Sixth Week Of Lactation Research Articles

Serum protein electrophoretic pattern in dairy cows during the periparturient period

ABSTRACTThis study was aimed at the evaluation of changes in the concentrations of serum protein fractions in 10 clinically healthy dairy cows in the period from 1 week before to 6 weeks after calving. Serum was analysed for total protein concentrations, and the relative and absolute values of protein fractions – albumin, alpha1- (α1), alpha2- (α2), beta1- (β1), beta2- (β2), and gamma- (γ) globulins. The concentrations of total proteins increased significantly from week 1 before parturition till the end of the sixth week of lactation (P < .001). In the concentrations of albumin, a slight decrease was observed 1 week after parturition, with a further decrease till the end of the study. The concentrations of α1- and α2-globulins increased significantly during the early stages of postpartal period (P < .01 and P < .001). The concentrations of β2-globulins showed an increasing trend after calving (P < .001). The concentrations of γ-globulins increased 3 and 6 weeks after calving (P < .001). These results showed dynamic changes in the serum protein electrophoretic pattern during peripartum period which reflect the physiological response of the organism to the variation of metabolic and immune functions occurring from gestational non-lactating to a non-gestational lactating state in periparturient dairy cows.

Intake, milk production and weight change curves for lactating Holstein x Zebu cows under grazing

The purpose of this study was to evaluate feed intake and develop lactation and weight change curves for Holstein x zebu cows under grazing. Eighteen F1 cows were used, divided into three treatments; 6 were Holstein x Gir (HGI), 6 were Holstein x Guzerat (HGU), and another 6 were Holstein x Nelore (HNE), under the feeding conditions of pasture plus concentrate with 22% of crude protein (CP). To estimate individual feed intake at pasture, 2 markers were used: titanium dioxide to estimate fecal dry matter (DM) excretion, and the indigestible acid detergent fiber (iADF) to estimate individual pasture intake. The Wood (1967) model was used to evaluate milk yield and the parameters were estimated for each genetic group, as follows: HGI = 17.2667*t0.0652*e-0.00424t; HGU = 18.1470*t0.0332*e-0.00408t; and HN = 14.2836*t0.1059*e-0.00552t. The NEFA contents varied according to different genetic groups (P&lt;0.001). It was concluded that the estimated peak DMI occurs during the sixth week of lactation, when the DMI by the different genetic groups was stabilized. The HGI cows have greater cumulative production at 305-d.

Trans Isomeric fatty acids are inversely related to the availability of long-chain PUFAs in the perinatal period

We summarize data on the potential interaction of trans isomeric fatty acids [trans fatty acids (TFAs)] with the availability of long-chain polyunsaturated fatty acids (LC-PUFAs) in the perinatal period. Today, TFA intakes in pregnant and lactating women can be estimated to be ∼1% of energy in the majority of the population. The significant inverse associations seen between TFAs and LC-PUFAs in pregnant women in 3 different European populations investigated in a recent study raise doubts about the nutritional adequacy of high TFA intakes during pregnancy. In a recent study on the TFA content of human milk in a sizable group of mothers at the sixth week of lactation, both arachidonic and docosahexaenoic acids correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs, and at the sixth month of lactation arachidonic acid correlated significantly inversely to 18-carbon TFAs but not to 16-carbon TFAs. Similarly, significant inverse correlations were seen between 18-carbon TFAs and arachidonic and docosahexaenoic acids in both artery and vein wall lipids in a sizable group of healthy term infants. The TFA data obtained in umbilical blood vessel wall lipids were related to the neurologic condition of healthy children at 18 mo of age: children with minimal neurologic dysfunction at age 18 mo had significantly higher cord blood vein wall trans octadecadienoic acid values than did neurologically normal children. Total TFA values as well as total 18-carbon TFA values in umbilical vein wall lipids were significantly inversely associated with neurologic optimality score. Contradictory data renders it impossible to draw firm conclusions on the role of TFAs in modifying fetal growth; however, TFA exposure may be a confounding parameter in studies that investigate the relation between fetal fatty acid supply and intrauterine growth.

