Milk Yield Of Dams Research Articles

Effects of dam milk yield and milk composition on birth weight and growth performance of Anatolian buffalo calves

This study was conducted to determine the effects of the dam’s milk yield and composition on birth weight, 6-month, and 12-month live weight (LW) of Anatolian buffalo calves born in 2017 and 2018 years in Çorum province, Türkiye. Calving age had a significant impact on daily milk yield (DMY) (P=0.031), lactation milk yield (LMY) (P=0.048) and solids-not-fat (SNF) (P=0.034). DMY (P=0.022) and fat content (P=0.005) were affacted by calving season. Suckling period and calf sex had no significant impact (P>0.05) on DMY, LMY, fat content, and solids-not-fat (SNF) (P>0.05). The dam’s calving age had a significant impact on birth weight (P=0.029), except for 6-month and 12-month live weight (LW). Calving season affected 6-month (P=0.002) and 12-month LW (P=0.012) without birth weight. The suckling period and calf sex were not significantly affected on the birth weight, 6-month, and 12-month LWs (P>0.05). The highest 6-month LW (P=0.025) was determined in the calves of high DMY buffaloes (>6.50 kg). The DMY of the dam had no effect on the birth weight and 12-month LWs (P>0.05). The calves of buffaloes with the highest LMY (>1300 kg) were observed the highest birth weight (P=0.040) and 6-month LW (P=0.046). The dam’s fat and SNF content had no effect on the birth weight, 6-month, and 12-month LWs. To conclude; “higher milk yield resulted in higher birth weight” means that better dams give better calves, suggesting that buffalo keepers should feed buffalo cows sufficiently to get heavier calves at least.

PSVI-23 Effects of Creep-Feeding Supplementation on Growth Performance of Nellore Calves and Milk Yield of Dams

Abstract The study aimed to evaluate the effect of creep-feeding on growth performance of beef calves and milk yield of dams, during nursing phase. The experiment lasted 170 days, from December/2021 to May/2022, the calves were born in September/2021 and creep-feeding supplementation started from approximately 70 days of life until weaning. The experimental design used was a randomized block [blocked by body weight (BW) of calves]. The experimental units were the paddocks (8 units per treatment, and ten replicates per paddock), totalling 156 pairs cow/calf (86 pairs of male calves and 70 pairs of female calves). The treatments consisted of creep-feeding or not creep-feeding the calves: control treatment (CONT; mineral supplement ad libitum) and creep-feeding treatment (CREEP; energetic protein supplement; 5 g/kg of BW· animal-1· /day-1). There was mineral supplement ad libitum for all the dams. The pairs cow/calf were kept in an area of Urochloa brizantha cv. Marandu. The data were analyzed using the SAS PROC MIXED. Male calves subjected to CONT showed less BW (-15 kg) at weaning and decreased average daily gain (ADG; -100g/day) until weaning (P < 0.01; Figure 1), while female calves showed no difference in BW and ADG (P > 0.12; Figure 2). The dams did not show difference in milk yield until weaning (P > 0.27) for male and female calves (Figure 3). This difference in results related to gender is explained by the fact that there are differences in the performance of males and females, mainly due to hormonal issues. Usually, females are born lighter than males and tend to have decreased performance throughout the whole production cycle. For milk yield and performance of dams, our results agree with what is found in the literature. There are some studies which also evaluated milk production of dams when the offspring were creep-fed, and found similar milk yield for those whose offspring received supplement in relation to those who did not receive it. This is likely because calves prefer milk, supplement, and forage, in that order, so it seems unlikely that calves would replace milk with supplements. And these results show us that the difference in the BW at weaning of males was caused by the creep-feeding supplementation.

