Dairy Heifers Research Articles

Heifers with positive genetic merit for fertility traits reach puberty earlier and have a greater pregnancy rate than heifers with negative genetic merit for fertility traits

This study investigated the hypothesis that dairy heifers divergent in genetic merit for fertility traits differ in the age of puberty and reproductive performance. New Zealand's fertility breeding value (FertBV) is the proportion of a sire's daughters expected to calve in the first 42 d of the seasonal calving period. We used the New Zealand national dairy database to identify and select Holstein-Friesian dams with either positive (POS, +5 FertBV, n = 1,334) or negative FertBV (NEG, -5% FertBV, n = 1,662) for insemination with semen from POS or NEG FertBV sires, respectively. The resulting POS and NEG heifers were predicted to have a difference in average FertBV of 10 percentage points. We enrolled 640 heifer calves (POS, n = 324; NEG, n = 316) at 9 d ± 5.4 d (± standard deviation; SD) for the POS calves and 8 d ± 4.4 d old for the NEG calves. Of these, 275 POS and 248 NEG heifers were DNA parent verified and retained for further study. The average FertBV was +5.0% (SD = 0.74) and -5.1% (SD = 1.36) for POS and NEG groups, respectively. Heifers were reared at 2 successive facilities as follows: (1) calf rearing (enrollment to ∼13 wk of age) and (2) grazier, after 13 wk until 22 mo of age. All heifers wore a collar with an activity sensor to monitor estrus events starting at 8 mo of age, and we collected weekly blood samples when individual heifers reached 190 kg of body weight (BW) to measure plasma progesterone concentrations. Puberty was characterized by plasma progesterone concentrations >1 ng/mL in at least 2 of 3 successive weeks. Date of puberty was defined when the first of these samples was >1 ng/mL. Heifers were seasonally bred for 98 d starting at ∼14 mo of age. Transrectal ultrasound was used to confirm pregnancy and combined with activity data to estimate breeding and pregnancy dates. We measured BW every 2 wk, and body condition and stature at 6, 9, 12, and 15 mo of age. The significant FertBV by day interaction for BW was such that the NEG heifers had increasingly greater BW with age. This difference was mirrored with the significant FertBV by month interaction for average daily gain, with the NEG heifers having a greater average daily gain between 9 and 18 mo of age. There was no difference in heifer stature between the POS and NEG heifers. The POS heifers were younger and lighter at puberty, and were at a lesser mature BW, compared with the NEG heifers. As a result, 94 ± 1.6% of the POS and 82 ± 3.2% of the NEG heifers had reached puberty at the start of breeding. The POS heifers were 20% and 11% more likely to be pregnant after 21 d and 42 d of breeding than NEG heifers (relative risk = 1.20, 95% confidence interval of 1.03-1.34; relative risk = 1.11, 95% confidence interval of 1.01-1.16). Results from this experiment support an association between extremes in genetic merit for fertility base on cow traits and heifer reproduction. Our results indicate that heifer puberty and pregnancy rates are affected by genetic merit for fertility traits, and these may be useful phenotypes for genetic selection.

Circulating progesterone concentrations and preovulatory follicle diameters affecting ovulatory response in crossbred dairy heifers, following a 7-day progesterone-based synchronization protocol.

The present study was aimed at evaluating the differences of ovarian follicular dynamics and circulating progesterone (P4) concentrations between crossbred Holstein heifers that ovulated and did not ovulate after a P4-based synchronization protocol. Twenty-one crossbred (Holstein × Thai native) heifers with random stages of the oestrous cycle were subjected to the ovulation synchronization protocol, using an intravaginal P4-releasing device (Eazi-Breed CIDR®) for 7 days. Out of 21 CIDR-treated heifers, 14 ovulating heifers were classified as the ovulatory group and 7 non-ovulating heifers were considered the anovulatory group. The heifers having new wave emergence in ovulatory and anovulatory groups were 11/14 (78.6%) and 4/7 (57.1%), respectively. In ovulating heifers, the mean (± SEM) diameter of preovulatory follicle (PF, mm) was significantly larger, compared to non-ovulating heifers (7.21 ± 0.32 versus 4.04 ± 0.44; P = 0.001), while the mean (± SEM) follicular growth rates (mm/d) in non-ovulating heifers tended to be lower, compared to ovulating heifers (0.73 ± 0.17 versus 1.06 ± 0.08; P = 0.07). The mean (± SEM) circulating P4 concentration (ng/ml) throughout the CIDR protocol (0-10 days) in non-ovulating heifers was significantly higher, in comparison with ovulating heifers (2.82 ± 0.27 versus 1.83 ± 0.16; P = 0.02). However, no significant difference in the mean corpus luteum volume between groups was observed. In conclusion, the present results suggested that elevated circulating P4 concentrations and smaller PF diameters could cause ovulation failure in crossbred Holstein heifers, following a 7-day CIDR-based synchronization protocol.

