Dairy Heifers Research Articles

The effect of stocking density and a blind on the behavior of Holstein dairy cattle in group maternity pens. Part I: Calving location, locomotion, and separation behavior

In a more natural setting, dairy cows separate from herdmates and seek a secluded area to give birth. However, on many dairy facilities, cows calve in barren group pens with limited space, which may limit their ability to perform these behaviors. The objective of this study was to determine the effect of stocking density and provision of a blind (a single-sided solid partition) in group bedded pack maternity pens on the behavior of dairy cattle. The study included 4 experimental treatments: (1) high stocking density (7.7-12.9 m2 of lying space/cow) with a blind, (2) low stocking density (15.4-25.8 m2) with a blind, (3) high stocking density without a blind, and (4) low stocking density without a blind. We analyzed the effect of these treatments on locomotor and separation behavior as well as blind use during the 24 h before calving. A total of 127 primiparous heifers and 247 multiparous cows were housed in 16 mixed-parity groups (4 groups per treatment) from approximately 3 wk before to immediately after calving. Locomotor behavior increased from 24 to 2 h before calving regardless of treatment but increased the most in high stocking density pens without a blind. Additionally, heifers performed more locomotion than cows. Animals increased their distance from other cows beginning approximately 4 h before calving. Animals in low stocking density pens had a greater distance from other cows compared with those in high stocking density pens. Additionally, heifers had a greater distance from penmates during the 4 h before calving than cows. More animals calved in the area of the pen that contained a blind compared with the same respective areas of high and low stocking density pens that did not contain a blind. These results suggest that periparturient dairy cattle in group maternity pens are motivated to seek seclusion at calving, but increased stocking density may impede their ability to do so. Providing additional space and a blind may benefit periparturient dairy cows and heifers by facilitating natural calving behaviors.

Effect of sealing strategy on the feeding value of corn silage for growing dairy heifers

Our objective was to compare the performance of dairy heifers fed diets based on whole-plant corn silage stored in bunker silos sealed with either standard polyethylene film (white-on-black, actual thickness 121 ± 3.1 µm) covering the top surface, held in place with rows of tires every 3 m (PE) or an oxygen barrier system comprised of an ethylene-vinyl alcohol film (actual thickness 46.7 ± 2.5 µm) lining side walls and covering the silage, protected with a woven anti-UV cover and gravel bags placed around the edges and every 3 m across the silo (OB). Whole-plant corn was mechanically harvested at 39% dry matter (DM), packed in bunker silos, and sealed with PE or OB covering methods. After 6 mo of storage, silos were opened and fed to 26 Holstein heifers (260 ± 89.1 kg of shrunk body weight) for 60 d. Heifers were blocked by initial weight (13 blocks with 2 heifers each block) and housed in individual pens. Diets contained (on a DM basis) 80% corn silage (PE or OB), 17.5% soybean meal, and 2.5% mineral mix. Dry matter intake was measured daily, whereas shrunk body weight, hip height, heart girth, and body condition score were measured at the beginning and end of the experiment. Feeding behavior was recorded on d 24 and 46, and total-tract digestibility was measured from d 26 to 30 and 48 to 52. Data of intake, feeding behavior, and digestibility were averaged by animal for the whole feeding period before the statistical analysis. Data of animal performance were analyzed as a randomized complete block design. Initial shrunk body weight was used as a covariate for analyses of intake and body measures. During feed-out, silage quality was also assessed at the top (15 cm depth from upper surface) and bottom layer (135 cm depth from upper surface) and analyzed as a split-plot design. Silage stored under the OB sealing system had less yeast, mold, and NH3-N, and more lactic acid and ethanol-soluble carbohydrates. An interaction between sealing strategy and silo layer showed that OB silage had lower values of temperature, pH, anaerobic spores, acetic acid, and DM loss, and greater in vitro DM digestibility and aerobic stability, especially in the top layer. The proportion of inedible silage was lower in OB than in PE treatment (0.82 vs. 4.00% DM). Total-tract digestibility was similar between treatments, but animals that received the OB diet had higher DM intake by approximately 9% (9.39 vs. 10.20 kg/d) due to a faster eating rate and a greater number of meals per day. Therefore, OB treatment increased the digestible energy intake by 8% (26.3 vs. 28.3 Mcal/d) and average daily gain by 12% (1.08 vs. 1.21 kg/d). Body condition score change was similar between treatments, but heifers fed OB had greater heart girth and tended to have higher hip height. In conclusion, replacing a standard PE film with an OB sealing system improved silage conservation and performance of growing dairy heifers.