PSVI-22 Effect of Creep-Feeding on Feeding Behavior of Nellore Calves

Abstract The study aimed to evaluate the effect of creep-feeding on feeding behavior of beef calves, during nursing phase. The experiment lasted 170 days; from December/2021 to May/2022, the calves were born in September/2021 and creep-feeding supplementation started from approximately 70 days of life until weaning. The feeding behavior was evaluated twice on d 70 and d 120 post creep-feeding). The experimental design used was a randomized block [blocked by body weight (BW) of calves]. The experimental units were the paddocks (8 units per treatment, ten replicates per paddock), totalling 156 pairs cow/calf (86 pairs of male calves and 70 pairs of female calves). Two paddocks per treatment and 8 pairs per paddock were sorted for behavior analysis, totalling 32 pairs cow/calf (16 pairs of male calves and 16 pairs of female calves). The treatments consisted of creep-feeding or not creep-feeding the calves: control treatment (CONT; mineral suppement ad libitum) and creep-feeding treatment (CREEP; energetic protein supplement; 5 g/kg of BW· animal-1· /day-1). There was mineral supplement ad libitum for all the dams. The pairs cow/calf were kept in an area composed of Urochloa brizantha cv. Marandu. and idleness, suckling, grazing and creep-feeding or mineral supplementation were evaluated. The data were analyzed using the SAS PROC MIXED. There was no difference in feeding behavior of calves at 70 days of creep-feeding for idleness (P = 0.80), grazing (P = 0.59) and suckling (P = 0.30; Figure 1). Creep-feeding calves spent 14 minutes longer on supplementation than non-creep-feeding calves (P < 0.01). At 120 days of creep-feeding (180 days of age), calves that received creep feeding supplementation spent less time grazing (difference of 67 min; P < 0.01), more time on supplementation (+28 min; P < 0.01) and idleness (+42 min; P = 0.05) and similar time on suckling (P = 0.76; Figure 2).There was no difference in any of the variables at different times (P >0.08) for the dams (Figure 3). Animals in creep-feeding spend less time grazing but suckling in a similar amount of time compared with those that consumed only mineral supplement, which corroborates with the results on milk yield of dams, which were similar for both treatments.

Effect of weaning system on lamb growth, mammary gland development and ewe milk production in dairy sheep managed in an outdoor pasture-based commercial farming system

The objective was to merge science and practice to determine the feasibility of a mixed suckling and milking system compared with a traditional exclusive suckling management system on the production performance of dairy sheep and their progeny in an outdoor pasture-based farming system at commercial scale. At 14 d postpartum, twin- and triplet-bearing mixed-age East Friesian ewes were randomly allocated to either a mixed system of once-a-day milking,suckling and early weaning (MS, n=61) or control with exclusive suckling and later weaning (Ctrl, n=57) using a randomised block design. MS lambs had lower live weight at weaning (14.6 vs. 16.7 kg; P<0.001) but 3-5weeks post-weaning average daily gain and mammary gland mass was similar between groups. Ewe lamb mammary mass was positively associated with post-weaning but not pre-weaning live weight gain (P<0.01). Weaning system influenced the percentage of protein, total solids and fat (MS > Ctrl) while milk yield, somatic cell count and lactose levels were not different. This study highlighted that the MS comparedwith Ctrl system had no negative effects on dam or progeny performance.

The effectiveness of evaluation of sires by indicators of milk productivity of daughters by the method of comparison of «daughters-dams»

The purpose of the work was to evaluate the sires in terms of milk productivity of daughters by comparing the method “daughters-dams” in the herd of OOO “BMK” Bogdanovichsky area in Sverdlovsk region. It was found that the milk yield for 305 days of lactation in the daughters of the sire Fennek 4241542328 was 8815±323,2 kg with the difference between the milk yield of daughters and the milk yield of dams 705 kg and the coefficient of variability 17,9 %. Sire Altadublin 8820742 was evaluated as neutral in milk yield of daughters for 305 days of lactation, while his daughters showed milk yield less than dams by 34 kg. The mass fraction of fat in the milk in the daughters of the sire Altadublin 8820742 was lower than that in dams by 0,09 %. In the daughters of sires Bosch 2733, Fennek 4241542328 and Lan 666626709, it was higher than in dams by 0,12 abs.%, 0,02 and 0,11 abs.%, respectively. The sires Bosch 2733, Fennek 4241542328 and Lan 666626709 were evaluated as improvers by the mass fraction of protein in milk, the indicators of their daughters exceeded the indicator in dams by 0,42 abs.%, 0,40 and 0,41 abs.% (P < 0,01–0,001), respectively. The sire Altadublin 8820742 was evaluated as neutral, because in terms of the mass fraction of protein in milk, his daughters surpassed their dams by only 0,03 abs.%. Taking into account the genealogical structure of Black-and-White breed of the Urals, it is necessary to evenly use the gene pool of all promising lines of Holstein breed such as Wes Ideal 933122, Montwick Chieftain 95679, Reflection Sovereign 198998.