Feed Intake, Nutrient Digestion, Growth and Reproductive Performances of Boran-Friesian Cross Breed Dairy Heifers Through Different Wheat Straw to Concentrate Feeds

This study was conducted to examine the effect of different wheat straw and concentrate proportions on feed intake, nutrient digestibility, growth and reproductive performances of F1 cross breed (Boran X Friesian) dairy heifers. Wheat straw (WS) with 93% dry matter content was chopped (3-5 cm in length) and mixed with concentrate, molasses and water. The amount of water used for the preparation of total mixed ration was three fold of the molasses amount. Twelve dairy heifers (90.45 ± 7.37 kg LW, mean ±S.D) were randomly assigned to one of the three dietary treatments (WS80= 80% WS: 20% concentrate; WS60 = 60% WS: 40% concentrate) and WS40 = (40% WS: 60% concentrate) in a completely randomized block design. The diets were offered <i>ad-libitum</i> and allowing 15-20% refusal. The experiment was consisted of 345 days of feeding trial and 7 days for the measurement of digestibility. Different wheat straw and concentrate proportion had no significant effect on organic matter intake of dairy heifers. In contrast, dry matter (DM), crude protein (CP) and acid detergent fiber (ADF) and neutral detergent fiber (NDF) intakes were greater when the heifers were fed WS40 versus the other treatments. The greater (P<0.001) DM, CP, ADF and NDF digestibility, feed conversion efficiency and growth rate were observed in WS40 than the other treatments. The greater (P<0.001) body weight at first service for dairy heifers was perceived in WS80 than the other dietary treatments. Conversely, the smallest age at first service, age at first conception and number of service per conception for dairy heifers was noticed in WS40 than the other dietary treatments. Raising dairy heifers by using 40% wheat straw and 60% concentrate can be recommended for practical application.

In-vitro Antimicrobial Activity and In-vivo Prophylactic Influence of Tulathromycin against Respiratory Diseases in Dairy Heifers Exposed to Cold Stress

In-vitro Antimicrobial Activity and In-vivo Prophylactic Influence of Tulathromycin against Respiratory Diseases in Dairy Heifers Exposed to Cold Stress

Effect of Tannin-rich Mimosa pigra Leaf Meal in Molasses-based Blocks on Feed Intake, Rumen Parameters, and Blood Metabolites of Dairy Heifers

Effect of Tannin-rich Mimosa pigra Leaf Meal in Molasses-based Blocks on Feed Intake, Rumen Parameters, and Blood Metabolites of Dairy Heifers

Abstracts from the Proceedings of the 33rd Biennial Conference of the Australian Association of Animal Sciences

