Holstein cows (1.89 ± 0.31 lactations and 159.44 ± 14.34 DIM) were compared. Initially, experimental groups were selected visually, then a genomic test confirmed each the hair coat type of each cow. Vaginal temperature was recorded by means of a HOBO TidbiT v2 Water Temperature datalogger secured to a blank CIDR. Light intensity exposure was recorded using a HOBO Pendant MX Temperature / Light datalogger secured to the top of a neck collar, as an index of solar radiation exposure (previously validated by our group). Data were recorded in each cow every 15 seconds for 48 consecutive hours (August 4-5, 2022) and averaged by hour for statistical analysis using the GLIMMIX Procedure of SAS. The week before the study SLICK cows showed greater milk yields than their WT counterparts (20.76 ± 0.55 vs.8.60 ± 0.56 kg/d; P = 0.0073). No time by hair coat type interaction was observed for vaginal temperatures (P = 0.1396). However, time (P < 0.0001) and hair coat type (P = 0.0042) affected vaginal temperature. The SLICK cows presented lower vaginal temperatures than their WT counterparts, with daily averages of 39.08 ± 0.09 and 39.45 ± 0.10°C, respectively. A time by hair coat type interaction (P = 0.0293) was observed for the light intensity exposure of the cows. The SLICK cows had greater light intensity exposure than their WT counterparts at 1,000 h (15,467.00 ± 1,584.92 vs.10,057.00 ± 787.35 lx; P < 0.0001), 1,100 h (12,028 ± 1,660 vs. 8,571.11 ± 888.13 lx; P = 0.0078), and 1,200 h (13,191.00 ± 2,188.86 vs.10,923.00 ± 1,904.31 lx; P = 0.0801). No other differences in light intensity exposure were observed. Slick-haired cows were able to maintain a lower daily vaginal temperature, even with a greater exposure to direct solar radiation, further suggesting a superior thermoregulatory capacity. Concurrently, a greater milk production was observed in the slick-haired group. Future studies should evaluate grazing activity under direct solar radiation exposure in both hair coat groups.

155 Effect of lactation number on pregnancy losses in dairy cattle

155 Effect of lactation number on pregnancy losses in dairy cattle

Effects of production stage and fertility traits on milk production of pasture-grazed Holstein and Jersey cows in a Mediterranean-type climate region

The aim of this study was to compare the milk production of Holstein and Jersey cows on pasture as affected by parity, lactation stage, calving season, age at first calving, and calving interval. Test-day lactation records of 122 Holstein and 99 Jersey cows, varying from parities 1 to 6, were collected using standard milk recording procedures. Cows were managed and kept as one herd on kikuyu over-sown with ryegrass pasture and received 7 kg of concentrate (as fed) containing 170 g/kg crude protein per day. Across parities, the means for milk yield, milk fat, milk protein, dry matter intake, and body weight were 23.8 ± 6.2 and 17.9 ± 4.4 kg/day; 3.89 ± 0.03 and 4.66 ± 0.03%; 3.17 ± 0.02 and 3.59 ± 0.02%; 17.8 ± 2.6 and 14.4 ± 2.1 kg/day; and 567 ± 3.49 and 411 ± 3.84 kg for Holstein and Jersey cows, respectively. Milk yield increased by 26.5% in Holsteins and 23.7% in Jerseys from first to fourth lactation. Mean lactation number was 2.5 ± 0.15 and 3.0 ± 0.17; test-day milk yield for summer was 21.2 ± 0.28 and 16.5 ± 0.31 kg/day; and winter was 21.3 ± 0.28 and 16.4 ± 0.32 kg/day; age at first calving was 26.4 ± 0.3 and 26.2 ± 0.3; and inter-calving period was 13.9 ± 0.18 and 13.2 ± 0.17 months, for Holstein and Jersey cows, respectively. With inter-calving periods of 13 months, 13.1 to 15.0 and above 15 months, the 305-day Holstein cow milk yield was 7324 ± 181, 7768 ± 193, and 7927 ± 211 kg, whereas that of Jerseys was 5400 ± 135, 5621 ± 244, and 5724 ± 234 kg, respectively. In this study, Jerseys performed better than Holsteins in lactation number and calving interval. Holsteins, however, had a higher increase in milk yield from first to fourth lactation, whereas age at first calving did not differ.

