Effect of monopropylene glycol on luteinizing hormone, metabolites, and postpartum anovulatory intervals in primiparous dairy cows

This study examined the effect of monopropylene glycol (MPG) supplementation on LH secretion, postpartum interval to first ovulation, and milk production in heifers calving with poor body condition score (BCS). Forty-seven heifers were allocated to 3 treatments: 1) heifers with high BCS (BCH; n = 13) that calved at a BCS of 3.4 (BCS scale of 1 to 5); 2) heifers with low BCS (BCL; n = 17) that calved at a BCS of 2.8; and 3) heifers with low BCS that calved at a BCS of 2.8 and were assigned to receive MPG supplementation (BCL + MPG; n = 17) and grazed pasture ad libitum. Monopropylene glycol was drenched (250 mL) twice daily for 16 wk after calving. Patterns of change in plasma LH were measured at 2 and 5 wk after calving. Pulsatile release of LH at 2 and 5 wk was greater in BCL + MPG and BCH cows compared with the BCL control cows. The BCL + MPG cows had lower NEFA concentrations than did the BCL cows during wk 1 to 6 after calving. At 12 wk postpartum, the proportion of cows cycling was 77, 82, and 28% for the BCH, BCL + MPG, and BCL treatments, respectively. Mean milk fat yield was greater for the BCH treatment during the first 12 wk postpartum compared with the BCL + MPG or BCL treatments, which did not differ from each other. Results of this study indicate that MPG supplementation reduced the interval from calving to first ovulation in heifers having poor body condition at calving.     

Effect of restricted feeding and monopropylene glycol postpartum on metabolic hormones and postpartum anestrus in grazing dairy heifers

This study was designed to determine the effects of feed restriction and monopropylene glycol (MPG) supplementation on the reproductive, milk production, and somatotropic axes in dairy heifers postpartum. At calving, 49 Holstein-Friesian heifers were allowed either unrestricted (UNR; n = 18) or restricted access to pasture with (RES+MPG; n = 13) or without (RES; n = 18) MPG supplementation (250 mL drenched twice daily for 150 d). The average body condition score (BCS) of the heifers was 5.3 ± 0.2 on a scale from 1 to 10 (where 1 = emaciated and 10 = obese). Body condition score and body weight were similar among the groups at calving and decreased after calving for all groups. However, body weight loss was around 10% greater for the RES and RES+MPG groups from wk 3 to 12 compared with UNR group. The length of the postpartum anestrous interval was similar for all groups (47, 51, and 45 ± 5 d for the UNR, RES, and RES+MPG, respectively). Average milk production, protein, fat, and lactose yields during the first 12 wk postpartum were greater in the UNR group than in the RES and RES+MPG groups. Feed restriction affected plasma concentrations of insulin, with lower concentrations in the RES group compared with the UNR group. There were no differences in plasma concentrations of insulin between the RES+MPG group and the UNR or RES groups. An effect of feed restriction was observed on insulin-like growth factor-I concentrations and also a treatment by time interaction with a changing pattern through time as concentrations in the UNR group increased relative to the RES and RES+MPG groups. There were no differences in growth hormone concentrations among the groups. Glucose concentrations were lower in the RES group when compared with RES+MPG and UNR groups and this difference lessened over time. Plasma concentrations of nonesterified fatty acids were greater in the RES group compared with the RES+MPG and UNR groups. Leptin concentrations in the UNR group were greater than in the RES and RES+MPG groups. Hepatic growth hormone receptor 1A, total growth hormone receptor, and insulin-like growth factor-I relative mRNA expressions decreased postpartum with no effect of feed restriction, MPG supplementation, or interaction between time and treatment. During a challenge with MPG, insulin secretion was stimulated but no effect on postpartum anestrous interval in the treatment groups was observed. It was concluded that restricted pasture availability postpartum in dairy heifers calving in optimal BCS had no effect on the postpartum anestrous interval. It did however decrease milk production; thus, we can infer that monopropylene glycol supplementation does not act to prevent loss of milk yield.     

Calving body condition score affects indicators of health in grazing dairy cows

The objectives of this study were to determine the effect of calving body condition score (BCS) on cow health during the transition period in a pasture-based dairying system. Feed inputs were managed during the second half of the previous lactation so that BCS differed at drying off (BCS 5.0, 4.0, and 3.0 for high, medium, and low treatments, respectively: a 10-point scale); feed allowance was managed after cows were dried off, such that the BCS differences established during lactation remained at the subsequent calving (BCS 5.5, 4.5, and 3.5; n = 20, 18, and 19, for high, medium, and low treatments, respectively). After calving, cows were allocated pasture and pasture silage to ensure grazing residuals >1,600 kg of DM/ha. Milk production was measured weekly; blood was sampled regularly pre- and postpartum to measure indicators of health, and udder and uterine health were evaluated during the 6 wk after calving. Milk weight, fat, protein, and lactose yields, and fat content increased with calving BCS during the first 6 wk of lactation. The effect of calving BCS on the metabolic profile was nonlinear. Before calving, cows in the low group had lower mean plasma β-hydroxybutyrate and serum Mg concentrations and greater mean serum urea than cows in the medium and high BCS groups, which did not differ from each other. During the 6 wk after calving, cows in the low group had lower serum albumin and fructosamine concentrations than cows in the other 2 treatment groups, whereas cows in the low- and medium-BCS groups had proportionately more polymorphonucleated cells in their uterine secretions at 3 and 5 wk postpartum than high-BCS cows. In comparison, plasma β-hydroxybutyrate and nonesterified fatty acid concentrations increased linearly in early lactation with calving BCS, consistent with a greater negative energy balance in these cows. Many of the parameters measured did not vary with BCS. The results highlight that calving BCS and, therefore, BCS through early lactation are not effective indicators of functional welfare, with the analyses presented indicating that both low and high BCS at calving will increase the risk of disease: cows in the low group were more prone to reproductive compromise and fatter cows had an increased risk of metabolic diseases. These results are important in defining the welfare consequences of cow BCS.     