Encapsulated calcium butyrate (ECAB, ButiPEARL™, Kemin Industries, Inc. Des Moines, Iowa) is a novel and innovative feed technology developed to release butyrate continuously and slowly in the gastrointestinal tract of animals. Butyrate promotes rapid growth and development of rumen papillae for a better absorption of digested nutrients that enables dairy calves to transition smoothly from liquid milk to concentrates with minimal metabolic disorders (Pereira et al. 2017; Eckert et al. 2015; Ferreira & Bittar, 2011). This study investigated the effect of supplementing dairy heifer calves with ButiPEARL™ on average daily weight gain, liveweight and body conformation traits. The study was conducted using forty-eight newly born heifer calves (7 ± 0.4 days old; average liveweight 39.3 ± 5.3 kg) comprising purebred and crossbred Friesians, Jersey and Swedish Red. Calves were kept under the same pasture-based management system and utilised in a complete randomised experimental design for eleven weeks. The treatment groups included the Control (no supplementation), Low (4 kg/t) and High (6 kg/t) doses of ButiPEARL™. Feed intake, liveweight, average daily weight gain and body conformation parameters were subjected to a repeated measures general mixed model (proc mixed) analysis in SAS. Treatment diet, calf breed, dam parity, week of measurement and their first-order interactions fitted as fixed effects, while dam age was fitted as a random effect and all the initial body weight and conformation measurements fitted as covariates. Dose affected liveweight, average daily weight gain, chest girth, withers height, body length and body condition score (P < 0.05). The Low dose resulted in the highest average daily weight gain (0.83 ± 0.03 kg/day), heaviest liveweight (72.08 ± 1.6 kg), widest chest girth (95.94 ± 0.7 cm), longest body length (82.92 ± 0.6 cm) and best body condition score (1.99 ± 0.1; Table 1). Calves assigned to Control and High doses had similar liveweights (65.37 ± 1.4 kg vs 65.74 ± 1.5 kg), average daily weight gain (0.71 ± 0.0 kg vs 0.74 ± 0.0 kg) and chest girth (93.35 ± 0.7 cm vs 92.91 ± 0.7 cm; Table 1). These findings suggest that calf starter rations containing 4 kg/t ButiPEARLTM will improve overall liveweight and body conformation traits of newborn calves in a pasture-based system. Practical implications of supplementing neonatal dairy calves with ECAB is the potential to wean calves early and reduce age at first calving, which has been shown to result in improved lifetime performance. References Eckert E, Brown H, Leslie K, DeVries T, Steele M (2015) Journal of Dairy Science 98, 6315-6326. Ferreira L, Bittar C (2011) Animal 5, 239-245. Pereira GR, Barcellos JOJ, Sessim AG, Tarouco JU, Feijo FD, Neto JB, Prates ER, Canozzi MEA (2017) Revista Brasileira de Zootecnia. 46, 413-420.

Effect of season and temperature before and after calving on the future milk production of born heifers

Effect of season and temperature before and after calving on the future milk production of born heifers

The effect of individual versus pair housing of dairy heifer calves during the preweaning period on measures of health, performance, and behavior up to 16 weeks of age

Pair housing of dairy heifer calves during the preweaning period helps meet the natural social needs of the calf and has been shown to improve growth and starter intake during the preweaning period as compared with individual housing. However, there is little evidence to suggest that pair-housed calves maintain their social and growth advantages past the weaning phase. The objective of this study was to investigate the effect of pair housing on measures of calf performance, health, and behavior up to 16 wk of age. Healthy Holstein and crossbred heifer calves were enrolled in the study after colostrum feeding, with the first calf randomly assigned to 1 of 2 housing treatments: pair (PR; 2 hutches with common outdoor space) or individual (INDV; 1 hutch plus outdoor space). All calves were bucket fed 4 L of milk replacer twice daily and weaned at 50 d of age. Weaned calves (6/group) remained with their treatment group until exit from the study at 16 wk. A venous blood sample was collected from each calf between 24 h and 7 d of age to test for serum total protein (g/dL). Body weights (kg) were obtained at birth, weaning, and 16 wk. Each enrolled calf was scored for health each week and calf health treatments were also collected. A hair sample was collected from the left shoulder at birth and 16 wk to assess hair cortisol (pg/mL). At enrollment, each calf was fitted with a triaxial accelerometer on the left hind leg for continuous recording of standing and lying time (min/24 h) for 16 wk. Latency to find feed, water, and lie down (min) at entrance to the weaned pen were recorded by continuous video observation. Open field testing with a novel object was performed at 5, 10, and 16 wk. Behaviors analyzed by video observation included latency to approach the object (s), vocalizations (n), and time spent immobile, walking, or running (s/10 min). Linear mixed models were used to determine the effect of treatment (INDV or PR) on calf growth, activity, and behavioral outcomes, which accounted for time, breed, the interaction of time and treatment, the random pen, and variability in testing day and repeated measurements within calf when appropriate. Twenty-four Holstein and crossbred calves (PR: n = 12, 6 pairs; INDV: n = 12) were enrolled from November 2 to December 23, 2018. The PR calves were 7.1 kg heavier at weaning and gained 0.15 kg/d more during the preweaning period as compared with INDV calves. In the 24 h after movement to the postweaning pen, PR calves lay down for longer periods of time (14.3 vs. 11.0 ± 0.4 h/d), and PR calves urinated more during novel object testing at 5 wk of age. Our study demonstrated benefits, such as better growth and increased lying time, of pair housing calves during the preweaning period.