Optimizing breeding structures and related management in community-based goat breeding programs in the Borana pastoral system of Ethiopia

The study simulated different potential breeding programs to design the optimal breeding structure and operational management structure for Borana goat. It evaluated different scenarios using ZPLAN+ software to maximize the genetic gain, discounted profit and to determine the optimum size of the base population for a community-based breeding program (CBBP) nucleus. The study analyzed the different combinations of objective traits in the index, assessed the effect of changing the breeding buck to doe ratio, evaluated the impact of improved kid survival, and determined the optimum size of the base population for a CBBP. A two-tier breeding program based on 577 does in the CBBP and 1,006 does in the surrounding base flocks was assumed, where selected CBBP bucks were disseminated to the base populations. Combining the weight of kids at six months (SMWT) and the lactation milk yield of dams (LMY) in the selection index resulted in a genetic gain doe−1 generation−1 of 0.13 kg, 0.58 kg, 0.02 and 0.004 for SMWT, LMY, the number of kids that survived to market age (NKS) and the number of kids born (NKB), respectively. This also generated a total discounted profit of US$5.76 doe−1 over 10 year investment period. This result was 30 percent higher than when LMY was evaluated separately and 225.7 percent higher than when SMWT was evaluated separately. The addition of NKB and NKS traits in the selection index did not significantly change the genetic progress and the profit. However, further optimization of the combined SMWT and LMY by improving mating ratio only, and a combined improvement in mating ratio and kid survival rate resulted in a substantial increase in profit to US$11.13 doe−1 and US$15.58 doe−1, respectively over 10 year investment period. The maximum discounted profit was attained when the base population size was 3,579 breeding does. This resulted in accumulated total profit of US$14,776 over the 10 year investment period. A two-tier dispersed CBBP with a unit size of about 577 does in the nucleus and 3,579 does in the base is recommended. In Borana goat community-breeding program, breeding buck need to be selected using an index combining at least own live weight and dam milk yield performance. Essential requirements for ensuring the sustainability of such programs are also discussed in the paper.

A mathematical nutrition model adequately predicts beef and dairy cow intake and biological efficiency.

The beef cow-calf sector accounts for 70% of feed consumed and greenhouse gases emitted for the beef industry, but there is no straightforward method to measure biological efficiency in grazing conditions. The objective of this study was to evaluate a mathematical nutrition model to estimate the feed intake and biological efficiency of mature beef cows. Data from dams (N = 160) and their second and third progeny (312 pairs) were collected from 1953 through 1980. Individual feed intake was measured at 28-d intervals year-round for dams and during 240-d lactation for progeny. Body weights of progeny were measured at 28-d intervals from birth to weaning, and of dams at parturition and weaning each production cycle. The milk yield of dams was measured at 14-d intervals. Dam metabolizable energy intake (DMEI) and milk energy yield (MEL) of each cow were predicted using the Cattle Value Discovery System beef cow (CVDSbc) model for each parity. Biological efficiency (Mcal/kg) was computed as the ratio of observed or predicted DMEI to observed calf weaning weight (PWW). Pearson correlation coefficients were computed using corr.test function and model evaluation was performed using the epiR function in R software. Average (SD) dam weight, PWW, DMEI, and observed MEL were 527 (86) kg, 291 (47) kg, 9584 (2701) Mcal/production cycle, and 1029 (529) Mcal, respectively. Observed and predicted DMEI (r = 0.93 and 0.91), and observed and predicted MEL (r = 0.58 and 0.59) were positively correlated for progeny 2 and 3, respectively. The CVDSbc model under-predicted DMEI (mean bias [MB] = 1,120±76 Mcal, 11.7% of observed value) and MEL (MB = 30±25 Mcal, 2.9% of observed value). Observed and predicted progeny feed intake were not correlated (r = 0.01, P-value = 0.79). Observed and predicted biological efficiency were positively correlated (r = 0.80 and 0.80, P-value ≤ 0.05) for parity 2 and 3, respectively, and the CVDSbc model under-predicted biological efficiency by 11% (MB = 3.59±0.25 Mcal/kg). The CVDSbc provides reasonable predictions of feed intake and biological efficiency of mature beef cows, but further refinement of the relationship between calf feed intake and milk yield is recommended to improve predictions. Mathematical nutrition models can assist in the discovery of the biological efficiency of mature beef cows.