Comparison of peripartum metabolic status and postpartum health of Holstein and Montbéliarde-sired crossbred dairy cows

Objectives of the current experiment were to evaluate plasma concentrations of metabolites and haptoglobin peripartum, uterine health and involution, and follicle growth and resumption of cyclicity of Holstein (HO) and Montbéliarde-sired crossbred cows. Cows (52 HO and 52 crossbred) were enrolled in the study 45 d before expected calving date. Cows had body weight and body condition score recorded on d −45, −14, 0, 1, 28, and 56 relative to calving. Dry matter intake was calculated for a subgroup of cows (25 HO and 38 crossbred) from 6 wk before to 6 wk after calving. Blood was sampled weekly from d −14 to 56 relative to calving for determination of glucose, nonesterified fatty acid, and β-hydroxybutyrate concentrations; from d −7 to 21 relative to calving for determination of haptoglobin concentration; and from d 14 to 56 postpartum for determination of progesterone concentration. Cows were examined at calving and on d 4, 7, 10, and 14 postpartum for diagnosis of postparturient diseases, on d 24 postpartum for diagnosis of purulent vaginal discharge, and on d 42 postpartum for diagnosis of subclinical endometritis. Uteri and ovaries were examined by ultrasonography every 3 d from d 14 to 41 postpartum. Milk yield and composition were measured monthly and yield of milk, fat, protein, and energy-corrected milk were recorded for the first 90 d postpartum. Body weight was not different between Holstein and crossbred cows, but HO cows had reduced body condition score compared with crossbred cows. Even though DMI from 6 wk before to 6 wk after calving tended to be greater for HO cows (16.8 ± 0.7 vs. 15.3 ± 0.5 kg/d), HO cows tended to have more pronounced decline in dry matter intake, expressed in percentage of body weight from d −15 to 0 relative to calving. Energy-corrected milk and nonesterified fatty acid and β-hydroxybutyrate concentrations were not different between breeds. No differences were observed in incidence of retained fetal membranes, metritis, and subclinical endometritis, but HO cows tended to be more likely to have pyrexia from d 0 to 15 postpartum (50.0 vs. 31.4%) and to have greater incidence of purulent vaginal discharge (44.2 vs. 26.5%) than crossbred cows. Holstein cows were more likely to have at least 1 uterine disorder postpartum than crossbred cows (63.5 vs. 36.7%). No differences between breeds were observed in uterine involution. Holstein cows had larger subordinate follicles (10.1 ± 0.4 vs. 8.9 ± 0.5) and a greater number of class III follicles (1.6 ± 0.1 vs. 1.2 ± 0.1) than crossbred cows. Furthermore, the first corpus luteum postpartum of HO cows was diagnosed at a slower rate compared with crossbred cows. Crossbred cows had improved uterine health compared with HO cows and this may have been a consequence of heterosis and (or) breed complementarity and less pronounced decrease in DMI during the last days of gestation.     

Risk factors that affect reproductive target achievement in fertile dairy cows

The aims of the present study were to investigate (1) the risk factors that influence the achievement of reproductive targets postpartum (pp) and (2) the key factors that influence pregnancy rate following first artificial insemination (AI) in dairy cows. Ninety-eight Holstein-Friesian pp cows were blood sampled from wk 1 to 4 pp for hematology and biochemistry. Reproductive tract health was assessed weekly by ultrasonography and vaginal mucus scoring. Body condition score (BCS), lameness score, and milk yield were assessed every 2 wk. Milk samples for progesterone assay were collected twice weekly and on d 4, 5, and 7 after AI. Risk factors associated with achieving reproductive targets depended on (1) increased metabolic activity of the liver (increased glutamate dehydrogenase at calving and increased γ-glutamyl transpeptidase in wk 4), (2) a competent immune system (increased neutrophils in wk 1; decreased α₁-acid glycoprotein in wk 1, 2, and 3), (3) an endocrine system that was capable of responding by producing sufficient triiodothyronine in wk 2 and increased insulin-like growth factor I in wk 3 and 4, (4) a lower negative energy balance status (decreased nonesterified fatty acid concentration in wk 1; decreased β-hydroxybutyrate concentration in wk 2; BCS loss between calving and d 28 pp <0.5), (5) good reproductive tract health [normal uterine scan at d 45 pp; clear vaginal mucus discharge at first ovulation and at d 45 pp; resumed ovarian cyclicity by the end of the voluntary waiting period (≥d 35 pp)], and (6) adequate diet (to ensure increased glutathione peroxidase in wk 2 and 3 and increased magnesium in wk 4). Risk factors that increased the odds of a successful first AI were previous ovulation(s) (odds ratio = 3.17 per ovulation), BCS >2.5 at AI (odds ratio = 3.01), and clear vaginal mucus (score = 0) compared with purulent mucus (score >0) 4 d after first AI (odds ratio = 2.99). In conclusion, this study identified key risk factors in the early pp period that give a higher probability of cows achieving their reproductive targets and of having a first-AI pregnancy.     