Short communication: Associations of serum biomarkers of stress and inflammation measured at arrival with health, mortality, and growth of calves transported within the first 4 days of life

The objective of this study was to assess the association between serum concentrations of haptoglobin (Hp), cortisol, and l-lactate following transport of dairy heifer calves within their first week of life with health, mortality, and growth during the preweaning period. Blood samples were collected at arrival and included a cohort of 168 Jersey and Jersey-cross calves from 8 different sources located in Minnesota. All calves were raised at a single facility in New Mexico. Incidence of respiratory disease (BRD) and mortality during the preweaning period (60 d of life) were extracted from the farm's software database. Individual body weight was measured at birth and at weaning to estimate average daily gain. No simple linear correlations were found between the biomarkers. The incidence of BRD during the preweaning period was 7.7%. While cortisol and l-lactate serum concentrations were not associated with BRD, Hp was negatively associated with BRD. Receiving operating characteristic curve analysis was performed to determine the optimal threshold value for Hp [threshold ≤0.63 μmol/L (63 μg/mL), area under the curve = 0.65]. A Cox's proportional hazards model revealed that calves with Hp concentration ≤0.63 μmol/L were more likely to be diagnosed with BRD (hazard ratio = 5.0, 95% confidence interval = 1.3-19.0). A mixed linear model showed that calves with Hp concentration ≤0.63 μmol/L tended to have lower average daily gain (454.4 vs. 479.9 g/d) during the preweaning period than calves with Hp >0.63 μmol/L at arrival. Overall mortality of the cohort was 3.5%, and Hp was not associated with mortality. Although circulating concentrations of l-lactate and cortisol measured at arrival were not associated with BRD incidence during the preweaning period of heifer calves transported within the first 4 d of life, calves with serum Hp concentration >0.63 μmol/L were less likely to be diagnosed with BRD and tended to grow more than calves with Hp ≤0.63 μmol/L. Further research is needed to replicate these results in a larger cohort and to better understand the possible influence of greater inflammatory status at arrival on health and growth of calves transported to a calf-raising facility.

Gene Expression of Metalloproteinases and Endogenous Inhibitors in the Lamellae of Dairy Heifers With Oligofructose-Induced Laminitis.

Bovine laminitis leads to huge economic losses and animal welfare problems in the dairy industry worldwide. Numerous studies suggested that several metalloproteinases (MPs) may play vital roles in the failure of epidermal attachment. To the best of our knowledge, the present study is the first to investigate and characterize the gene-level changes in distinct MPs and endogenous inhibitors using oligofructose (OF)-induced bovine laminitis model. The objective of this study was to determine aberrant MPs and related inhibitors of bovine laminitis in gene level, and to provide reasonable directions for the further protein-level research. Twelve normal Chinese Holstein dairy heifers were randomly divided into treatment group (n = 6) and control group (n = 6). The heifers in the treatment group were administered with OF solutions at a dose of 17 g/kg of body weight via a stomach tube. The heifers were then humanely euthanized when they met the criteria of bovine laminitis. The heifers in the control group were administered with deionized water at a dose of 2 L/100 kg of body weight. They humanely euthanized at 72 h. The gene expressions of MPs and endogenous inhibitors, namely, matrix metalloproteinases (MMPs), A disintegrin and metalloproteinases (ADAMs), and A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTs), and tissue inhibitors of metalloproteinases (TIMPs) in the lamellae from two groups were determined via real-time quantitative PCR. The gene expressions of MMP-2, MMP-9, ADAMTS-4, and ADAMTS-5 significantly increased (P < 0.05), whereas that of TIMP-2 significantly decreased (P < 0.05) in the treatment group relative to the control group. No significant difference was found in the gene expressions of ADAM-10, ADAM-17, TIMP-1, and TIMP-3. These results indicated that the gene-level imbalanced condition of MPs and their TIMPs may be the basic cause for the failure of epidermal attachment. At the same time, more detailed protein-level studies would be needed to further clarify the roles of MPs and TIMPs in the pathogenesis of bovine laminitis, especially to MMP-2, MMP-9, ADAMTS-4, ADAMTS-5, TIMP-2 as well as related substrates (e.g., aggrecan and versican).