Comparative analysis of buffalo and cow milk for quality characteristics and β-N-acetyl-glucosaminidase activity in non-infected animals

In Pakistan, milk quality control standards are yet to be established. The prime objective of this study was to develop the standard referencevalues for the milk pH, its somatic cell count (SCC), electric conductivity (EC) and NAGase i.e., milk enzyme in the noninfected milk of localbuffalo breed i.e., Nilli-Ravi also known as Black-gold of Pakistan and cows i.e., Sahiwal and other crossbred cows kept locally mostly formilch purpose. A total of 30 animals with lactation number 1-5 (in early lactation of two months) from each breed group were selectedfor milk samples. Samples were then tested for mastitis through Surf Field Mastitis test and microbiological culturing. Reference valueswere determined using negative samples. Fore-mentioned parameters were analyzed for collected Milk samples. The values for NAGaseand SCC were the most eminent in the crossbred cow’s milk i.e., (56.07±2.33 U/mL) & (178645.83±2324.0/mL) respectively. EC value(5.7±0.04) was strikingly high in Sahiwal cow’s milk. Milk of Nilli-Ravi was found superior in quality, based on its lower values of SSC,EC and NAGase. Mean values of each parameter were also compared among different quarters and found to be statistically similar. Inconclusion, milk of Nilli-Ravi was found superior in quality and current findings can be used to provide base line information for NAGaseand other components of milk quality and udder health for above mentioned dairy types.

Late embryo mortality in Holstein cows inseminated with Holstein or Limousine frozen semen.

The objective of this study was to compare the late embryo mortality (LEM) rate (losses approximately between 32 and 53 days of gestation) and Pregnancy Specific Protein B (PSPB) and progesterone (P4) concentrations on day 32 post AI in Holstein cows bred with either Holstein or Limousine semen. A sample size of 1082 cows per group diagnosed pregnant between 28- and 35-days post breeding was calculated. The study consisted of evaluating LEM (%) in a cohort of Holstein cows bred with Holstein semen (HO × HO) or Limousine semen (HO × LM), to compare pregnancy loss from 28 to 35 days post breeding to 50-57 days post breeding. A logistic regression model to compare embryo losses was developed considering as main explanatory variable the cohort (HO × HO embryo vs. HO × LM embryo), correcting by lactation number, breeding season, days to breeding and AI technician. HO × HO embryos had greater LEM (15.16%) than HO × LM embryos (9.79%). Cows bred in summertime had higher LEM (15.23%) than cows bred in no-summertime (9.88%). There were no differences among AI technicians. Within summertime there was no difference in LEM (%) between groups within each lactation number; yet, within no-summertime, LEM (%) was higher in HO × HO than HO × LM within each lactation number. Pregnancy SPB optical densities were significantly greater in the HO × HO than in the HO × LM (p= .023) group; yet, the concentration of P4 was not different between groups (p> .05).

Histological Characteristics of the Endometrium and its Affecting Factors in Dairy Cattle (Bos taurus) on Embryo Transfer Day

Abstract In cows embryo transfer occurs on the 7th day of the oestrous cycle. Embryo survival and successful pregnancy depend on many factors, including early interaction between embryo and endometrium. Therefore, the aim of our research was to describe histo-morphological characteristics of endometrium in donor and recipient cows on obtaining and transfer day, respectively (7th day of the oestrus cycle). In addition, progesterone and oestradiol levels, the ipsilateral and contralateral corpus luteum, animal age, lactation number and days postpartum were determined. The results of the study revealed a significant difference in endometrial gland cell size, vacuolisation of glandular epithelium cytoplasm, and stromal oedema in the donor and recipient cows. However, these parameters were related only to the level of progesterone in the blood, and no other investigated factors in this study.

