First Period Of Lactation Research Articles

Evaluation of rations of high-yielding cows with different energy levels

The materials of the publication reflect the results of scientific research conducted on the Simmental breed dairy cows in the conditions of the “Pchany-Denkovych” farm in the Stryi district of the Lviv region. The study is based on optimizing the normalized energy nutrition of dairy cows with a milk yield of 6000 kg or more per lactation. The main objective of the research was to study the impact of different levels of energy nutrition of cows by lactation phase and its effect on productivity, hematological indicators, the level of individual rumen metabolites, digestibility of essential nutrients, nitrogen balance, and live weight dynamics. Three groups of eight cows each were selected for research. The rations of the experimental animals provided for the inclusion of a protein-fat concentrate in the compound feed at the rate of 5–10 % by nutrition. The main ration consisted of bulk fodder, cereal-bean hay, hay, silage, and balanced compound feed, which were fed from the feed table in the form of a mixture prepared in a feed mixer–the farm practices year-round uniform feeding of cows with a walking yard. The deficiency of mineral substances in the diet was replenished due to iodized salt, monocalcium phosphate, and polysalts of trace elements. Feeding and housing conditions for all experimental animals during the comparison period lasting 15 days were the same and differed in the reference period in terms of nutrient availability in percentages. The analysis of the obtained results showed that increasing the energy supply of cows had a positive effect on milk productivity. In the first period of lactation, the highest yield was obtained from cows of the third group, which indicates that the experimental animals are approaching the maximum possible potential productivity. This trend persists both in the second and third periods. The increased level of energy nutrition due to the use of protein-fat concentrate had a positive effect on the increase in the live weight of cows. During the analysis of the obtained indicators of the rumen content, a probable increase in the number of amylo- and cellulolytic bacteria was revealed - the quantitative advantage (second and third group) compared to the control is 1.52–2.33 and 1.67–2.54 million/ml. A similar pattern is observed in the number of proteolytic bacteria, which contributed to the increase in the enzymatic activity of the microflora. Regarding the digestibility of the primary nutrients of the feed, their growing trend was established in the second and third groups, which confirms the results of the balanced experiment. Thus, animals of the second group are characterized by the highest digestibility and assimilation of nitrogen. Its positive balance was (+7.1) compared to the third and (+3.0) to the first, in which the nitrogen balance was negative. The use of nitrogen for milk in these groups was the highest: from consumed – 31.7 % and from digested – 48.5 %. Thus, the conducted studies provide a reason to recommend that the farm use a protein-fat concentrate of 5% of the diet's total nutrition in the feeding of dairy cows. Its use will ensure an increase in the level of milk productivity and will make it possible to optimize the energy nutrition of cows during the calving period and mid-lactation.

Estimation of partial lactation milk yields in Saanen goats raised in semi-intensive conditions

Objective: The objective of this study was to estimate the lactation curves of Saanen goats by using individual milk yields in the early, mid and 0-6 months periods of lactation. For this purpose, Wood’s lactation curve was used to estimate lactation yields. Material and Methods: Milk yields of Saanen goats in different periods of lactation were estimated. For this purpose, the Wood’s lactation curve model was adapted to a total of 480 milk yield measured at 14-day intervals of 40 Saanen goats. Milk yields of goats in the first three months of lactation in January-March, mid-lactation in April-June, and 0-6 months in January-June were estimated. Results: According to the harmony of Wood's model, the determination of coefficient values of the estimations of milk yields in the first, mid-lactation and 0-6 months of lactation are 0.84, 0.87 and 0.84, respectively. The root mean square errors of Wood's model are 0.91 for the first period of lactation, 0.81 for the mid-lactation period and 0.30 for the from 0 to 6 months of lactation period. Conclusions: According to the results obtained in this study, Wood's model was found sufficient to define the lactation curve in Saanen goats. However, it would be beneficial to conduct similar studies with larger herds and yield records.