The Effects of Dairy Heifer Age at Training on Rate of Learning and Retention of Learning in a Virtual Fencing Feed Attractant Trial

A better understanding of factors that influence learning of cattle with respect to new virtual fencing technology is required to inform the development of best practice training protocols and guide the introduction of the technology to naïve dairy cattle. This experiment examined the effect of age on (1) the efficiency of associative pairing of audio and electrical stimuli in dairy heifers and (2) the retention of this associative pairing over a long period of time without use. Fifty-nine Holstein dairy heifers were used in feed attractant trials where audio cues and electrical stimuli were delivered through manually controlled training collars. Heifers were allocated to four treatments that differed in the age at which naïve animals underwent training; these were 6-months (“6M”; n = 15), 9-months (“9M”; n = 15), 12-months (“12M”; n = 15), or 22-months of age (“22M”; n = 14). Animals in the 6, 9, and 12M treatments underwent a second round of training at 22-months of age (i.e., at the same time as naïve 22M heifers). Heifers received an audio stimulus (2 s; 84 dB) when they breached a virtual fence after which a short electrical stimulus (0.5 s; 3 V, 120 mW) was administered if they continued to move forward. If the animal stopped moving forward no further stimuli were applied. There were no effects of age treatment on the total number of interactions with the virtual fence (P &amp;gt; 0.05). During initial training, 22M heifers received a lower proportion of electrical stimuli (i.e., responded to audio without requiring the electrical stimulus; P &amp;lt; 0.001) and more frequently stopped walking (P = 0.01) and turned back (P = 0.008) following administration of the audio cue compared to younger heifers. Previous training at an early age did not improve the responsiveness of heifers to virtual fencing when re-trained at 22-months of age (P &amp;gt; 0.05). We conclude that dairy heifers should be trained to virtual fencing technology close to calving age rather than earlier in their ontogeny and that stock be re-trained following an extended period without virtual fencing technology.

HUMORAL IMMUNE RESPONSE IN CROSS-BRED HEIFERS IMMUNIZED WITH BRUCELLA ABORTUS STRAIN RB51 VACCINE IN MILITARY DAIRY FARM OF BANGLADESH

Background: Brucellosis is a chronic zoonotic disease with negligible mortality rate that might be the reason not to attract the concerned authority to prevent and eradicate it in low income endemic countries. Recently, it has been recognized as a re-emerging zoonotic disease not only in low income countries but also its eradicated developed world. Objective: The main objective was to determine the humoral immune response (HIR) in crossbred dairy heifers immunized with Brucella abortus strain RB51 vaccine by using indirect ELISA Materials and Methods: Each of the 20 randomly selected B. abortus sero-negative crossbred (Holstein-Friesian  Local) dairy heifers aged between 4 to 8 months old at the Military Dairy Farm received 2.0 ml imported commercial B. abortus SRB51 strain vaccine subcutaneously in the neck region at day 0 and then booster dose at 60 days after first vaccination with similar dose and route during the period from June to October 2020. Each of the collected serum samples of 20 heifers at day 0, 7, 14, 21, 28, 60, 90, 120 and 150 was tested to detect the antibody status by using commercial indirect ELISA kit. Results: The humoral immune response (HIR) in terms of antibody levels detected by OD values in the serum of immunized cross-bred dairy heifers by using B. abortus strain RB51 commercial vaccine resulted 0.097  0.0032 (mean  SE) OD value at 0 day (i.e. pre-immunization) and 0.108 ± 0.0032 at 7th day. After that, the OD value started to rise from day 14 (OD value 0.124 ± 0.0032) and reached to a peak level at 60 days (OD value 0.223  0.0032) with the initial vaccination. Booster vaccination inoculated at 60 days resulted peak antibody level in terms of OD value (0.313  0.0032) at the day 90 and then the antibody level started to decline from 120 days (OD value 0.242  0.0032) to 150 days (OD value 0.199 0.0032) in cross-bred dairy heifers. Conclusions: This study suggests that the commercial B. abortus RB51 strain vaccine has induced satisfactory HIR with initial inoculation and significantly higher HIR produced with a booster dose in crossbred heifers by using commercial I-ELISA. The presence of Brucella antibodies have importance on sero-diagnosis whereas the cell mediated immunity (CMI) plays major role in protection against brucellosis which needs further investigation in cross-bred heifers in Bangladesh. Keywords: Brucellosis, SRB51 vaccine, Humoral immune response, I-ELISA, Cross-bred heifers, Bangladesh

Effect of storage of wet brewer's grains with incremental levels of salt on apparent total tract nutrient digestibility and purine derivative excretion in dairy heifers.