Development of a Nomogram to Estimate the 60-Day Probability of Death or Culling Due to Severe Clinical Mastitis in Dairy Cows at First Veterinary Clinical Evaluation

Severe clinical mastitis is a frequent disease of dairy cattle. An effective mean of predicting survival despite treatment would be helpful for making euthanasia decisions in poor prognosis cases. The objective was to develop a nomogram for prediction of death or culling in the 60 days following a severe mastitis episode in dairy cows at first veterinary visit in farm settings. A total of 224 dairy cows presenting severe clinical mastitis and examined for the first time by a veterinarian were included in a prospective study. Clinical and laboratory (complete blood cell count, L-lactate, cardiac troponin I, milk culture) variables were recorded. Animals were followed for 60 days. A nomogram was built with an adaptive elastic-net Cox proportional hazards model. Performances and relevance were evaluated by area under the receiver operating characteristic curve (AUC), Harrell's concordance index (C-index), calibration curve, decision curve analysis (DCA) and misclassification cost term (MCT). The nomogram included: lactation number, recumbency, depression intensity, capillary refilling time, ruminal motility rate, dehydration level, lactates concentration, hematocrit, band neutrophils count, monocyte count, and milk bacteriology. The AUC and C-index showed a good calibration and ability to discriminate. The DCA suggested that the nomogram was clinically relevant. Euthanizing animals having less than 25% probability of survival is economically optimal. It could be used for early euthanasia decisions in animals that would not survive despite treatment. To facilitate the use of this nomogram by veterinarians, a web-based app was developed.

A STUDY OF SERUM LACTATE AS A PREDICTOR OF SEVERITY IN DENGUE INFECTION

Background Dengue infections caused by the four antigenically distinct dengue virus serotypes (DENV1, DENV2, DENV3, DENV4) of the family Flaviviridae are the most major arboviral diseases in humans in terms of geographic spread, morbidity, and mortality. Objective serum lactate as a predictor of severity in dengue infection Methodology A prospective observational study was carried out among indoor patients admitted to the general medicine department of the tertiary care hospital SMIMER Surat. The study's duration was 15 to 18 months. Result our study found out of a total of 154 cases, the majority of cases belonged to 83(53.90%) cases were from less than 30 years. the male contributed 96 (62.34%), the majority of cases had a duration of fever 39(25.32%), 66 (42.66%) cases had high LDH, comparison of serum lactate dehydrogenase with the severity of dengue mean lactate dehydrogenase of dengue without severity was mean was 148.45 and SD 11.81, while in severe dengue mean serum lactate dehydrogenase 388.23 and SD 99.47 with p value 0.001 which was statically significant. Conclusion According to this study, it is preferable to monitor serial lactate levels as opposed to using a single lactate number.

Genetic and nongenetic factors affecting body weight in Nili Ravi buffaloes

Live body weight of Nili Ravi buffaloes was studied to investigate the effect of certain environmental sources of variation such as herd, lactation number, lactation stage, season of recording and age of buffaloe at the time of recording alongwith appraisal of genetic parameters of body weight including heritabilities, genetic correlation and phenotypic correlation of body weight with mik yield. Five milking herds belonging to Nili Ravi buffaloe breed in Punjab were utilized in this study. Data recorded during 2010 to 2012 included 839 observations. Estimation of genetic parameters were carried out by Best Linear Unbiased Prediction (BLUP) procedure through ASREML set of coputer program. Least square mean for body weight was found as 523.13±81.63 with a coefficient of variation of 15.60%. Herd, stage of lactation, lactation number, recording season and buffalo’s age at the time of recording significantly affected live body weight. Univariate analysis of body weight indicated that heritability estimate for body weight was 0.33±0.07. Phenotypic correlations of body weight with milk yield in 305 days and milk yield on day of recording were found as 0.071±0.034 and 0.090±0.053 while genetic correlations were found as 0.16±0.00 and 0.20±0.00, respectively. High heritability and positive genetic correlation of body weight with milk yield suggested that body weight should be included in selection program for improved milk yield in Nili Ravi buffaloes.

