The effects of dry period versus continuous lactation on metabolic status and performance in periparturient cows

Graduate Student Literature Review: The challenge of drying-off high-yielding dairy cows

The cessation of lactation (i.e., dry-off) in dairy cattle is an area of research that has received much focus in recent years. The dry period is necessary to optimize tissue remodeling of the mammary gland, but represents a stressful event, incorporating several changes in daily routine, diet, and metabolism. Moreover, the high milk yields achieved by modern cows in late gestation exacerbate the need for relevant manipulations in the days around dry-off, as excessive accumulation of milk might jeopardize the success of the dry period, with potential negative effects on future lactation. Production levels over 15 kg/d are an additional risk factor for udder health, delay mammary involution, and worsen metabolic stress and inflammatory responses. Furthermore, the pressure to reduce antibiotic usage in farm animals has resulted in increased attention on the dry period, given that historically most dairy cattle were provided prophylactic intramammary antibiotic treatment at dry-off as a means to reduce the risk of intramammary infections in the subsequent lactation. Several strategies have been proposed over the years to cope with these challenges, aiming to gradually reduce milk yield before dry-off, promoting at the same time the start of mammary involution. Among them, the most common are based on feed or nutrient restriction, a decrease in milking frequency, or administration of prolactin inhibitors. These practices have different capacities to reduce milk yield through different mechanisms and entail several implications for udder health, animal welfare, behavior, endocrine status, metabolism, and inflammatory conditions. The present review aims to provide a comprehensive overview of the dry-off phase in high-yielding cows and of the impact of high milk production at dry-off, and to describe possible strategies that might be implemented by farmers and veterinarians to optimize this critical phase in an integrated way.

Transition cow nutrition and management strategies of dairy herds in the northeastern United States: Part I-Herd description and performance characteristics

Our objective was to describe management and herd characteristics of the transition period on freestall dairy herds in the northeastern United States using an on-farm survey and prospective cohort design. Enrolled herds (n = 72) had a median of 900 milking cows (range: 345-2,900) and a rolling herd average of 12,674 kg (standard deviation ± 1,220 kg), and 87.2% (n = 82/94) of fresh pens were milked at least 3×/d. The prevalence of herds with ≥15% of sampled cows with elevated concentrations of nonesterified fatty acids prepartum (≥0.27 mmol/L, 2-14 d before parturition) and postpartum [primiparous: ≥0.60 mmol/L, multiparous: ≥0.70 mmol/L, 3-14 d in milk (DIM)], β-hydroxybutyrate postpartum (≥1.2 mmol/L, 3-14 DIM), and haptoglobin postpartum (≥1 g/L, 0-12 DIM) was 51%, 51%, 51%, and 57%, respectively. In most herds, cows were moved to a calving pen when showing signs of labor (73.6%; n = 53/72) instead of 0 to 3 d before expected calving (26.4%, n = 19/72). Cows remained in the calving or maternity pen for a median (range) time of 2 (0-24) h after parturition before moving to the next pen. Primiparous cows remained in the first pen moved to after parturition for a longer period than multiparous cows [median (range) days: 12 (1.5-25) vs. 6 (1.5-22)]. Approximately 20% of herds had routine vaccinations administered in the maternity or calving pen, first pen after parturition, or both. Almost all herds (n = 69/72) performed fresh cow health checks; however, only 53% (n = 38/72) locked up all fresh cows daily. More herds housed primiparous and multiparous cows in separate pens during the far-off dry (65.3%; n = 47/72) and high-lactation (81.9%; n = 59/72) periods compared with the close-up dry (31.9%; n = 23/72) and fresh periods (27.8%; n = 20/72). At least half of the pens observed during the far-off dry, close-up dry, and fresh periods had a stocking density <100%. Approximately one-third of pens observed during the far-off dry period had feed pushed up ≤4×/d compared with approximately 15 to 20% of pens observed during the close-up dry, fresh, and high-lactation periods. More than half of the total mixed ration samples acquired from the far-off and close-up dry period visits had greater than the recommended proportion of particles in the 19-mm screen of the Penn State Particle Separator. The results of this observational study illustrated the range of management practices used in freestall herds in this region and lay the groundwork for future hypothesis-driven studies using this sampled population.

Effects of changes in diet energy density and milking frequency and a single injection of cabergoline at dry-off on feeding behavior and rumination time in dairy cows

•

Diluting the lactation diet with straw induced feeding behavior changes.

•

Behavioral effects of gradual milking cessation were unclear.

•

Cabergoline induced a reduction in feeding behavior lasting approximately 24 h.

Dry-off is a typical management practice, but research on the effects of dry-off on feeding behavior in high-yielding cows is limited. The present study investigated the effects of 2 diet energy densities: lactation diet (normal energy density, NORM) versus a lactation diet diluted with 30% straw (reduced energy density, REDU), both offered ad libitum, and 2 daily milking frequencies (2× vs. 1×) during the 7 d before dry-off day (d 0), and the effects of an injection of either a dopamine agonist [cabergoline (CAB); Velactis, Ceva Santé Animale; labeled for use only with abrupt dry-off; i.e., no reduction in feeding level or milking frequency before the last milking] or saline (SAL) following the last milking on d 0 (2 × 2 × 2 factorial arrangement), on automatically monitored feeding behavior and rumination time in 119 clinically healthy, loose-housed, pregnant, lactating Holstein cows during the week before and after d 0. From d 0, all cows were fed the same dry-cow diet ad libitum. Data were analyzed in R using mixed-effects models. Over the days before d 0, REDU cows spent 30% more time feeding at a 50% lower feeding rate, visited both assigned and unassigned feed bins more frequently, and spent more time ruminating than NORM cows. No clear behavioral effects of reduced milking frequency were found. Within 24 h following injection, CAB cows spent approximately 40% less time feeding at a lower feeding rate, visited their feed bin 28% less often, and spent 40% less time ruminating than SAL cows, irrespective of treatment before dry-off. The current study demonstrates that reducing diet energy density for 1 wk before dry-off led to clear behavioral changes in high-yielding cows. Administering CAB after the last milking induced decreased feeding behavior lasting approximately 24 h, indicating collateral effects other than reduced prolactin secretion.

