Search

Effects of year, season, parity, age, their two-way interactions, lactation length and calving interval on milk yield were investigated utilizing 9,086 lactation records collected from 1930 to 1975 from six breed groups kept in one herd at Karnal, India. The breed groups involved three native breeds (Sahiwal, Red Sindhi and Tharpakar) and three crossbreds with Brown Swiss (F1crosses between Brown Swiss and three native breeds, inter se crosses, and ¾ Brown Swiss). Breed, year, season, parity, age and all of the two-way interactions with the exception of breed × season and parity × season were important. Tharpakar produced more milk than Sahiwal and Red Sindhi by 232 and 204 kg. The milk production difference between Sahiwal and Red Sindhi was only 28 kg. The three crossbreds outproduced the purebreds by an average of 766 kg; however, differences in management could have favored crossbreds. Among the crossbreds, F1crosses were superior. The linear and quadratic regressions on lactation length accounted for 28% of the variation in milk yield after year, season, parity, age and their interactions were absorbed. Calving interval and lactation length together accounted for 29%. Estimates of heritability, from paternal half-sib analyses, and repeatability of milk yield for Red Sindhi, Sahiwal and Tharpakar ranged from .10 to .30. Differences among heritability estimates from different parities were small when more than 500 records were involved.

Yorkshire weanling barrows weighing an average of 17 kg were assigned in four groups of eight pigs in each of two replicates (64 pigs) to a completely randomized experiment in a 2 × 4 × 4 factorial arrangement (slaughtered at 48 or 89 kg; fed 0, 20, 40 or 60% alfalfa meal; slaughtered at 2, 4, 8 or 12 hr after the last feeding). A level of 20% alfalfa meal, resulting in a level of 26% cell wall in the diet, had no significant effect on daily gain and feed-to-gain ratio compared with a level of 0 alfalfa meal; 40 or 60% alfalfa meal significantly depressed daily gain and efficiency of feed utilization compared with 0 or 20%. Backfat thickness was inversely related to level of alfalfa meal in the diet; cross-sectional area of the longissimusmuscle was not affected by diet. Weight of the empty gastrointestinal tract (all segments except stomach) was increased with increasing fiber in the diet. Apparent digestibility of dry matter, cellulose, hemicellulose and nitrogen was progressively decreased with increasing fiber. Percentage of dry matter in digesta of all sections of the gastrointestinal tract was negatively correlated with cell wall content of diet and digesta. The lower dry matter of digesta of pigs fed high fiber was associated with a faster rate of passage and is suggested as being responsible for the lower digestibility of dry matter, nitrogen and cell wall components in pigs fed high fiber diets. Pigs slaughtered at 48 kg body weight had significantly higher apparent digestibility of dry matter, nitrogen and cell wall constituents than pigs slaughtered at 89 kg, probably due to the higher rate of passage of digesta in the heavier pigs. It is concluded that the depressing effect of fiber on apparent digestibility is due to the greater rate of passage of digesta in pigs fed high fiber and that there is no significant adaptation to high fiber diets with age during the growing-finishing period.

The demand for red meat is rising rapidly throughout the world due both to increased human population and to shifts in the food buying habits in urban centers (FAO, 1973). This trend holds for all countries. With economic development, the ratio of purchasing starch foods to non-starchy foods has declined with a rise in consumption of vegetables and animal products (Perera et al., 1972). Although the starchy staple to non-starchy ratio has remained at about 56:44 in Egypt as a whole since the mid 1960's, the ratio for the city of Cairo has shifted to 51:49. This change in food habits has contributed to Egypt's current importation of 158,000 tons meat per year. Since 1970 importations of beef to Venezuela have increased about 10,000 tons per year. Of this, 95% goes to the large urban centers (Consejo de Bienestar Rural, 1972). In Japan per capita consumption of rice declined from 140 kg in 1955 to 117 kg in 1969.

Provisions of Title XII Amendment to the Foreign Assistance Act offer new challenges to U.S. universities through participation in the creation of national systems of agricultural education, extension and research in developing countries. A salient feature will be the determination of priorities for research to enhance economic and social benefits to small farms. This focus could lead U.S. Animal Scientists into an unaccustomed area of activity and contacts which should prove stimulating.In preparation of this report, viewpoints were solicited from a number of animal scientists with extensive experience overseas. The inquiries sought definitions for small farms (animal), some of the research requirements, characteristics of small farmers or herders, and factors limiting their contributions to food supplies. The objectives of the report are to draw attention to several of the problems we will encounter and to point out a few of the apparent shortcomings of present technology for applicability to small farms.