Milk yield estimation during suckling using the double oxytocin injection-milking and the double weighing–suckling methods in dairy goats

The aim was to verify the validity of the double oxytocin-milking (DOT) method as milk yield estimator during the suckling period of lactating dairy goats. To this end, it was necessary to determine whether the weighing–suckling–weighing (WSW) and DOT methods of milk yield estimation satisfied the criteria to be considered valuable, the accuracy between both methods and the suitability of DOT to evaluate actual milk. At parturition, sixty lactating Murciano–Granadina breed goats were separated into 2 groups, in mixed (MS; n=24) and artificial rearing (ARS; n=36) management systems. Until the sixth week of lactation (weaning), MS goats suckled one kid while kids from ARS goats were artificially reared; moreover, goats in both systems were submitted to once-a-day milking. Once per week, actual milk yield for ARS goats and potential milk yield were recorded using DOT method for all goats, except for 12 goats in ARS which remained as a control. Twelve goats from each management system were used to evaluate diurnal variation in milk production (DVM) by DOT method for 6 consecutive days in week 4 of lactation. No difference in DVM was found by DOT method in 4-h milk production of goats in MS (P=0.099) or ARS (P=0.220), which allowed sixfold multiplication of milked milk volume to obtain potential milk per day. ARS goats subjected to a weekly DOT and control group goats showed a similar (P=0.379) lactation curve for the first 6 weeks of lactation. The DOT method slightly overestimated (3.4%, P=0.005) the milk yield evaluated by WSW method for goats under an MS, but fitted the actual milk obtained by common milk records for the group of goats in an ARS submitted to the DVM test (P=0.357) and the group in ARS alone (P=0.163). The DOT method applied for 8 consecutive days led to a drop of 6–12% in milk yield during the following week for both production systems. In conclusion, DOT was an accurate method to estimate milk yield during the first weeks of lactation both in MS and ARS under the conditions of this experiment.

Condição corporal e desempenho produtivo de cabras Alpinas no início de lactação

Objetivou-se avaliar a influência da condição corporal ao parto sobre os parâmetros produtivos de cabras Alpinas no início da lactação. Sessenta e oito cabras foram distribuídas em três grupos, de acordo com o escore de condição corporal (baixo, entre 1,00 e 2,75; intermediário, entre 2,75 e 3,50; e alto, entre 3,50 e 5,00) e avaliadas do parto até a oitava semana de lactação. Realizaram-se o controle diário do consumo alimentar e da produção leiteira e avaliações semanais de peso corporal, escore da condição corporal e composição do leite. Os animais com escore corporal alto apresentaram menor consumo de matéria seca, fibra em detergente neutro e proteína bruta em comparação àqueles com escores corporais baixo e intermediário. O período médio de recuperação do consumo de matéria seca dos animais das três condições corporais foi de 16 dias (2,3 semanas) do pós-parto, com estabilização até o final do experimento. Na sexta semana de lactação, o peso corporal dos animais com escore corporal baixo se igualou ao daqueles com escore corporal intermediário. Não houve efeito da condição corporal ao parto nas variações de ECC e da produção leiteira ao longo do período. O teor de gordura do leite dos animais com escore corporal alto foi menor nas duas primeiras semanas pós-parto em comparação ao dos animais com escores corporais baixo e intermediário. Elevada condição corporal ao parto influencia negativamente o consumo voluntário de cabras leiteiras no início da lactação, mas quando se utiliza dieta de alta qualidade e com altos níveis de energia, a influência da condição corporal ao parto inexiste para variações de peso, de escore da condição corporal e produção leiteira dos animais.

Commencement of luteal activity in three different selection lines for milk yield and fertility in Norwegian Red cows

Relationships among commencement of luteal activity (C-LA), milk yield, and energy balance (EB) were investigated in 3 selection lines of Norwegian Red cows at the Norwegian University of Life Sciences from 1994 through 2001. The cows were selected for low genetic merit for milk yield (LMP), high genetic merit for milk yield (HMP), and a combination of high indices for milk yield and fertility (HI). Breeding values for fertility were based on 56-d nonreturn rate. The material included 268 lactations from 147 cows. Milk samples for progesterone analysis were drawn 3 times weekly from 1994 through 1998, and 2 times weekly from 1999 to 2001. Commencement of luteal activity was defined as the first 2 consecutive measurements of progesterone concentration >3 ng/mL not earlier than 10 d after calving. Selection line was significantly related to C-LA, so that the least squares mean days from calving to C-LA were 22.5, 30.4, and 27.2 d for LMP, HMP, and HI cows, respectively. The HMP cows produced more milk than the LMP cows. The average milk yield in the sixth week of lactation was 24.0, 27.1, and 25.3kg for LMP, HMP, and HI cows, respectively. The interval to C-LA decreased for the HMP and HI cows after phenotypic adjustment for EB in the model. Least squares means for the interval to C-LA were 23.2, 29.7, and 25.6 d for the LMP, HMP, and HI cows, respectively, in a model that included parity, selection lines, and EB as covariates. Cumulated EB during the first 4 wk of lactation, which itself differed between selection lines, did not fully account for differences in interval to C-LA between selection lines. Thus, the results of the present investigation indicate that selection for milk yield negatively affects C-LA over and above the effects caused by concurrent changes in EB. The increase in days to C-LA caused by selection for high yields can be reduced if selection for milk yield is combined with fertility in the breeding program.