Effects of mannan-oligosaccharide and Bacillus subtilis supplementation to preweaning Holstein dairy heifers on body weight gain, diarrhea, and shedding of fecal pathogens

The objective of this clinical trial was to evaluate the effectiveness of probiotic, prebiotic, and synbiotic supplementation on average daily weight gain (ADG), duration of diarrhea, age at incidence of diarrhea, fecal shedding of Cryptosporidium oocysts, enteric pathogens, and the odds of pneumonia in preweaning dairy heifer calves on a commercial dairy. Feeding prebiotics and probiotics may improve health and production of calves. Hence, healthy Holstein heifer calves (n = 1,801) from a large California dairy were enrolled at 4 to 12 h of age and remained in this study until weaning at 60 d of age. Calves were block randomized to 1 of 4 treatments: (1) control, (2) yeast culture enriched with mannan-oligosaccharide (prebiotic), (3) Bacillus subtilis (probiotic), and (4) combination of both products (synbiotic), which were fed in milk twice daily from enrollment until weaning. Serum total protein at enrollment and body weight at 7, 42, and 56 d of age were measured. Fecal consistency was assessed daily for the entire preweaning period. A subgroup of 200 calves had fecal samples collected at 7, 14, 21, and 42 d for microbial culture and enumeration of Cryptosporidium oocysts by direct fluorescent antibody staining. Synbiotic-treated calves had 19 g increased ADG compared with control calves for overall ADG, from 7 to 56 d. From 42 to 56 d, prebiotic-treated calves had 85 g greater ADG and synbiotic-treated calves had 78 g greater ADG than control calves. There was no difference in duration of the first diarrhea episode, hazard of diarrhea, or odds of pneumonia per calf with treatment. Probiotic-treated calves had 100 times lower fecal shedding of Cryptosporidium oocysts at 14 d and prebiotic-treated calves had fewer Escherichia coli and pathogenic E. coli at 42 d compared with control calves. Although there were no effects on duration of diarrhea or pneumonia incidence, greater ADG in the late preweaning period may reflect treatment effects on enteric pathogens during the rearing process. The decreased shedding of Cryptosporidium should reduce infectious pressure, environmental contamination, and public health risks from Cryptosporidium. Our findings suggest ADG and potential health benefits for calves fed prebiotics, probiotics, and synbiotics and can help the dairy industry make informed decisions on the use of these products in dairy production.

Adaptation and withdrawal of feeding dried Aspergillus oryzae fermentation product to dairy cattle and goats on in vitro NDF digestibility of selected forage sources.

Nutritional fermentation aids [dried Aspergillus oryzae fermentation product (AO)] are used in livestock production to increase nutrient digestion and production efficiency. The objective was to determine AO impact on neutral detergent fiber (NDF) degradation of selected forage sources (FS). A series of in vitro fermentation experiments were conducted using rumen fluid (RF) from rumen fistulated dairy heifers or dairy goats evaluating AO at 0.0, 0.3, or 0.6 g/L inclusion rates. In experiment I, the optimum AO concentration using alfalfa hay (AH), Bermuda grass (BG) hay, and peanut skins (PS) was determined via 48-h in vitro neutral detergent fiber digestion (IVNDFd). In experiment II, 0.0 g/L and 0.3 g/L AO were used to determine in vitro dry matter digestion (IVDMD), in vitro organic matter digestion (IVOMD), IVNDFd, and NDF digestion kinetics. In experiment III, in vivo AO ruminal adaptation (AD) and withdrawal (WD) times were determined for both dairy heifers and goats on IVDMD, IVOMD, IVNDFd, and NDF digestion kinetics. In experiment I, IVNDFd was similar using RF from dairy heifers or goats with IVNDFd being increased 10%, 28%, and 23% for AH, BG, and PS, respectively, at 0.3 g/L of AO compared with 0.0 g/L AO, while adding 0.6 g/L AO reduced IVNDFd among all FS. In experiment II, IVNDFd was greater when adding 0.0 g/L AO compared with 0.3 g/L AO using dairy goat RF (26.7% and 37.6%, respectively) among all FS. The mean retention time and 50% digestion times were greater, while digestion rate was lower for PS compared to AH and BG. In vitro dry matter (DM) and organic matter (OM) digestibilities were greater with AO for AH and BG compared to PS but varied with RF donor source. In experiment III, in vitro DM digestibility increased then decreased with adaptation time, while AO withdrawal increased digestion of DM, OM, and NDF. The NDF digestion kinetics were similar across all FS (AH, BG, and PS), which resulted in no clear determination of AO adaptation and withdrawal times needed for AO efficacy. The optimal AO inclusion rate was determined to be 0.3 g/L for improving in vitro NDF digestion, but subsequent experiments could not confirm that inclusion rate. Inclusion rates greater than 0.3 g/L depressed NDF degradation, which should be avoided due to depression of NDF digestion. Sourcing ruminal fluid from dairy heifers or goats for conducting in vitro fermentations resulted in similar DM, OM, and NDF digestion and NDF degradation kinetics.