Antioxidant potential of milk obtained from Holstein-Friesian cows with regard to the subsequent lactations and stage of lactation

The aim of the research was to assess the content of components showing antioxidant activity in the milk of Holstein-Friesian cows and changes in the total antioxidant status during subsequent lactations and their stages. The material for analysis consisted of milk collected from 90 cows (30 for each analysed lactation number: I - primaparous; II - multiparous in second lactation; III - multiparous in third lactation) during three periods: 1 - up to 100 days of lactation, 2 - 101-200 days of lactation, and 3 - 201-305 days of lactation. The basic chemical composition, casein content, somatic cell counts, selected whey proteins and fat-soluble vitamins were determined in the milk. The total antioxidant status (TAS) of milk was also measured. With the subsequent lactation, the content of components with antioxidant properties, i.e. vitamins A and E, and albumins (α-lactalbumin and β-lactoglobulin), decreased significantly (p≤0.01). Simultaneously, a decrease in the level of TAS in milk was noted. The lactation phase had a minor effect on the antioxidant potential of milk. The obtained high correlation coefficients between the value of the TAS and the content of vitamins A, E and β-lactoglobulin indicate that the content of these compounds largely determines the antioxidant potential of milk. On the other hand, the obtained negative correlations between the level of antioxidant potential and the daily milk yield (r = -0.347, p≤0.05) suggest that the high productivity of cows negatively affects the antioxidant value of milk.

The Influence of Selected Factors on the Nutritional Value of the Milk of Cold-Blooded Mares: The Example of the Sokólski Breed

This study assessed the effect of access to pasture, lactation number, and foals' sex on the nutritional value of milk (79 samples) from nine mares. The following were analysed: content of dry matter, protein, fat, lactose, and ash; percentages of α-lactalbumin (α-La), β-lactoglobulin (β-Lg), serum albumin (SA), immunoglobulins (Ig), lactoferrin (Lf), and lysozyme (Lz) in the total protein; and the fatty acid profile. Mares without access to pastures were shown to produce milk with a higher dry matter content, including fat, lactose, and ash; higher percentages of β-Lg, α-La, Ig, and Lf; and a better fatty acid profile. The milk from mares with access to pasture contained more protein, including higher percentages of SA and Lz. Milk from mares in lactations 4-6 had the highest fat and protein concentrations and the lowest lactose concentration. The α-La level was highest in lactation 1, Lf in lactations 2-3, and Lz in lactations 4-6. Milk from mares in lactations 4-6 had the best fatty acid profile (the lowest concentration of saturated fatty acids (SFAs) and the highest concentration of monounsaturated fatty acids(MUFA) and polyunsaturated fatty acids (PUFA)). Milk from mothers of female offspring had higher dry matter, fat, and protein concentrations, a higher share of lysozyme, and a better fatty acid profile.

Survival analysis of productive life in Florida dairy goats using a Cox proportional hazards model.

Longevity is an economically important trait, since extending the functional life of a doe would allow us to keep the most productive females in the herd as long as possible, and this could result in the increased profitability of dairy farms. Thus, the objectives of this study were to determine the most important factors that influence the length of productive life (LPL) of female Florida goats and to estimate its genetic additive variance using a Cox proportional hazards model. The data consisted of 70,695 productive life records from 25,722 Florida females kidding between 2006 and 2020. A total of 19,495 does had completed their productive life while 6227 (24.2%) does had censored information. The pedigree contained information on 56,901 animals. The average censoring age and average failure age after first kidding for LPL were 36 and 47 months respectively. The model included, as time-independent effects, the age at first kidding and the interaction between herd, year and season of birth of the doe, and as time-dependent effects, the age at kidding, the interaction between herd, year and season of kidding, the within-herd class of milk production deviation, and the interaction between the lactation number and the stage of lactation. All fixed effects had a significant effect on LPL (p < 0.05). Does with older ages at the first kidding and an earlier age at kidding were at higher risk of being culled. A large difference among herds was observed in terms of culling risk, which highlighted the importance of adequate management practices. Also, high-producing does were less likely to be culled. The estimate of the additive genetic variance was 1.844 (in genetic standard deviation), with a heritability estimate of 0.58 ± 0.012. The results of this study are expected to contribute to the development of a genetic model for genetic evaluation of the length of the productive life of Spanish dairy goat breeds.