Electrophoretic separation of esterase-5 allozymes of Drosophila pseudoobscura in gels of different acrylamide concentrations and in different buffer systems has revealed the existence of six different alleles within the most frequent class, esterase-5(1.00), and three alleles in the other most frequent class, esterase-5(1.07). Two of the alleles affect subunit binding. Esterase-5 allozyme classes based on electrophoresis in 5% acrylamide gels are therefore highly heterogeneous.

Factors affecting digestibility such as dry matter intake, metabolic loss and ability of cattle and buffaloes to select the Napier grass were studied at the University of the Philippines, College of Agriculture.Napier grass was lower in dry matter, fibrous components and gross energy, but higher in crude protein and ash content at 45 than at 60 days of age. Buffaloes digested 2% to 4% more of most nutrients than cattle during the wet season; but species effects were not different during the dry season. Metabolic losses were lower for buffaloes than for cattle during the wet season and slightly higher during the dry season. Variation in metabolic losses affected differences in digestibility. Negative digestion coefficients for silica could have been due in part to slow erosion and passage of soil and rocks that settled to the bottom of the rumen and reticulum.Dry matter intake was significantly lower for buffaloes in all trials. Lower dry matter intakes contributed to higher digestibilities by buffaloes in the wet season. Less metabolic loss by cattle was probably responsible for lack of animal species differences in digestibility during the dry season. In the dry season buffaloes selected the leafier portions of the Napier grass; but this was not reflected in higher digestion coefficients. The 2% to 4% higher digestibilities observed for the buffaloes over cattle on wet season grass would probably not be biologically significant. The fact that the cattle had higher intakes of dry matter would be more significant in increasing production, i.e., milk or weight gain, than the higher digestion coefficients of the buffaloes while eating less. During the wet season, chopping the Napier grass significantly increased the digestibility of dry matter, with the reverse in the dry season. It is not readily apparent why chopping the feed increased digestibility in one instance and not in another. Wilting markedly increased intake and digestibility of the Napier grass, and significantly lowered the metabolic losses. Apparently, some chemical or enzymatic change within the plant during the wilting period caused an increase in digestibility of the cell wall.

If livestock productivity is to be improved the relationships between the animals and the environment will have to be better understood.

INVESTIGATIONS were conducted with beef females to study the long-time effects of 32 C and 60% relative humidity on reproductive efficiency and adaptation, including growth rates. Physiological responses —ovarian activity, length of estrous cycle, fertility, body temperature, respiration rate, hair coat growth, body growth rate and water intake were studied.In females accustomed to cold weather (avg 1.2 C), rectal temperatures and respiration rates increased approximately 1.5 C and 90 respirations/minute, respectively, reaching a peak at 7 weeks and by the 11th week all had either plateaued at a level different from the preliminary period or had returned to normal levels. The most pronounced change observed was the shedding and decreased hair coat depth in the winter females. These females had become anestrus but had on the average reestablished their cycles by the 16th week. When these females were bred, they conceived and delivered normal calves.In females accustomed to summer weather (avg 24.4 C), body temperatures and respiration rates rose rapidly, then declined rapidly followed by marked fluctuations. The depression of gains were less than the winter conditioned females and had returned to normal by the fifth week. The hair coat continued to grow for 4 weeks and then remained stable. None of the summer condition females ceased to cycle when exposed to the 32 C heat stress. When summer conditioned females were exposed to 38 C all became anestrus.

Data from the Red Sindhi-Jersey crossbreeding investigations conducted at three stations were studied to determine the possible effects of varying degrees of Sindhi inheritance on gestation length, birth weight and age at first calving.Each 25% of Sindhi inheritance increased gestation length approximately three days, thus suggesting an additive genetic effect. Parity of calving, sires within breeds and interaction of sire and sex had a significant effect on gestation length but sex differences were not significant.Gestation length, age of dam, sires within breeds and the interaction of sex and sire had significant effects on birth weight. The interaction of sex and breed was not significant. The F1crossbred calves showed heterosis for birth weight even after adjustment for gestation length. The ¾ J calves were heavier at birth than Jerseys but this might be attributed primarily to increased gestation length. The ¼ J crossbred calves were generally smaller than any of the other groups and the differences were more pronounced when gestation length was considered.The results of this study indicate that up to 75% Sindhi inheritance may be used in combination with Jerseys without delaying the age of first calving beyond that normally considered satisfactory for purebred Jerseys.