Objectives of this study were to evaluate apparent total tract nutrient digestibility and purine derivative (PD) excretion in dairy heifers limit-fed diets containing wet brewer's grains (WBG) treated with salt. A 12-wk replicated 4 × 4 Latin square was conducted using 8 Holstein heifers of 224.5 ± 19.4 d of age, and body weight (BW) of 219.2 ± 28.1 kg (mean ± SD). Fresh WBG were treated with 0%, 0.8%, 1.6%, and 2.4% salt and stored for 4 d before being fed. Salt was added either to the WBG or separately to equalize the amount of salt in the diet. The diet contained 9% grass silage, 47% corn silage, 19% corn meal, 17.6% WBG and salt, 2% soybean meal, and 3% mineral mix. Diets were formulated to be limit-fed at 2.15% of BW, provide 14% crude protein (CP) and 2.27 Mcal metabolizable energy (ME)/kg of dry matter (DM). Heifers were adapted to diets for 14 d followed by a 7-d collection period. Dry matter intake (DMI) was recorded daily during the collection week while BW was recorded once a week. Urine and fecal samples were collected during the last 4 d of the collection period. Acid insoluble ash was used as an internal marker to determine apparent nutrient digestibility. Weight loss of WBG during storage was determined from days 1 to 11 and initial and final yeast and mold counts were determined. Final yeast counts were similar among treatments while final mold counts tended to be lesser (P = 0.07) for the 0.8% and 1.6% salt treatments. Urinary volume was similar among treatments while allantoin (P = 0.14), and uric acid (P < 0.01) and total PD excretion tended to increase (P = 0.13) quadratically. DMI was varied by treatment (linear, quadratic, and cubic effects P < 0.01). Heifers fed the 0.8% treatment had the least DMI. Nonfiber carbohydrate (NFC) digestibility linearly decreased (P < 0.04) as salt increased. Digestibilities of DM, and organic matter (OM), tended to decrease (P < 0.10) with increasing levels of salt added to WBG. Fat digestibility was quadratic with the greatest value for the 1.6% treatment. Treating WBG with salt reduced its deterioration based on lesser mold counts for the 0.8% and 1.6% treatments. These treatments had resulted in greater fat digestibility and tended to have increased PD excretion suggesting improved microbial protein synthesis.

Short- and long-term effects of initial serum total protein, average starter feed intake during the last week of the preweaning period, and rearing body gain on primiparous dairy heifers' performance