Effects of dietary and milking frequency changes and administration of cabergoline on clinical udder characteristics in dairy cows during dry-off

We investigated the effects of 2 diet energy densities [normal lactation diet (NORM) vs. energy-reduced diet (REDU), both fed for ad libitum intake] and 2 daily milking frequencies [twice (2×) vs. once (1×)] during 1 week before the dry-off day, as well as effects of an injection of either a dopamine agonist [cabergoline (CAB); Velactis, Ceva Santé Animale, Libourne, France; labelled for use only with abrupt dry-off, e.g. no reduction in diet energy density or milking frequency before the last milking] or saline (SAL) following the last milking, on clinical udder characteristics of Holstein cows. During a week before and after the last milking, the following measures were recorded: palpation-based udder firmness and soreness; image-based hock-hock distance; responsiveness to mechanical udder stimulation and degree of udder fill measured with a dynamometer. Before the last milking, REDU cows displayed lower odds of having a firm udder and lower degree of udder fill, as well as lower responsiveness to mechanical udder stimulation, than NORM cows. After the last milking, REDU cows displayed shorter hock-hock distance compared with NORM cows. The effects of milking frequency on the clinical udder characteristics were unclear. Within 24 h following injection, CAB cows showed lower odds of having a firm udder, shorter hock-hock distance, and lower degree of udder fill than SAL cows, irrespective of treatment group before dry-off. In this study, reducing diet energy density prior to dry-off, and to some extent administering the dopamine agonist cabergoline after the last milking, resulted in fewest clinical udder changes.

Effect of dry period length on plasma minerals and oxidative stress around parturition and milk yield in high-producing Holstein dairy cows

The aim of present study was to evaluate the effect of dry period length (56 vs. 28 days) on plasma minerals, albumin, total protein and globulin, oxidative status, and milk production in high-producing dairy cows (13,500 ± 1800 kg milk in previous 305-day lactation). A total of 120 multiparous Holstein cows were used in a repeated measurement mixed model (animal was considered random effect) with two experimental groups and 60 replicates each: 1-long dry period (LDP, 56-day dry period) and 2-short dry period (SDP, 28-day dry period). While LDP cows received two different rations in far-off and close-up periods (DCAD = 189 and - 130 Meq/Kg, respectively), the SDP cows received only the close-up ration (- 130 Meq/Kg) without passing the far-off stage. Blood samples for minerals, oxidative stress, and metabolites (albumin, total protein) were collected on calving day, 24 and 48 h after parturition. Milk samples of all cows in each group were collected monthly (four months from parturition to 120 DIM) and analyzed for milk fat, protein, and somatic cell count (SCC). Results showed that SDP had no effect on plasma calcium (Ca), ionized calcium (iCa), magnesium (Mg), and phosphorus (iP). Total antioxidant capacity (TAC) in the SDP cows was higher (P < 0.05) than the LDP cows. The treatment had no significant effect on plasma concentration of total protein, albumin, globulin, and superoxide dismutase (SOD) activity. A positive significant (P < 0.05) correlation was observed between plasma Mg and TAC in SDP group. Short dry period reduced (P < 0.05) milk production (48.39 vs. 51.95 kg/day; about 7%) during the first 120 days in milk. However, SDP cows had higher (P < 0.05) milk protein content compared to LDP group. The log-transformed of somatic cell count (LnSCC) was not affected by the treatment. It was concluded that a short dry period (28 days) had no negative effect on plasma Ca, iCa, Mg, and iP and even could improve TAC in high-producing Holstein cows.

Assessing effects of dietary and milking frequency changes and injection of cabergoline during dry-off on hunger in dairy cows using 2 feed-thwarting tests

We investigated the single and combined effects of 2 feeding levels (normal lactation diet vs. energy-reduced diet, both fed for ad libitum intake) and 2 daily milking frequencies (twice vs. once) during 1 wk before the dry-off day (d 0), as well as an intramuscular injection of either a dopamine agonist (cabergoline; Velactis, Ceva Santé Animale; labeled for use only with abrupt dry-off, e.g., no reduction in feeding level or milking frequency before the last milking) or saline after the last milking on d 0 on the feeding motivation of clinically healthy, loose-housed, pregnant, lactating Holstein cows. From d 0, all cows were fed the same dry-cow diet for ad libitum intake. Cows were subjected to 2 feed-thwarting tests, a test in the home pen using their diets (test A: d -6, -1, and 1; during 35 min when the feed bins were filled, but locked) and another test carried out in an adjacent pen in which access to concentrate provided in a familiar plastic box was blocked by a wire-mesh lid (test B: d -5 and 2). In test A, we recorded how often cows attempted to feed per 35 min, whether cows vocalized during the 35-min period, and latency to feed within 300 s after feed bins were unlocked. In test B, we recorded latency to approach either of 2 familiar boxes (the wire-mesh box and an identical open box with a small portion of concentrate) within 600 s and how often cows directed behaviors toward the wire-mesh box (number of occurences/5 min). On d -6 (test A), no clear differences in feeding motivation among treatments were found. On d -5 and -1, cows fed the energy-reduced diet displayed a higher probability of vocalizing (test A), were more than 50% quicker to feed (test A), were approximately 5× quicker to approach a box (test B), and directed 60% more behavior toward the wire-mesh box (test B) than cows fed the normal diet. Moreover, cows fed the energy-reduced diet attempted to feed approximately 75% more on d -1 compared with d -6 (test A). On d 2 (test B), cows previously fed the normal diet directed 40% more behavior toward the wire-mesh box than cows previously fed the energy-reduced diet. Reducing feeding level, either before or on the dry-off day, resulted in consistently increased feeding motivation, interpreted as a sign of hunger. No clear effects of change in milking frequency, singly or combined with reduced diet energy density, on feeding motivation were found before d 0. Whereas, on d 2, cows previously milked twice daily were quicker to approach a box than cows previously milked once daily. Cows injected with cabergoline attempted to feed more, but showed lower probability of vocalizing compared with saline-injected cows (d 1; test A), irrespective of treatment before d 0. The effects of cabergoline on feeding motivation are not easily interpreted and warrant further investigation. From a hunger perspective, reducing milking frequency rather than diet energy density seems to be a less negative management to reduce milk production before dry-off.