Prepartum dietary management of energy intake affects postpartum intake and lactation performance by primiparous and multiparous Holstein cows

An experiment was conducted to determine the effect of plane of energy intake prepartum on postpartum performance. Primiparous (n = 24) and multiparous (n = 23) Holsteins were randomly assigned by expected date of parturition to 1 of 3 prepartum energy intakes. A moderate energy diet [1.63 Mcal of net energy for lactation (NE_L)/kg; 15% crude protein (CP)] was fed for either ad libitum intake (OVR) or restricted intake (RES) to supply 150 or 80% of National Research Council (2001) energy requirement, respectively, for dry cows in late gestation. To limit energy intake to 100% of NRC requirement at ad libitum dry matter intake (DMI), chopped wheat straw was included as 31.8% of dry matter (DM) in a control diet (CON; 1.21 Mcal of NE_L/kg of DM; 14% CP). Multiparous and primiparous cows assigned to OVR gained body condition during the dry period [initial body condition score (BCS) = 3.3], but were not overconditioned by parturition (BCS = 3.5). Multiparous cows in the OVR group lost more BCS postpartum than multiparous RES or CON cows. Primiparous cows lost similar amounts of BCS among dietary treatment groups postpartum. Addition of chopped wheat straw to CON diets prevented a large decrease in DMI prepartum in both primiparous and multiparous cows. During the first 3 wk postpartum, DMI as a percentage of BW was lower for multiparous OVR cows than for multiparous RES cows. Prepartum diet effects did not carry over through the entire 8-wk lactation period. Because of greater mobilization of body stores, OVR cows had greater milk fat percentage and greater 3.5% fat-corrected milk yield during the first 3 wk postpartum. Multiparous cows assigned to OVR experienced a 55% decrease in energy balance and primiparous cows a 40% decrease in energy balance during the last 3 wk before parturition, compared with CON or RES cows that had little change. Multiparous cows fed OVR had a greater contribution of energy from body energy reserves to milk energy output than either CON or RES cows. Overfeeding energy prepartum resulted in large changes in periparturient energy balance. Even in the absence of overconditioning, a large change in DMI and energy balance prepartum influenced postpartum DMI and BCS loss, especially for multiparous cows. Chopped wheat straw was effective at controlling energy intake prepartum, although primiparous cows did not achieve predicted DMI. Even so, controlling or restricting energy intake in primiparous cows was not detrimental to lactational performance over the first 8 wk of lactation.     

Short communication: A positive relationship between the first ovulation postpartum and the increasing ratio of milk yield in the first part of lactation in dairy cows

The aim of the present study was to examine the relationship between characteristics of the lactation curve, on the basis of daily milk yield, and ovulation within 3 wk postpartum as an indicator of early return to luteal activity in dairy cows. Lactation records from 46 lactating Holstein cows between calving and 305 d postpartum were studied. Milk samples were collected twice weekly between d 7 and 100 for later determination of progesterone concentrations. Occurrence of an early first ovulation was determined by an increase in milk progesterone by 3 wk after calving. Milk yield was recorded daily until 305 d postpartum, and average yield was calculated weekly. The lactation curve was characterized by 8 indices on the basis of the weekly average of milk yield as follows: a) first-week milk yield; b) peak milk yield; c) actual 305-d milk yield; d) peak week; e) difference in milk yield between the first week and peak week; f) difference in milk yield between the peak week and last week (43rd week postpartum); g) ratio of increase in milk yield between wk 1 and the week of peak yield; and h) ratio of decline in milk yield between the week of peak yield and the last week. Indices g and h were calculated as linear. The number of cows having ovulated by 3 wk postpartum was 22 (47.8%). The resumption of ovarian cycles with normal luteal phases occurred earlier in ovular cows than in anovular cows (32.0 d vs. 57.1 d). Although total milk yield did not differ between ovular and anovular cows, the ratio of increase in milk yield from the first week to the peak week (index g) in ovular cows was smaller compared with that of anovular cows (1.71 vs. 2.54). In addition, the ratio of increase in milk yield from the first week to the third week postpartum was greater in anovular cows by 3 wk postpartum (ovular = 1.43 ± 0.23 vs. anovular = 2.32 ± 0.29). In conclusion, the present study demonstrates that a greater increasing ratio of milk yield during early lactation may delay resumption of ovarian cycles after parturition. Therefore, this study is the first to demonstrate statistically that a smaller increasing ratio of milk yield (index g) during early lactation may have a beneficial effect on the first ovulation by 3 wk postpartum.     