IMPLEMENTATION OF AN EXCLUSIVE BREASTFEEDING POLICY IN WONOGIRI REGENCY

Introduction: Breastfeeding is the best intake to fulfill nutrition of babies aged 0-6 months. In Wonogiri Regency, exclusive breastfeeding achievement in 2017 is 53.62% and 25 out of 34 public health centers haven’t reached the target yet. Method: This research was descriptive research type with observational approach and cross-sectional design. Sample was 34 public health centers in Wonogiri Regency, with nutritionist, midwives and health cadres from each public health centers as respondents. The data were collected using interview and questionnaire techniques, and correlation analysis performed using the contingent coefficient method. Result: show that communication factors showed good result for respondent’s knowledge, consistency in obtaining socialization and transmission to carry out further socialization. Resource factors show that availability of nutrition staff isn’t sufficient and funds lack for activities related to exclusive breastfeeding. On disposition factors, respondents disagree with the gift provided from the formula milk distributor because it can inhibit achievement of exclusive breastfeeding purpose. And many public health centers still don’t have exclusive breastfeeding SOP. Conclusion: It can be concluded that training, availability of facilities and infrastructures in lactation room and number of staff positively affect target achievement of exclusive breastfeeding. The effort that can be done is by giving counselling of breastfeeding to workers and healthcare staff, fulfillment of facilities and infrastructure of lactation room to support exclusive breastfeeding, making SOP related to breastfeeding for public health centers.

Distribution of Births of Bafra Sheep Reared in the Mediterranean Region during the Day

In this study, the distribution of birth data during the day (24 hours) of 651 lambs born in 2019-2022 of Bafra sheep reared in a private sheep farm in Kızıllı village of Antalya province was investigated. In the study, the effects on the distribution of births during the day and the characteristics of lambs such as birth type, sex, difficult and normal births, and dam’s lactation number were investigated. The 24 hours were divided into four equal periods such as 06:01-12:00 = 1, 12:01-18:00 = 2, 18:01-00:00 = 3, and 00:01- 06:00 = 4 to evaluate the distribution within the day. χ2 (Chi-square) test analysis was used to determine whether the characteristics such as, birth type, sex, difficult and normal births, and dam’s lactation number affected the distribution of births during the day. As a result of the analysis, the distribution of a total of 651 lamb births during the day was observed as 260 heads (39.9%) at 06:01-12:00, 199 heads (30.6%) at 12:01-18:00, 109 heads (16.7%) at 18:01- 00:00, and 83 heads (12.7%) at 00:01-06:00, respectively. In the first and second time periods between 06:01 and 18:00, 70.5% (459 heads) of lamb births occurred. The ratio and number of lambs in sex distribution were determined as 45.8% male (298 head) and 54.2% female (353 head), respectively. The number and rate of lamb births of ewes in the first lactation comprised 366 heads and 56.2%, respectively. According to the χ2 test of the time periods of the births, the effect of the lamb's birth type (P

Influence of non-genetic factors on first lactation and lifetime performance traits in Nili-Ravi buffaloes