Use of fat-soluble vitamins and feed additives in cow diets

The authors have created modern effective methods for controlling the vitamin content of highly productive lactating cows during the first period of lactation. The results were obtained on the content of vitamins in the diet, milk and blood when feeding with supplements Vitaminol and phytocomplex at 10, 15 and 20 g per animal unit daily separately and with mixed feed. The authors monitored the levels of vitamins A, carotene, D and E in cow's milk and serum. Scientific research was carried out for the agricultural enterprise "Novgorodsky Becon" of the Novgorod region. The cows ration was balanced by 50 nutrients and biologically active substances in accordance with the recommendations for animal feeding (Moscow, Russian Academy of Agricultural Sciences, 2003). Studies of the content of vitamins were carried out using the silage-concentration type of ration fed to lactating black-and-white cows in conditions without grazing. We conducted 2 scientific experiments and 2 physiological experiments with cows during the first 100 days of their lactation. The increase in the level of vitamin A in milk and blood was due to the use of feed additives in the diets. The use of feed additives increased the vitamin D levels in milk and serum. The balance of calcium and phosphorus metabolism in cows is positive. The use of "Vitaminol" together with compound feeds increased the level of calcium by 5.6 6.3 and phosphorus by 4.4 4.9 grams per 1 kg of milk with the natural fat content. The diets were admixed with the "Vitaminol" and phytocomplex ratio of Ca: P (1.3: 1) and Na: K (0.2: 1). With the same doses of feed additives, the ratio of acid and alkaline elements in the diets was the same: Vitaminol was 0.743 and phytocomplex was 0.709. Due to the use of "Vitaminol", the concentration of vitamin E in milk is 4.6-6 times higher than that in the control group, in blood and blood serum.

Digestibility of substances, balance of Nitrogen, Zinc and Manganese in highly productive cows of the Holstein breed of German selection in the first period of lactation for feeding mixed ligand complexes of Zinc, Manganese and Co-balt

The article deals with the results of research to study the digestibility of nutrients in the ration and metabolism of Nitrogen, Zinc and Manganese in high-yielding Holstein cows of German selection in the first period of lactation for feeding mixed ligand complexes of Zinc, Manganese and Cobalt. The research was performed in the conditions of Terezyne Ltd., Bila Tserkva district, Kyiv region. There was an increase in the coefficients of digestibility of dry matter in cows of the 2nd-5th experimental groups compared with animals of the 1st control group, respectively by 1.8–3.5 % (P < 0.05); organic matter by 0.3–2.5 %; crude protein by 0.5–4.2 % (P < 0.05 – P < 0.01); crude fat by 1.1–1.8 %; crude fiber by 1.3–3.3 % and nitrogen-free extractives by 2.1–4.2 %. Cows of the experimental groups consumed more Nitrogen than the cows of the control group: 20.18 g or 2.4 % – the 2nd group, 55.06 g or 6.6 % – the 3rd, 42.52 g or 5, 1 % – 4th and 28.98 g or 3.5 % – 5th experimental group due to better eating of the feed mixture. General consumption level of Nitrogen in relation to excreted with milk and deposited in the body of cows of the control group was 32.02 %, and in animals of the 2nd, 3rd, 4th and 5th experimental groups – 33.59 %; 37.31; 36.99 and 34.97 %. In relation to the total digested amount, the proportion of Nitrogen deposited in the body and excreted with milk in animals of the control group was 42.38 %, and in the experimental – 44.25–47.34 %. Doses of Zinc, which provided its existing rate of 54–85 % due to the mixed ligand complex, positively influenced on the the metabolism of trace elements in the organism of experimental cows. Assimilation of Zinc in the organism was determined by the amount of its secretions with milk and deposits in the body and in absolute terms it was the lowest in cows of the 4th and 5th experimental groups – 562.7 mg and 671.6 mg against 740.8 mg in the 1st control group and the largest – 784.7 mg and 801.3 mg in animals of the 2nd and 3rd experimental groups. The use of a mixed ligand complex of manganese ensured its positive balance in the organism of cows and the absorption of the trace element in the organism of experimental cows ranged from 22.5 % in the 2nd experimental group to 33.2 % in the 3rd experimental group. The best indicators for the metabolism of Nitrogen, Zinc and Manganese were got in the third experimental group whose cows were fed a feed mixture, that in 1 kg of DM contained, mg: Zinc – 54.7; Manganese – 54.7; Cobalt – 0.7; Selenium – 0.3; Copper – 12 and Iodine – 1.1.