Effect of late-gestation heat stress in nulliparous heifers on postnatal growth, passive transfer of immunoglobulin G, and thermoregulation of their calves

Youngstock such as nulliparous pregnant dairy heifers are not typically considered for active cooling, as they are thought to be more heat tolerant than mature cows. Recently, the benefits of heat stress abatement in pregnant heifers were studied, but the effect of in utero hyperthermia on the calf is still unknown. Herein, we aimed to investigate the effects of late-gestation heat stress in nulliparous heifers on the growth, immune, and thermoregulatory responses of their calves. Pregnant nulliparous dams were randomly selected for either active cooling (CL; fans and soakers; n = 15) or heat stress (HT; n = 16) 60 d before expected calving. After birth, respiration rate, rectal temperature, skin temperature, and sweating rate were obtained from their heifer calves at 24 h and on d 14, 28, 42, and 56. Blood samples and body weights were both collected for measurement of total protein and hematocrit and calculation of average daily gains, respectively. Gestation length was shorter in HT heifers (272 vs. 276 ± 1.28 d) relative to CL heifers. Birth weights, weaning weights, body weights up to d 56, and average daily gain from birth to weaning were not different between in utero HT (IUHT; n = 13) and in utero CL (IUCL; n = 12) calves. Apparent efficiency of absorption of immunoglobulin G tended to be lower in IUHT calves (26.3 vs. 42.7 ± 9.0%), and serum IgG concentrations from birth to d 56 were significantly lower in IUHT calves relative to IUCL calves (22.0 vs. 32.4 ± 4.47 g/L). Postnatal respiration rate, rectal temperature, sweating rate, total protein, and hematocrit were not different between in utero treatments. There was a tendency for IUHT calves to have lower skin temperature at 24 h (34.9 vs. 36.9 ± 1.05°C), and skin temperature tended to be elevated in IUHT calves at d 56 (29.6 vs. 27.9 ± 1.05°C). In summary, the lack of heat stress abatement during late gestation reduces gestation length of nulliparous heifers. Additionally, providing active cooling to nulliparous heifers during the prepartum period confers immune benefits to their offspring, although it does not translate to growth improvements.

Effects of a blend of essential oils in milk replacer on performance, rumen fermentation, blood parameters, and health scores of dairy heifers.

The aim of this study was to evaluate how the inclusion of a blend of essential oils in milk replacer (MR) affects different outcomes of dairy heifers. The outcomes evaluated: feed intake, performance, body development, blood cells and metabolites, insulin-like growth factor-1 (IGF-1), rumen fermentation, fecal scores, and respiratory scores. All outcomes were evaluated during pre-weaning (4-60 d of age), and carry-over effects during post-weaning (61-90 d of age) periods. The experimental units utilized were 29 newborn Holstein × Gyr crossbred dairy heifers, with genetic composition of 5/8 or more Holstein and 3/8 or less Gyr and body weight (BW) at birth of 32.2 ± 5.2 kg. Experimental units were assigned to either a control (CON, n = 15) or a blend of essential oil supplementation (BEO, n = 14) treatment, maintaining a balance of genetic composition. The BEO was supplemented in the MR with 1 g/d/calf of a blend of essential oils (Apex Calf, Adisseo, China) composed by plant extracts derived from anise, cinnamon, garlic, rosemary, and thyme. During the pre-weaning phase, all heifers were fed 5 L of MR/d reconstituted to 15% (dry matter basis), divided into two equal meals. Water and starter were provided ad libitum. During the post-weaning, animals received a maximum of 3 kg of starter/d, and ad libitum corn silage, divided into two meals. Feed intake, fecal and respiratory scores were evaluated daily. The BW was measured every three days, while body development was recorded weekly. Blood samples were collected on 0, 30, and 60 d of age for total blood cell count, weekly and on the weaning day to determinate ß-hydroxybutyrate, urea and glucose, and biweekly for IGF-1. Ruminal parameters (pH, volatile fatty acids, ammonia-N, and acetate:propionate proportion-C2:C3) were measured on days 14, 28, 42, 60, 74 and 90. A randomized complete block design with an interaction between treatment and week was the experimental method of choice to test the hypothesis of the BEO's effect on all outcomes. An ANOVA procedure was used for continuous outcomes, and a non-parametric test was used for the ordered categorical outcomes, both adopting a CI = 95%. Results indicated that there was not enough evidence to accept the alternative hypothesis of the effect of BEO in MR on feed intake, performance, body development, and blood metabolites during both pre-weaning and post-weaning periods. However, results indicated that the inclusion of BEO in MR significantly affects the proportion of C2:C3 during pre- and post-weaning (P = 0.05). Similarly, the effect was significant for basophil (P ≤ 0.001), and platelet (P = 0.04) counts pre-weaning. The interaction between week and treatment was also significant for lymphocytes (P ≤ 0.001), revealing a cumulative effect. Lastly, fecal scores were also significant (P = 0.04) during pre-weaning, with lower values for BEO. The BEO contributed to ruminal manipulation in pre-weaning and carry-over effects in post-weaning, immunity improvement, and decreased morbidity of neonatal diarrhea in the pre-weaning phase.

