Minerals to dairy cows with focus on calcium and magnesium balance

Both clinical and subclinical deficiency of calcium and magnesium may cause problems in dairy cows. Clinical hypocalcaemia most commonly occurs at calving and onset of lactation and is associated with milk fever, while clinical hypomagnesaemia occurs under certain dietary conditions. Factors affecting the calcium and magnesium status in dairy cows were examined in this thesis. The effect of dietary magnesium (0.19 and 0.43 % of dry matter) and potassium (1.9, 2.8, and 3.7 % of dry matter) on magnesium digestibility and magnesium balance was assessed using a Latin square design with six lactating cows. The effect of supplying dietary calcium to dry cows (0.49, 0.93, and 1.36 % of dry matter) on calcium and magnesium homeostasis was investigated in 29 periparturient cows. A case-control study was used to investigate whether mineral feeding during the last part of the dry period differed between 30 herds with high incidence of milk fever, and 22 herds with no milk fever. Finally, the effect of prepartum milking for 1 to 7 days on calcium homeostasis was investigated in 15 cows around calving. Magnesium uptake in lactating cows was found to depend on the level of dietary magnesium, but not on the potassium concentration. Dietary calcium had no effect on hypocalcaemia at calving, and was not different between herds with high milk fever incidence and herds without milk fever. However, high levels of calcium in the diet resulted in decreased magnesium absorption. High amounts of potassium in the diet were associated with increased risk of high milk fever incidence, while high amounts of dietary magnesium were associated with decreased risk of high milk fever incidence. Prepartum milking decreased plasma calcium levels and activated the calcium homeostatic mechanisms. However, there were no differences in the degree of hypo¬calcaemia at calving, and plasma concentration of calcium decreased within 1 h after calving, indicating that factors other than milk removal alone were responsible for the decrease in plasma calcium levels at calving. The conclusion was that cows should be fed high amounts of magnesium and low amounts of potassium during the last part of the dry period to avoid milk fever, while the potassium concentration in the diet of lactating cows is of less importance regarding magnesium uptake. Milk removal affects calcium homeostasis, but the effect on the risk of milk fever is unclear

Using machine learning methods to predict dry matter intake from milk mid-infrared spectroscopy data on Swedish dairy cattle

In this research communication we compare three different approaches for developing dry matter intake (DMI) prediction models based on milk mid-infrared spectra (MIRS), using data collected from a research herd over five years. In dairy production, knowledge of individual DMI could be important and useful, but DMI can be difficult and expensive to measure on most commercial farms as cows are commonly group-fed. Instead, this parameter is often estimated based on the age, body weight, stage of lactation and body condition score of the cow. Recently, milk MIRS have also been used as a tool to estimate DMI. There are different methods available to create prediction models from large datasets. The main data used were total DMI calculated as a 3-d average, coupled with milk MIRS data available fortnightly. Data on milk yield and lactation stage parameters were also available for each animal. We compared the performance of three prediction approaches: partial least-squares regression, support vector machine regression and random forest regression. The full milk MIRS alone gave low to moderate prediction accuracy (R-2 = 0.07-0.40), regardless of prediction modelling approach. Adding more variables to the model improved R-2 and decreased the prediction error. Overall, partial least-squares regression proved to be the best method for predicting DMI from milk MIRS data, while MIRS data together with milk yield and concentrate DMI at 3-30 d in milk provided good prediction accuracy (R-2 = 0.52-0.65) regardless of the prediction tool used