Data from three stations are presented on comparative body weights, body dimensions and the external surface area of purebred Jerseys and various combinations of Red Sindhis and Jerseys.In general the crosses gained faster than Jerseys up to 12 months of age but only the F1and ⅝ Jersey crosses remained larger at 18 months and first lactation. All crosses having 75% or less Sindhi inheritance showed some degree of heterosis for weight gain up to 6 months but the F1groups were the only ones which consistently exceeded the higher parent. Due to variation in response to the environment and the numbers involved, the degree of heterosis in the other combinations was not as evident.The trend of skeletal growth was very similar to that for weight in that the crosses tended to excel the Jerseys at the earlier ages but very little of the advantage carried through to the first lactation. There were indications of heterosis in skeletal growth but it was not as pronounced as for weight. Crossing of the two breeds appeared to have the greatest effect on body length, size of head, slope of rump and fleshing. As little as 25% Sindhi inheritance had a distinct effect on these measurements.Indications were that crossing the breeds had a small effect on total body surface area. It is evident that although the Sindhi had a marked effect on certain phenotypic characteristics in the crosses; namely, the dewlap, navel fold, hump, size of ears and head, that would give the appearance of greater surface area, these were largely offset by a more compact body.

Anaplasmosis is an infectious disease of cattle characterized by intraerythrotic bodies, anemia and fever. The disease is most prevalent in the South and West and causes large economic losses annually.Experiences in the dairy herd of the Iberia Livestock Experiment Station over the past 7 years illustrates the hazards of having to contend with the disease. In this herd, 28% of the animals having clinical attacks died and those lactating cows which recovered had an average loss in lactation yield of 26% in milk and 31% in milk-fat. Evidence thus far does not show that the “carrier state” is a serious detriment to production, but introducing susceptible animals into a herd may cause serious losses where the disease and the vectors of the disease are prevalent. This study shows that if susceptible cattle are to be introduced into anaplasmosis areas, they should be under 2 years of age and be brought in during the “off” vector season. There are indications that the incidence of infection can be reduced even though a herd is in an infected area.

As part of a series of investigations to determine some of the internal body adjustments made by cattle in response to heat stress, studies were conducted in a psychrometric chamber to examine changes in rumen acids, blood glucose, ketones and hematocrit. Holstein cows and yearling Hereford heifers exposed to 90° F. temperature were compared with pair-mates kept under prevailing ambient conditions (36–78° F.). There was also a group of Angus heifers exposed to 100° F. for 7 weeks.Total VFA concentrations were lower at 90° F., with lower acetic acid concentrations being largely responsible. Changes in total VFA concentrations were consistently correlated to a significant degree with rectal temperature (−.49 to −.78**), and rate of respiratory evaporative loss (−.64 to −.71**), but the relationships of VFA levels to dry matter and water intake, blood glucose and blood ketones were quite variable. In the low temperature groups, rectal temperature was positively correlated with hematocrit, but in the chamber groups there was a negative relationship, dependent on the level of ambient temperature (−.22 to −.70**). Hematocrit was also negatively associated with respiration rate (−.59), respiratory vaporization (−.65**), surface evaporation (−.43) and dry matter intake (−.26) in the Holstein chamber group. Hematocrit had a positive but quite variable relation to rumen volatile fatty acid levels. Indications are that the direct effect of the heat stress will bring about some changes in rumen acid concentrations. The extent can not be discerned because of the indirect effects—viz., decreased feed intake and increased water intake taking place concurrently. Results from these studies indicate that changes in rumen acid levels and blood constituents (viz., hematocrit) may be involved in the adjustment to heat stress.

A method is described for measuring the rate of water evaporation from selected areas of skin without altering markedly the humidity of the air to which it is exposed. Air is circulated alternately through a capsule attached to the skin and an absorber containing a saturated solution of a salt giving the desired vapor pressure. The gain in weight of the absorber indicates the evaporation from the skin. A supplementary “maintenance” circuit is used to keep up air flow through capsules when they are not subject to measurement.Examples are given of results obtained by the use of this apparatus on cows under hot conditions. Different areas give different rates, especially under the less hot conditions. The rate of evaporation is increased with the hotter conditions. No significant differences are found between Jersey and Sindhi-Jersey crossbred cows for areas on the forechest and paunch. The rates for these areas under severely hot conditions (105° F., and 34 mmHg vapor pressure) reach 660 gm./sq. m., hr.The same technique applied to rabbits under the same hot conditions revealed virtually no evaporation.