Effects of positive reinforcement training for heifers on responses to a subcutaneous injection

Cattle are subjected to routine procedures that require restraint and close contact to humans, which are both potentially aversive to the animal. Positive reinforcement training techniques may affect how animals perceive and respond to these procedures. The objectives of the current study were to describe a positive reinforcement regimen used to train cattle to stand still for a sham injection, and to assess the effects of this training on the responses to an actual injection. Eight "agency" heifers were trained, over an average of 85 ± 4.6 sessions, with positive reinforcement (i.e., animals received a grain reinforcer for desired behaviors) to enter a headlock, and they were habituated with counterconditioning and desensitization to a sham injection (i.e., animals were gradually exposed to the sensation of the sham injection, paired with access to grain). The headlock remained open at all times to allow heifers to leave. Eight "habituation" heifers were exposed to the treatment area and headlock for an equal number of sessions and duration as agency heifers, and 7 "naïve" heifers were provided no exposure to the treatment area. Once agency heifers tolerated the sham injection, all animals received a 1-mL subcutaneous injection of 0.9% NaCl while in the head lock (habituation and naïve heifers were locked in but agency heifers were free to withdraw). Immediate responses to the injection, starting with tenting of the skin, were video recorded and summarized as a reactivity score, which included the number of steps, head tosses, and backing-up movements; we also recorded the latency to approach the treatment area and headlock for 3 d after the injection. Of the agency heifers, 5 remained standing for the actual injection, whereas 3 heifers moved out of the headlock for a brief period (1, 3, and 5 s, respectively). Habituation heifers had a higher reactivity score [17.5 (10.5-28); median (IQR)] than agency [6 (2-13.5)] and naïve heifers [6 (5-7)]. Averaged over the 3 d after injection, agency heifers showed lower latencies to come to the treatment area [8.7 (7.2-24.2) s] than did habituation [50.5 (28-60) s] and naïve [53.7 (18-60) s] heifers. Agency heifers voluntarily entered the headlock within 1.3 (1-1.5) s but, with one exception, none of the other heifers did so within the allowed 15 s. These results indicate that dairy heifers can be trained with positive reinforcement and counterconditioning to voluntarily accept a painful procedure, and that training can reduce avoidance behaviors during and after the procedure.

Lameness in dairy heifers: a narrative review of control strategies

Lameness is a prevalent condition in mature dairy cows, but the common underlying diseases — sole bruising-sole ulcers, white line lesions and digital dermatitis — invariably arise from management factors in first lactation or rearing. The published evidence would indicate once infected by the Treponemes causing digital dermatitis, heifers retain these bacteria in the skin despite apparent clinical resolution, meaning the emphasis of control should be placed on minimising risk of early life exposure, largely through biocontainment, foot cleaning and foot disinfection. For sole bruising and sole ulcers, there has been a major switch from the acidosis and laminitis-base models of disease, to a biomechanical pathogenesis for claw horn lesions. This has focused attention on the development and preservation of the digital cushion, with the emphasis on preventive strategies combined with early intervention involving anti-inflammatory drugs among other things. This article reviews the evidence-based underpinning the rationale that heifers should be the focus of foot health control, a message that can be challenging to convey when the perceived problem invariably sits with how to deal with chronic, end-stage lesions.

Use of an automatic needle-free injection device for foot-and-mouth disease vaccination in dairy heifers

The foot-and-mouth disease (FMD) vaccination of Thai dairy cows is routinely conducted to control and prevent the disease. In Thailand, FMD control strategies include a subcutaneous route (s.c.) vaccination with 2 ml of inactivated FMD vaccine 2–3 times a year produced by the Department of Livestock Development (DLD). A new way of vaccination was introduced in the form of an automatic needle-free injection device. This technology has several important advantages, such as requiring less animal restraint, reduced time and labour with high precision, and a consistent delivery system. Here, the effectiveness of an automatic needle-free injection (ANFI) device was evaluated in 30 dairy heifers (randomly divided into three groups, 10 in each group) in the FMD vaccine delivery. The first group was subcutaneously (s.c.) vaccinated using a conventional hypodermic needle with 2 ml of the vaccine, the second group received the same, but using a CO<sub>2</sub>-powered ANFI device, and the third group received the vaccine using the same ANFI device, but administered intradermally (i.d.) with only 1 ml of the vaccine. The blood samples collected up to 120 days post-vaccination revealed that both injection methods resulted in a similar serological response. The results suggest that the i.d. and s.c. ANFI systems are effective and safe. Moreover, the i.d. use of the ANFI enabled the possibility to half the vaccination dose with the same efficacy. Therefore, the ANFI can be used as an alternative approach for FMD vaccination by s.c. or i.d. routes in dairy cows in Thailand. Ultimately, reducing the use of restraint devices and labour will improve the vaccination for the prevention and control of FMD and may improve the cows’ welfare.

