Dry Period Length Research Articles

Influence of different nutritional planes in the dry period on immunoglobulin G concentration of bovine colostrum

High-quality colostrum is important for successful rearing of calves. Parity and length of dry period have been discussed as factors influencing the quality of colostrum. However, the role of the nutritional plane of the cow during the dry period and its effect on the colostral immunoglobulin G (IgG) concentration remains unclear. Results from studies carried out in sheep suggest that colostrum volume as well as composition can be affected by different energy levels prepartum. Furthermore, recent publications in the field of human medicine have found lower concentrations of IgG in colostrum from women suffering from an altered insulin response. Because dry cows on a high-energy diet are at increased risk to develop insulin resistance, and their colostrum volume and IgG concentration might be affected in a similar manner as that in other species, the objective of this study was to evaluate the effect of different nutritional planes during the dry period on colostrum composition.

A canonical response of precipitation characteristics to global warming from CMIP5 models

AbstractIn this study, we find from analyses of projections of 14 CMIP5 models a robust, canonical global response in rainfall characteristics to a warming climate. Under a scenario of 1% increase per year of CO2 emission, the model ensemble projects globally more heavy precipitation (+7 ± 2.4%K−1), less moderate precipitation (−2.5 ± 0.6%K−1), more light precipitation (+1.8 ± 1.3%K−1), and increased length of dry (no‐rain) periods (+4.7 ± 2.1%K−1). Regionally, a majority of the models project a consistent response with more heavy precipitation over climatologically wet regions of the deep tropics, especially the equatorial Pacific Ocean and the Asian monsoon regions, and more dry periods over the land areas of the subtropics and the tropical marginal convective zones. Our results suggest that increased CO2 emissions induce a global adjustment in circulation and moisture availability manifested in basic changes in global precipitation characteristics, including increasing risks of severe floods and droughts in preferred geographic locations worldwide.

Changes in Milk Proteome and Metabolome Associated with Dry Period Length, Energy Balance, and Lactation Stage in Postparturient Dairy Cows

The early lactation period of dairy cows, which produce high quantities of milk, is normally characterized by an insufficient energy intake to cover milk production and maintenance requirements. Mobilization of body reserves occurs to compensate this negative energy balance (NEB), and probably as a consequence there is a higher susceptibility to diseases and metabolic disorders. There are several diagnostic methods to detect NEB, usually involving ketosis related parameters. Due to the easy availability of milk this is a preferred matrix, but simple and robust predictors of NEB level are missing. To better understand the physiological mechanism of NEB, milk of cows subjected to different dry period lengths, in different energy balance status and lactation stage, were analyzed by untargeted metabolomics and proteomics techniques. Milk of cows in severe NEB showed higher concentrations of acute phase response proteins, unsaturated fatty acids, and galactose-1-phosphate. Improved energy balance (EB) resulted in higher concentration of cholesterol, cholesterol synthesis related proteins, and stomatin. The presence of stomatin and galactose-1-phosphate in milk was strongly dependent on the EB of the cows. These novel and interesting findings warrant more in-depth research to assess their applicability as robust indicators of NEB in milk and to clarify the role of stomatin and galactose-1-phophate in milk of dairy cows in NEB.

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.

Losses in milk yield, fat and protein contents according to different levels of somatic cell count in dairy goats

To estimate the losses in milk yield, fat content and protein content according to different levels of somatic cell count (SCC), and to evaluate the influence of some variation factors on SCC in Saanen, Alpine and Nubian U.S. goats, data obtained from twelve dairy goat farms and seven different breeds for the period 2003–2010 were used. Individual milk yield was measured monthly during lactation. Somatic cell count, fat (%F) and protein (%P) contents were determined using automated equipment. SCC was transformed to a log scale (SCS). In a first analysis, the fix effects ANOVA procedure was used to evaluate the influence of different variation factors on SCS. In an additional analysis and using only first lactation data, losses in test day milk yield and test day %F and %P according to the SCS recoded level, were estimated for Alpine, Nubian and Saanen breeds. Effects of test day milk yield level (MY), %F level, %P level, flock, breed, year and season of kidding, lactation number, litter size, length of dry period, lactation days at each sampling as covariate, significantly influenced SCS (P<0.01). The estimated losses in test day milk yield according to the recoded level of SCS used for Alpine, Nubian and Saanen breeds were 0.5–12.9%, 0.4–29.1% and 0.2–15.4%, respectively. For %F loss estimated for Alpine, Nubian and Saanen goats these were 0.01–10.8%, 0.5–7.6% and 1.1–16.0%, respectively. Estimated losses in %P for the same breeds were from 0.30% to 7.8%, 0.5% to 7.2% and 2.0% to 15.0%, respectively. Results suggest the need for the establishment of prevention and control programs of subclinical mastitis based on SCS routine monitoring in commercial goat herds.