A method is described for visualizing the significance of series of temperature and humidity readings made at different times, in different places, or under different circumstances. Each series is plotted on a psychrometric chart; statistical treatment carried out, using the chart lines as class limits; the outlying points joined to make an envelope; and the mean and standard error clearly plotted on the chart. The ease of interpretation is illustrated with data from Louisiana.

Jersey and Sindhi-Jersey crossbred cows were subjected for six hours to a standard hot atmosphere (105° F., and vapor pressure 34 mm. Hg) at repeated intervals of two months or longer, and observations made on rectal temperature and respiratory rate. Between tests the animals were kept in the barn or on pasture under climatic conditions prevailing at Beltsville, Maryland.The rectal temperature responses are found to vary markedly with the time of year. The responses show a maximum in February, and a smaller maximum in August, with a minimum in May–June.Repeatability coefficients for the rectal temperature responses in heifers (8–22 months of age) remain fairly low until the responses are sorted into three seasonal groups: April–July (low); August–September and February–March combined (high); and October–January (intermediate). They then reach high and satisfactory levels.The results are explained in terms of two sets of response to stress—yield or slip responses, the compensatory responses—which are differentially affected by the seasonal conditions (hot, temperate, cold) under which the animals live between tests.Repeatability coefficients for respiratory rate responses to the test hot atmosphere remain low, even after seasonal sorting.

The surface area was measured on 20 adult Jersey and 20 adult Sindhi-Jersey crossbred cows with a surface integrator, the construction and use of which is described. The areas were compared with the body weights. Neither the ratio of surface area to body weight, nor the ratio of surface area to the two-thirds power of body weight, showed a significant difference between the two groups.In spite of the close similarity in proportional surface area, the heat tolerance of the two groups was markedly different. This indicates that differences in heat tolerance of animals such as these are not primarily due to differences in proportional surface area even though the presence of large dewlaps, etc., might suggest that such a difference in surface area would be found.The relationship between surface area and body weight in the animals reported here, and in animals of adult size reported elsewhere in the literature, is well enough expressed by a straight line. It is suggested that there is no advantage to be gained from the more complex exponential relationship introduced by using a fractional power of body weight when comparisons are to be made between adult animals.

Twenty purebred Jersey cows and 20 Red Sindhi × Jersey (F1) cows were examined (a) at a “normal” temperature of 57°–84°F., and (b) after 3 hours exposure to 105° F. with a vapor pressure of 34 mmHg. Observations were made on rectal temperature, respiratory rate, and respiratory volume. The method of measuring respiratory volume is described.The crosses showed a smaller rise in rectal temperature (1.87± 0.152° F.) than did the Jerseys (3.06±0.23° F.). Both the final respiratory volume and the rise in respiratory volume, however, were also slightly smaller in the crosses. Furthermore, the correlation between respiratory volume and rectal temperature in cows exposed to comparable heat stress was a positive one, often of high magnitude.It is concluded that the superior heat tolerance of the crosses cannot be attributed to a more sensitive respiratory response, but that the higher respiratory activities are compensatory responses displayed by the individuals with the lower heat tolerance. The crosses, however, did show a more marked reduction of tidal volume (−0.48±0.131 l./resp.) than the Jerseys (−0.29±0.113 l./resp.), which should further reduce the risk of an induced alkalosis.Respiratory rate proved to be a less sensitive index of heat tolerance than respiratory volume. Under these conditions there was no significant correlation between rectal temperature and respiratory rate.

To explore the potential of cattle to produce both milk and beef, the genetic aspects of beef production among Holstein-Friesian bulls pedigree selected for milk were studied. The data included growth records of 504 bulls (DPT) by 120 sires (SPT) pedigree selected for progeny testing by American Breeders Service, 1964 to 1971. DPT bulls with proofs had an average predicted difference for milk (PMD) of +180 kilograms. The daughter average was 7,273 kg per lactation under varying herd conditions.Sires accounted for 10% of the variation in average daily gain (ADG), 10% in daily gain per 100 kg body weight (DG/100) and 16% in body weight, indicating substantial genetic variability in beef traits. Sire variance components for beef traits varied with age. There were wide ranges in estimated breeding value (EBV) and estimated transmitting ability (ETA) for beef traits among DPT and SPT bulls, respectively.Ranking EBV among DPT bulls and ETA among SPT bulls for beef traits and selecting the top 10% and 20%, respectively, showed high selection differentials, empirically reflecting the potential for genetic improvement from selection.