Effects of feed intake and forage-to-concentrate ratio on the relationship between the ruminal mat score and rumen fermentation and rumination activity in dairy heifers

Effects of feed intake and forage-to-concentrate ratio on the relationship between the ruminal mat score and rumen fermentation and rumination activity in dairy heifers

Effects of Feeding Level and Breed Composition on Intake, Digestibility, and Methane Emissions of Dairy Heifers.

Simple SummaryThe nutrients requirements of dairy cattle is the most used system to formulate dairy cattle diets. However, these guidelines were developed based on research using mostly purebred Holstein in temperate conditions and did not determine nutrient requirements of crossbred Holstein × Gyr or Gyr animals raised in a tropical environment. Studies conducted in tropical conditions demonstrated that breed largely affected the nutrient requirements of crossbred and Gyr cattle, which limits the use of this system. Our objective was to evaluate the effects of two feeding levels and three breed compositions on nutrient intake, digestibility, performance, and methane emissions of prepubertal (10-month-old) dairy heifers. We observed that feeding diets to allow gains of 400 and 800 g/day resulted in greater daily gain than the formulated, overestimating the nutritional requirements of the heifers. Overall, breed composition did not affect dry matter intake, but it did result in differences in nutrients digestibility coefficients and feed efficiency. Feeding prepubertal heifers above maintenance requirements was the main driver in reducing CH4 intensity in confinement conditions.The dairy Nutrients Requirements of Cattle (NRC) was developed using data from purebred Holsteins and it might not accurately predict the performance of crossbred cattle. Our objectives were to evaluate the effects of two feeding levels (FLs) and three breed compositions (BCs) on nutrient intake, digestibility, performance, and methane (CH4) emissions of prepubertal dairy heifers. We used thirty-six heifers from three BCs: purebred Holstein (H), purebred Gyr (G), and F1 Holstein × Gyr (HG). Each BC had 12 animals and the experiment was designed as twelve incomplete three by three Latin squares, in a factorial arrangement three by two, with three BCs and two FLs (400 and 800 g/day). Total tract nutrient digestibility was determined using total fecal collection and DMI was individually measured. The data were analyzed using the PROC MIXED in SAS. Dry matter intake of all nutrients increased from the medium to high feeding level and the nutrients digestibility coefficients did differ among BCs. Achieved body weight gain in the medium FL treatment was greater than those predicted using the NRC, suggesting that crossbred and Gyr heifers have similar performance to Holsteins. Breed composition does not influence body weight gain of confined dairy heifers, but Holstein heifers fed a medium FL had higher feed efficiency and reduced CH4 emissions intensity.

A field study using different technologies to detect calving at a large-scale hungarian dairy farm.

The objective of this study was to investigate three different calving detection systems in order to assess and compare their efficiency. The study was conducted at a large-scale dairy farm involving 54 Holstein-Friesian dairy cows and heifers. Animals were fitted with multiple devices: a rumination measuring device (Ruminact® (RA)), an intravaginal thermometer (Vel'Phone® (VP)) and a tail movement sensor (Moocall® (MC)) 5 to 7days before expected calving and were removed after parturition. RA detects rumination time (RT) and calculates it in 2-hr intervals. VP detects a decrease in vaginal temperature that might indicate calving within 48hr and the drop in temperature resulting from the expulsion of the device at calving (EXP message). MC detected increased tail movements and if they persisted for one hour, 1HA message was sent. If they continued during the subsequent hour, then 2HA message was sent. Messages sent by MC within 4hr before calving (C4) were selected retrospectively as true positives for the prediction of calving, using the significant changes in RT as a baseline. All other messages were categorized as false positive. The mean value of RT decreased in a non-significant manner between interval -22 and -4 before calving. Significant decrease of RT was detectable between the two intervals of -4 and -2 before calving (24.7±18.6min/2hr and 14.0±13.0min/2hr, respectively). There was no significant difference between RT of primiparous and multiparous animals. EXP messages were accurate (positive predictive value 100%) indicators of the onset of calving. We received on average 12.7±15.2 messages/animal (11.0±10.1 and 16.6±22.2 for cows and heifers, respectively). Positive predictive value was 12.6%. The number of false-positive messages was significantly higher in heifers. All three automatic systems could be used in a large-scale farm environment.