71 Evaluation of the CVDS Beef Cow Model to Estimate Biological Efficiency in Mature Cows

Abstract There is no clear method to measure biological efficiency in grazing beef cows. The objective of this study was to evaluate a nutrition model to estimate biological efficiency in mature cows. Data from dams (n = 160) and their 2nd and 3rd progeny were collected from 1953 through 1980. Individual feed intake was measured at 28-d intervals for lifetime of dams and during 240-d lactation for progeny. Body weight of progeny were measured at birth and weaning, and dams at parturition and weaning each production cycle. Milk yield of dams was measured at 14-d intervals by hand milking. Metabolizable energy required (MER) and predicted milk energy yield (MEY) of each cow was computed using the CVDS beef cow model for each parity. Biological efficiency was computed as the ratio of cow ME intake (MEI) to calf weaning weight (WW) based on observed (MEI/WW) and predicted (MER/WW) values. Pearson correlation coefficients were computed using corr.test function in R software. Average (SD) cow weight, calf weaning weight, cow MEI, and observed MEY were 507 (81) and 548 (88) kg, 287 (49) and 294 (44) kg, 9406 (2695) and 9721 (2686) Mcal, and 1009 (538) and 1051 (521) Mcal, for progeny 2 and 3, respectively. Cow MEI and MER (0.87 and 0.85), and observed and predicted MEY (0.51 and 0.51) were positively correlated for progeny 2 and 3, respectively. The CVDS model under predicted cow MEI [mean bias = 1685 (1718) and 1658 (1702) Mcal] and MEY [mean bias = 82 (465) and 129 (450) Mcal] for progeny 2 and 3, respectively. Observed and predicted progeny feed intake were not correlated. Observed and predicted biological efficiency were positively correlated (0.63 and 0.61) for progeny 2 and 3, respectively. In conclusion, nutrition models can reasonably predict biological efficiency, but further refinement of the relationship between calf feed intake and milk yield could improve prediction.

72 Relationships Among Lifetime Feed Efficiency Traits in Growing Heifers, Mature Cows and Their Progeny

Abstract Uncertainty exists in relationships among feed efficiency traits in different production stages. The objective of this study was to evaluate the relationships among feed efficiency traits measured in various stages of production. Data were collected from 1953 through 1980 from dams (n = 160), and their progeny (n = 406). Individual feed intake was measured from 240 d of age through weaning of 3rd calf for dams, and from weaning to slaughter for progeny. Body weight was measured at 28-d intervals until first parturition for heifers and slaughter for progeny, and cows were weighed at parturition and weaning each production cycle. Milk yield of dams was measured at 14-d intervals throughout lactation. Residual feed intake was computed as the residual from linear regression of daily DMI on metabolic mid-test body weight, average daily gain, and milk yield for dams only with year-diet-breed factor as a random effect using lmer function in R software. Pearson correlation coefficients were computed using corr.test function. Pearson correlations of RFI with DMI ranged from 0.58 to 0.74 and with feed:gain or feed:milk ranged from 0.24 to 0.67 within production stage. Heifer RFI was correlated with cow RFI during parity 1 (0.74), but not parity 2 (0.11) or 3 (-0.06). Heifer RFI was correlated with progeny 3 RFI (0.17), but not progeny 1 or 2 RFI. Cow RFI was weakly correlated among parities (0.25 to 0.36) whereas feed:milk was strongly correlated (0.56 to 0.70). Cow RFI was not correlated with progeny RFI of the same parity. In conclusion, RFI was poorly correlated across stage of production.

Effects of nutritional practices in different periods on some yield characteristics of Kilis goats

Aims: In this study, the effects of supplementary feeding during gestation and lactation period on birth and weaning weights of kids and milk yield of dams in Kilis goats were investigated.Methods and Results: In the study, experimental goats were divided into three groups as control group, short-term feeding (STF) group and long-term feeding (LTF) group. The control group was kept under breeder’s management conditions. Supplementary feed of 750 g/head/day were given to the goats from the last 20 days of gestation to 90th days after birth in the STF group, and from last 40 days of gestation to the end of lactation in LTF group. At the end of the experiment, the highest lactation period was 220.2 days in the LTF group, followed by STF and control groups (P <0.05). Likewise, in the LTF and STF groups, the lactation milk yield, which was determined as 466.2 and 426.3 liters respectively, was higher than the control group (316.4 liters) (P <0.05).Conclusions: It was concluded that supplementary feeding during gestation and lactation periods caused an increase in milk yield and lactation length of Kilis goats.Significance and Impact of the Study: At the end of study, it can be stated that if supplementary feeding is made during gestation or lactation, milk yield characteristics of Kilis goats will be improved. Suckling period for the goats is the period when pasture conditions are good. For this reason, even in the goats managed only in the pasture, milk yield of mothers is sufficient for multiple born kids.