Association between dry period length and lactation performance, lactation curve, calf birth weight, and dystocia in Holstein dairy cows in Iran

In this study, 65,971 lactations on 41,842 cows in 64 herds were used to determine the association between dry period length (DPL) and lactation performance, lactation curve, calf birth weight, and the incidence of calving difficulty during the subsequent parity in Holstein dairy cows in Iran. The length of the dry period was classified into 7 categories: 0 to 35d, 36 to 50d, 51 to 60d, 61 to 70d, 71 to 85d, 86 to 110d, and 111 to 160d. Cows with the standard DPL (51 to 60d) produced more 305-d milk, fat, and protein over the next lactation compared with those with shorter dry periods. Shorter dry periods (0 to 35d and 36 to 50d) were associated with lower initial milk yield, steeper inclining and declining slopes of the lactation curve, and higher milk persistency compared with dry period length of 51 to 60d. Peak lactation was achieved later in cows with 0- to 35-d and 36- to 50-d dry period length than in those with dry period length of 51 to 60d. We also observed a relationship between DPL and calf birth weight: smaller calf birth weight was recorded with a dry period of 51 to 60d compared with longer dry periods. The incidence of calving difficulty did not differ in cows with 51- to 60-d dry period compared with cows with 0- to 35-d and 36- to 50-d dry periods. In conclusion, the results of this study did not support previous findings that suggested a shorter dry period could be beneficial to dairy production.

Effect of different dry period lengths on milk production and somatic cell count in subsequent lactations in commercial Dutch dairy herds

Shortening the dry period (DP) has been proposed as a management strategy to improve energy balance in early lactation. It is well known that both shortening and complete omission of the DP reduces milk production in the subsequent lactations. In most of these studies milk production data were obtained from planned animal experiments where cows were randomly assigned to DP length treatments, and cow management and diet composition did not differ among treatments. It may therefore be hypothesized that cows on commercial herds which apply a no-DP or short-DP-strategy, and support this by management adjustments, will have a less dramatic reduction in milk production. In this study, milk production and somatic cell count (SCC) following different DP lengths was investigated under commercial circumstances. Milk production of 342 cows (2,077 test-day records) was available from 5 Dutch commercial dairy herds which started a no DP-strategy for all cows. Test days of the year before applying the no-DP strategy are used as control (323 cows, 1,717 test-day records). Six other herds applied an individual cow approach and have different preplanned DP lengths within one herd. From these herds, information on 81 cows (482 test-day records) with a DP length between 0 and 20d, 127 cows (925 test-day records) with a DP length between 21 and 35d, and 143 cows (1,075 test-day records) with a DP length of more than 35d was available. A generalized linear model incorporating an autoregressive covariance structure accounting for repeated test-day yields within cow was developed to estimate the daily yield (milk, fat and protein) and SCC of all cows. Applying no DP for all cows in the herd resulted in a reduction in postpartum milk production compared with within-herd control lactations (until 305 DIM) between 3.2 and 9.1kg/d, which was a reduction of 12 and 32%, respectively. For the 6 herds that applied an individual cow approach with different preplanned DP lengths, the cow-specific DP strategy was based on milk production and SCC approximately 2mo before calving. Cows with a preplanned DP length ranging between 0 and 20d had a reduction in postpartum milk production between 5.7 and 13kg/d compared with cows with a DP length of >35d. Cows with a preplanned DP length ranging from 21 to 35d had a numerically lower milk production (between 0.6 and 5.3kg/d) than cows with a preplanned DP length of >35d, but this difference was significant in only one herd. When corrected for milk yield, no difference in postpartum SCC for cows with different DP lengths was found.