Magnesium status in dairy cows : a field study

Magnesium is an essential mineral that is important for several physiologic and biochemical processes in the body. Deficiency of magnesium is mainly associated with grass tetany, but can also appear in cows during the indoor period. Since long it is known that potassium has a negative effect on the absorption of magnesium. Due to the fact that potassium fertilisation leads to a higher potassium content in forage, it is of interest to study interactions of potassium on the magnesium balance in dairy cows. There are few studies about magnesium feeding to dairy cows in Sweden and the purpose of this study was to investigate how much magnesium and from which feed-sources dairy cows in Sweden get their magnesium. Data was collected from seven farms in the northern part of Uppland and from seven farms in Skaraborg in Sweden. Four of the investigated farms had an organic production system (KRAV). At the farm visits information concerning the feeding of the cows and their milk production was gathered. Furthermore urine samples were collected from 10 % of the cows at each farm. A surplus of absorbed magnesium is excreted in the urine, thus by determining the content of magnesium in urine a good indication of the magnesium status in the cows could be achieved. The content of magnesium and potassium in the diets was determined based on feed analysis data obtained from the farmers, analyses of collected feed samples and information by the feed manufacturers. Calculated magnesium intake per cow was in average 50 g/day and varied between 30 and 70 g/day. The average urinary excretion of magnesium was 5.8 g/day and cow, varying from 2.2 to 8.2 g/day. Magnesium intake was compared with the magnesium excretion in urine and the variation between farms was explained partly by differences in magnesium intake and magnesium concentration in the diet, but also of the influence of potassium on the magnesium absorption. The absorption, calculated as the proportion of the intake that was excreted in urine and milk, was in average 17 %, which did not differ from the literature value of 16 % for the coefficient of absorption for magnesium from natural feedstuffs. Recommended value of total diet K/Mg-ratio is 4-5 and the average in this study was 6.8. A low K/Mg-ratio in the diet gave higher urinary excretion of magnesium, which indicates a that high potassium level mat negatively interact with magnesium uptake The K/Mg-ratio in the forage for the four organic farms had strong influence of magnesium absorption, a low K/Mg-ratio gave a higher coefficient of absorption. In average 47 % of the magnesium intake came from the concentrates, 37 % from the forage and 16 % from the mineral feed. More than 60 % of the magnesium from the concentrates came from commercial feedstuffs and in average 46 % of the magnesium in the total diet originated from commercial feedstuffs.Magnesium är ett livsnödvändigt mineral och är viktig för flera fysiologiska och biologiska processer. Magnesiumbrist associeras främst med beteskramp, men kan även drabba kor på stall. Det är sedan länge känt att kalium har en negativ inverkan på magnesiumupptaget och eftersom att kaliumgödslingen av vallfoder ökat är det intressant att se hur det påverkar kornas magnesiumförsörjning. Då det finns få studier om hur magnesiumutfodringen ser ut i svenska mjölkkobesättningar var målsättningen med denna studie att kartlägga hur mycket och från vilka fodermedelskällor som dagens mjölkkor får sitt magnesium. Materialet som legat till grund för studiens resultat inhämtades på 14 mjölkkogårdar, varav sju låg i norra Uppland och sju i Skaraborg. Fyra av de 14 besättningarna var anslutna till KRAV. Vid gårdsbesöken samlades uppgifter om kornas utfodring och mjölkproduktion in. Urinprov togs från ca 10 % av korna i besättningen. Ett överskott av absorberat magnesium utsöndras nästan uteslutande i urinen varvid urinprov analyserade på magnesiuminnehåll därför ger en bra indikation på kons magnesiumstatus. Utifrån utfodringsuppgifterna från lantbrukarna beräknades, för urinprovskorna, foderstater med avseende på magnesium- och kaliuminnehåll. Beräknat magnesiumintag jämfördes med respektive kos magnesiumutsöndring i urinen. Medelintaget av magnesium var 50 g/dag, med variation mellan 30 och 70 g/dag och medelutsöndringen av magnesium i urinen uppgick till 5,8 g/dag, med spridning från 2,2 till 8,2 g/dag. Variationen mellan besättningar förklarades bland annat av skillnader i magnesiumintag och magnesiumkoncentrationen i foderstaten, vidare inverkade även kaliumnivån på magnesiumabsorptionen. Den beräknade medelabsorptionen av magnesium, beräknad efter antagandet att allt absorberat magnesium utsöndras i mjölk och urin, var 17 %, vilket inte skiljer sig från litteraturen där man räknar med en absorptionskoefficient på 16 % för en blandfoderstat. Totalfoderstatens K/Mg-kvot bör enligt rekommendationen ligga mellan 4-5, här låg den genomsnittliga kvoten på 6,8. En låg K/Mg-kvot gav en högre magnesiumutsöndring. För de fyra KRAV-besättningarna såg man ett starkt samband mellan grovfodrets K/Mg-kvot och magnesiumabsorptionen, en låg K/Mg-kvot gav högre absorptionskoefficient. Resultatet tyder på att mycket kalium i förhållande till magnesium påverkar magnesiumupptaget negativt. I genomsnitt fick korna ungefär 47 % av sitt dagliga magnesiumintag från kraftfodret, 37 % från grovfodret och 16 % från mineralfodret. Av kraftfoderdelen kom mer än 60 % av magnesiumet från koncentratet och totalt kom i genomsnitt 46 % av det dagliga magnesiumintaget från kommersiella fodermedel (koncentrat/färdigfoder + mineralfoder)