Effects of parity on uterine involution and resumption of ovarian activities in postpartum Chinese Holstein dairy cows

Favorable uterine involution and ovarian activity are very important for the next reproductive cycle of postpartum cows. The objective of this study was to evaluate the effect of parity on uterine involution and resumption of ovarian activity in Chinese Holstein dairy cows after calving under similar postpartum nutritional conditions. Traits of the status of uterus and ovaries detected by ultrasonography, dry matter intake (DMI), milk yield, body condition score (BCS), and estradiol concentration in milk samples were analyzed for 46 Chinese Holstein dairy cows in various parities (primiparous = 18; biparous = 13; multiparous = 15). The results showed that there was no significant difference for DMI, BCS, and milk yield among different parities; all cows were considered to be under similar nutritional conditions. Days of the previous gravid uterine horn involution were significantly greater in primiparous dairy cows than in biparous and multiparous dairy cows. Days from calving to ovulation (first and second) and the number of follicular waves to first ovulation were significantly greater in primiparous cows than in multiparous cows. In summary, there was a significant negative relationship between parity and postpartum uterine involution and resumption of ovarian activity in Chinese Holstein cows under similar body conditions.     

Effects of body condition score at calving on indicators of fat and protein mobilization of periparturient Holstein-Friesian cows

The objective was to study the effects of body condition score (BCS) at calving on dairy performance, indicators of fat and protein mobilization, and metabolic and hormonal profiles during the periparturient period of Holstein-Friesian cows. Twenty-eight multiparous cows were classed according to their BCS (0 to 5 scale) before calving as low (BCS ≤2.5; n = 9), medium (2.75 ≤ BCS ≤ 3.5; n = 10), and high (BCS ≥3.75; n = 9), corresponding to a mean of 2.33, 3.13, and 4.17 points of BCS, and preceding calving intervals of 362, 433, and 640 d, respectively. Cows received the same diets based on preserved grass to allow ad libitum feed intake throughout the study, and lactation diet contained 30% of concentrate (dry-matter basis). Measurements and sampling were performed between wk −4 and 7 relative to calving. No significant effects were observed of BCS group on dry matter intake (kg/d), milk yield, BCS loss, plasma glucose, and insulin concentrations. The high-BCS group had the lowest postpartum energy balance and the greatest plasma concentrations of leptin prepartum, nonesterified fatty acids and β-hydroxybutyrate postpartum, insulin-like growth factor 1, and milk fat content. Milk fat yield was greater for the high- than the low-BCS group (1,681 vs. 1,417 g/d). Low-BCS cows had the greatest concentration of medium-chain fatty acids (e.g., sum of 10:0 to 15:0, and 16:0), and the lowest concentration and secretion of preformed fatty acids (e.g., cis-9 18:1) in milk fat. Milk protein secretion was lowest in the low-BCS group, averaging 924, 1,051, and 1,009 g/d for low-, medium-, and high-BCS groups, respectively. Plasma 3-methylhistidine was greater in wk 1 and 2 postpartum compared with other time points, indicating mobilization of muscle protein. Plasma creatinine tended to be lower and the 3-methylhistidine: creatinine ratio was greater in low- compared with medium- and high-BCS cows, suggesting less muscle mass but more intense mobilization of muscle protein in lean cows. High-BCS cows were metabolically challenged during early lactation due to intense mobilization of body fat. Conversely, limited availability of body fat in low-BCS cows was associated with increased plasma indicators of body protein mobilization during the first weeks of lactation, and lower milk protein secretion. These results should be confirmed using an experimental approach where calving BCS variation would be controlled by design.     

Behavior during transition differs for cows diagnosed with claw horn lesions in mid lactation

Claw horn lesions, including sole hemorrhages and sole ulcers, are a major cause of lameness in dairy cattle. These lesions often develop in the weeks around calving and become visible 8 to 12 wk later. The aim was to determine whether cows that are diagnosed with claw horn lesions several weeks after calving behave differently during the calving period when the lesions are thought to first develop. The claws of 26 multiparous Holstein dairy cows were scored for sole hemorrhage severity and presence of sole ulcers 2 wk before calving, 3 wk after calving, and every 4 wk thereafter until 15 wk after calving. Of the 26 cows, 13 cows had no or low lesion scores up to 15 wk and 13 cows had at least 1 new severe lesion or sole ulcer diagnosed between 7 and 15 wk after calving. Behavior (dry matter intake, feeding time and rate, number and size of meals, standing time, number and duration of standing bouts, location of standing, and displacements at the feed bunk) was recorded from 2 wk before calving to 3 wk after calving. Behavior during the 2 wk before calving, first 24 h after calving, 1 wk after calving, and 2 to 3 wk after calving was compared between cows with and without lesions in mid lactation. Multivariate regression was used to determine the predictive value of each behavior and combination of behaviors on lesion diagnosis. Cows diagnosed with lesions in mid lactation spent more time standing than cows without lesions during the 2 wk before (832 ± 29 vs. 711 ± 29 min/d) and 24 h after (935 ± 46 vs. 693 ± 46 min/d) calving. These differences were driven by an increase in the time spent perching with front feet in the stall (241 ± 22 vs. 147 ± 22 min/d at 2 wk before calving) and an increase in standing bout duration (101 ± 10 vs. 56 ± 10 min/bout at 24 h after calving). Compared with cows without lesions, cows with lesions consumed feed at a faster rate (86 ± 3 vs. 77 ± 3 g/min) during the 2 wk before calving and consumed more feed (17.9 ± 0.9 vs. 12.3 ± 0.9 kg/d) during the 24 h after calving. The number of displacements at the feeder was not different between groups. These results indicate that a combination of feeding and standing behavior during the transition can serve as early indicators of claw horn lesions in mid lactation.     