Analyses of the impact of climate change on water resources components, drought and wheat yield in semiarid regions: Karkheh River Basin in Iran

AbstractWater resources availability in the semiarid regions of Iran has experienced severe reduction because of increasing water use and lengthening of dry periods. To better manage this resource, we investigated the impact of climate change on water resources and wheat yield in the Karkheh River Basin (KRB) in the semiarid region of Iran. Future climate scenarios for 2020–2040 were generated from the Canadian Global Coupled Model for scenarios A1B, B1 and A2. We constructed a hydrological model of KRB using the Soil and Water Assessment Tool to project water resources availability. Blue and green water components were modeled with uncertainty ranges for both historic and future data. The Sequential Uncertainty Fitting Version 2 was used with parallel processing option to calibrate the model based on river discharge and wheat yield. Furthermore, a newly developed program called critical continuous day calculator was used to determine the frequency and length of critical periods for precipitation, maximum temperature and soil moisture. We found that in the northern part of KRB, freshwater availability will increase from 1716 to 2670 m3/capita/year despite an increase of 28% in the population in 2025 in the B1 scenario. In the southern part, where much of the agricultural lands are located, the freshwater availability will on the average decrease by 44%. The long‐term average irrigated wheat yield, however, will increase in the south by 1.2%–21% in different subbasins; but for rain‐fed wheat, this variation is from −4% to 38%. The results of critical continuous day calculator showed an increase of up to 25% in both frequency and length of dry periods in south Karkheh, whereas increasing flood events could be expected in the northern and western parts of the region. In general, there is variability in the impact of climate change in the region where some areas will experience net negative whereas other areas will experience a net positive impact. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Effect Of Drying- Off Period And Teat Dipping On Productivity Of Dairy Cows

This study was conducted to investigate effect of period of drying off and teat dipping on dairy cow production. This study was carried out at Sami Asaad Dairy Farm at Abo-Hamad city in SharkiaProvince in the period from first of December, 2010 till end of November, 2011. The data were obtained from farm book record and were collected from one hundred dairy cows (Holstein Friesian) to assess the effect of length of dry off period, age and lactation season on dairy cow production. The obtained results showed that the cows with a dry period of 45, 46 and 59 days, had the highest milk yield at 305-day. So, increasing the dry period lead to an increase in milk yield of subsequent lactation. Furthermore, the total milk production was increased gradually from 3 to 7 years, after that it decreased. Also to evaluate the effect of teat dipping on dairy cow’s milk production in the period from first of July till end of September, 2011; the data obtained from sixteen dairy cows (Holstein Frisian), divided into 2 groups, group A (n= 8) wherethe udder washed, dried with a clean toilet tissues and the teats dipped in 70% ethyl alcohol solution, while group B (n=8) without teat dipping. The results revealed that the teat dipping after milking decrease the incidence of mastitis and increase milk yield. In conclusion, length of dry off period, age, lactation season and teat dipping have significantly effect on milk yield in dairy cows.

Efecto de la duración del período seco en la posterior producción y reproducción en vacas Holstein

El registro de los partos de vacas Holstein desde enero 1983 a diciembre 2006 que comprende 1190 rebaños con 384717 partos, se utilizaron para evaluar los factores que afectan la duración del período seco y el efecto de los actuales días secos en las posteriores producciones y reproducciones de las vacas Holstein iraníes. Los análisis estadísticos de los días secos y características productivas y reproductivas en este estudio se realizaron con modelos lineales mixtos. La duración del período seco (DD) de las vacas se agrupa en 14 clases desde menos de 10 días hasta &gt; 130 días. El promedio de DD fue de 100.46 días en vacas Holstein iraníes. Las vacas primíparas tuvieron el menor DD y la media de DD disminuyó a lo largo de los años de 1983 a 2006 y las de parición de verano tenían el DD más corto (p &lt;0.001). Las vacas dentro de las clases DD de 51-60 y 61-70 tuvieron el mayor rendimiento real de leche, la producción de leche en equivalente-madura, producción de leche ajustada, producción de grasa ajustada, producción de proteína y el rendimiento ajustado a equivalente-madura de proteína (p &lt;0.05 ). Además, las vacas dentro de la clase de 0-10 DD tuvo el mayor porcentaje de grasa ajustada, porcentaje de grasa en equivalente-madura y el porcentaje de proteína ajustado (p &lt;0.05). Nuestros resultados actuales muestran una reducción en el intervalo entre partos y en la edad al parto en las vacas con menor longitud de días secos que en otras con una duración del period seco más largo (p &lt;0.05). Teniendo en cuenta la reciente iniciativa de acortar los períodos secos, vale la pena destacar que con 51 a 70 DD se proporciona un rendimiento máximo en vacas Holstein iraníes.