Effectiveness of a feed additive with a high degree of protein protection in feeding fresh cows

Intensive dairy farming in modern conditions is impossible without a solid forage base and the use of high-quality forage resources. A high level of cow productivity presupposes adequate nutrition for the animal at all physiological periods of its life. Due to the fact that cows consume relatively little feed during the first period of lactation, the primary task of livestock breeders is to provide the body of highly productive animals with the necessary amount of energy, protein and other nutrients. The article presents the data of a scientific experiment on the use of non-degradable protein in the rumen PassPro Balance in diets for fresh cows. The feed additive under study contributes to an increase in the level of dry matter consumption by animals. The average daily milk yield of the experimental group, which received the studied supplement, significantly increased by 12.0% (P <0.05) in comparison with the control group. There was also established a tendency to an increase in the fat content in the milk of cows from the experimental group. According to the biochemical analysis of the blood serum of cows, the level of albumin in all animals was within the physiological norm. The content of globulins was below the norm in animals of all groups without significantly significant differences. The activity of the AST and ALT enzymes between the groups did not differ significantly. However, it should be noted that in both groups these indicators were within the normal range. The level of alkaline phosphatase tended to increase in the experimental group by 20.8% in comparison with the control group. Feeding PassPro Supplements Balance in the diets for the experimental group made it possible to receive 2565,00 rubles of additional profit, while the level of profitability of milk production increased by 2.02% relative to control.

The relationship of the live weight of sheep of various ethological types with the live weight of their offspring

The aim of the study is to determine the live weight of Karakul sheep of Karakalpak suras of different ethological types in different physiological periods, the live weight of offspring and the relationship between these indicators. The study was conducted at Ltd “Istiklol karakul naslchilik”. During the study, the reaction of feed conversion was taken into account when classifying sheep according to ethological types. The live weights were measured on electronic scales. The data was processed biometrically. We studied the indicators of sheep’s live weight during the second period of lambing, the first period of lactation, the second period of lactation and after leaving the lactation period. These results were compared with the live weight at birth of their offspring. The results of the study showed that the live weight of the first ethological type of sheep was high in all physiological periods, and their offspring also had a higher live weight than their peers. The results of the study can be used in breeding in order to create herds that allow receiving the offspring with high live weight. The results of studies of the relationship between the live weight of the Karakalpak suras of Karakul sheep of different ethological types in different physiological periods and the live weight of their offspring are presented.

Energy evaluation of cows using genetic markers

The aim of the study was to research the polymorphism of allelic variants of somatotropin GH genes and pituitary-specific transcription factor PIT-1 and its influence on bioenergetic parameters of high-yielding of Holstein breed cows in intensive milk production technology (cold method of growing heifers, early insemination of heifers. high daily operating loads on the body, etc.). Genotypes of cows were determined by PCR. Blood DNA was examined in a genetic laboratory. Isolation of genomic DNA was performed using resin “Chelex-100”. The reaction was performed in an amplifier “Tertsyk”. For the energy assessment of first-born cows used indicators of net maintenance energy (MJ per day), net milk energy (MJ per day), total net energy consumption (MJ per day), the value of the energy index (the share of energy released from milk, %), productivity index (kilogram of 4 % milk per 1 MJ), net energy consumption per 1 MJ of milk (MJ), energy released with milk per 1 kg of metabolic mass (MJ). The best energy parameters in cows by GH gene – LL genotype, by pituitary-specific transcription factor PIT-1 – AB genotype, and among paired genotypes – LL/AB and LL/BB. In these animals, bioenergetic indicators for the first and second periods of lactation were higher than their peers of LV, BB and LV/BB genotypes by 2.0–15.2 %, with a reliable result for most traits. In particular, during the first lactation period, the advantage of cows of the LL/AB genotype over the LV/BB genotype in terms of bioenergetic indicators was 3.9–15.2 %, significantly less than in the second lactation period in the range of 1.8–7.4 %. In the genome of pituitary-specific transcription factor PIT-1, better bioenergetic parameters were found in cows of genotype AB than in cows of genotype BB. The difference in bioenergetic parameters is explained by the higher lactotropic function of the L and A alleles, and is the result of a greater complementary effect on the functioning of the alleles of the associated genes in the complex genotype. This was confirmed by the analysis of variance of one-factor complexes, which revealed a stronger influence of genotypes on bioenergetic parameters during the first period of lactation than the second. However, the strength of the influence of the paired genotype on the GH and PIT-1 genes was always high regardless of the lactation period and ranged from 8.9 to 20.9 % (P < 0.01–0.001). In the future, it is of interest to study the formation of the exterior and constitution of cows of different genetic influences under the influence of polymorphisms in the GH and PIT-1 genes.