Effects of dry period length on milk yield and content and metabolic status of high-producing dairy cows under heat stress

The objective of the present study was to investigate the effects of shortening dry period (DP) on milk yield, milk composition, and blood parameters in cows under heat stress. For this purpose, three DP groups were considered (30, 45, and 60 days), and 14 heat-stressed high-producing dairy cows (7 primiparous and 7 multiparous) were assigned to each DP group. The results showed that shortening the DP (from 60 to 30 days) decreased a 305-day milk yield in subsequent lactation. The difference in milk yield between 30- and 60-day DP groups was significant in the second 100 days of lactation. Accounting for additional milk yield before calving completely compensate for the loss of milk production resulting from shortening the DP. Milk protein, lactose, and solids non-fat percentages were significantly lower for cows with a 60-day DP compared to cows with a 45- or 30-day DP. Serum BHBA and urea concentrations were significantly higher, and serum glucose concentration was significantly lower for cows with a 60-day DP compared to cows with a 30-day DP. In conclusion, results showed that shortening the DP improved the metabolic status of heat-stressed transition dairy cows without decreasing total milk yield.

Evaluation of customized dry-period strategies in dairy cows

Shortening or omitting the dry period to improve the energy balance in early lactation have the trade-offs of reduction in milk production and loss of opportunity for dry-cow therapy (DCT; i.e., intramammary antibiotic use at dry-off). Customized dry-period strategies (i.e., deciding upon DCT and dry-period length per cow) could mitigate negative effects of short or no dry periods on milk production and udder health and simultaneously retain benefits from improved energy balance and fertility. In this study, we evaluated 3 decision trees to customize dry-period strategies for individual cows. In the control tree (CT), all cows had a 60-d dry period, with DCT if somatic cell count (SCC) was >150,000 cells/mL before dry-off. In decision tree 1 (T1), parity 1 and parity >1 cows were assigned DCT if SCC was ≥150,000 cells/mL and SCC ≥50,000 cells/mL, respectively; whereas in decision tree 2 (T2), the threshold for DCT was SCC ≥200,000 cells/mL for all animals. In T1 and T2, cows with DCT were assigned a 60-d dry period, whereas cows without DCT were assigned a 30-d or 0-d dry period if their milk production remained >12 kg/d at 67 and 37 d before calving, respectively. Cows were monitored from 8 wk before to 14 wk after calving. Milk production and composition, SCC, body condition score, body weight, and occurrence of treatment for disease (related to calving and start of lactation) were compared between CT (n = 61 cows), T1 (n = 59 cows), and T2 (n = 63 cows). Effects of decision trees (CT, T1, T2) and of dry-period strategies (60-d dry with or without antibiotics, 30-d dry, or 0-d dry) on measured variables were analyzed separately with mixed models, effects on udder-health status with a logistic regression, and occurrence of treatment for diseases with a Pearson chi-squared test. In T1, 36% of cows qualified for 30-d and 2% for 0-d dry periods, whereas in T2 this was 51% and 30% for 30-d and 0-d dry periods, respectively. Compared with CT, cows in T1 and T2 on average produced more milk in the 8 wk before calving (0.2 vs. 3.9 vs. 7.1 kg/d in CT vs. T1 vs. T2), and less in the 14 wk after calving (40.0 vs. 37.0 vs. 35.2 kg/d in CT vs. T1 vs. T2). There was no difference in udder-health status in the transition period among decision trees. In the first 14 wk after calving, recovery of body weight was greater for T2 than CT and T1. Overall, 30-d and 0-d dry periods reduced milk revenues, but this might be financially compensated by improved cow health with customized dry-period strategies.

Assessing response to dry-off in dairy cows kept outdoors using spontaneous behaviours and infrared thermography-a pilot study

We used spontaneous behaviours to assess response to dry-off involving abrupt dietary and milking frequency changes, followed by regrouping, after the last milking in 15 clinically healthy Holstein-Frisian cows kept outdoors. Moreover, we explored the potential of infrared thermography to detect eye temperature variations possibly induced by dry-off. On days - 1, 0, 1 and 2 relative to dry-off, we recorded whether cows vocalised during feed delivery; ate fresh feed within 5 min; and mean maximum eye temperature at approximately 1 h after feed delivery. On days 1 and 2, cows were more likely to eat fresh feed compared to days - 1 and 0. No difference in likelihood of vocalising was found. Compared to day - 1, eye temperature was substantially higher on days 0 and 2. Collectively, the results suggest that cows responded, both behaviourally and physiologically, to the abrupt dry-off management. The interpretation of the current findings deserves further investigation using larger sample sizes, more controlled environments and further behavioural, physiological, cognitive and clinical measures.

Review: Dry period length in dairy cows and consequences for metabolism and welfare and customised management strategies

Shortening or omitting the dry period improves the energy balance and metabolic status of dairy cows in early lactation. Metabolic, behaviour and welfare effects throughout lactation, however, are unclear. The current paper reviews long-term metabolic and welfare consequences of short and no dry period, as well as feeding strategies and individual cow characteristics that could support in optimising management of cows with a short or no dry period. The paper will conclude with impacts of short and no dry periods at herd level and in practice. Energy balance after no or a short dry period is more positive during the complete subsequent lactation. After the initial improvement in early lactation, cows after no dry period tend to fatten and may have a too low lactation persistency to be continuously milked until the onset of the subsequent lactation. Reducing dietary energy level for cows with no dry period reduced fattening during the complete lactation but did not improve lactation persistency. Feeding a more lipogenic diet for cows with a short or no dry period did not affect the energy balance or lactation persistency during the complete lactation, although a lipogenic diet resulted in lower plasma insulin and IGF-1 concentration and greater plasma growth hormone concentration, compared with a glucogenic diet. Effects of dry period length on udder health are ambiguous, whereas short and no dry periods improved fertility in most studies. Omission of the dry period changed behaviour of cows both before and after calving, with a longer lying time and greater feed intake after calving, suggesting a better adaptation to a new lactation. Individual cow characteristics like parity, genotype, prepartum body condition score, and milk yield level determined the metabolic response of cows to a short or no dry period. In conclusion, short or no dry periods increase the energy balance in the complete lactation. Feeding strategies can be used to limit fattening of cows with no or short dry period, but the studied feeding strategies did not increase lactation persistency. Improved fertility and behavioural changes around calving suggest a better adaptation to a new lactation in case of no dry period. Customised dry period lengths for individual cows could improve metabolic status of cows at risk of a severe negative energy balance while minimising milk losses.