Impact of climate change on harvest security and biomass yield of two timothy ley harvesting systems in Norway

SUMMARYPredicted future climate changes in northern Europe include increased air temperature and altered precipitation patterns. There is a lack of knowledge about potential climate change effects on the biomass yield and security of agricultural crops. The present study determined the potential impact of future climate change on the yield and harvest security of timothy (Phleum pratense L.). Harvest security was assessed using data on accumulated precipitation and the length of dry spell period within the 7 days after cutting. Timothy production as a function of weather, soil and management practices was simulated using the LINGRA model for the periods 1961–90, 2046–65 and 2080–99, and the locations Apelsvoll, Ås, Sola, Tromsø and Værnes in Norway and harvest systems with 600 and 800 °C days between cuts. One hundred years of daily weather data were generated with the LARS-WG tool, using future daily weather data sets based on 12 Global Climate Models. Total seasonal biomass yield varied between 690 g dry matter (DM)/m2 for the 800 °C days harvesting regime in the period 1961–90 at Tromsø and 1548 g DM/m2 for the same harvesting regime in the period 2046–65 at Sola. In general, the biomass was higher in the two future periods than in 1961–90 across locations and harvesting regimes, mainly owing to more cuts per season. Accumulated precipitation after cutting varied between 12·2 mm after the first cut for the 600 °C days harvesting regime in the period 1961–90 at Værnes and 42·5 mm after the fourth cut in the 800 °C days harvesting regime in the period 2080–99 at Sola. The longest duration of dry spell 7 days after pre-planned harvest varied between 1·8 days after the fourth cut at Sola in the 600 °C days harvesting regime for the period 2080–99, and 3·9 days after the first cut at Ås in the 800 °C days harvesting regime for the period 2046–65. Potential consequences of these results are discussed.

WPŁYW DŁUGOŚCI OKRESU ZASUSZENIA KRÓW PIERWIASTEK I STARSZYCH NA ICH UŻYTKOWOŚĆ W KOLEJNYM CYKLU PRODUKCYJNYM

Analysis was made of the effect of dry period length in first-calf heifers and older cows from the active population of cows in the Pomerania and Kujavia regions on their performance in the next production cycle. The GLM, FREQ and CORR PEARSON procedures of the SAS package were used for statistical calculations. It was found that a dry period of 41-60 days is the most favourable in terms of next lactation milk yield. Any shortening of the dry period, especially to less than 20 days, is particularly inadvisable for first-calf heifers. Dry periods of 21-40 days are the most favourable considering survival of cows (especially the oldest cows) in the next production cycle. Extending the standard dry period of 41-60 days by 20 days causes a slight decrease in performance (as determined by the parameters mentioned above) but extending it by another 20 days is highly detrimental. Especially in the oldest cows, a dry period that is too long (over 100 days) may carry the risk of increased culling in the herd, shorter lactations and poorer reproductive performance.

Dry period length and performance of cows in the subsequent production cycle

Abstract. The effect of dry period length on performance in the next production cycle was investigated in the active population of cows from the Pomerania and Kuyavia regions of Poland. Dry length period of the cows was calculated and classified (0, 1–20, 21–40, 41–60, 61–80, 81–100, &gt;100 days). The GLM, FREQ and CORR PEARSON procedures of the SAS package 9.1 were used in the statistical calculations. The problem of dry period length was found to be debatable. A dry period of 40–60 days would be the most favourable in terms of milk, fat and protein yield in the next lactation, the course of parturition and the proportion of calves born alive, and a dry period of 21–60 days would be the most beneficial in terms of the proportion of cows surviving the next production cycle. Extending or shortening the standard dry period of 40–60 days by 20 days causes a slight decrease in performance determined by the above parameters, whereas extending and especially shortening the dry period by another 20 days, or the absence of a dry period, have a severely negative effect. Compared to cows that had been dry for 40–60 days, the cows whose calving was not preceded by a dry period had lower lactation yield (by 25 % for milk, by 24 % for fat and by 20 % for protein), lower daily milk yield (by 22 %), were significantly more prone to miscarriage, and more frequently gave birth to dead calves, calves with physical defects or grossly malformed calves. Too long a dry period (beyond 100 days) may carry a risk of higher culling levels in the herd, shorter lactations, health abnormalities, and poorer reproductive performance.