Influence of Mastitis on Milk Yield in Holstein Cows

The objectives of the current study were to investigate the incidence of mastitis in a private dairy herd and the effect of the disease on the lactation milk yield (LMY), and on the daily average of the weekly milk yield (DMY). Only cows with no disease and cows with mastitis were included in the analyses. Mixed model procedures were used to analyse the DMY. Incidence of mastitis in the herd was 26.22%. The incidences of first, second and third parity groups were 19.94%, 33.74% and 40.74%, respectively. Daily milk losses because of mastitis varied between 0.76 kg/d and 4.56 kg/d. The total milk loss was 600.87 kg for cows that became mastitic in the first six weeks of lactation and was 503.86 kg for cows that became mastitic after the sixth week of lactation. The milk losses of cows that contracted mastitis after the sixth week of lactation, began three weeks before the diagnosis. The mastitic cows failed to reach their healthy levels of milk yield during the rest of the lactation. The results indicate that weekly lactation records are useful in early detection of mastitis.

The effects of handling by humans at calving and during milking on the behaviour and milk cortisol concentrations of primiparous dairy cows

This study examined the effects of human presence at the time of calving of primiparous cows, and the behaviour of the stockperson during milking on the behaviour of the cows during milking and in response to an experimenter in a standard 5-min test (human test). Cows which were not handled around the time of their first calving ( n=7) displayed a higher ( P<0.05) number of flinch, step and kick (FSK) responses during the first 20 weeks of lactation than cows which were handled ( n=7); most of these FSK responses occurred in the close presence of the stockperson. It is of interest that although the two treatments did not differ in the amount of extra assistance given by the stockperson, the number of FSK responses of cows was strongly ( P<0.01) and positively correlated with the amount of extra assistance given by the stockperson in the form of attaching a kick-bar, replacing dislodged cups or steadying the cow by holding the tail or leg. Cows in the no handling treatment were also slower ( P<0.05) to enter areas within 1 and 2 m of the experimenter in the human test conducted in the sixth week of lactation and had higher ( P<0.05) mean cortisol concentrations in their milk than cows in the handling treatment. It is proposed that the lower FSK response of cows that received human contact at the time of their calving was a result of these cows being less fearful of humans. Although the two stockpersons differed significantly ( P<0.01) in the proportion of physical interactions which were negative (aversive) in nature that they directed towards cows, the stockpersons had no significant influence on the behaviour of the cows during milking. However, the number of physical interactions that the cow received that were of a positive nature was significantly ( P<0.05) correlated with the total number of FSK responses displayed in the first 2 weeks of lactation. It appears that stockpersons recognize those cows with a high FSK response and attempt to quieten them with the use of interactions that are positive in nature.

Lactation pattern in Scottish Blackface and East Friesland × Scottish Blackface cross-bred ewes