Increasing metabolisable energy and protein supplementation to stimulate the subsequent milk production during late gestation by increasing proliferation and reducing apoptosis in goat mammary gland prepartum

In total, 32 pregnant goats were assigned randomly to four diets fed from Day 100 of pregnancy to Day 30 after parturition, to determine the effects of metabolisable energy (ME) and metabolisable protein (MP) supplementation levels on feed intake, subsequent colostrum and milk production and expression of genes regulating mammary-cell proliferation and apoptosis. Diets were as follows: (1) diet with ME and MP provided according to NRC recommendations (control), (2) diet with extra 10% ME, (3) diet with extra 10% MP, and (4) diet 1 with 10% extra of both ME and MP. Mammary biopsies were obtained from each udder half 24 h after parturition. Feed intake (g/day), and colostrum (kg/day) and milk (kg/month) production increased when the extra ME and MP were provided together prepartum and in early lactation (P &lt; 0.05). Relative mRNA expressions significantly increased in the mammary gland of insulin-like growth factor 1 (IGF-1, 4.3-fold), IGF-1 receptor (IGF-1R, 3.6-fold) and B-cell lymphoma 2 (Bcl-2, 4.6-fold), whereas insulin-like growth factor binding protein 3 (IGFBP-3, 3.2-fold), Bcl-2-associated X protein (Bax, 16.7-fold) and the ratio of Bax:Bcl-2 expressions significantly decreased (69.8-fold) with increased ME and MP levels fed in late gestation. In conclusion, colostrum production and milk yield in the early lactation period are sensitive to nutrient supply during gestation, where increased dietary ME as well as MP supplementation levels during late gestation will favour mammary development, by increasing expression of genes stimulating cellular proliferation (IGF-1, IGF-1R, Bcl-2) and reduced those stimulating apoptosis (IGFBP-3, Bax).

Milk Metabolomics Data Reveal the Energy Balance of Individual Dairy Cows in Early Lactation

In early lactation, dairy cows typically have a negative energy balance which has been related to metabolic disorders, compromised health and fertility, and reduced productive lifespan. Assessment of the energy balance, however, is not easy on the farm. Our aims were to investigate the milk metabolic profiles of dairy cows in early lactation, and to obtain models to estimate energy balance from milk metabolomics data and milk production traits. Milk samples were collected in week 2 and 7 after calving from 31 dairy cows. For each cow, the energy balance was calculated from energy intake, milk production traits and body weight. A total of 52 milk metabolites were detected using LC-QQQ-MS. Data from different lactation weeks was analysed by partial least squares analysis, the top 15 most relevant variables from the metabolomics data related to energy balance were used to develop reduced linear models to estimate energy balance by forward selection regression. Milk fat yield, glycine, choline and carnitine were important variables to estimate energy balance (adjusted R²: 0.53 to 0.87, depending on the model). The relationship of these milk metabolites with energy balance is proposed to be related to their roles in cell renewal.

Effects of dry period length on production, cash flows and greenhouse gas emissions of the dairy herd: A dynamic stochastic simulation model

Shortening or omitting the dry period of dairy cows improves metabolic health in early lactation and reduces management transitions for dairy cows. The success of implementation of these strategies depends on their impact on milk yield and farm profitability. Insight in these impacts is valuable for informed decision-making by farmers. The aim of this study was to investigate how shortening or omitting the dry period of dairy cows affects production and cash flows at the herd level, and greenhouse gas emissions per unit of milk, using a dynamic stochastic simulation model. The effects of dry period length on milk yield and calving interval assumed in this model were derived from actual performance of commercial dairy cows over multiple lactations. The model simulated lactations, and calving and culling events of individual cows for herds of 100 cows. Herds were simulated for 5 years with a dry period of 56 (conventional), 28 or 0 days (n = 50 herds each). Partial cash flows were computed from revenues from sold milk, calves, and culled cows, and costs from feed and rearing youngstock. Greenhouse gas emissions were computed using a life cycle approach. A dry period of 28 days reduced milk production of the herd by 3.0% in years 2 through 5, compared with a dry period of 56 days. A dry period of 0 days reduced milk production by 3.5% in years 3 through 5, after a dip in milk production of 6.9% in year 2. On average, dry periods of 28 and 0 days reduced partial cash flows by €1,249 and €1,632 per herd per year, and increased greenhouse gas emissions by 0.7% and 0.5%, respectively. Considering the potential for enhancing cow welfare, these negative impacts of shortening or omitting the dry period seem justifiable, and they might even be offset by improved health.

Consequences of dietary energy source and energy level on energy balance, lactogenic hormones, and lactation curve characteristics of cows after a short or omitted dry period