Influence of dry period length on reproductive performance and productivity of Lacaune dairy sheep under an intensive management system

Intensive management is almost the only way to ensure dairy farm profitability. The dry period length (DPL) is a key factor in the productivity and health of dairy cows, but whether the same is true of dairy sheep is unclear. This study investigated the effects of DPL on the performance of Lacaune sheep under intensive management. We recorded 8136 lactations from 4220 ewes on one farm for the period 2005-2010, and data from a total of 6762 complete lactations 1-4 were included in the study. The length of the dry period following the current lactation was studied. The larger the total milk yield (MY) and daily milk yield (DMY), the shorter was the DPL before the next lactation. DPL correlated with MY (r=-0·384), DMY (r=-0·277) and the lambing-to-conception interval (LC; r=0·201, P<0·0001) in the global analysis of all lactations (lactations 1-4). The influence of previous-DPL (P-DPL), or the length of the period prior to the start of the next lactation, was studied for 4318 lactations. P-DPL was classified into five intervals: very short (P-DPL-XS), 1-30 d; short (P-DPL-S), 31-60 d; medium (P-DPL-M), 61-90 d; long (P-DPL-L), 91-120 d; and very long (P-DPL-XL), >120 d. P-DPL positively correlated with lambing-to-next conception interval (LNC; r=0·095, P<0·0001) for lactations 1-4. LNC was significantly shorter for P-DPLs that were very short, short, or long (P-PDL-XS, 144·2±67·8 d; P-PDL-S, 149·1±57·2 d; P-PDL-L, 152·0±53·7 d) than for groups with very long or medium P-PDLs (P-DPL-XL, 161·5±62·9 d; P-DPL-M, 169·0±74·8 d; P<0·0001). Moreover, P-DPLs that were very short, long, or very long were associated with the lowest milk yields (P-PDL-XS, 377±215 l; P-PDL-l, 370±168 l; P-PDL-XL, 396±196 l). These yields were significantly lower than the yields for short and medium P-DPLs (P-DPL-S, 432±187 l; P-DPL-M, 436±191 l; P<0·0001) when averages of lactations 1-4 were analysed. These results indicate that lactations with larger MY are followed by a shorter dry period, and that a dry period of 30-90 d leads to larger yields in the next lactation. The best LNC was associated with the shortest Previous-DPL. Hence, 30-60 d should be the optimal dry period length for Lacaune sheep under intensive conditions.

무강수일수와 강우효과를 고려한 개선된 표준강수지수 개발

본 연구에서는 가뭄의 심도에 직접적으로 영향을 주는 무강수일수를 고려하고, 강수에서 기인하는 지표면유출 효과를 반영한 가뭄해갈에 유효한 강수를 산정하여 기존의 SPI3을 개선한 Modified SPI를 제시하였다. 1973년부터 2009년까지 각종 보고서 및 문헌자료를 통해 실제 발생한 가뭄사례를 수집하여 행정구역별 가뭄공간정보를 생산하고, 동일기간 전국 69개지점에서산정된 가뭄지수를 우리나라 전체 공간으로표현하여각종 지수의 적합성을 평가하기 위하여ROC 분석을 수행하였다. 개선된 가뭄지수 제시를 위하여 총 강우량 중단기적인 유출에 기여할 것으로 판단되는 부분을 절삭하여 유효강우를 산정하였으며, 월단위의 무강수일수를 십분위, 누적분포함수로 변형하여 기존의 지수에 가중치를 부여하였다. 분석결과 유출량을 고려한 강우의 절삭은 기존의 SPI3에 비하여 상대적으로 높은 가뭄감지능력을 보여주었으며, 무강수일수를 고려한 가뭄지수의 개선은 누적분포함수의 수치를 고려함으로서 상당히 개선된 가뭄감지 능력을 보여주었다. A modified standardized precipitation index was developed by considering the length of dry period and surface run-off effect. The official reports and newspapers on drought from 1973 to 2009 were quantified to evaluate drought indices. The developed index was evaluated using the receiver operating characteristic analysis. In order to suggest improved drought index, we cut the precipitation amount that may do not contribute the mitigation of drought and weight dry period by considering cumulative distribution, decile distribution of dry periods. Drought detection capability of the suggested index has improved by weighting of dry period effects and considering precipitation amounts contributing drought mitigation.