Effects of high potassium intake on the magnesium balance in dairy cows

Magnesium is one of the most important minerals in the body and it participates in many essential processes, such as energy metabolism and protein synthezis. Magnesium deficiency in cattle may occur when they are let out for pasture in the spring, and is associated with tetany, known as grass staggers. A high yielding dairy cow often loses more magnesium daily in the milk than she has available in the body, and magnesium thereby needs to be provided in the feed to prevent the cow from being affected by deficiency symptoms. The uptake of magnesium is mainly located to the rumen and is not regulated by hormones. The surplus is excreted in the urine by the kidneys. The digestibility of magnesium in common feedstuff is about 20%. Many studies, mainly on dry cows or sheep, have shown that the absorption of magnesium in the rumen is negatively affected by the presence of potassium ions. To compensate the lower uptake, extra magnesium can be supplied when the potassium content in the diet is high. The purpose of this study was to investigate how the magnesium balance in lactating cows was affected by increasing levels of potassium in the diet, and to determine in which level of potassium extra magnesium needed to be provided. The hypothesis was that the cows would absorb less magnesium when fed diets with increasing potassium concentration, and that this would be compensated for by increasing levels of magnesium. Six lactating cows were fed two levels of magnesium (1,9 and 3,7 g/kg DM) and three levels of potassium (19, 28 and 37 g/kg DM) during six experimental periods in a Latin square design. Spot samples of feces, urine and milk were analyzed for magnesium to be able to calculate the magnesium balance. Samples of the blood and the rumen fluid were also taken. The pH was measured in the urine and the rumen fluid, and the consistency of the feces was estimated. Creatinine in the urine and acid insoluble ash in the faeces were used as markers to calculate the daily amount of urine and faeces produced. The results showed that the cows excreted more magnesium in the urine when they were given extra magnesium in their diets. This indicates that they absorbed more magnesium from the rumen. The concentration of magnesium in the rumen fluid and in the plasma was higher when the cows were fed increased levels of magnesium. The concentration of magnesium in milk was not affected by treatment. The absorption, calculated as the proportion of the intake that was excreted in urine and milk, was lower when the diets were supplied with extra magnesium, 12,1 % vs 16,4 %. The feces had a more soft consistency when the magnesium intake was higher. The level of potassium had no influence on the magnesium balance, but had an impact on the rumen and urine pH. The calculated absorption of magnesium was lower than what has been showed by earlier studies. The lack of effect of increased potassium concentration can be due to the chosen levels of magnesium and potassium in the experimental diets. Another reason could be the differences between lactating cows and dry cows or sheep.Magnesium är ett av de viktigaste mineralerna i kroppen. Magnesium är delaktigt i många viktiga processer, till exempel energimetabolismen och proteinsyntesen. Brist på magnesium hos kor kan inträffa när de kommer ut på bete på våren, och kan yttra sig som kramper, s.k. beteskramp. En högproducerande mjölkko förlorar ofta mer magnesium enbart i mjölken dagligen än vad hon har tillgängligt i kroppen, och magnesium måste därför tillföras via fodret för att inte kon ska drabbas av bristsymtom. Det huvudsakliga upptaget av magnesium sker i våmmen, och är inte hormonellt styrt. Överskottet utsöndras via njurarna i urinen. Smältbarheten för magnesium i vanliga fodermedel ligger på ca 20 %. Många studier, de flesta utförda med sinkor eller får, har kunnat visa att magnesiumupptaget i våmmen påverkas negativt av förekomsten av kaliumjoner. För att kompensera ett minskat upptag av magnesium kan extra magnesium tillföras i foderstaten då fodret innehåller mycket kalium. Syftet med detta försök var att se hur magnesiumbalansen hos mjölkande kor påverkas av ökade nivåer av kalium i foderstaten och att komma fram till vid vilken nivå av kalium extra magnesium kan behöva tillsättas. Hypotesen var att korna vid ett ökat intag av kalium skulle absorbera en mindre mängd magnesium, men att detta skulle kompenseras vid tillförsel av extra magnesium. Sex mjölkande kor fodrades med 2 nivåer av magnesium (1,9 och 4,3 g/kg ts) och 3 nivåer av kalium (19, 28 och 37 g/kg ts) under sex perioder i en romersk kvadrat. Prover på träck, urin och mjölk analyserades med avseende på magnesium för att kunna upprätta en magnesiumbalansräkning, även blodprover och prover på våmvätskan togs och pH mättes i urin och våmvätska. Dessutom bedömdes träckkonsistensen. För att beräkna den dagliga mängden träck och urin användes saltsyraolöslig aska respektive kreatinin som markörer. Resultaten visade att korna utsöndrade mer magnesium i urinen då de fick extra magnesiumtillskott. Det visar att de då absorberade mer magnesium ur våmmen. Magnesiumkoncentrationen i våmvätskan var högre då korna fick magnesiumtillskott, liksom magnesiumkoncentrationen i blodplasman. Koncentrationen i mjölk påverkades inte av tillförsel av magnesium. Absorptionen, beräknad som andelen av intaget som utsöndrades i mjölk och urin, var lägre då korna fick extra magnesium, 12,1 % mot 16,4 %. Träckkonsistensen var lösare då korna fick magnesiumtillskott. Ingen påverkan av kaliumnivåerna på magnesiumbalansen kunde ses, men däremot hade kaliumnivåerna höjande påverkan på pH-värdet i både våmvätska och urin. Den beräknade absorptionen av magnesium var lägre än vad många tidigare studier visat. Att effekten av kalium uteblev kan bero på att nivåerna av magnesium och kalium i detta försök inte var tillräckligt höga eller låga. Det kan också vara så att mjölkande kor är mindre känsliga för höga kaliumnivåer i fodret än vad sinkor och får är