Omitting the dry period (DP) generally reduces milk production in the subsequent lactation. The aim of this study was to evaluate the effect of dietary energy source-glucogenic (G) or lipogenic (L)-and energy level-standard (std) or low-on milk production; energy balance (EB); lactogenic hormones insulin, insulin-like growth factor 1 (IGF-1), and growth hormone (GH); and lactation curve characteristics between wk 1 and 44 postpartum in cows after a 0-d or 30-d DP. Cows (n = 110) were assigned randomly to 3 transition treatments: a 30-d DP with a standard energy level required for expected milk yield [30-d DP(std)], a 0-d DP with the same energy level as cows with a 30-d DP [0-d DP(std)], and a 0-d DP with a low energy level [0-d DP(low)]. In wk 1 to 7, cows were fed the same basal ration but the level of concentrate increased to 6.7 kg/d for cows fed the low energy level and to 8.5 kg/d for cows fed the standard energy level in wk 4. From wk 8 postpartum onward, cows received a G ration (mainly consisting of corn silage and grass silage) or an L ration (mainly consisting of grass silage and sugar beet pulp) with the same energy level contrast (low or std) as in early lactation. Cows fed the G ration had greater milk, lactose, and protein yields, lower milk fat percentage, greater dry matter and energy intakes, and greater plasma IGF-1 concentration compared with cows fed the L ration. Dietary energy source did not affect EB or lactation curve characteristics. In cows with a 0-d DP, the reduced energy level decreased energy intake, EB, and weekly body weight gain, but did not affect milk production or lactation curve characteristics. A 30-d DP resulted in a greater total predicted lactation yield, initial milk yield after calving, peak milk yield, energy intake, energy output in milk, days to conception [only when compared with 0-d DP(low)], plasma GH concentration [only when compared with 0-d DP(std)], and decreased weekly body weight gain compared with a 0-d DP. A 30-d DP decreased both the increasing and the declining slope parameters of the lactation curve and the relative rate of decline in milk yield (indicating greater lactation persistency) compared with a 0-d DP, and decreased plasma insulin and IGF-1 concentration, and EB. In conclusion, feeding a G ration after wk 7 in milk improved energy intake and milk production, but did not affect EB compared with an L ration. For cows without a DP, a reduced dietary energy level did not affect milk production and lactation curve characteristics, but did decrease EB and weekly body weight gain. A 30-d DP increased milk yield and lactation persistency, but decreased milk fat and protein content, EB, and plasma insulin and IGF-1, compared with a 0-d DP.

The effect of dry period length and postpartum level of concentrate on milk production, energy balance, and plasma metabolites of dairy cows across the dry period and in early lactation

Shortening or omitting the dry period (DP) improves energy balance (EB) in early lactation because of a reduction in milk yield. Lower milk yield results in lower energy demands and requires less energy intake. The aim of this study was to evaluate the effects of DP length and concentrate level postpartum on milk yield, feed intake, EB, and plasma metabolites between wk -4 and 7 relative to calving of cows of second parity or higher. Holstein-Friesian dairy cows (n = 123) were assigned randomly to 1 of 2 DP lengths: 0-d DP (n = 81) or 30-d DP (n = 42). Prepartum, cows with a 0-d DP received a lactation ration based on grass silage and corn silage (6.4 MJ of net energy for lactation/kg of dry matter). Cows with a 30-d DP received a dry cow ration based on grass silage, corn silage, and straw (5.4 MJ of net energy for lactation/kg of dry matter). Postpartum, all cows received the same basal lactation ration as provided to lactating cows prepartum. Cows with a 0-d DP were fed a low level of concentrate up to 6.7 kg/d based on the requirement for their expected milk yield (0-d DP-L; n = 40) or the standard level of concentrate up to 8.5 kg/d (0-d DP-S; n = 41), which was equal to the concentrate level for cows with a 30-d DP (30-d DP-S; n = 42) based on requirements for their expected milk yield. Prepartum dry matter intake, concentrate intake, basal ration intake, energy intake, plasma β-hydroxybutyrate (BHB), and insulin concentrations were greater and plasma free fatty acids (FFA) and glucose concentrations were lower, but EB was not different in cows with a 0-d DP compared with cows with a 30-d DP. During wk 1 to 3 postpartum, milk fat yield and plasma BHB concentration were lower and dry matter intake and concentrate intake were greater in cows with a 0-d DP compared with cows with a 30-d DP. During wk 4 to 7 postpartum, fat- and protein-corrected milk (FPCM), lactose content, and lactose and fat yield were lower in 0-d DP-L or 0-d DP-S cows compared with 30-d DP-S cows. Basal ration intake, EB, body weight, plasma glucose, and insulin and insulin-like growth factor-1 concentrations were greater and plasma FFA and BHB concentrations were lower in 0-d DP-L and 0-d DP-S cows compared with 30-d DP-S cows. Concentrate and energy intake were lower in 0-d DP-L cows than in 0-d DP-S or 30-d DP-S cows. Milk yield and concentrations of plasma metabolites did not differ in wk 4 to 7, although EB was lower in wk 6 and 7 postpartum in 0-d DP-L cows than in 0-d DP-S cows. In conclusion, a 0-d DP reduced milk yield and improved EB and metabolic status of cows in early lactation compared with a 30-d DP. Reducing the postpartum level of concentrate of cows with a 0-d DP did not affect fat- and protein-corrected milk yield or plasma FFA and BHB concentrations in early lactation but did reduce EB in wk 6 and 7 postpartum.

[Investigation of influence factors on quantity of first colostrum in Holstein Friesian cows and their relation to postpartum calcium concentration]

OBJECTIVE

The aim of this study was to investigate the factors that affect the quantity of the first colostrum in Holstein Friesian cows and the relationship to the blood serum calcium concentration postpartum. It should be verified whether: 1. the lactation number is the main influencing factor; 2. the quantity of the first colostrum is etiologic for developing parturient paresis.

MATERIAL AND METHODS

An observational study was conducted from April 2012 to March 2013 at a commercial dairy farm (2278 Holstein Friesian cows). The analysis comprised the following variables: blood serum concentrations of calcium, phosphorus, non-esterified fatty acids, and β-hydroxybutyrate; back-fat thickness; daily milk production; calving data; lactation number; male parent of the cow; length of gestation; age at first calving; duration of the dry period; fertility parameters of prelactation; diseases during the dry period and up to 3 days postpartum. A stepwise analysis of the data for correlations and influencing factors was conducted by means of variance, correlation, and multiple linear regression analyses.

RESULTS

The mean colostrum quantity was 5.6 kg with a standard deviation of 3.41 kg. A number of influencing factors affected the colostrum quantity. One quarter of the variability of the colostrum quantity could be explained by the influencing factors examined. A dominant effect of the lactation number was not confirmed. Instead, the effect of the lactation number was attenuated by the more potent factors milk production in the following lactation period, diseases after calving, duration of the dry period, the male parent of the cow (genetics), and the weight of the calf.