Influence of levels of supplementary concentrate mixture on lactation performance of Red Sokoto does and the pre-weaning growth rate of their kids

Twenty pregnant Red Sokoto goats (liveweight, 28 ± 1.30 kg) were used in a completely randomized design to determine the effect of varying levels of concentrate on lactation performance. The concentrate, which contained 4% palm oil, was fed at levels of 1.0, 1.5, 2.0 and 2.5% of body weight of the does in addition to a basal diet of Digitaria smutsii hay offered ad libitum. The corresponding dietary treatments were designated as 1.0%C, 1.5%C, 2.0%C and 2.5%C, respectively. The goats were balanced for parity and randomly allocated to give five animals per treatment, and stall-fed individually.The intake of dry matter and daily milk production linearly and quadratically increased (P<0.05) to the levels of concentrate supplementation. Increase in level of concentrate mixture supplementation affected (P<0.05) milk fat content and milk fat yield, but not other milk constituents. Persistency of milk production was numerically higher at higher levels of concentrate supplementation. Whereas 1.0%C, 1.5%C and 2.0%C could not prevent weight loss in the does, the 2.5%C significantly (P<0.05) promoted average daily gain (11.11 g/head/day) during lactation. The dam milk yield significantly (P<0.01) accounted for 61% of variation in kids pre-weaning average daily gain (ADG). It is concluded that concentrate mixture containing 4% palm oil can be fed at 2.5% of body weight without adverse effect on total dry matter intake, while enhancing postpartum weight gains, higher milk yield, persistency of milk production, pre-weaning growth of kids in Red Sokoto goats.

EVALUATION OF PRODUCTIVE AND REPRODUCTIVE PERFORMANCES OF BLACK BENGAL GOATS IN RAJSHAHI GOVERNMENT GOAT DEVELOPMENT FARM IN BANGLADESH

Background: The Black Bengal goat (BBG) is well adapted food animals with profitable productive and reproductive traits being naturally reared to enhance economic status and food security in rural people. Bangladesh government has taken program through establishment of ‘Government Goat Development Farms’ (GGDF) to enhance the goat rearing activities of the smallholders at rural level but the research reports on the productive and reproductive performances of goats in these GGDF are very limited. Objective: The main objective of this study was to evaluate the productive and reproductive performances of the BBG reared in semi-intensive system at the Rajshahi GGDF Materials and Methods: The Rajshahi GGDF had 398 goat populations of which 121 does were selected to study the productive and reproductive performances during the period from July 2010 to June 2011. The age of first estrus, conception rate by natural service, gestation length, post-partum heat, kidding interval, litter size, survivability of kids, morbidity and mortality of kids and their seasonal influence were studied. Results: The age of young female BBG showed 1st estrus varied from 180 to 270 with an average of 204  27 days. The conception rate varied from 88 to 100 with an average of 97% with natural services. The gestation length varied from 145 to 182 with an average of 150  5 days. The post-partum heat period varied from 60 to 90 days with an average of 69  7 days. The kidding interval varied from 199 to 268 with an average of 219  13 days. The litter size varied from 1 to 3 with an average of 2. Out of 234 kids borne, 47.44% were male and 52.56% female with higher mortality in male (10.81%) than female (5.69%) with an overall average mortality of 8.12%. There was no significant influence of season and parity on the birth weight of kids. However, the heavier birth weight of kids was recorded in male (1.38 kg) than female (1.17kg) kids. The birth of twin kids (56.41%) was found significantly (p &lt; 0.0001) highest in comparison to triplets (26.92%), single (11.54%) and quadruplet (5.13%). Conclusions: The results support promising breeding and reproductive efficiency of BBG under local environmental conditions and therefore, there is a need to be improved milk yield of dam and control of morbidity and mortality in BBG kids. It may be concluded that the productive and reproductive performances of the BBG reared by using semi-intensive system of management appears to be encouraging at the Rajshahi GGDF which could be extended and compared to research findings with other four GGDF in Bangladesh.