Use of infrared thermography to estimate enteric methane production in dairy heifers

ABSTRACT The trial aimed to investigate the use of infrared thermography (IRT) to estimate enteric methane production in dairy heifers. The study lasted 5 days with 36 Gyr, Gyr x Holstein and Holstein heifers. The sulphur hexafluoride (SF6) tracer technique was used to estimate methane emission. Superficial body temperature was obtained with an infrared camera (FLIR® T300) on each side of the animals at 20-minute intervals during eight hours after the morning feeding. Data were analysed using Pearson’s correlation analysis and multivariate regression analysis, as well as two multivariate tests to investigate the relationship with methane emission. The analysis considered all the data together (total) and three subsets: initial (0–150 minutes), middle (150–300) and final period (300–442 minutes after feeding). Based on R2 and canonical correlations, the best predictive capacity of methane emission by IRT occurred in the initial and final periods after feeding. Infrared thermography may be a good estimator of methane emission using the SF6-tracer technique when considering the flanks’ temperature.

The effects of diurnal heat stress in dairy heifer calves

<span style="font-size:10.0pt;line-height:107%;font-family:&quot;Times New Roman&quot;,serif;mso-fareast-font-family:Calibri;mso-fareast-theme-font:minor-latin;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language:AR-SA">The present study was conducted to examine how dairy heifer calves would respond to a heat stress bout in terms of growth relative to nutrient intake. Nine Holstein and 2 Jersey heifer calves (n = 11) were individually housed and enrolled in a study containing 3 experimental periods (P). Period 1 lasted 7 d during which baseline measurements were obtained. During period 2 (7 d), calves were subjected to diurnal heat stress (<b>dHS</b>) employed by maintaining barn temperature at 33°C (92°F) from 0900 to 2100 h and letting it be equilibrated with outside temperature [24°C (75°F)] during the night. Follow-up measurements were made over 4 d (P3) immediately after dHS. Calves consumed 25% less feed during the day but compensated for it consuming more feed (35%) in night during dHS. Despite DMI (kg/d) being similar between dHS and baseline, ADG and feed efficiency decreased significantly during dHS. These effects are likely consequence of nutrient repartitioning towards the activated immune system and away from productive processes (i.e., growth), as blood haptoglobin increased 3-fold during dHS. Nonetheless, calves exhibited compensatory growth concurrently with increased DMI and drinking water per unit of DMI immediately following dHS. Overall, dHS severely hampers growth and feed efficiency of dairy heifer calves despite unaltered DMI relative to baseline. Understanding nutrient partitioning in calves during and after heat stress could help mitigate the adverse effects and help calves effectively recover from heat stress.</span>

Pasture and animal production in silvopastoral and open pasture systems managed with crossbred dairy heifers

The objective of this study was to evaluate the pasture traits and performance of crossbreed dairy heifers in a silvopastoral system (SPS) and open pasture (OP) of Urochloa decumbens, after 14-years of management. In the SPS, an average reduction of 46% in the photosynthetically active radiation (PAR) was calculated in relation to the OP. Experimental design was a randomized complete block, with three replications and two treatments (SPS and OP), evaluated in two seasons (summer and autumn), during three years. The paddocks were managed under continuous stocking with Holstein × Gyr heifers. The herbage mass was greater in OP, but a greater leaf and lower dead material percentages were observed in the SPS. The OP had higher tiller population than SPS only in the first year. The herbage accumulation was higher in the OP during autumn; however during summer only a trend was observed. The crude protein content was greatest in SPS, while the fiber constituents and forage digestibility did not vary with system. The stocking rate was greater in OP in the second year and similar between systems in the other years. Average daily gains were similar between systems, regardless of season and experimental year, while the OP showed a greater gain per area in the third experimental year. Despite of the difference in some variables, after 14–16 years of establishment, it was observed only a small decrease in the animal productive per area in SPS in the last year, in relation to OP, which indicates a high resilience of SPS, even under intense shading.