The objective of this research was to evaluate the effects of various non-genetic factors on first lactation and lifetime productivity in Nili-Ravi buffaloes, including season of birth, period of birth, age at first calving, season of first calving, period of first calving, and number of lactations completed. The livestock data on first lactation and lifetime performance traits relevant to 501 Nili-Ravi buffaloes were collected from the history sheet of the animal for a period from 1983 to 2017 (i.e., 35 years) and maintained at the Indian Council of Agricultural Research—Central Institute for Research on Buffaloes (ICAR-CIRB) sub-campus, in Nabha, Punjab, India. To evaluate the least-squares means (LSMs) and the effect of non-genetic factors on performance traits, a least-squares analysis model was applied. The overall LSM for age at first calving (AFC) was 45.03 ± 0.40 months and ranged from 34 to 54 months. The results indicated that the effect of AFC was highly significant (p ≤ 0.01) on first lactation total milk yield (FLTMY), first lactation standard milk yield (305 days or less) (FLSMY), first peak milk yield (FPY), and first lactation length (FLL) in the Nili-Ravi breed of buffaloes. FLTMY, FLSMY, and FPY were highest (2,250.08 ± 48.16 kg, 1,944.68 ± 31.20 kg, and 9.32 ± 0.16 kg/day, respectively) for animals with an AFC of 42–48 months. Furthermore, FLTMY, FLSMY, and FLL were highest (2,411.02 ± 68.68 kg, 2,008.81 ± 44.49 kg, and 357.43 ± 8.13 days, respectively) in animals that first calved in the autumn season. However, the lowest first dry period (FDP), first service period (FSP), and first calving interval (FCI) (110.63 ± 7.42 days, 125.48 ± 9.04 days, and 443.63 ± 9.00 days, respectively) were found for animals that first calved in the rainy season. The overall LSM for herd life (HL), productive life (PL), productive days (PDs), unproductive days (UDs), total lifetime milk yield (total LTMY), standard lifetime milk yield (standard LTMY), milk yield per day of productive life (MY/PL), milk yield per day of productive days (MY/PDs), and milk yield per day of herd life (MY/HL) were estimated as 3,779.84 ± 31.86 days, 2,078.55 ± 24.32 days, 1,552.74 ± 20.06 days, 525.81 ± 12.44 days, 10,229.71 ± 195.31 kg, 9,203.64 ± 173.52 kg, 4.86 ± 0.08 kg/day, 6.46 ± 0.08 kg/day, and 2.66 ± 0.04 kg/day, respectively. The effect of AFC on HL, PDs, UDs, total LTMY, and standard LTMY was highly significant (p ≤ 0.01). Furthermore, the effect of season of first calving on HL, PL, and PDs was significant (p ≤ 0.05). In addition, the effect of the period of first calving on HL, PDs, standard LTMY, and total LTMY was significant (p ≤ 0.05). In these contexts, it can be concluded that the buffaloes of the Nili-Ravi breed with an AFC of 42–48 months performed better than animals with a later AFC in terms of production, reproduction, and lifetime traits.

Association between Rumination Times Detected by an Ear Tag-Based Accelerometer System and Rumen Physiology in Dairy Cows.

Monitoring rumination activity is considered a useful indicator for the early detection of diseases and metabolic disorders. Accelerometer-based sensor systems provide health alerts based on individual thresholds of rumination times in dairy cows. Detailed knowledge of the relationship between sensor-based rumination times and rumen physiology would help detect conspicuous animals and evaluate the treatment's success. This study aimed to investigate the association between sensor-based health alerts and rumen fluid characteristics in Holstein-Friesian cows at different stages of lactation. Rumen fluid was collected via a stomach tube from 63 pairs of cows with and without health alerts (ALRT vs NALRT). Pairs were matched based on the day of lactation, the number of lactations, and health criteria. Rumen fluid was collected during and after health alerts. The parameters of color, odor, consistency, pH, redox potential, sedimentation flotation time, and the number of protozoa were examined. Results showed differences between both groups in odor, rumen pH, sedimentation flotation time, and protozoan count at the first rumen fluid collection. Within the groups, greater variations in rumen fluid parameters were found for ALRT cows compared to NALRT cows. The interaction between health alert and stage of lactation did not affect the rumen fluid parameters.

Occurrence of abomasal displacement in dairy cows from High-yielding dairy farms of Paraná State, Southern Brazil

The present study aimed to verify the occurrence of displacement of the abomasum (DA) in dairy herds from a high-yielding dairy region of Southern Brazil. Data on breed, age, lactation number, days after calving, breeding system, number of animals, and number of lactating cows in the herd were obtained from 135 cases of DA. A total of 39 herds, and 6,454 cows, including 2,987 lactating cows from the municipality of Palmeira, Paraná State, were included in this study. The overall prevalence of DA was 2.09%, and occurrence of DA during lactation was 4.42%. Left displacement was more prevalent, with 94.07% of the cases. The mean number of lactations and age of the cows were 2.5±1.16 lactations and 50.9±18.5 months, respectively. DA occurred predominantly in the semi-intensive breeding system (68.1% of cases), during the first 4 weeks postpartum (84.4% of cases), in Black and White Holstein-Friesian cows (94.07% of cases), and during the winter (31.1% of cases). Cows with DA in high-yielding dairy farms in Southern Brazil were similar to cows from herds of high-milk-yielding regions of North America and Europe. Multiparous Black and White Holstein-Friesian cows showed the highest prevalence of DA during the transition period, mostly on the left side.