CONCLUSIONS AND CLINICAL RELEVANCE

Selective breeding for high milk production and using bulls whose female offspring have high milk production can at the same time lead to breeding for high colostrum quantities. A dry period duration of 50 days is recommendable with respect to colostrum quantity. The two hypotheses could not be confirmed.

Effects of dry period length and dietary energy source on milk yield, energy balance, and metabolic status of dairy cows over 2 consecutive years: Effects in the second year

The objective of the current study was to evaluate the effect of dry period (DP) length on milk yield, energy balance (EB), and metabolic status in cows fed a lipogenic or glucogenic diet in the second year after implementation of DP and dietary treatments. Holstein-Friesian dairy cows (n=167) were assigned randomly to 1 of 3 DP lengths (0, 30, or 60d) and 1 of 2 early lactation diets (glucogenic or lipogenic) for 2 consecutive years. Results of the first year were reported previously. In the second year, 19 cows in the 0-d DP group were attributed to a new group (0→67d DP) because these cows had a milk yield of <4kg/d at least 30d before expected calving date and were dried off. Milk yield was recorded and EB was calculated from wk -8 to 9 relative to calving. Blood samples were taken weekly from wk -3 to 8 relative to calving. Liver samples were taken in wk -2, 2, and 4 relative to calving. At the onset of lactation, cows with a 0-d or 0→67-d DP had greater body condition score (BCS) than cows with a 60-d DP. During the first 9wk, cows with a 0- or 30-d DP produced 5.0 and 4.3kg less milk per day, respectively, but had similar EB compared with cows with a 60-d DP. Cows with a 0- or 30-d DP produced additional milk precalving, which could compensate milk yield losses in the first 9wk postcalving. Cows with a 0-d DP did not have milk yield losses or improve EB in the second year as much as in the first year. Cows with a 0-d DP had greater plasma insulin and insulin-like growth factor-I (IGF-I) and lower liver triacylglycerol concentrations than cows with other DP lengths. Cows with a 0→67-d DP had lower EB, and greater plasma free fatty acids (FFA) and β-hydroxybutyrate (BHB) concentrations than cows with other DP lengths. Feeding a glucogenic diet increased plasma glucose, IGF-I, and insulin concentrations, and decreased plasma FFA, BHB, and urea concentrations compared with a lipogenic diet, independent of DP length. In conclusion, omitting the DP or feeding a glucogenic diet improved metabolic status in early lactation of the second year after implementation of DP length and dietary treatments, although effects of omitting the DP were less pronounced in the second year than in the first year. The less pronounced improvement of EB in the second year was related to the high BCS at the onset of lactation and reduced milk yield losses in cows with a 0-d DP.

Effect of maternal dry period length on colostrum immunoglobulin content and on natural and specific antibody titers in calves

The objective was to study the effect of dry period length in dairy cows on immunoglobulin content and natural antibodies (NAb) titers in colostrum, growth, and plasma natural and specific antibody titers in plasma of calves. Holstein-Friesian dairy cows (n=167) were randomly assigned to 3 dry period lengths (0, 30, or 60 d). Colostrum production, concentration of colostrum IgG and IgM, and titers of NAb (isotypes IgG and IgM) binding keyhole limpet hemocyanin (KLH) and human serum albumin (HuSA) in colostrum were measured. Female calves were immunized with both KLH and HuSA at wk 6 and 10 of life. Titers of NAb and specific antibody (SpAb) for isotypes IgG, IgM, and total immunoglobulin (IgT) binding KLH or HuSA were determined in plasma of female calves. Primary and secondary antibody responses to KLH or HuSA from wk 6 and 10 were expressed as the increase in antibody titers to wk 10 and 11 of life after primary and secondary challenges, respectively. Pregnancy length for cows with a 0-d dry period was 3d shorter compared with cows with a 30- or 60-d dry period. Birth weight of calves from cows with a 0-d dry period was lower compared with calves from cows with a 30-d dry period. Growth of calves until 12 wk of life was not affected by dry period length. Colostrum production and IgG and IgM concentration in colostrum were lower for cows with a 0-d dry period than a 60-d dry period. Natural IgG and IgM titers binding KLH or HuSA were lower in colostrum from cows with a 0-d dry period compared with cows with a 60-d dry period. Natural antibody titers (IgG, IgM, and IgT) binding KLH or HuSA in plasma were lower during the first 2 wk of life for calves from cows with a 0-d dry period compared with calves from cows with a 30- or 60-d dry period. After primary and secondary immunization of calves with KLH and HuSA, SpAb titers of calves were not affected by dry period length. After secondary immunization, the response of IgG and IgT binding KLH was higher in plasma of calves from cows with a 0-d dry period. The results of this study demonstrate that, although omission of the dry period of dairy cows leads to lower plasma NAb titers in calves during the first 2 wk of life, SpAb titers in calves were not affected and even the secondary antibody responses were enhanced compared with calves from cows with a 30- or 60-d dry period.

A survey of drying-off practices on commercial dairy farms in northern Germany and a comparison to science-based recommendations

While dry cow management is important for health, milk production and fertility information on drying-off procedures implemented on commercial dairy farms is lacking. Current drying-off management procedures on commercial dairy farms were evaluated using a questionnaire and results compared with recommendations given in the current literature. Ninety-one participants from a farmer education event completed the survey. On average, cows were dried off seven weeks before calving. Only 9.9 per cent of the farms had a dry period length of five weeks or less. A continuous milking regime without dry period was not established on any farm participating in the survey. Most farmers performed an abrupt drying-off (73.0 per cent). Only 11.8 and 15.0 per cent attempted to lower milk yield prior to drying-off by reducing milking frequencies and adjusting feed rations, respectively. While a blanket antibiotic dry cow treatment was carried out on 79.6 per cent of the farms, selective dry cow treatment was not mentioned by any farmer. Although 77.4 per cent preponed the drying-off date in low-yielding cows, an altered drying-off procedure in high-yielding dairy cows was rare (9.7 per cent). This survey provides an insight into drying-off procedures currently applied on commercial dairy farms in northern Germany.