Changes of total versus extreme precipitation and dry periods until the end of the twenty-first century: statistical assessments for the Mediterranean area

Changes of total precipitation, extreme precipitation, and dry periods in the Mediterranean area until the end of the twenty-first century have been assessed by means of statistical downscaling. Generalized linear models using predictors describing the large-scale atmospheric circulation as well as thermodynamic conditions have been applied for the projections under A1B and B1 scenario assumptions. The results mostly point to reductions of total and extreme precipitation over the western and central-northern Mediterranean areas in summer and autumn and to increases in winter. In contrast, over the eastern Mediterranean area widespread precipitation increases are assessed in summer and autumn, whereas reductions dominate in winter. In spring, total and extreme precipitation decreases prevail over the whole Mediterranean area. Total and extreme precipitation decreases mostly come along with increases of the maximum dry period length. Vice versa precipitation increases are commonly accompanied by a shortening of the maximum dry period length.

Effects of continuous lactation and short dry periods on mammary function and animal health

The dry period is required to facilitate cell turnover in the bovine mammary gland in order to optimize milk yield in the next lactation. Traditionally, an 8-week dry period has been a standard management practice for dairy cows based on retrospective analyses of milk yields following various dry period lengths. However, as milk production per cow has increased, transitioning cows from the nonlactating state to peak milk yield has grown more problematic. This has prompted new studies on dry period requirements for dairy cows. These studies indicate a clear parity effect on dry period requirement. First parity animals require a 60-day dry period, whereas lactations following later parities demonstrate no negative impact with 30-day dry period or even eliminating the dry period when somatotropin (ST) is also used to maintain milk yields. Shortened dry periods in first parity animals were associated with reduced mammary cell turnover during the dry period and early lactation and increased numbers of senescent cells and reduced functionality of lactating alveolar mammary cells postpartum. Use of ST and increased milking frequency postpartum reduced the impact of shortened dry periods. The majority of new intramammary infections occur during the dry period and persist into the following lactation. There is therefore the possibility of altering mastitis incidence by modifying or eliminating the dry period in older parity animals. As the composition of mammary secretions including immunoglobulins may be reduced when the dry period is reduced or eliminated, there is the possibility that the immune status of cows during the peripartum period is influenced by the length of the dry period.

Effect of dry period management on mammary gland function and its endocrine regulation in dairy cows

The objective of this study was to evaluate the effect of shortening the dry period on the mammary gland and the hormonal regulation of its functions. Holstein cows (n=18) were assigned to a short dry period (SDP; 35 d; n=9) or a conventional dry period (CDP; 65 d; n=9). All cows were fed the same diets, with the exception that, during the dry period, the SDP cows received only the pre-calving diet for 35 d, whereas the CDP cows were fed a high-fiber diet from 65 to 28 d before calving and then received the same pre-calving diet as the SDP cows. Mammary gland functional capacity was evaluated at 70 days in milk, and mammary biopsies were taken in early and midlactation. Dry period length averaged 64.3±1.1 and 31.9±1.0 d for the CDP and SDP cows, respectively. The SDP cows had a lower milk yield and a lower energy-corrected milk yield compared with the CDP cows. The SDP cows also had a lower dry matter intake from wk 5 to 20 of lactation and tended to have lower plasma concentrations of β-hydroxybutyrate from wk 1 to 4. Prepartum serum progesterone and estradiol concentrations were unaffected by the dry period management. Serum growth hormone concentrations and milking-induced prolactin release were similar in both groups. However, during the period when the CDP cows were dry but the SDP cows were still being milked (wk −9 to −6), serum prolactin concentrations were higher in the SDP cows than in the CDP cows. The SDP cows had a lower milk BSA content than the CDP cows after the dry period and similar milk lactose concentrations, suggesting that their mammary tight junctions were closed following parturition and, therefore, that the later stage of their lactogenesis was not impaired by SDP management. In early and midlactation, mammary cell apoptosis and proliferation rates as well as mammary expression of genes involved in the function of this tissue were unaffected by the dry period management strategy. For cows in their second lactation, mammary gland functional capacity at 70 d in milk tended to be lower in the SDP cows. In conclusion, even though SDP management decreased milk production during the subsequent lactation, it did not affect mammary cell activity. Although direct evidence is still lacking, decreased mammary cell growth during the dry period is likely responsible for this negative effect. The higher prolactin concentrations in lactating cows during late gestation could be involved in this effect. More research is needed to test these hypotheses.