Growth records of 504 pedigree selected Holstein-Friesian bulls by 120 sires collected for progeny testing at the American Breeders Service, Inc., DeForest, Wisconsin from 1964 to 1971, were studied to determine the shape of the growth curve, relationships among body weights and growth rates at various ages and to estimate heritability of growth.Body weight and average/daily gain were consistently higher than the previous growth standards for Holstein-Friesian bulls. Bulls weighed about 480 kg at 15 months, which was 46% of average mature weight. Average daily gain ranged from 1.3 to 0.8 kg between 6 and 18 months of age. A sustained high rate of gain was observed even beyond recommended slaughter age which clearly shows that Holstein-Friesian bulls with potentially high milk production levels also have a good capacity to produce beef.Body weights, expressed as deviations from contemporary group averages, at successive ages were positively correlated but the relationships declined as intervals between ages increased, indicating that using earlier weights to predict later weights would be effective only at shorter age intervals. There were no definite relationships between growth rates at subsequent ages, implying that growth rates obtained for a certain age range should be applied only for that particular age range. Correlations between body weight and growth rates were largely negative, suggesting that heavier animals at certain ages tended to gain less in subsequent periods.Within group heritabilities for body weight increased with age from 6 to 30 months of age but gradually declined thereafter. The trends for average daily gain (ADG) and daily gain per 100 kg body weight (DG/100) were almost the opposite for body weight. The overall average heritability estimates for body weight, ADG and DG/100 were 0.83, 0.44 and 0.46, respectively.Since the majority of the Holstein-Friesians being born are progeny of AI sires, the values for growth rate will serve as a standard for Holstein-Friesian males.

Records from two herds in India and two in Columbia representing respectively two breeds of Bos indicus(Hariana and Deshi) and two Bos taurusbreeds—Blanco Orejinegro (BON) and Costeño Con Cuernos (CCC) were evaluated for breeding efficiency and viability. Average age at first calving was 52.1, 46.3, 39.5 and 40.7 months for Hariana, Deshi, CCC and BON. Season of birth did not influence age at calving. Ranking for calving interval was similar, average 479, 418, 396 and 382 days with season effects significant (P<.05) for only Deshi. BON and CCC had fewer days open but much shorter lactation periods, average 73 and 157, thus days carried calf in lactation were similar for all breeds. Percent of time dry per calving interval was high for all breeds, 44.2, 36.7, 64.1 and 81.0 for Hariana, Deshi, BON and CCC. Average annual mortality of females by 12 months of age was 23.6% for Hariana, 17.0% Deshi and 27.0% BON. In the same herds 46.4%, 51.1% and 49.0% of females born alive lived to first calving and annual losses among cows were 18.0%, 17.0%, and 21.0%; therefore, affording little opportunity for selection among females. Temperament, as determined by response to the milking process with and without the calf present, showed all the breeds were similar in this respect. Environmental effects were most important for all traits but genetic differences were indicated for age at first calving and milk yield. On a theoretical basis little gain could be expected in net dairy merit from crosses between the Columbian and Indian breeds.

OVER 4,000 lactation records, irrespective of length up to 300 days, for one or more calvings of 1,460 Hariana cows were used to determine the relative contribution of certain environmental factors to lactation milk yield. There were 42% of records with recorded conditions that could have made them abnormal in length and yield. Reproductive disorders, physical injury, calf died, cow died and cow sold reduced both length of lactation and milk yield significantly. Aftosa, mastitis and miscellaneous causes were unimportant. Loss of calf resulted in short lactations and 16.4% less yield (P<.05). System of roughage feeding—green vs.dry—was not important. Although frequency of milking was confounded by years, 3X gave about 12% higher yield than 2X. Effects of season of calving, year, age of calving, the interactions and length of lactation were significant (P<.05) with the latter accounting for 45% of the total variation in yield. Days open, days dry and calving interval accounted for only 2 to 6% of the total variance in lactation yields. The proportional change in production with advancing age was similar to that for European breeds. Adjustment factors for age and short records due to death of calf are presented. This study clearly shows that the customary procedure of deleting short lactation records when attempting to evaluate differences among cows of breeds indigenous to tropical areas will lead to serious biases. Dropping short records removes a large proportion of low yielders where no cause can be identified but such a procedure removes only a small portion of the records where environmental disturbances could be a factor influencing the estimated value of cows. Tendency for the vast majority of cows to cease lactation following death of calf shows this factor should be taken into consideration where the milking process is carried out in the presence of the calf. Although milk yield may appear associated with age, adjustment for age differences should only be considered after taking into account possible effects of lactation length, the time after starting the herd and year effects. It is also evident that in adjusting to a common age, the age of calving is more appropriate than lactation number.