Effects of dry period length and dietary energy source on metabolic status and hepatic gene expression of dairy cows in early lactation

In a prior study, we observed that cows with a 0-d dry period had greater energy balance and lower milk production compared with cows with a 30- or 60-d dry period in early lactation. The objective of the current study was to evaluate the influence of dry period length on metabolic status and hepatic gene expression in cows fed a lipogenic or glucogenic diet in early lactation. Holstein-Friesian dairy cows (n=167) were assigned randomly to 3×2 factorial design with 3 dry period lengths (n=56, 55, and 56 for 0-, 30-, and 60-d dry, respectively) and 2 early lactation diets (n=84 and 83 for glucogenic and lipogenic diet, respectively). Cows were fed a glucogenic or lipogenic diet from 10d before the expected calving date and onward. The main ingredient for a glucogenic concentrate was corn, and the main ingredients for a lipogenic concentrate were sugar beet pulp, palm kernel, and rumen-protected palm oil. Blood was sampled weekly from 95 cows from wk 3 precalving to wk 8 postcalving. Liver samples were collected from 76 cows in wk -2, 2, and 4 relative to calving. Liver samples were analyzed for triacylglycerol concentrations and mRNA expression of 12 candidate genes. Precalving, cows with a 0-d dry period had greater plasma β-hydroxybutyrate, urea, and insulin concentrations compared with cows with a 30- or 60-d dry period. Postcalving, cows with a 0-d dry period had lower liver triacylglycerol and plasma nonesterified fatty acids concentrations (0.20, 0.32, and 0.36mmol/L for 0-, 30-, and 60-d dry period, respectively), greater plasma glucose, insulin-like growth factor-I, and insulin (24.38, 14.02, and 11.08µIU/mL for 0-, 30-, and 60-d dry period, respectively) concentrations, and lower hepatic mRNA expression of pyruvate carboxylase, compared with cows with a 30- or 60-d dry period. Plasma urea and β-hydroxybutyrate concentrations were greater in cows fed a lipogenic diet compared with cows fed a glucogenic diet. In conclusion, cows with a 0-d dry period had an improved metabolic status in early lactation, indicated by lower plasma concentrations of nonesterified fatty acids, greater plasma concentrations of glucose, insulin-like growth factor-I, and insulin, and lower mRNA expression of pyruvate carboxylase in the liver, compared with cows with a 30- or 60-d dry period. Independent of dry period length, the glucogenic diet also improved the metabolic status compared with the lipogenic diet.

Effects of shortening the dry period of dairy cows on milk production, energy balance, health, and fertility: a systematic review

A dry period of 6-8 weeks for dairy cows is generally thought to maximise milk production in the next lactation. However, the value of such a long dry period is increasingly questioned. In particular, shortening the dry period shifts milk production from the critical period after calving to the weeks before calving. This shift in milk production could improve the energy balance (EB), health and fertility of dairy cows. The objective of this study was to systematically review the current knowledge on dry period length in relation to milk production, EB, fertility, and health of cows and calves. A meta-analysis was performed for variables where at least five studies were available. Overall, both shortening and omitting the dry period reduces milk production, increases milk protein percentage and tends to reduce the risk of ketosis in the next lactation. Individual studies reported an improvement of EB after a short or no dry period, compared with a conventional dry period. Shortening or omitting the dry period did not affect milk fat percentage and shortening the dry period did not alter the odds ratio for mastitis, metritis, or fertility measures in the next lactation. So, current evidence for an improvement of health and fertility of dairy cows is marginal and may be partly explained by the limited number of studies which have evaluated health and fertility in relation to dry period length, the limited number of animals in those studies and the variable responses reported.

Improving Productive and Reproductive Performance of Holstein Dairy Cows through Dry Period Management

To determine the effects of dry period (DP) length on milk yield, milk composition, some blood metabolites, complete blood count (CBC), body weight and score and follicular status, twenty five primiparous and multiparous Holstein cows were assigned to a completely randomized design with DP-60 (n = 13) and DP-20 (n = 12) dry period lengths. Cows in the DP-60 produced more milk, protein, SNF, serum non-esterified fatty acids (NEFA) and beta hydroxyl butyrate acid (BHBA) compared with cows in DP-20 (p≤0.05). Serum glucose, blood urea nitrogen (BUN), urea, and glutamic oxaloacetic transaminase (GOT) were all similar among the treatments. Body Condition Score (BCS), body weight (BW), complete blood count (CBC) and health problems were similar between the treatments. Diameter of the first dominant follicle and diameter of the dominant follicle on d 14 were different among the treatments. Thus, results of this study showed that reducing the dry period length to DP-20 had a negative effect on milk production, milk composition and reproductive performance in Holstein dairy cows.

Effects of pre-partum milking of dairy cows on calcium metabolism at start of milking and at calving

This experiment studied the effect of pre-partal milk removal on calcium metabolism at start of milking and at calving. Nine cows of the Swedish Red breed were milked for 1-7 days pre-partum. The average milk yield at the first milking was 4.8 l, and the average yield the last day prior to calving was 13.4 l. Five cows were used as control cows and were only milked post-partum. Samples of plasma and urine were taken to determine the effect of pre-partum milking and calving on levels of calcium, magnesium, parathyroid hormone and plasma C-terminal crosslinked telopeptide of type 1-collagen (CTx), used as a marker of bone resorption. Pre-partum milking resulted in a decrease in plasma calcium that was evident 2 days after the first milking. Parathyroid hormone increased at the same time, and CTx started to increase from 24 h after the first milking. There were no effects on plasma magnesium or urinary output of calcium or magnesium. The first week after calving, there were no differences between pre-partum milked cows and control cows in plasma or urine variables, or in milk yield. In conclusion, pre-partum milking activated the calcium-restoring mechanisms but did not improve calcium status at calving.