The aim of this study was to evaluate the short- and long-term effects of initial serum total protein (STP) concentration, average starter feed intake (SI) during the last week of the preweaning period, and average daily gain (ADG) on the growth, fertility, and performance of Holstein heifers during their first lactation. Eighty-four female Holstein dairy calves were weaned at d 56 of age and then the study continued until the end of the first lactation. Growth performance, including body weight, ADG, withers height, and its change were analyzed monthly from 3 to 450 d of life, and reproduction data and performance in the first lactation of primiparous dairy heifers over a 4-yr period (2015 to 2019) were recorded. In the first 24 h of life, calves received 4 L of colostrum (<2 h and <12 h after birth); on d 2 and 3: 2 feedings/d of 2 L of transition milk; from d 4 to 49: 6 L/d of milk replacer (150 g of powder/L as-fed) in 3 feedings; and from d 50 to 56: 2 L/d of milk replacer in 1 feeding. The calves were fed pelleted starter feed from d 4 to 56, and after that from 8 wk until 3 mo of age, a dry total mixed ration with an 85:15 ratio of weaning pelleted starter to straw. From 3 to 7 mo and from 8 mo of age to calving, the total mixed ration contained 16.9% and ~14.0% crude protein, respectively, on a dry matter basis and ~2.40 Mcal of metabolizable energy/kg on a dry matter basis. The results of the current study showed that the initial STP concentration of primiparous dairy heifers was associated with improved growth performance, especially greater body weight and withers height. In addition, with increasing levels of initial STP concentration, age at first estrus, artificial insemination (AI) service, pregnancy, and calving was decreased by 16, 18, 25, and 25 d, respectively. Initial STP concentration was positively correlated with milk production and increased total milk yield and yield of energy-corrected milk by about 1,558 kg and 1,149 kg during first lactation. Calves with higher average starter feed intake during the last week of the preweaning period had better growth performance, which in turn was positively associated with fertility parameters, accelerated first estrus (by 17 d), and reduced age at AI service (by 13 d). Preweaning ADG was favorably associated with fertility performance of heifers, with faster occurrence of first estrus and a reduction in age at AI service, pregnancy, and calving. Also, increasing preweaning ADG increased milk yield, energy-corrected milk, and 4% fat-corrected milk at 305 DIM by about 829, 754, and 763 kg at first lactation of primiparous heifers. These results indicate that in the rearing period, particular attention should be paid to the initial STP concentration, average SI during the last week of this period, and rearing ADG to increase growth, fertility, and performance in the first lactation of primiparous dairy heifers.

Grazing of cover crops in integrated crop-livestock systems

Conventional agriculture is specializing rapidly into the management of few monoculture crops, threatening crop diversity and questioning the sustainability of extensive cropping systems. The grazing of cover crops in integrated crop-livestock systems could be a feasible biologically based technology to restore crop diversity and mitigate ecological issues in cropping systems. However, there is limited evidence on plausible synergies or trade-offs for the practice, and about how grazing plans could affect the herbage production and services from cover crops. This work assessed the effects of cattle grazing on the primary and secondary production of annual ryegrass (Lolium multiflorum) in an integrated ryegrass–soybean rotation system. Specifically, the prediction for synergistic effects of cattle grazing on the ryegrass herbage production, residual crop cover and animal performance were tested in a 2-year (2014 and 2015) study comprising a randomized complete block design of four grazing intensity treatments, replicated three times. A no-cattle grazing treatment (NG), used as control, or continuous grazing with Holstein heifers (~220kg live weight) at targeted sward heights of 5, 10, 15 and 20cm (hereafter referred as G5, G10, G15 and G20, respectively) was applied to ryegrass plots. The herbage production and residual herbage cover of ryegrass, and the average daily gain (ADG, kg/day) and live weight gain per hectare (LWG, kg/ha) of heifers were analyzed by ANOVA (P<0.05) and compared by the TukeyHSD test (P<0.05). Regression models were used to estimate relationships between herbage production, animal performance and sward height. The herbage production was 60% higher (P<0.01) for the grazing treatments compared to NG. The residual herbage for G15 and G20 was not different than that for NG and increased linearly as sward heights increased, reaching highest values for G15 and G20. Maximum ADG was 1.10kg/day for ryegrass grazed at a 20.6cm height, whereas maximum LWG was 427kg/ha for ryegrass grazed to a 16.1cm height. The results support the hypothesis for synergistic effects of using annual ryegrass as a dual forage and service cover crop. Moderate grazing intensity to sward height of 12–18cm with continuous stocking led to optimized forage production and utilization by dairy heifers.

Textured vs pelletted feed impact on dairy heifers pre-weaning

Textured vs pelletted feed impact on dairy heifers pre-weaning

Measurement of transfer of colostral passive immunity in dairy calves

Measurement of transfer of colostral passive immunity in dairy calves

Nutritive value of ensiled Italian ryegrass and winter cereal mixture

Nutritive value of ensiled Italian ryegrass and winter cereal mixture

Economics of respiratory disease in dairy replacement heifers.