Lying behavior and postpartum health status in grazing dairy cows

Many cows have difficulty making the transition from pregnancy to lactation, as evidenced by the high incidence of disease that occurs in the weeks after calving. Changes in lying behavior can be used as an indicator of illness, yet no work to date has evaluated this relationship in dairy cows on pasture. The objectives of this study were to describe the lying behavior of grazing dairy cows during the first 3 wk after calving and determine the relationships between transition diseases and lying behavior. Our convenience sample included 227 multiparous and 47 primiparous Holstein cows from 6 commercial farms. Cows were recruited as they calved during the spring calving period. Electronic data loggers (Hobo Pendant G Acceleration, Onset Computer Corp., Pocasset, MA) recorded lying behavior at 1-min intervals. Diseases were recorded up to 21 d in milk, and cows were subsequently categorized into 3 health categories: (1) healthy, not lame and had no other signs of clinical (retained placenta, milk fever, metritis, mastitis) or subclinical (ketosis, hypocalcemia) postpartum diseases; (2) lame, identified as being clinically or severely lame with no other signs of clinical or subclinical postpartum disease; and (3) sick, diagnosed as having one or more clinical postpartum diseases (with or without a subclinical disease) but not lame. This last group was further divided into 2 groups: those that were diagnosed with a single clinical health event and those diagnosed with more than one clinical event. Lying behavior differed between primiparous and multiparous cows; primiparous cows divided their lying time into more bouts than did multiparous cows (9.7 ± 0.54 vs. 8.4 ± 0.26 bouts/d) and spent less time lying down than multiparous cows (7.5 ± 0.38 h/d vs. 8.5 ± 0.19 h/d). Lying behavior was also affected by illness; primiparous cows that developed more than one clinical disease, excluding lameness, spent more time lying, and tended to have longer lying bouts in the days following calving compared with healthy cows; multiparous severely lame cows spent more time lying down (1.7 h longer per day) compared with multiparous cows that were nonlame. Clinically lame cows had fewer lying bouts per day and these bouts were of longer duration than healthy nonlame cows. In summary, changes in lying behavior after calving were associated with postpartum health status in grazing dairy cows.     

Effects of dry period length and concentrate protein content in late lactation on body condition score change and subsequent lactation performance of thin high genetic merit dairy cows

Improving body condition score of thin cows in late lactation is necessary, because cows that are thin at drying off exhibit decreased fertility postpartum and are at increased risk of disease and of being culled in the subsequent lactation. Offering a diet low in crude protein (CP) content in late lactation may help to improve body condition score (BCS) at drying off, whereas imposing an extended dry period (EDP) has been advocated as another way to increase BCS at calving. To test these hypotheses, 65 thin cows (mean BCS 2.25 at 14 wk precalving) were managed on 1 of 3 treatments between 13 and 9 wk prepartum: normal protein control {NP; grass silage + 5 kg/d of a normal protein concentrate [228 g of CP/kg of dry matter (DM)]}, low protein [LP; grass silage + 5 kg/d of a low-protein concentrate (153 g of CP/kg of DM)], or EDP (cows dried off at 13 wk precalving and offered a grass silage-only diet). Both NP and LP cows were dried off at wk 8 prepartum, after which all cows were offered a grass silage-only diet until calving. After calving, all cows were offered a common diet (supplying 11.1 kg of concentrate DM/cow per day) for 19 wk. Between 13 and 9 wk prepartum, LP cows had lower DM intake, milk yield, and body weight than NP cows. Whereas EDP cows had lower serum β-hydroxybutyrate and fatty acid concentrations than those of NP cows, BCS at wk 9 prepartum did not differ between treatments. Cows on the LP treatment continued to have lower DMI and BW than those of NP and EDP cows between 8 wk prepartum and calving, but only EDP cows had a higher BCS at calving. Treatment did not affect calving difficulty score or calf birth weight. Although all cows were offered a common diet postpartum, cows on the LP treatment had lower DM intake and milk fat + plus protein yield than cows on any other treatment during the 19-wk period postpartum, but we found no differences in any postpartum indicator of body tissue reserves. The treatments imposed from wk 13 to 9 prepartum had no effect on any fertility or health parameters examined postpartum. Extending the dry period for thin cows improved their BCS at calving but did not allow these cows to achieve the target BCS of 2.75, and we found no beneficial effects of this treatment on cow performance postpartum. Offering a lower-protein diet to thin cows in late lactation did not improve BCS at calving above that of cows on a normal protein diet, but had unexplained long-term negative effects on cow performance.     