SummaryMilk yield of 2-year-old Scottish Blackface and of East Friesland × Scottish Blackface ewes rearing single or twin lambs was estimated by the oxytocin method on 1 day each week up to the 14th week of lactation. Both groups of ewes had been reared from birth under good nutritional conditions. They were housed in individual pens from mid-pregnancy and offered a liberal ration of a pelleted concentrate food until parturition. Similar food was offered ad libitum during lactation.The cross-bred ewes rearing singles or twins produced significantly more milk in the first 12 weeks (181 and 258 kg respectively) than did pure Blackface ewes in the same period (144 and 208 kg respectively). The pattern of lactation differed between breeds. Cross-bred ewes attained higher maximum yields between the second and sixth weeks (2·37 and 3·32 kg/day, respectively, for single- and twin-suckled ewes) than did the Blackface ewes (1·97 and 2·88 kg/day). The yield from the cross-breds was sustained at a higher level throughout lactation. In the third 4-week period cross-bred ewes rearing single and twin lambs produced 116 and 92%, respectively, of their yield in the first 4 weeks whilst Blackface ewes produced 87 and 65%, respectively.In the sixth week of lactation the milk produced by the two breed groups was similar in quality (mean value of solids-not-fat 11·04% and fat 5·48%) but by the 11th week the fat percentage of milk produced by Blackface ewes had increased significantly to 7·34% whereas that of the cross-breds had remained almost unchanged.Single-suckled ewes gained weight throughout lactation but twin-suckled ewes remained relatively constant. Lambs reared as singles by cross-bred or Blackface ewes reached a mean live weight of 36·2 and 35·0 kg at 102 days of age, respectively, compared with 33·6 and 30·1 kg for twin lambs. Food intake of all ewes increased until the fifth or sixth week of lactation.

Enterovirus Neutralizing Activity in the Milk of Sows

Enteroviruses mere isolated front 14 of 27 rectal swabs which were collected from weaned piglets, but not from 22 swabs from suckling piglets nor from extracts prepared front various levels of the intestinal tracts of 6 suckling piglets. Scrum samples from 7 of hi sows in the herd contained enterovirus neutralising antibodies, and enterovirus neutralizing activity was demonstrated in milk samples from the same sows up to the sixth week of lactation. It is postulated that the ingestion of milk containing enterovirus neutralizing substances protects suckling piglets from infection with these viruses.

Changes associated with pregnancy and lactation in some extra–reproductive organs of the ewe

SUMMARYThe food intake, the apparent digestibilities of dry matter, and of nitrogen were measured in housed Blackface ewes during late pregnancy, lactation, and after the lambs were weaned. The ewes were slaughtered serially together with non-breeding controls, and the liver, ruminal mucosa, intestines, CNS and carcass were weighed. In association with differing reproductive status marked changes occurred in the content of dry matter and protein in the alimentary organs, but not in the CNS, and the mean weight of DNA in the CNS for all the animals was 130 ± 20 (S.D.) mg.All of the alimentary organs became hypertrophied during lactation, and regressed after weaning. Maximum values for the liver and ruminal mucosa occurred in the sixth week of lactation, and were maintained until weaning. The small intestine reached maximum weight after 4 weeks of lactation.

Liver Lipids of Lactating Bovine: Fatty Acid Composition

The quantity and composition of the hepatic lipids of two groups of lactating cows, maintained on low-protein, low-energy, and high-protein diets were compared in the initial and sixth week of lactation. The lipid of livers from animals on the inferior diet was almost twice that of animals on the high-protein diet in the first week of lactation. However, within six weeks the lipids of livers from both groups of cows were comparable. The fatty acid analyses revealed that the lipids from cows on the low-protein, low-energy diets contained higher quantities of saturated and short-chain fatty acids than from cows maintained on the high-protein corn diet.

Electrophoretic and Immunoelectrophoretic Analysis of the Proteins in the Sow’s Mammary Secretions throughout Lactation

Lactation in the sow can be separated into 3 stages, based on the relative concentrations of 3 electrophoretic whey proteins in the mammary secretions: (1) parturition (approximately 72 hours); (2) midlactation (approximately third day to sixth week); (3) late lactation (approximately sixth week to dryness). The concentration of protein (18 per cent), and dry matter (28 per cent), in the secretion at parturition, decreases rapidly to its lowest levels during midlactation (protein, 5 per cent; dry matter, 16 per cent). In late lactation there is a gradual increase to approximately 10 per cent protein and 24 per cent dry matter. Whey proteins accounting for 80 per cent of the total protein at parturition rapidly decrease to 50 per cent, at which level they remain until midlactation. Around the fifth or sixth week of lactation, casein increases to approximately 70 per cent of the total protein, and this relationship persists to the end of the lactation. Using immunoelectrophoretic techniques, only 1 of the major electrophoretic fractions of the sow’s mammary secretions (SMS) appeared to be exclusively a whey protein. The major antigens of the remaining electrophoretic fractions were serologically related to porcine serum proteins. Antibodies to casein, a ‘milk protein’ by definition, could not be demonstrated in the antisera used in this study. Although the quantitative changes in SMS whey proteins are pronounced at the various stages of lactation, the kinds of protein as expressed by im munoelectropherograms appear in the main unchanged.