A Survey on Mono-, Polyunsaturated Fatty Acids, Desaturase Indices and Atherogenic Index in the Milk Fat of Local Breeds (Cabannina, Varzese and Valdostana) Reared in Northern Italy

In this paper the characteristics of the fatty acid profile in local Italian bovine breeds (Cabannina, Varzese and Valdostana) are compared with those of Friesian, a known cosmopolite breed during the first period of lactation. The local breeds show a general trend to have higher unsaturated fatty acid percentages, as well as lower desaturase indices (related to C14, C16 and C18) and atherogenic index, with respect to Friesian cows. The results can add further information aiming to re-evaluate an almost lost local treasure in Northern Italy.

The influence of condition on the metabolic profile of Czech Fleckvieh cows in the perinatal period

Abstract. The objective of the study was to determine the influence of Czech Fleckvieh cow‘s condition before parturition on chosen blood biochemical indices in perinatal period and at the beginning of lactation. The study was conducted on 38 multiparous cows 3–14 days prepartum. The cows were selected with respect to body condition score (BCS): BCS>4 points (group I, n=18) and BCS<4 points (group II, n=20). Blood was collected at 3–14 and 1–2 days prepartum and 1–2, 21 days postpartum and analyzed for lipid-carbohydrate, protein parameters and enzymatic activity. Cow‘s condition, milk yield and composition were also estimated. Changes in Czech Fleckvieh cow‘s condition in a transition period do not have any clear influence on milk yield and composition. An excessive BCS before calving leads to its higher decrease at the beginning of lactation and may indirectly point to a higher energy deficiency in the first period of lactation. It is confirmed by glucose concentration in blood serum decrease (P<0.01) in 3rd week of lactation when compared to cows with a proper condition before calving (3.39 vs. 2.45 mmol/l). Overnormative condition before calving also negatively influences the content of triacylglycerols, alkaline phosphatase and total bilirubin in blood serum in the first days postpartum. TAG transport from liver to blood is impaired at the beginning of lactation in cows with high condition prepartum. The study demonstrated that in Czech Fleckvieh dairy type cows intensified lipolysis and ketogenesis in perinatal period do not take place pointing to high adaptation possibilities of their metabolism.

Estrous synchrony in a group of African elephants ( Loxodonta africana) under human care

Synchrony of estrous, and consequently of conception and birth of young, may be of adaptive significance for certain mammals. Among the species in which estrous synchrony has been suspected several times are elephants, but clear evidence is still missing. We determined estrous cycles of African elephants ( Loxodonta africana) ( n = 4) at the Vienna Zoo, Austria, between June 2003 and January 2006 by measuring serum progesterone levels from weekly blood samples. Except for the dominant female when she was intensively lactating, all animals showed clear cycles or progesterone release with a mean period of 105.3 ± 15.37 days. For most of the study period, estrous cycles were asynchronous between females. However, after re-occurrence of the progesterone cycle in the dominant female following the first period of lactation, all four females showed high synchrony of progesterone release over the two subsequent cycles. Large changes in individual period lengths indicated that synchronization was due to the adjustment of cycle length in subdominants to that of the dominant female. We used a bootstrap procedure, based on resampling measured times of progesterone peaks, to determine if this apparent synchrony could have been caused by chance alone. This statistical analysis indicated that between-individual variances of the timing of progesterone peaks were much smaller that to be expected by chance ( P = 0.009). This finding represents the first evidence for estrous synchrony between elephants. We discuss various hypotheses to explain the biological function of cycle synchrony in elephants.