The effect of out-wintering pad design on hoof health and locomotion score of dairy cows

This study compared locomotion, hoof health, and lameness of dairy cows confined in either indoor free stalls (FS) or 1 of 3 out-wintering pad (OWP) designs. Out-wintering pad treatments were 1) uncovered OWP with a concrete feed apron (UP); 2) covered OWP with a concrete feed apron (CO); and 3) uncovered OWP on top of which grass was ensiled so that the cows could self-feed (SP). Cows were assigned to treatment at drying off using a randomized complete block design. They remained on treatment until calving, when they were turned out to pasture. Sole lesions, heel erosion, dermatitis, and claw hardness on both hind feet were scored according to severity at assignment to treatment, at calving, and 9 and 14 wk postpartum. Locomotion score was recorded weekly after calving for 14 wk. Incidence of clinical lameness was recorded during the treatment period and in the subsequent lactation. Treatment had no effect on sole lesion score, but scores increased over time (calving = 5.5 ± 1.3, wk 9 = 10.8 ± 1.3, wk 14 = 14.2 ± 1.3, mean ± SE). Self-fed cows had higher heel erosion scores (6.4 ± 0.4) than FS and CO cows (4.7 ± 0.4 and 4.7 ± 0.4, respectively) at calving. Cows on SP had the highest dermatitis scores [1.14 (0-2) mean (interquartile range)] and FS cows the lowest [0.51 (0-0)]. Hooves were hardest at assignment to treatment (43.9 ± 0.6) with a significant reduction in hardness at calving (40.0 ± 0.6). The hooves of CO cows were harder than those of SP and UP cows (CO = 43.3 ± 0.7, SP = 41.7 ± 0.7, UP = 41.7 ± 0.7, Shore D scale). There was no treatment effect on locomotion scores or lameness incidence. Higher dermatitis scores and heel erosion in SP may be due to exposure to excreta and moisture, because the SP treatment had no manure removal system at the feed face. In FS, the alleys and the feed face were cleaned regularly by automatic scraper, explaining the lower dermatitis scores recorded indoors. Providing shelter for OWP likely reduced exposure to environmental moisture. This ensured that the hooves of CO cows remained as hard as those of FS cows. Low correlations between hardness and pathologies indicate that other factors are involved in the development of hoof pathologies. Confining dry dairy cows on OWP does not increase locomotion scores or lameness incidence.     

Short dry period management improves peripartum ruminal adaptation in dairy cows

The present study aimed to determine whether the improvement in postpartum energy balance frequently reported in cows under short dry period management could be due to an improvement in ruminal function related to the reduction in the number of diet changes before calving. Six multiparous and 6 primiparous Holstein cows equipped with ruminal cannula were assigned to 6 blocks of 2 cows each according to parity, projected milk production at 305 d, and expected calving date. Within each block, cows were randomly assigned to either a conventional (CDP; 63.2 ± 2.0 d) or a short dry period (SDP; 35.2 ± 2.0 d) management in a randomized complete block design. The CDP cows were fed a far-off diet until 28 d before calving, followed by a prepartum diet, whereas SDP cows received only the prepartum diet. After calving, both groups were fed the same lactation diet. Milk yield and dry matter intake (DMI) were recorded daily and milk composition, weekly. Blood samples were taken twice a week during the first 4 wk postcalving and weekly otherwise. Omasal and ruminal samples were collected approximately 3 wk prior and 3 wk after calving. From 28 d before calving until calving, when the 2 groups of cows were fed the same prepartum diet, there was no effect of the dry period length management on DMI, plasma concentrations of β-hydroxybutyrate, nonesterified fatty acids, and glucose and nutrient digestibility in the rumen. However, CDP cows tended to have lower ruminal pH and higher ruminal concentrations of total volatile fatty acids than SDP cows. From calving to 60 d in milk, daily DMI was higher for SDP than for CDP cows (22.3 ± 0.44 vs. 20.7 ± 0.30 kg), but milk production and milk concentrations and yields of fat, protein, and total solids were not affected by the dry period length management. After calving, body weight loss was reduced and body condition score tended to increase more rapidly for SDP than for CDP cows. Nutrient digestibility in the rumen, expressed in kilograms per day, was greater or tended to be greater for SDP cows, but differences were no longer significant when expressed per unit of nutrient ingested. The decrease in plasma nonesterified fatty acids and β-hydroxybutyrate in SDP cows without effect on milk yield suggests an improved energy balance likely due to greater DMI. Results from the present study seem to indicate that reducing the number of diet changes before calving could facilitate ruminal adaptation to the lactation diet and improve energy balance postpartum.     