Risk and success factors for good udder health of early lactation primiparous dairy cows

We compared the management and housing of dairy heifers from calf to calving in herds that were very successful versus less successful in preventing mastitis in early lactation primiparous cows. This retrospective observational study included 170 Swedish dairy herds. Eligible herds were identified from the Swedish official milk recording scheme (SOMRS). Each herd had at least 60 cows per year, production data from 3 consecutive years, and at least 10 primiparous cows per year with their first milk recording 5 to 35 d after calving and their second milk recording 20 to 40 d after the first milk recording. In each herd, primiparous cows with a low (≤75,000 cells/mL) cow somatic cell count (CSCC) at both the first and second milk recording were categorized as low-low (LL); those with a high (>100,000 cells/mL) CSCC at both recordings were categorized as high-high (HH). Cows with high CSCC at the first recording and low at the second were categorized as high-low (HL). The annual proportions of LL, HL, and HH cows within each herd were calculated. Herds with an above-median proportion of LL, HL, or HH cows during the first year of a 3-yr selection period, and above the third quartile proportion of LL, HL, or HH cows, respectively, during the second and third year were identified. These herds (LL herds, n = 129; HL herds, n = 92; HH herds, n = 139) were contacted until a maximum of 60 herds per category had agreed to participate. Field technicians/veterinarians visited each herd once in the mid to late indoor season to collect data on housing and management of the heifers from birth to calving. Additional data were retrieved from the SOMRS. Associations between herd category (LL, HL, or HH) and variables collected were analyzed in 8 multivariable multinomial logistic regression submodels covering herd characteristics, milk-fed calves, heifers in early pregnancy, heifers in late pregnancy, calving and colostrum period, miscellaneous factors, summarized heifer housing data, and general health, culling, and fertility data. A final multivariable model was built from the results of the submodels and univariable analyses. The final model showed that having a standard operating procedure for colostrum feeding was more common in LL and HL herds than in HH herds; the mean bulk milk SCC and overall culling rate due to udder health was higher in HH herds than in LL and HL herds; and automatic milking was less common in LL herds than in HL and HH herds. Several herd and management variables differed between herd categories in the submodels. In conclusion, we identified several success factors for herds with good udder health among early lactation primiparous cows. This knowledge can be used to improve preventive measures in dairy herds to ensure sustainable and economic milk production.

A Cohort Study Risk Factor Analysis for Endemic Disease in Pre-Weaned Dairy Heifer Calves.

Simple SummaryMost dairy heifer calves are removed from their dam and reared on milk from birth until weaning at around nine weeks of age. During this period they are susceptible to diseases which reduce their welfare and later performance in the dairy herd and can cause mortality. This study investigated the risk factors for disease on 11 UK dairy farms. Each calf received a weekly clinical examination. Out of 492 heifers recruited, diarrhoea, bovine respiratory disease (BRD) and umbilical disease were recorded in 48.2%, 45.9% and 28.7%, respectively. This was assessed using a composite disease score (CDS), reflecting severity and duration. The CDS for diarrhoea decreased when more calves were born in the same week, but this increased the risk of umbilical disease. The CDS for BRD was reduced by housing calves in fixed groups and feeding them more milk. Being born at a warmer time of year reduced the severity of BRD but increased it for umbilical disease. Calves acquire their initial immunity by ingesting antibodies in colostrum. Better immunity reduced the severity of BRD but failed to protect against diarrhoea or umbilical disease. Calves with a higher circulating concentration of the metabolic hormone insulin-like growth factor 1 (IGF-1) experienced less severe disease. Providing farmers and veterinarians with a better understanding of such risk factors helps them to improve their management practices to reduce disease incidence.Dairy heifer calves experience high levels of contagious disease during their preweaning period, which may result in poor welfare, reduced performance or mortality. We determined risk factors for disease in a cohort study of 492 heifers recruited from 11 commercial UK dairy farms. Every animal received a weekly examination by a veterinarian from birth to nine weeks using the Wisconsin scoring system. Multivariable models were constructed using a hierarchical model with calf nested within farm. Outcome variables for each disease included a binary outcome (yes/no), disease duration and a composite disease score (CDS) including both severity and duration. Diarrhoea, bovine respiratory disease (BRD) and umbilical disease were recorded in 48.2%, 45.9% and 28.7% of calves, respectively. A higher heifer calving intensity in the week of birth reduced the CDS for diarrhoea, with a marginal benefit of improved passive transfer (serum immunoglobulin G (IgG) measured at recruitment). The CDS for BRD was reduced by housing in fixed groups, higher mean temperature in month of birth, increasing milk solids fed, increasing IgG, and higher plasma IGF-1 at recruitment. Conversely, higher calving intensity and higher temperature both increased the CDS for umbilical disease, whereas high IGF-1 was again protective. Although good passive transfer reduced the severity of BRD, it was not significant in models for diarrhoea and umbilical disease, emphasising the need to optimise other aspects of management. Measuring IGF-1 in the first week was a useful additional indicator for disease risk.

Effect of grouping on behaviour of dairy heifers and cows in the transition period.