Modification of Microclimate to Improve Milk Production in Tropical Rainforest of Thailand

The objective of this study was to evaluate the effect of electric fan installation for milk production improvement of dairy cattle in Thailand. The study was conducted using 2 small-holder dairy farms in Chiang Mai province, during April to August 2004. Electric fans were installed in front of each row of cows. Each of the two rows of cows in the barn was defined as an experimental unit, thus each farm had two experimental units. The fans were operated alternately in 7-day intervals between rows of cows within each farm during the day or between 8.00 am to 8.00 pm. Non-operation periods were used as control. Milk yields were recorded. Data on environmental temperature and humidity were obtained from Chiang Mai Meteorological Center. Result from statistically analysis of milk record suggested an interaction between lactation period and fan installation. Therefore, this interaction term of lactation period and fan installation (PERIOD_FAN) was added as a variable to the regression model. Due to the repeated data collection of milk yield from the same cow (alternate week), milk yield was analyzed by repeated measure analysis (Mixed model). Least square means were calculated for all levels and used to compare between each pair-wise values. The final data were collected from the total of 18 cows with 2,072 data. Overall means and SEM of milk yields and days in milk separated into farm were 14.7±0.06 kg/day and 176.3±2.2 days, and 15.2±0.22 kg/day and 202.5±3.7 days for farm A and farm B, respectively. For multivariable analysis, only PERIOD_FAN and humidity were significantly associated with milk yield. Only the first period of lactation showed that the amount of milk yields during fan installation was higher than that of non-fan installation (p<0.05). Cows with fan installation produced approximately 1.2 kg/cow more milk than cows without fan installation during this period. In conclusion, the use of electric fan operated during the day time increased milk production of cows during the first period of lactation. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 6 : 811-815)

Trend in ash and mineral element content of milk from Haflinger nursing mares throughout six lactation months

Ten Haflinger nursing mares were controlled throughout a whole lactation period. Mares (400–540 kg live weight; 4–12 parities) were reared in a stud in Brescia province (Northern Italy). Eighty milk samples were taken by hand milking of one gland at days 4, 20, 40, 60, 80, 120, 150 and 180 post-partum. From days 4 to 180 post-partum, the ash content dropped from 0.58 to 0.28 g/100 g of milk ( P<0.001). In the same period, the content of the mineral elements also decreased significantly ( P<0.001): Ca from 1240 to 519 ppm; P from 704 to 310 ppm; Mg from 104 to 44 ppm; K from 773 to 387 ppm; Na from 297 to 166 ppm; Cl − from 279 to 181 ppm. Changes were most relevant in the first period of lactation (at day 40: −32% ash; −28% Ca; −30% P; −27% Mg; −29% K; −33% Na; −41% Cl −). Ash and minerals showed a curvilinear trend relative to days of lactation that was well described by cubic equations.

PreproTRH178–199 and Two Novel Peptides (pFQ7 and pSE14) Derived from Its Processing, Which Are Produced in the Paraventricular Nucleus of the Rat Hypothalamus, Are Regulated during Suckling**This work was supported by the National Science Foundation (Grant No. IBN-9507952 to E.A.N.).

Suckling increases preproTRH messenger RNA in hypothalamic paraventricular neurons (PVN) and also markedly increases TRH release during the first period of lactation. Whether lactation alters preproTRH processing resulting in the generation of novel proTRH-derived peptides that may be involved in the regulation of PRL secretion lactation is not known. Therefore, in the present study we determine whether some other peptides derived from proTRH potentially contribute to lactation-induced PRL secretion. We have recently demonstrated that two members of the family of prohormone convertases PC1 and PC2 play a significant role in proTRH processing. PC1 is the major contributor in proTRH processing, whereas PC2 may have a specific role in cleaving TRH from its extended forms. In this study, we used a recombinant vaccinia virus system to coexpress rat preproTRH complementary DNA with PC1, PC2, and the neuropeptide 7B2 in GH4C1 cells (somatomammothophs, rat). We found that two novel peptides, preproTRH(178-184) (pFQ(7)), and preproTRH(186-199) (pSE(14)), were formed after the cleavage of their precursor preproTRH(178-199) (pFE(22)) by only PC2. Their formation was confirmed by microsequence analysis. Anatomical analyses revealed that these peptides are also found in the rat PVN. In addition, we found that pFE(22), pSE(14) and pFQ(7) produced a dose-dependent release of PRL from primary cultures of pituitary cells compared with one of the well studied secretagogues of PRL, TRH. To establish whether these peptides might play a role in vivo in the regulation of PRL release, we took rat litters on postnatal day 4, separated the pups from their mothers for 6 h, and then reunited the pups and mothers for 45 min. At the end of this period, the mothers were killed, acidic extracts of microdissected PVN were prepared and subjected to SDS-PAGE, followed by slicing and analysis by pFE(22) RIA. Forty-five minutes of suckling induced a marked 6-fold increase in serum levels of PRL. In addition, PVN levels of pFE(22) and pSE(14) increased approximately 5-fold during the same period in the acutely suckling females. Lactating animals that were separated from their litters and never reunited with their pups had low levels of PRL, and pFE(22) and pSE(14). These data provide the first evidence for alterations in proTRH processing in the PVN during lactation and suggest that the products of this altered processing may play a physiological role in the regulation of PRL secretion.