Challenges in the nutrition and management of herbivores in the temperate zone

The expected higher global demand for animal proteins and the competition for starch and sugars between food, fuel and feed seem to favour herbivores that convert solar energy captured in fibrous plants into animal products. However, the required higher production level of herbivores questions the sustainability of this conversion. An increase in herbivore production can be achieved by increasing the number of animals associated with the increasing demand of plant biomass or by improving the efficiency with which plant biomass is converted into meat and milk. The potential to increase food production by cattle, the main food-producing herbivore in the temperate zones outside China, was considered in three production systems: grassland-based, mixed rain-fed and mixed irrigated systems. The potential to increase plant biomass production in grassland-based systems seems limited, unless fertiliser is imported in large quantities and crop production is increased, sacrificing valuable, high-quality grasslands, which often conflicts with sustainable production methods. Also, in mixed systems with high inputs of fertiliser or water, improvements in plant biomass production seem marginal and the main challenges for these systems are in breeding high-quality plant biomass at lower levels of fertiliser and the use of new co-products from food processing and bio-based economies. Consequently, the main challenge in herbivore nutrition management is to improve the efficiency of plant biomass utilisation. Stocking rate management along with seasonal variation in the grazing capacity of grasslands and moderate use of fertiliser may increase meat production in grassland-based systems by 400%. Improving plant biomass utilisation in the more industrialised mixed rain-fed systems seems possible by better feed storage technologies and for dairy cattle by improving animal health and lifetime production level. Managing the transition period seems crucial to achieve more sustainable mixed rain-fed and mixed irrigated dairy production systems. Whether sustainable production methods will be implemented also depends on macro-economic conditions and awareness of regional and global environmental concerns.

Effects of continuous milking during the dry period or once daily milking in the first 4 weeks of lactation on metabolism and productivity of dairy cows

The objective was to compare the effects of 3 management systems in high-yielding dairy cows on metabolic profiles and milk production. Thirty-six multiparous Brown Swiss cows were randomly assigned to 1 of 3 treatment groups (n=12 cows/group): the control (C) group, in which cows were dried off 56 d before calving and milked twice daily throughout next lactation (305 d); the once daily milking (ODM) group, in which cows were dried off 56 d before calving and milked once daily for the first 4 wk of lactation and twice daily for the remaining lactation; and the continuous milking (CM) group, in which cows were milked twice daily until calving and also during the subsequent lactation. Serum glucose concentrations decreased between wk 1 and 4 exclusively in C cows. Serum concentrations of NEFA and BHBA in the first 4 wk of lactation were highest in C cows compared with ODM and CM cows. Decreased backfat thickness during early lactation and reduction of body condition score were markedly more pronounced in C cows compared with ODM and CM cows. Mean lactational milk yield of C cows [11,310+/-601 kg of energy-corrected milk (ECM)/305 d] was approximately 16% higher compared with ODM cows (9,531+/-477 kg of ECM/305 d) and CM cows (9,447+/-310 kg of ECM/305 d). The lactation curve of CM cows compared with C cows was characterized by a similar time of peak yield (wk 3), a reduced peak yield, and no obvious differences in persistency. Mean percentage of milk protein was significantly higher for CM cows (3.91%) compared with C cows (3.52%). In contrast, once daily milking was accompanied by a reduced and significantly delayed peak yield (wk 8) compared with the control treatment, whereas persistency was better and milk protein (3.79%) was higher in ODM cows than in C cows. In conclusion, continuous milking and once daily milking, targeting the interval before or after calving, respectively, substantially reduced the metabolic challenge of fresh cows and improved milk protein percentage. Continuous milking and once daily milking increased milk protein percentage markedly; furthermore, once daily milking during the first 4 wk of lactation improved the lactation curve.

Oxidative stress indicators and metabolic adaptations in response to the omission of the dry period in dairy cows

The effects of dry period omission on oxidative stress and metabolic indicators around calving were studied. Seventeen Italian Friesian cows were randomly assigned to two groups, homogeneous for milk yield and parity, and managed either with a traditional 55-d dry off period (n=8) or continuously milked till parturition (n=9). Between 60 d before expected calving and 90 d after calving, body condition (BCS) was recorded and blood samples were collected to measure cortisol, urea, cholesterol, glucose, NEFA, triglycerides, insulin, malondialdehyde (MDA), total glutathione (GSH) and glutathione peroxidase (GPx) activity. BCS changes after calving were not different between the two groups. The normally dried group showed lower (P<0.05) glucose concentrations on day 7 before calving, greater (P<0.01) non-esterified fatty acid concentrations at 7 d and 15 d after calving, and greater (P<0.01) triglyceride concentrations for all the period before calving. On the other hand, plasma MDA was not different between groups. On average, plasma GSH concentrations were greater in continuously milked cows after calving (P<0.05), while plasma GPx was greater with continuous milking up to parturition (P<0.01). The results confirmed that omitting the dry period leads to an improved energy balance. The degree of oxidative stress was not detrimental for animal health, and the slight modifications of GPx observed prepartum were possibly related to continuous milk secretion. The differences in plasma GSH observed after calving may depend upon sulphur amino acid sparing in continuously milked cows.

Effect of recombinant bovine somatotropin and a shortened or no dry period on the performance of lactating dairy cows

The objective of this study was to determine the effects of altering dry period length in multiparous dairy cows (n = 341) on milk production for a full lactation (294 d). The study used 3 commercial herds in the western United States. Cows producing greater than 8,400 kg of mature-equivalent milk were assigned to treatments 60 d before their due dates. The 4 treatments were 1) 60-d dry period, label use of recombinant bovine somatotropin (rbST; 60d-L); 2) 32-d dry period, label use of rbST (32d-L); 3) 0-d dry period, label use of rbST (0d-L); and 4) 0-d dry period, continuous use of rbST (0d-C). Cows with shortened dry periods produced 625, 1,000, and 1,042 kg of milk during the prepartum period for treatments 2 to 4, respectively. During the postpartum period, cows on the 32d-L treatment produced similar amounts of milk compared with the 60d-L treatment (11,490 vs. 11,968 kg, respectively). However, cows on the 0d-L (10,316 kg) and 0d-C (10,195 kg) treatments produced significantly lower amounts of milk during the postpartum period compared with the 60d-L treatment. Total milk production from the prepartum and postpartum periods was not altered significantly and was 11,974, 12,112, 11,310, and 11,230 kg for treatments 1 to 4, respectively. The concentrations of beta-hydroxybutyrate and nonesterified fatty acids in serum after calving were decreased for cows on the 32d-L, 0d-L, and 0d-C treatments compared with cows on the 60d-L treatment, which may indicate improved metabolic status.