Regrouping dairy cows is a common feature of dairy farm management. Cows are grouped based on lactation stage, age, milk yield and other factors. Regrouping cows during the dry period (from far-off area to close up area and from close up area to the main herd) brings new challenges. This is especially true for heifers who, after being confirmed gravid, may be grouped into a new pen with dried off cows. The aims of this study were to determine how grouping affects activity, nearest neighbour relationships and aggression, and how heifers' acclimatization to a new group differs from cows. Therefore, the hypotheses were that regrouping cows has less of an effect on older cows compared to heifers, and cows' individuality affects acclimatization to a new group. Aggression data were recorded using a video camera that was directed at the feed bunk, and activity was recorded with activity monitors that were attached around the right hind leg. Synchrony and distance to nearest neighbour were recorded, as was the cows' location on the first 3 d from the day they returned to the main herd. Motion index, mean number of steps and number of lying bouts were significantly higher after calving compared to the week before calving and the difference was higher amongst heifers compared to cows (P < 0.001). Both cows and heifers lay down more in the strawyard compared to cubicle housing (P < 0.01) and cows were more aggressive than heifers in both housing systems (P < 0.001 and P < 0.05, respectively). As hypothesized, heifers were more affected by regrouping and cows with more experience settled quicker to their new environment.

The effect of dairy heifer pre-breeding growth rate on first lactation milk yield in spring-calving, pasture-based herds

Optimising heifer growth rate may offer an opportunity to improve lifetime milk yield per cow, enhancing the environmental and economic efficiency of dairy farming operations. The effect of dairy heifer pre-breeding average daily weight gain (ADGPB) on first lactation milk yield was investigated. This observational study employed a data set comprising 265 Holstein-Friesian, or Holstein-Friesian-cross-Jersey heifers from seven commercial, spring-calving, pasture-based dairy herds, where the major component of the diet was grazed grass. These were weighed at birth and prior to breeding and ADGPB was calculated. Milk recordings were performed throughout the heifers' first lactation and 305-day yield figures calculated from these records. Yields were corrected to 4% fat and 3.1% protein to create standardised 305-day milk yield (SMY), which was the outcome of interest. Median ADGPB was 0.72 kg/day. Median 305-day yield was 5 967 kg. Linear regression was used to investigate the effect of weight and genetic, age and first calving factors on SMY. Pre-breeding average daily weight gain, age at first calving and predicted transmitting abilities for milk protein production and calving interval were all significant in the final model, which also included the random effects of farm and month of calving within year. ADGPB was quadratically related to first lactation SMY, with an ADGPB of 0.82 kg/day corresponding to the maximum predicted SMY. The model predicted that a heifer growing at 0.82 kg/day would produce 1 120 kg more SMY than a heifer growing at 0.55 kg/day, 218 kg more than a heifer growing at 0.7 kg/day and 103 kg more than a heifer growing at 0.90 kg/day. Manipulation of heifer growth rate may offer a viable method of increasing first lactation milk yield.

Effect of photoperiod before and during first gestation on milk production and prolactin concentration in dairy heifers

Holstein heifers (n = 45) were subjected to treatments according to a 2 × 2 factorial design where the main effects were the photoperiod treatments during the second isometric (ISO, 52-61 wk of age) and the second allometric (ALLO, 62 wk of age to 8 wk before calving) periods of mammary gland development. During the ISO period, heifers were subjected to either a short-day photoperiod (SDP; 8 h light, 16 h dark; n = 22) or a long-day photoperiod (LDP; 16 h light, 8 h dark; n = 23). During the ALLO period, the photoperiodic treatments were either maintained (SDP:SDP, n = 11; LDP:LDP, n = 11) or switched (SDP:LDP, n = 11; LDP:SDP, n = 12). The treatments ended 8 wk before calving. All animals were then subjected to about 16 h of light per day. Serum prolactin (PRL) concentration during the ISO period was greater in heifers exposed to LDP than in those exposed to SDP. For the first 20 wk of the ALLO period, heifers exposed to LDP had greater serum concentration of PRL than those exposed to SDP. On the other hand, previous exposure to LDP during the ISO period reduced the concentration of PRL compared with those exposed to SDP during that period. During the second 20 wk of the ALLO period, PRL concentration remained greater in the serum of heifers then exposed to LDP than SDP, but serum PRL was greater in heifers exposed to LDP during the ISO period. During the last weeks before calving, when all animals were exposed to LDP, previous exposure to LDP during the ALLO period reduced serum PRL. Early-lactation milk (wk 1-5) and energy-corrected milk (wk 2-6) production were higher in the heifers exposed to SDP than in those exposed to LDP during ALLO. Photoperiod had no effect on milk production after that period. In conclusion, the results do not support to the hypothesis that photoperiod affects mammary gland development during the second allometric phase. However, they confirm that a short-day photoperiod in late gestation enhances milk production in the following lactation in primiparous heifers. Using serum PRL as an indicator of the photoperiodic response, we can conclude that responsiveness to the photoperiodic signal is still conditioned by a previous photoperiod several months after it ends.