DETECTION OF ESTRUS AND MASTITIS: FIELD PERFORMANCE OF A MODEL

A new detection model ( ‘ IMAG model ’ ) for estrus and mastitis in dairy cows was tested on four farms during several years. Such a test is necessary because information is lacking about the performance of detection models under field conditions. The test gave insight into the field performance of the IMAG model and the results were compared with the results of older models and with the results predicted by experts. Sensor data of milk yield, milk temperature, electrical conductivity of milk and animal activity were the inputs for the IMAG model. The IMAG model is based on time series analysis combined with a Kalman filter. This structure yields cow–dependent model parameters and combines data of different sensors. Results were compared with the manufacturer ’ s model (supplied with the sensors), based only on exponential smoothing on data from one sensor. The sensor equipment differed between farms. The sensitivity (percentage of estruses detected) for estrus varied from 63 to 80%, depending on the threshold used. Specificity (non–estruses not detected as estrus) varied from 94 to 98%. The sensitivity for clinical mastitis varied from 55 to 80%, depending on the threshold used. The specificity for mastitis varied from 94 to 99%. Significant differences existed between farms, in sensitivity for estrus and mastitis. The applied equipment could only partially explain the differences in estrus and mastitis detection results between farms. No relation between stage of lactation and activity level was found, although a lower activity level in the first period of lactation might be expected. The main conclusion is that a detection model can give good results, but only if the equipment is working properly. The new model outperformed the manufacturer ’ s model.

Insulin in Bovine Colostrum and Milk: Evolution Throughout Lactation and Binding to Caseins

The changes in insulin concentration in bovine milk in the first period of lactation and its association with other milk proteins were studied. Highest concentration was found in the first milking (327ng/ml). This concentration fell within the first 24h postpartum to about 50% of its initial value. By d 3, the level was about 25%, and, on d 7, a stable concentration was reached at approximately 46ng/ml (about 14% of its initial value). This concentration is about 100 times higher than that in serum, which suggests a specific mechanism of transfer from blood to milk. Colostral whey obtained by ultrafiltration or ultracentrifugation contains much less insulin than colostrum. When colostrum or milk was incubated with [125I]insulin and whey and casein fractions were separated by precipitation, it was observed that most insulin remained with the casein. However, when colostrum was incubated with [125I]insulin and subjected to gel filtration, most of the radioactivity corresponded to free insulin, indicating that insulin is associated with the precipitated casein but not with the casein micelles in solution.

Live Weight Changes, Feed Consumption, Milk Yield and Energy Balance in Dairy Cattle during the First Period of Lactation

Abstract The purpose of this study was to estimate any breed differences and to investigate the interrelationships between live weight changes, feed consumption, milk production in kg energy corrected milk (kg ECM) and the therefrom calculated energy balance with emphasis on the first part of lactation. Altogether 508 lactations were studied for 153 cows from the same herd in first to fifth lactation of the following Swedish dairy cattle breeds: Swedish Red and White (SRB), Swedish Friesian (SLB), reciprocal F1-crosses of the two breeds, and Swedish Jersey (SJB). The gamma function (Y n=an b·ecn) was fitted to each animal's records in order to derive secondary traits from the functions. A Mixed Model Procedure was used to estimate breed and parity effects and variance components. The average goodness of fit to the function, as assessed by the R 2 value, was best for milk production data, followed by feed consumption, while lower R 2 values were obtained for live weight changes and especially for energy ba...