Relationships between fertility and postpartum changes in body condition and body weight in lactating dairy cows

The relationship between energy status and fertility in dairy cattle was retrospectively analyzed by comparing fertility with body condition score (BCS) near artificial insemination (AI; experiment 1), early postpartum changes in BCS (experiment 2), and postpartum changes in body weight (BW; experiment 3). To reduce the effect of cyclicity status, all cows were synchronized with Double-Ovsynch protocol before timed AI. In experiment 1, BCS of lactating dairy cows (n = 1,103) was evaluated near AI. Most cows (93%) were cycling at initiation of the breeding Ovsynch protocol (first GnRH injection). A lower percentage pregnant to AI (P/AI) was found in cows with lower (≤2.50) versus higher (≥2.75) BCS (40.4 vs. 49.2%). In experiment 2, lactating dairy cows on 2 commercial dairies (n = 1,887) were divided by BCS change from calving until the third week postpartum. Overall, P/AI at 70-d pregnancy diagnosis differed dramatically by BCS change and was least for cows that lost BCS, intermediate for cows that maintained BCS, and greatest for cows that gained BCS [22.8% (180/789), 36.0% (243/675), and 78.3% (331/423), respectively]. Surprisingly, a difference existed between farms with BCS change dramatically affecting P/AI on one farm and no effect on the other farm. In experiment 3, lactating dairy cows (n = 71) had BW measured weekly from the first to ninth week postpartum and then had superovulation induced using a modified Double-Ovsynch protocol. Cows were divided into quartiles (Q) by percentage of BW change (Q1 = least change; Q4 = most change) from calving until the third week postpartum. No effect was detected of quartile on number of ovulations, total embryos collected, or percentage of oocytes that were fertilized; however, the percentage of fertilized oocytes that were transferable embryos was greater for cows in Q1, Q2, and Q3 than Q4 (83.8, 75.2, 82.6, and 53.2%, respectively). In addition, percentage of degenerated embryos was least for cows in Q1, Q2, and Q3 and greatest for Q4 (9.6, 14.5, 12.6, and 35.2% respectively). In conclusion, for cows synchronized with a Double-Ovsynch protocol, an effect of low BCS (≤2.50) near AI on fertility was detected, but change in BCS during the first 3 wk postpartum had a more profound effect on P/AI to first timed AI. This effect could be partially explained by the reduction in embryo quality and increase in degenerate embryos by d 7 after AI in cows that lost more BW from the first to third week postpartum.     

Using gait score, walking speed, and lying behavior to detect hoof lesions in dairy cows

The objective was to determine whether changes in the different components of gait, walking speed, and lying behavior were associated with hoof pathologies in lactating Holstein cows. In experiment 1, 53 cows had their gait scored, their walking speed estimated, and their lying behavior monitored before clinical assessment of the hooves. Multiparous cows with ulcers scored higher than cows without ulcers for overall gait score [numerical rating score (NRS); 3.3 ± 0.2 vs. 2.8 ± 0.2], back arch, joint flexion, asymmetric steps, and reluctance to bear weight. Although cows with ulcers did not walk more slowly than cows without ulcers (1.4 m/s), they spent more time lying down (827.8 ± 29.1 vs. 738.2 ± 15.5 min/d) because of longer lying bouts (93.3 ± 5.9 vs. 79.7 ± 3.4 min). In experiment 2, 47 cows were monitored for hoof health and changes in gait score from 4 wk before to 24 wk after calving. Differences were found after calving between cows that developed an ulcer and cows that did not for NRS (3.1 ± 0.1 vs. 2.35 ± 0.1), back arch, joint flexion, asymmetric steps, and reluctance to bear weight. Numerical rating score, back arch, and asymmetric steps were able to discriminate cows with ulcers at least 4 wk before the diagnosis. Cows that developed a sole ulcer had a faster decline in lying time during the periparturient period and a faster increase beginning in wk 2 after calving. The NRS was a more consistent predictor of sole ulcers than lying behavior or speed. The NRS was able to discriminate cows with ulcers across studies at a high intraobserver accuracy and reasonable specificity and was able to predict the presence of ulcers at least 4 wk before diagnosis. Abduction/adduction of the rear legs, head bob, and tracking-up did not consistently discriminate cows with ulcers, and we suggest that these measures are less useful for on farm gait assessment. Compared with the other gait attributes, back arch, joint flexion, asymmetric steps, and reluctance to bear weight best predicted the presence of sole ulcers.     

Evaluation of continuous lactation and increased milking frequency on milk production and mammary cell turnover in primiparous Holstein cows

We hypothesized that early-lactation increased milking frequency, in combination with bovine somatotropin (bST), would improve milk yield in continuously milked (CM) primiparous glands through greater mammary epithelial cell (MEC) function, proliferation, and reduced apoptosis (cell turnover). Primiparous cows were randomly assigned to a 2 × 2 × 2 factorial with a split-plot design to either a continuous bST (+bST, n = 4) or no bST (−bST, n = 4) treatment throughout the study. Within each animal, udder halves were randomly assigned to either a CM or a 60-d dry period (control). During late gestation, CM glands were milked twice daily until calving or until spontaneous dry-off. At calving, cows were milked either twice or 4 times daily and udder-half milk yield was recorded until 30 d postpartum. Mammary biopsies were conducted on −19 ± 13, −8 ± 6, +2, +7, and +20 d relative to calving. Postpartum milk yield was reduced in CM udder halves. Reduced milk yield in CM half udders from cows administered bST and milked 4 times daily was 35% compared with 65% in CM half udders in cows not provided bST and milked twice daily. Proliferation of MEC tended to be greater in control vs. CM tissue at 8 ± 6 d prepartum. Mammary epithelial cell proliferation was greater during the prepartum period (d −19, −8) compared with postpartum time points (d 2, 7, 20). Apoptosis of MEC was not affected by dry period length, but was elevated during the first 7 d postpartum compared with levels measured at −19, −8, and 20 d. Bovine somatotropin did not alter MEC turnover in primiparous CM or control glands. The use of increased milking frequency and bST alleviated, but did not prevent, reductions in milk yield of CM primiparous cows.     