Genetic parameters of forage dry matter intake and milk produced from forage in Swedish Red and Holstein dairy cows

High-yielding dairy cows are often fed high proportions of cereal grain and pulses. For several reasons, it would be desirable to replace these feed sources with forage, which is not suitable for human consumption. Feeding large amounts of forage to dairy cows could also make dairy production more publicly acceptable in the future. In this study, we estimated genetic parameters for total dry matter intake (DMI), DMI from forage (DMIFor), energy-corrected milk (ECM), and ECM produced from forage (ECMFor). A total of 1,177 lactations from 575 cows of Swedish Red (SR) and Holstein (HOL) dairy breeds were included in the study. Mixed linear animal random regression models were used, with fixed effect of calving season and lactation week nested within parity 1 and 2+, fixed effect of calving year, and random regression coefficients for breeding value (up to linear) and permanent environmental effect (up to quadratic) of the cow. Heritability for DMI and DMIFor was generally higher for HOL than for SR in all-parity data and in later parities; however, the opposite was true for first parity. Heritability for DMI and DMIFor during the first 8 wk averaged 0.11 and 0.15, respectively, in all-parity data for the 2 breeds. Corresponding values for ECMFor and ECM were 0.21 and 0.29, respectively. In first parity, values were 0.32, 0.36, 0.28, and 0.51, respectively. The genetic correlation between DMI and DMIFor was high, above 0.83, and fairly constant across the lactation. The genetic correlation between ECMFor and ECM was close to unity in the later part of lactation for both breeds, but was around 0.8 in the early lactation for both breeds; it decreased for HOL to 0.54 in wk 17. The genetic correlations between DMI and ECMFor and between DMIFor and ECMFor were low and negative for HOL (absolute value similar to 0.2-0.3), but changed for SR from weakly positive in early lactation to negative values and back to positive toward the end of lactation. For most traits, the correlation between wk 1 and wk 8 into the lactation was very high; the lowest value was for DMI in HOL at 0.81. The genetic correlation between parities was rather high in the first part of the lactation. During the first 8 wk, the correlation was lower for HOL than for SR, except for ECM. We found that DMIFor and ECMFor showed reasonably large heritability, and future work should explore the possibility of genomic evaluations