Bovine respiratory disease (BRD) is a frequent disease concern in dairy cattle and is most commonly diagnosed in young dairy heifers. The impact of BRD is highly variable, depending on the accuracy and completeness of detection, effectiveness of treatment, and on-farm culling practices. Consequences include decreased rate of weight gain, a higher culling risk either as heifers or as cows, delayed age at first service, delayed age at first calving, and in some cases, lower future milk production. In this data set of 104,100 dairy replacement heifers from across the USA, 36.6% had one or more cases diagnosed within the first 120 days of age with the highest risk of new cases occurring prior to weaning. Comparison of the raising cost for heifers with BRD and those without a recorded history of BRD resulted in an estimated cost per incident case occurring in the first 120 days of age of $252 or $282, depending upon whether anticipated future milk production differences were considered or not. Current market conditions contributed to a cost estimate that is significantly higher than previously published estimates, driven in part by the losses associated with selective culling of a subset of heifers that experienced BRD.

Non-genetic effects affecting fertility traits in local Reggiana cattle

Submitted 2020-07-24 | Accepted 2020-09-22 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.338-346 The objectives of this study were to investigate non-genetic sources of variation of fertility in Reggiana cattle and identify the best model for future genetic analysis. Moreover, the variation of target fertility traits in the different parities and months of first service was evaluated. The investigated fertility traits were interval between calving and first insemination, interval between calving and conception, number of inseminations per conception, and calving interval. The dataset included 22,731 records of 10,502 cows, collected between 1986 and 2019. Four different models were tested: Model 1 included the fixed effects of herd-year-month of first service and parity; Model 2 separately accounted for herd-year and month of first service, in addition to parity; Model 1a and Model 2a were Model 1 and Model 2 with the addition of the effect of age at first insemination. Model 1 had an average coefficient of determination of 0.40 for the traits, and this value increased to 0.48 in Model 1a. Moving to Models 2 and 2a, the coefficient of determination dropped to average values of 0.21 and 0.27, respectively. Regarding the effect of month of first service, the best fertility performances were observed in March and April, whereas for parity effect the best performance was in third lactation. Model 1a presented the best R2 for all studied traits but data editing for age at first insemination was too strict. On the other hand, in Models 2 and 2a variance absorbed by fixed effects was low, and this resulted in potentially biased estimates. Model 1 was therefore the best trade off between data loss and predictivity. Keywords: fertility, local cattle, Reggiana, source of variation, modelling References Cavestany, D. et al. (1985). Effect of season and high environmental temperature on fertility of Holstein cattle. Journal of Dairy Science, 68(6), 1471–1478. https://doi.org/10.3168/jds.S0022-0302(85)80985-1 Forabosco, F., Mantovani, R. and Meneghini, B. (2011). European and Indigenous Cattle Breeds in Italy. Schiel & Denver Publishing Limited. Retrieved from https://books.google.it/books?id=BiA0YAAACAAJ Gandini, G. et al. (2007). Comparing local and commercial breeds on functional traits and profitability: The case of Reggiana dairy cattle. Journal of Dairy Science, 90(4), 2004–2011. https://doi.org/10.3168/jds.2006-204 Gonzalez-Recio, O. and Alenda, R. (2005). Genetic parameters for female fertility traits and a fertility index in Spanish dairy cattle. Journal of Dairy Science, 88(9), 3282–3289. https://doi.org/10.3168/jds.S0022-0302(05)73011-3 Groen, A. F. et al. (1997). Economic values in dairy cattle breeding, with special reference to functional traits. Report of an EAAP-working group. Livestock Production Science, 49(1), 1–21. https://doi.org/10.1016/S0301-6226(97)00041-9 R Core Team. (2017). R: A Language and Environment for Statistical Computing. Vienna, Austria. Schaeffer, L. R. (2018). Necessary changes to improve animal models. Journal of Animal Breeding and Genetics, 135(2), 124–131. https://doi.org/10.1111/jbg.12321 Tiezzi, F. et al. (2012). Genetic parameters for fertility of dairy heifers and cows at different parities and relationships with production traits in first lactation. Journal of Dairy Science, 95(12), 7355–7362. https://doi.org/10.3168/jds.2012-5775 Tiezzi, F. et al. (2011). Genetic analysis of fertility in the Italian Brown Swiss population using different models and trait definitions. Journal of Dairy Science, 94(12), 6162–6172. https://doi.org/10.3168/jds.2011-4661 Van Bebber, J. et al. (1997). Accounting for herd, year and season effects in genetic evaluations of dairy cattle: A review. Livestock Production Science, 51(1–3), 191–203. https://doi.org/10.1016/S0301-6226(97)00058-4