Milk yield potential of prolific avishaan and gmm sheep and their association with overall ewe productivity

A study was undertaken during 2015–2017 to assess the milk yield potential and to estimate the effect of dam's milk yield on ewe productivity efficiency of newly developed prolific Avishaan and GMM (25% Garole-75% Malpura) sheep at ICAR-Central Sheep and Wool Research Institute, Avikanagar, Rajasthan. A total of 369 test day milk records from 34 Avishaan ewes and 199 test day milk yield records from 19 GMM ewes were collected. Average milk recording period in GMM and Avishaan ewes was 66 and 74 days, respectively. Birth and weaning weight data of lambs born to these ewes were also collected. The data were analyzed using the general linear model procedure with different fixed effects and covariates in the model. The least squares means of daily milk yield was 672.73±15.60 g in Avishaan and 531.85±19.77g in GMM ewes. Daily milk yield was significantly affected by stage of lactation, dam's parity and type of birth in both the genotypes. The least squares means of 90-day lactation yield were 63.49±2.46 and 48.40±2.86 kg in Avishaan and GMM ewes, respectively. First parity ewes recorded the lowest lactation yield in both the genotypes. The least squares means of litter weight per ewe at weaning were 21.40±0.72 and 18.47±1.10 kg in Avishaan and GMM ewes, respectively. Positive correlations between ewe's milk yield with litter weight at weaning and average daily gain in litter weight was observed for both the genotypes. It can be concluded that prolific Avishaan sheep has higher milk yield potential compared to GMM sheep and higher milk yield in dam resulted in higher litter weight and average daily gain at weaning.

English

This study aimed at identifying Sheko cattle keepers&#39; preferences by way of phenotypic ranking and hypothetical choice experiment in their habitat in order to define the indigenous selection criteria. The ranking experiment report was based on 15 cows and 6 to 9 bulls. Three animals of the same sex were randomly assigned in one group that resulted into five groups for cows and two to three groups for bulls. Thirty cattle keepers belonging to another community were invited to rank the groups of experimental animals according to their own preferences and give the reasons why they had chosen the animals as 1st, 2nd, and 3rd. Then they were provided with life history of each cow, including age, milk yield, parity, calving interval and heart girth measurements; while for bulls, age, milk yield of dam, sire fertility and heart girth measurements were described to determine whether she/he would consider re-ranking them. The results of farmers&rsquo; preference for traits through both methods are not consistent. In phenotypic ranking, the results indicate that, milk yield, body conformation, body size and coat color were emphasized in the selection of cow while, body size, dairy character, draught character and coat color traits were important traits for selection of bull. Information on life history provided insight in the respondents&rsquo; ranking decisions. In choice experiments, the maximum likelihood estimates of the parameters for cow selection were significant in both lowland and midland agro-ecological zones (AEZs), except for calving interval in midland. The trait mothering ability was the most preferred trait followed by milk yield in both AEZs. For bulls the estimates were significant with the exception of growth rate in midland. It was found out that by this method breeding bulls are chosen based on milk performance of mother and temperament in both AEZs. Key words: Breeding objectives, choice experiment, lowland, midland, phenotypic ranking, Sheko. &nbsp

The milk yield of dams and its relation to direct and maternal genetic components of weaning weight in beef cattle

Cow milk yield is a critical component for the growth of the calves in the preweaning period. The genetic correlation between direct weaning weight and milk yield traits may cause a decrease in the maternal ability of cows when they are selected for the direct weaning weight of the calf. The objective of this study was to analyse the genetic and environmental components of some traits of interest in beef cattle breeds managed in mountain conditions by analysing the actual cumulative milk yield at 150 days obtained by milking (MY150) and the weight at birth (BW), at 90 days (W90), at weaning (W150), and mature weight (MW). Genetic evaluations were conducted using field data from 2679 calves born from 553 dams of Parda de Montaña beef cattle breed. The variances, genetic (both direct and maternal) and phenotypic, were estimated by a multi-trait animal model. Milk yield was correlated with maternal components of calf weight at 90 days and 150 days (genetic correlations of 0.59 and 0.48, respectively) and also correlated with a direct genetic component of W90 and W150 (genetic correlations of 0.58 and 0.54, respectively). The maternal heritability values for W90 and W150 were 0.023 (0.005) and 0.009 (0.004), respectively. The estimates of the direct-maternal genetic correlation for W90 and W150 were − 0.13 (0.11) and − 0.34 (0.16), respectively. Environmental effects, especially the sex of calf and dam parity for direct genetic effects and energy level of cow and body condition at calving for maternal effects, should be included in the evaluation models to obtain a proper estimation of genetic parameters for beef cattle evaluation. Genetic milk yield explains half the variation of maternal effects for W90 and W150. The prediction of milk yield will be better using maternal effects at 90 days than at 150 days. The combined index (maternal and direct) for the trait weight at 150 days yielded the highest economic response increasing the direct effect indirectly without decreasing the maternal effect at 150 days.