A randomized study on the effect of extended voluntary waiting period in primiparous dairy cows on milk yield during first and second lactation

Extending the voluntary waiting period (VWP) for primiparous cows can have a positive impact on fertil-ity without a negative impact on milk production per day in the calving interval (CInt). We investigated the effect of extended VWP during first lactation on milk yield (MY) during 2 consecutive lactations in primipa-rous cows. The study involved 16 commercial herds in southern Sweden. A total of 533 Holstein and Red dairy cattle (Swedish Red, Danish Red, Ayrshire) dairy cows were randomly assigned to a conventional 25 to 95 d VWP (n = 252) or extended 145 to 215 d VWP (n = 281). Data on calvings, inseminations, and test-day yields were retrieved from the Swedish Milk Record -ing System. Cows with VWP according to plan and completing 1 or 2 CInt with a second or third calving were included in the data analysis. Whole lactation and 305-d energy-corrected milk (ECM) yield were higher for the extended VWP group than the conventional VWP group in both the first lactation (12,307 vs. 9,587 and 9,653 vs. 9,127 kg ECM) and second lactation (12,817 vs. 11,986 and 11,957 vs. 11,304 kg ECM). We found no difference between the VWP groups in MY per day during the first CInt or during the first and second CInt combined, although MY per day during the second CInt was around 1.5 kg higher for cows with extended VWP than for cows with conventional VWP. Thus extended VWP for primiparous cows can be used as a management tool without compromising MY

A randomized study on the effect of an extended voluntary waiting period in primiparous dairy cows on fertility, health, and culling during first and second lactation

When the voluntary waiting period (VWP), defined as the days between calving and when the cow is eligible to receive the first insemination, is extended, high-yielding dairy cows may have better opportunities to regain energy balance before first insemination. This study investigated the effect of an extended (145–215 days in milk [DIM], n = 280) or conventional (25–95 DIM, n = 251) VWP treatment on fertility, disease incidence, and culling rate in cows during their first lactation. The cows were also followed through a second lactation without intervention regarding VWP, during which the farmers could decide when they wished to start the inseminations. This was done in a randomized-controlled study on 16 high-yielding commercial herds in southern Sweden, containing a total of 531 primiparous cows of the Holstein and Red Dairy Cattle breeds. Data from the Swedish national dairy herd recording scheme collected between August 2018 and September 2021 were used in the analysis, including records on breed, calvings, estrus intensity, inseminations, disease, somatic cell count, culling date, and culling reason. During first lactation, more cows receiving the extended VWP treatment showed strong estrus intensity (score 4–5, 55% vs. 48%) and fewer showed moderate estrus intensity (score 3, 35% vs. 43%) at first insemination, compared with cows receiving the conventional VWP treatment. First service conception rate (FSCR) was higher (67% vs. 51%) and number of inseminations per conception (NINS) was lower (1.6 vs. 2.0) during the first lactation for cows receiving the extended compared with the conventional VWP treatment. For disease incidence rate or culling rate expressed as number of events per cow-time in the study, we found no differences between the cows receiving the 2 VWP treatments in any lactation. Calving to first service interval during second lactation was longer (86 vs. 74 d) for cows with extended compared with conventional VWP. In conclusion, primiparous cows with extended VWP showed improved reproductive functions, in the form of higher estrus intensity, greater FSCR, and lower NINS, during the first lactation. However, we observed no apparent effect on these fertility measures during the following lactation (without VWP intervention) and no differences in disease prevalence or culling between cows receiving the 2 different VWP treatments in either lactation. Compliance with the planned VWP treatment was lower for cows with planned extended compared with planned conventional VWP treatment. We studied the “intention-to-treat” effect (i.e., the results for all cows randomized to each treatment regardless of whether the planned VWP was achieved or not) to identify any bias arising due to degree of compliance. However, we found no difference in culling rate between cows randomized to an extended VWP compared with those randomized to a conventional VWP. These findings can be used to support management decisions on VWP length in high-yielding dairy herds