Impact of parity differences on residual feed intake estimation in Holstein cows

Residual feed intake (RFI) has been used as a measure of feed efficiency in farm animals. In lactating dairy cattle, RFI is typically obtained as the difference between dry matter intake observations and predictions from regression on known energy sinks, and effects of parity, days in milk, and cohort. The impact of parity (lactation number) on the estimation of RFI is not well understood, so the objectives of this study were to (1) evaluate alternative RFI models in which the energy sinks (metabolic body weight, body weight change, and secreted milk energy) were nested or not nested within parity, and (2) estimate variance components and genetic correlations for RFI across parities. Data consisted of 72,474 weekly RFI records of 5,813 lactating Holstein cows collected from 2007 to 2022 in 5 research stations across the United States. Estimates of heritability, repeatability, and genetic correlations between weekly RFI for parities 1, 2, and 3 were obtained using bivariate repeatability animal models. The nested RFI model showed better goodness of fit than the nonnested model, and some partial regression coefficients of dry matter intake on energy sinks were heterogeneous between parities. However, the Spearman's rank correlation between RFI values calculated from nested and nonnested models was equal to 0.99. Similarly, Spearman's rank correlation between the RFI breeding values from these 2 models was equal to 0.98. Heritability estimates for RFI were equal to 0.16 for parity 1, 0.19 for parity 2, and 0.22 for parity 3. Repeatability estimates for RFI across weeks within parities were high, ranging from 0.51 to 0.57. Spearman's rank correlations of sires' breeding values were 0.99 between parities 1 and 2, 0.91 between parities 1 and 3, and 0.92 between parities 2 and 3. We conclude that nesting energy sinks within parity when computing RFI improves model goodness of fit, but the impact on the estimated breading values appears to be minimal.

Genetic Parameters for Functional Longevity, Type Traits, and Production in the Serbian Holstein.

In this study, the authors focused on the evaluation of the genetic parameters of longevity, milk yield traits, and type traits in dairy cattle populations in the Republic of Serbia. The total dataset used consisted of production records and pedigree data for 32,512 Holstein cows that calved from 1981 to 2015. The animal model was applied to determine the variance and covariance components and genetic parameters of the analyzed traits by applying the restricted maximum likelihood (REML) approach and using the programs VCE6 and PEST. The heritability of longevity traits was estimated using the Survival Kit V6.0 software package. Variance and covariance were estimated for five production traits: milk yield (MY), fat yield (FY), protein yield (PY), milk fat content (MC), and protein content (PC), and three longevity traits: length of productive life (LPL), lifetime milk yield (LMY), and the number of lactations achieved (NL) as well as for 18 standard type traits. Heritabilities for the milk, fat, and protein yield traits were 0.20 (MY), 0.15 (FY), and 0.19 (PY), respectively. The estimated coefficients of heritability for the longevity traits were higher when using the Weibull proportional hazards model compared to the traditional linear methods and ranged from 0.08 for NL to 0.10 for LPL. Heritability values for the type traits varied from a low of 0.10 (RLSsv-rear legs set-side view) to medium values of 0.32 (ST-stature). Genetic correlations were found between MY and the following longevity traits: LPL, LMY, and NL with values of -0.18, -0.11, and -0.09, respectively. Genetic correlations were found between MY and a number of linear type traits and varied from 0.02 (between MY and RUH-rear udder height) to 0.28 (between MY and FUA-fore udder attachment). Genetic correlations between the 18 investigated type traits ranged from -0.33 between TL (top line) and RTP (rear teats position) to 0.71 between AN (angularity) and RUH (rear udder height). Genetic correlations between most linear type traits and longevity traits (LPL, LMY, and NL) were generally negative and very low. The highest positive genetic correlation was found between UD and LPL (rxy = 0.38).