Effects of genetic and non-genetic factors on growth traits of high yielding dairy seed calves and genetic parameter estimates

The study was conducted to know the effects of several genetic and non-genetic factors like season, sex, year of birth, genotype of calves and milk yield of dam associated with growth performance of crossbred calves. Data were collected from registered farmers during the period of May, 2011 to April, 2013. Birth weight, three-month weight, six-month weight, weaning weight and heritability estimates of those growth performances were performed using a total of 82 registered calves which had pedigree information having the genotypes of 25% Local - 75% Friesian and 37.5% Local - 62.5% Friesian. The average birth, three-month, six-month and weaning weight of calves were 29.33, 64.32, 99.06 and 151.77 kg, respectively. The effects of non-genetic factors like sex, season of birth and genotype were non-significant (P>0.05) for the traits birth weight, three-month, six-month, weaning weight and average daily gain of calves. However, year of birth was found significant on birth (P

Phenotypic effects of calving ease on the subsequent fertility and milk production of dam and calf in UK Holstein-Friesian heifers

The effect of calving ease on the fertility and production performance of both dam and calf was studied in approximately 50,000 and 10,000 UK Holstein-Friesian heifers and heifer calves, respectively. The first objective of this study was to estimate the effect of a difficult calving on the subsequent first-lactation milk production by estimating lactation curves using cubic splines. This methodology allows the estimation of daily milk, protein, and fat yields following calvings of differing degrees of difficulty. Losses in milk yield after a difficult calving have been quantified previously; however, estimates are generally restricted to the accumulated yields at specific days in lactation. By fitting cubic splines, gaps (in which the shape of the lactation curve can be merely guessed) between estimations were avoided. The second objective of this study was to estimate the effect of a difficult birth on the subsequent performance of the calf as an adult animal. Even though the calving process is known to involve cooperation between dam and calf, the effect of a difficult calving has, until now, only been estimated for the subsequent performance of the dam. Addressing the effects of a difficult birth on the adult calf strengthens the importance of calving ease as a selection trait because it suggests that the benefit of genetic improvement may currently be underestimated. The effect of calving ease on the subsequent reproductive performance of dam and calf was analyzed using linear regression and with calving ease score fitted as a fixed effect. Dams with veterinary-assisted calvings required 0.7 more services to conception and 8 more days to first service and experienced a 28-d longer calving interval in first lactation compared with dams that were not assisted at calving. Effects of calving ease on the reproductive performance of the adult calf in first lactation were not detected. Losses in milk yield of the dam were significant between d 9 to 90 in milk subsequent to a veterinary-assisted calving, creating a loss of approximately 2kg of milk per day, compared with a nonassisted calving. Calves being born with difficulties showed a significant reduction in milk yield in first lactation, demonstrating the lifelong effect of a difficult birth. Compared with nonassisted calves, veterinary-assisted calves showed a loss of 710kg in accumulated 305-d milk yield, which was significant from 129 to 261 d in milk. This suggests that from birth to production, physiological effects of a bad calving are not negated. Results furthermore suggest a beneficial effect of farmer assistance at calving on the milk yield of both dam and calf, when moderate difficulties occurred.