The comparative efficacy of two long-acting dry-cow cephalonium products in curing and preventing intramammary infections

AIMS: To test equivalence between two different cephalonium dry-cow therapy (DCT) products with regard to the incidence of bacteriological cure of existing infections of quarters, the incidence of new intramammary infections (IMI) from 2–5 days postpartum and the incidence of clinical mastitis from drying-off to 21 days postpartum. METHODS: All cows (n=1,570) on four commercial dairy farms in Southland were eligible for inclusion. Power analysis using a variance inflation factor indicated a required minimum of 2,101 quarters per treatment group. Cows were blocked by herd, parity, previous history of mastitis and most recent somatic cell count (SCC), and then randomly allocated to either of two cephalonium treatments at the cow level, viz the treatment group (new formulation cephalonium) or the positive control group (existing reference formulation cephalonium). All quarters within a cow were assigned the same treatment. Samples collected from all quarters with a SCC ≥500,000 cells/mL at drying-off, and those with a positive culture postpartum were cultured, as well as samples from all quarters collected between 2–5 days postpartum. All cases of mastitis were recorded and sampled for culture. The risk of quarter-level incidence of bacteriological cure, IMI and clinical mastitis was modelled using a GLM and generalised estimating equation (GEE), including the effects of treatment group, age,farm, udder-health status at drying-off and length of dry period. RESULTS: For 829 infected quarters, the estimated incidence of bacteriological cure for all pathogens was 78.0 (95% CI=64.3–91.6)% for the treatment group and 75.7 (95% CI=61.6–89.8)% for the positive control group (p=0.71). Incidence of cure varied with the farm (p=0.001), type of pathogen pre-treatment (p=0.009) and log10SCC at drying-off (p<0.001). For 4,530 quarters, the estimated incidence of new IMI, with any pathogen, for treatment and positive control groups was 16.1 (95% CI=13.1–19.7)% and 16.0 (95% CI=13.0–19.5)% respectively (p=0.91). Incidence of IMI varied with farm (p<0.001), pathogen and SCC status before treatment (p<0.001), and length of the dry period (in days) (p<0.001). For 5,136 quarters, the estimated incidence of clinical mastitis was 1.0 (95% CI=0.5–1.7)% in the treatment group and 1.1 (95% CI=0.6–2.0)% in the positive control group (p=0.64). CONCLUSIONS: Use of the two different cephalonium products at drying-off in four dairy herds in Southland resulted in equivalence with respect to incidence of bacteriological cure of existing infections, incidence of new IMI postpartum, and incidence of clinical mastitis in early lactation.

Long term use of bovine somatotropic (bST) on reproduction and health of Nili-Ravi buffaloes

The study was conducted to determine the effect of long term use of bovine somatotropic hormone (bST) on days to first oestrus post-partum, number of services per conception, pregnancy rate, lactation length, dry period and calving interval for a period of three years, from 2004 to 2007. Thirty Nili-Ravi lactating buffaloes with approximately similar milk yields and stage of lactation were selected and randomly allocated to two treatments, A and B, with 15 animals in each group. Group A served as control while animals in group B were given injections of bovine somatotropic hormone (250 mg intramuscular per animal) at intervals of 14 days over a period of three years. The calving interval, dry period and lactation length were shorter by 71, 63.9 and 7 days, respectively, in the treated compared with the control group. The days to first oestrus post-partum, service period and services per conception were 160 ± 56.9 vs.98.2 ± 76.4 days, 207.0 ± 85.0 vs. 115.1 ± 107.0 days and 1.47 ± 1.1 vs. 1.31 ± 0.5 in group A vs. B, respectively. Statistically, differences were significant for post-partum oestrous and service period but for services per conception the difference was non-significant. Prevalence of mastitis was significantly higher in the treated animals while differences in body weights of the animals in the groups were not significant.