Energy balance and reproduction on dairy cows fed to achieve low or high milk production on a pasture-based system

This study investigated the energy balance, metabolic changes, reproduction, and health in Australian Holstein-Friesian cows of average genetic merit fed to produce 6,000 L of milk/cow per lactation (restricted production; Rp) on a predominantly grazed pasture diet, or 9,000 L of milk/cow per lactation (high production: Hp) on a more intensive feeding regimen by using a partial mixed ration to supplement pasture. The mean 4% fat-corrected milk (FCM) and standard deviation achieved was 8,466 ± 1,162 L/cow per lactation for the Hp herd and 6,748 ± 787 L/cow per lactation for the Rp herd. During early lactation, the degree of estimated negative energy balance was less in the Hp cows than in the Rp cows (−16.1 vs. −29.1 MJ/cow per day, respectively). Consequently, the mobilization of body reserves was also lower in the Hp cows, and this was reflected in lower concentrations of nonesterified fatty acids (0.70 vs. 0.84 mmol/L) and β-hydroxybutyrate (0.51 vs. 0.69 mmol/L) and greater concentrations of glucose (3.51 vs. 3.34 mmol/L) and insulin-like growth factor-I (78.9 vs. 58.7 ng/mL) for Hp and Rp cows, respectively. After calving, body condition score and body weight decreased to a similar extent in both herds and did not reflect the differences in mobilization of body reserves between the 2 herds. Reproductive performance was not significantly related to level of milk yield. The mean interval from calving to first active corpus luteum was 33 (SD = 20) d postpartum, and there were 1.4 (SD = 0.8) estrus cycles before the beginning of the breeding period (>50 d postpartum). The interval from calving to pregnancy was 114 d, and the pregnancy rate after 12 wk of mating was 74%. The number of cows with ovarian abnormalities was also similar between the 2 herds. Cows with a long postpartum anestrus had the lowest concentration of insulin-like growth factor-I. The number of health-related disorders was also similar between the herds, with the exception of mastitis, for which the incidence was significantly greater in the Hp cows. The results indicate that the production per cow could be increased from 6,748 L of FCM/cow per lactation for cows grazing pasture and supplemented with concentrates only at milking to 8,466 L of FCM/cow per lactation, in one lactation, by supplementing pasture with a partial mixed ration. Despite the fact that production per cow increased substantially, the degree of estimated negative energy balance and the metabolic changes in early lactation were lower and reproductive performance was maintained.     

Effect of feeding a negative dietary cation-anion difference diet for an extended time prepartum on postpartum serum and urine metabolites and performance

Forty-five multiparous Holstein cows and 15 springing Holstein heifers were used in a randomized block design trial to determine the effect of length of feeding a negative dietary anion-cation difference (DCAD) diet prepartum on serum and urine metabolites, dry matter (DM) intake, and milk yield and composition. After training to eat through Calan doors (American Calan Inc., Northwood, NH), cows within parity were assigned randomly to 1 of 3 treatments and fed a negative-DCAD diet for 3 (3W), 4 (4W), or 6 wk (6W) before predicted calving. Actual days cows were fed negative-DCAD diets was 19.2 ± 4.1, 27.9 ± 3.1, and 41.5 ± 4.1d for 3W, 4W, and 6W, respectively. Before the trial, all cows were fed a high-forage, low-energy diet. During the trial, cows were fed a diet formulated for late gestation (14.6% CP, 42.3% NDF, 20.5% starch, 7.1% ash, and 0.97% Ca) supplemented with Animate (Prince Agri Products Inc., Quincy, IL), with a resulting DCAD (Na + K − Cl − S) of −21.02 mEq/100 g of DM. After calving, cows were fed a diet formulated for early lactation (18.0% CP, 36.4% NDF, 24.2% starch, 8.1% ash, and 0.94% Ca) for the following 6 wk with a DCAD of 20.55 mEq/100 g of DM. Urine pH was not different among treatments before calving and averaged 6.36. No differences were observed in prepartum DM intake, which averaged 11.4, 11.5, and 11.7 kg/d for 3W, 4W, and 6W, respectively. Prepartum serum total protein, albumin, and Ca concentrations, and anion gap were within normal limits but decreased linearly with increasing time cows were fed a negative-DCAD diet. No differences were observed in serum metabolite concentrations on the day of calving. Postpartum, serum total protein and globulin concentrations increased linearly with increasing length of time the negative-DCAD diet was fed. No differences were observed in postpartum DM intake, milk yield, or concentration of fat or protein among treatments: 19.1 kg/d, 40.6 kg/d, 4.30%, and 2.80%; 19.6 kg/d, 41.5 kg/d, 4.50%, and 2.90%; and 18.6 kg/d, 41.0 kg/d, 4.30%, and 2.73% for 3W, 4W, and 6W, respectively. Results of this trial indicate that no differences existed in health or milk production or components in cows fed a negative-DCAD diet for up to 6 wk prepartum compared with those fed a negative-DCAD diet for 3 or 4 wk prepartum.