Dry matter intake, dry matter digestibility and growth performance in goats fed grass-based diet (Brachiaria or Cenchrus) compared with a concentrate-based diet

Dry matter digestibility (DMD), dry matter intake (DMI) and growth performance of concentrate- and forage-based diets were investigated using 24 growing Blended goats (12 males, 12 females) weighing 16.5±1.2 kg (mean±sd). Goats were blocked by sex and assigned randomly to three dietary treatments that were fed for 10 weeks, after two weeks of adaptation. Dietary treatments were MRG (40% maize bran, 40% rice bran, 20% Gliricidia leaf meal), BG (80% Brachiaria brizantha cv. Piatã, 20% Gliricidia leaf meal) and CG (80% Cenchrus ciliaris, 20% Gliricidia leaf meal). All diets contained sufficient nutrients to meet the requirements of growing goats. The MRG diet had lower DMI than CG, likely because MRG had small particle size and goats adapted slowly to that diet. Average daily weight gain was 10.7, 9.9 and 22.8 g/day for MRG, BG, and CG respectively, and did not differ among the diets. Goats fed MRG had lower overall live weight change than goats fed CG, while goats fed BG were intermediate. These findings indicate that B. brizantha cv. Piatã and C. ciliaris are equally useful as supplementary feedstuffs for growing goats during the dry season

Evaluation of rangeland condition in miombo woodlands in eastern Tanzania in relation to season and distance from settlements

Miombo woodlands sustainability in east and south-central Africa is threatened by human activities, including overgrazing. This study investigated seasonal variations in rangeland condition in three grazed areas in miombo woodlands in eastern Tanzania. Transect lines were established across the grazing areas, sampling points were identified and marked at every 10% of the length of transect line. Sampling points were categorised in different distances with respect to settlement. The line intercept method was used to collect data on vegetation cover and forage distribution, while herbaceous forage biomass was estimated using a disc pasture meter. A total of 118 different plant species were observed and grasses comprised 40.6% of all herbaceous species. Bothriochloa pertusa, Cynodon plectostachyus, Hyparrhenia rufa and Urochloa mosambicensis grass species dominated miombo grazed areas in various seasons and distances. These perennial grass species are desirable and indicated moderate grazing activities in miombo. Season affected grass cover, herbaceous forage biomass and nutritional composition. Grass cover and forage biomass were at the lowest during late dry season while forage nutritional quality was best during early dry season. Distance from settlement had no effect on grass cover and herbaceous forage biomass. Rangeland condition was generally fair, livestock stocking rate in continuously grazed drylands should be set at the lowest monthly forage biomass in order to ensure grazing land sustainability

GIT1 protects against breast cancer growth through negative regulation of Notch

Notch signalling is reported to be hyperactivated in oestrogen receptor-negative (ER-) breast cancer. Here the authors show that G protein-coupled receptor kinase-interacting protein 1 (GIT1) negatively regulates Notch signalling and tumour growth in ER- breast cancer by blocking Notch ICD nuclear translocation.Hyperactive Notch signalling is frequently observed in breast cancer and correlates with poor prognosis. However, relatively few mutations in the core Notch signalling pathway have been identified in breast cancer, suggesting that as yet unknown mechanisms increase Notch activity. Here we show that increased expression levels of GIT1 correlate with high relapse-free survival in oestrogen receptor-negative (ER(-)) breast cancer patients and that GIT1 mediates negative regulation of Notch. GIT1 knockdown in ER(-) breast tumour cells increased signalling downstream of Notch and activity of aldehyde dehydrogenase, a predictor of poor clinical outcome. GIT1 interacts with the Notch intracellular domain (ICD) and influences signalling by inhibiting the cytoplasm-to-nucleus transport of the Notch ICD. In xenograft experiments, overexpression of GIT1 in ER(-) cells prevented or reduced Notch-driven tumour formation. These results identify GIT1 as a modulator of Notch signalling and a guardian against breast cancer growth.</p