Different levels of mixed-ligande complexes of zinc, manganese and cobalt in feeding highly productive cows of the Ukrainian red-spotted dairy breed the first lactation period

Purpose. To study the effectiveness of feeding different levels of mixed-ligande complex of zinc, manganese and cobalt with Suplex Se to high-yielding cows of the Ukrainian red-spotted dairy breed in the first period of lactation and their impact on feed consumption, productivity and hematological parameters of blood. Methods. Five groups (one control and four experimental) of highly productive cows of the Ukrainian red-spotted dairy breed, 10 heads each, were selected for the research at «Terezyne» farm, Bila Tserkva district, Kyiv region, on the principle of analogues. Experimental cows were fed the same rations. For cows of the control group the optimal dose of a mixed-ligande complex of Zinc, Manganese and Cobalt was used, which was established in a previous experiment with concentration in 1 kg of dry matter (DM) of feed, mg: zinc – 60.8; manganese – 60.8 and cobalt – 0.78. In the 2nd experimental group, concentration of those trace elements was higher compared to the control by 10%, and in the 3rd, 4th and 5th experimental groups, respectively, 10, 20 and 30% lower. Results. The best results in terms of milk productivity were obtained from cows of the 4th experimental group. For 80 days of the experiment from cows of the 1st control group 3080 kg of milk of natural fat content was obtained, and of the 2nd, 3rd, 4th and 5th experimental groups – respectively 48, 112, 200 and 136 kg, or by 1.6; 3.6; 6.5 and 4.4% more. Lower doses of micronutrients meet the needs of highly productive cows in them, which has a positive effect on the reproductive functions of animals. The most effective was the dose for the cows of the 4th experimental group, where duration of the service period was 78.6 days against 91.9 days in the 1st control group, and one fertile insemination in this group took 1.8 times at 3.1 times in control. Analysis of hematological parameters of the experimental cows shows that different levels of mixed-ligande complexes of zinc, manganese and cobalt in concentrated feeds have a positive effect on the body and health of lactating cows. Conclusions. The best results of milk productivity and reproductive function were obtained from cows of the 4th experimental group, where concentration of zinc, manganese and cobalt due to their mixed-ligande complexes in 1 kg of DM feed was, mg: zinc – 42.6; manganese – 42.6; cobalt – 0.55. This dose of trace elements had a positive effect on the consumption of animal feed, their unit cost and hematological parameters of cows' blood.

The lactation cycle of Elephantulus myurus jamesoni (Chubb)

The development of the mammary glands follows the same course during all first pregnancies, regardless of the time of the breeding season. When a second or third pregnancy occurs at the beginning of the breeding season, the development of the glands during the pregnancy resembles the development during the first pregnancy once the embryos have reached the primary amniotic cavity stage. In all other pregnancies the development is complicated by a concurrent lactation and later involution. However, the structure of the glands during lactation is essentially the same, regardless of which pregnancy it follows, and of whether the lactation overlaps with a subsequent pregnancy, or occurs during anoestrus. Therefore it seems that the presence of developing embryos does not influence the course of lactation in any way. Owing to this similarity, the structure of the glands is the same in both the second and third pregnancies until the developing embryos are approximately 5 mm long, if the pregnancy occurs during the middle or at the end of the breeding season. It appears that the young are weaned when the developing embryos reach this size, i.e. 5 mm long. However, the changes in the glands during involution are affected not only by the time of the breeding season, but also by the pregnancy of the individual animal. When involution occurs during anoestrus it proceeds until a final state, only slightly more developed than the virgin condition, is reached. When involution occurs concurrent with the next pregnancy it differs according to the pregnancy of the individual animal. After a third pregnancy, which commenced either at the beginning or during the middle of the breeding season, the animal usually dies of old age before involution is established, but after a first or second pregnancy commencing at these times, involution takes place during the subsequent pregnancy. In these animals the extent to which the involution proceeds is governed by the size attained by the developing embryos at that particular time. When the involution occurs during a second pregnancy, i.e. after the first period of lactation, the most involuted condition is found when the embryos are 32-6 mm long. When it occurs during a third pregnancy, i.e. after the second period of lactation, involution is completed earlier, when the embryos are only 13-7 mm long, and this involution is more pronounced than that occurring during the second pregnancy. It is difficult to explain why this first period of involution should be more gradual, and take so much longer than the second. Moreover, in the latter there is a definite point whereafter involution is striking and rapid; this does not occur during the first period of involution. The only feasible explanation I can offer is that possibly, during the first period of pregnancy, lactation, and then involution, the regular cycle has not yet been established in the mammary glands. After this stage they may be fully mature, and the cycle stabilized.