Genetic improvement of Egyptian Nubian goats as sub–tropical dairy prolific breed

Egyptian Nubian (Zaraibi) goats, known to be a progenitor of the standard Anglo-Nubian, are raised as household dairy animal in North-East of Nile Delta and known for its high prolificacy. In 1990, sires of the present herd were selected based on their dam milk yield. From 2000, selection indices were applied on both males and females including body weights and milk yield of their dams at 1st parity. In all cases single-born goats were not allowed to breed. A total of 7298 E. Nubian does and 10,374 kids records were used to estimate annual genetic, phenotypic and environmental changes in milk yield, prolificacy, and growth traits. Total milk yield (TMY) averaged 253.1±1.5kg in 251.3±0.8 days of lactation (including 90 days suckling). Seventeen percent of the does produced more than 350kg of milk/lactation. Litter size averaged 2.1±.01 kids at birth and 1.6±.01 kids at weaning. Annual genetic changes were estimated based on the predicted breeding values over year of birth. It was positive and highly significant for TMY, (0.72kg/yr, P<.0001) and litter size at weaning (0.001kid/yr, P<0.001), which indicates positive response to the applied selection program. Annual phenotypic changes were negative for milk yield and growth traits, indicating unfavorable environmental conditions and the need for better management of the herd to explore its genetic potentiality. Genetic parameters were moderate for TMY and low for prolificacy traits, while their genetic correlation was moderate. It is recommended to apply more intensive selection program under favorable managerial conditions to explore the E. Nubian genetic potentiality as a subtropical dairy prolific breed.

Behavioural responses of 6-month-old beef calves prevented from suckling: influence of dam's milk yield

The objective of the present experiment was to compare the behavioural response of calves reared by cows of different milk yields to the prevention of suckling with the aid of nose-flaps that allowed the maintenance of social contact with the dam. Twenty Hereford or Hereford × Angus crossbred primiparous cows from a single herd remained with their calves suckling until the beginning of the experiment, in late summer–early autumn. Milk production was determined monthly during the lactation period and the pairs were selected according to the cows’ milk production, for higher or lower milk yield (HMY and LMY, respectively). On Day 0, suckling was prevented by placing a nose-flap anti-suckling device on each calf for 11 days. Calf behaviour was recorded from Day –3 to Day 5, using instantaneous sampling of individual animals in each group, and the calves were weighed monthly since birth, and on Days –8 and 11. Bodyweight profiles for HMY and LMY calves were similar until Day –8; from then on, up to Day 11, HMY calves lost weigh, whereas LMY calves gained weight. Suckling frequency before nose-flaps were fitted was similar for HMY and LMY calves. There was no relationship between the cow’s milk yield and the changes observed in behaviour. Apart from playing, all behaviours were affected by prevention of suckling. The distance between the calves and the dam, and the frequency of grazing and rumination, decreased after nose-flaps were placed, whereas vocalisations, suckling attempts, walking and standing increased. In conclusion, the behavioural responses to prevention of suckling did not differ between the 6-month-old calves reared by cows with high yields and those with low milk yields. The behavioural response of calves that were prevented from suckling but were kept with the dams indicates that the cessation of suckling contributes to the weaning distress of 6-month-old beef calves.

Relationships of Milk Production of Beef Cows to Postweaning Gain of the Calves

Milk yield from 158 Brangus cows bred to 6 sire breeds (Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, Romosinuano) was measured for 3 yr to estimate relationships of milk yield of cows and postweaning ADG of their calves on 2 postweaning systems (dry lot or wheat pasture). Milk yield was measured monthly 6 times per year and averaged over 1 mo. Calf postweaning ADG was calculated from the initiation of postweaning management treatments in the fall to the end of spring grazing in April. Calf ADG was regressed on dam 24-h milk yield, and interactions of linear and quadratic regression coefficients with calf sire breed and postweaning treatment of calf were evaluated. In general, regression analyses indicated that calf postweaning ADG was linearly related to dam milk yield, but the relationships depended on the calf sire breed and postweaning treatment (P < 0.01). On dry-lot management, greater cow milk production was associated with lesser postweaning ADG in Gelbvieh- (P < 0.05) and Bonsmara-sired (P < 0.01) calves, whereas greater cow milk production was associated with greater postweaning ADG in Brangus-sired calves (P < 0.01), and a similar trend was observed in Charolais-sired (P < 0.19) calves. On wheat pasture management, greater cow milk production was associated with greater postweaning ADG in Gelbvieh-sired calves (P < 0.11), with a trend for greater cow milk production to be associated with lower postweaning ADG in Romosinuano-sired calves (P < 0.25). Results indicate that accurate determination of the relationship of dam milk production and calf postweaning ADG will require consideration of both calf postweaning management and calf sire breed.