Growth and development of water buffalo and Friesian crossbred cattle, with special reference to the 'entire' and 'boneless' cuts

Twelve buffaloes, nine Friesian × Baladi and nine Friesian × (Friesian × Baladi) bulls were slaughtered over the live weight ranges 161–560 kg for buffaloes and 176–448 kg for cattle. Right sides of all carcasses were jointed and dissected and the increase in the weight of ‘entire’ and ‘boneless’ cuts and cut groups (i.e. pistol; BLRC) relative to the ‘entire’ and ‘boneless’ side weights, respectively, were examined using covariance analyses.

Increasing distoproximal and dorsoventral growth gradients were found in both species. Most noticeably, the sticking was early developing in buffaloes and late developing in cattle, whereas the shortloin developed approximately at an average rate in buffaloes and at a lower rate in cattle. Statistically significant but relatively slight differences were recorded between buffaloes and cattle in the adjusted means of the ‘entire’ and ‘boneless’ hind shank, sirloin (favouring buffaloes) and brisket (favouring cattle). Buffaloes were superior to cattle in weight of pistol. At an equal side weight of 73 kg buffaloes had significantly higher weight of pistol (maximum difference = 1·4 kg). At a 115 kg side weight, the maximum difference in ‘entire’ and ‘boneless’ pistol reached 3·58 and 5·04 kg, respectively.     

Genotype imputation in a tropical crossbred dairy cattle population

The objective of this study was to investigate different strategies for genotype imputation in a population of crossbred Girolando (Gyr × Holstein) dairy cattle. The data set consisted of 478 Girolando, 583 Gyr, and 1,198 Holstein sires genotyped at high density with the Illumina BovineHD (Illumina, San Diego, CA) panel, which includes ～777K markers. The accuracy of imputation from low (20K) and medium densities (50K and 70K) to the HD panel density and from low to 50K density were investigated. Seven scenarios using different reference populations (RPop) considering Girolando, Gyr, and Holstein breeds separately or combinations of animals of these breeds were tested for imputing genotypes of 166 randomly chosen Girolando animals. The population genotype imputation were performed using FImpute. Imputation accuracy was measured as the correlation between observed and imputed genotypes (CORR) and also as the proportion of genotypes that were imputed correctly (CR). This is the first paper on imputation accuracy in a Girolando population. The sample-specific imputation accuracies ranged from 0.38 to 0.97 (CORR) and from 0.49 to 0.96 (CR) imputing from low and medium densities to HD, and 0.41 to 0.95 (CORR) and from 0.50 to 0.94 (CR) for imputation from 20K to 50K. The CORR_anim exceeded 0.96 (for 50K and 70K panels) when only Girolando animals were included in RPop (S1). We found smaller CORR_anim when Gyr (S2) was used instead of Holstein (S3) as RPop. The same behavior was observed between S4 (Gyr + Girolando) and S5 (Holstein + Girolando) because the target animals were more related to the Holstein population than to the Gyr population. The highest imputation accuracies were observed for scenarios including Girolando animals in the reference population, whereas using only Gyr animals resulted in low imputation accuracies, suggesting that the haplotypes segregating in the Girolando population had a greater effect on accuracy than the purebred haplotypes. All chromosomes had similar imputation accuracies (CORR_snp) within each scenario. Crossbred animals (Girolando) must be included in the reference population to provide the best imputation accuracies.     

Economic merit of crossbred and purebred US dairy cattle

Heterosis and breed differences were estimated for milk yield traits, somatic cell score (SCS), and productive life (PL), a measure of longevity. Yield trait data were from 10,442 crossbreds and 140,421 purebreds born since 1990 in 572 herds. Productive life data were from 41,131 crossbred cows and 726,344 purebreds born from 1960 through 1991. The model for test-day yields and SCS included effects of herd-year-season, age, lactation stage, regression on sire's predicted transmitting ability, additive breed effects, heterosis, and recombination. The model for PL included herd-year-season, breed effects, and general heterosis. All effects were assumed to be additive, but estimates of heterosis were converted to a percentage of the parent breed average for reporting. Estimates of general heterosis were 3.4% for milk yield, 4.4% for fat yield, and 4.1% for protein yield. A coefficient of general recombination was derived for multiple-breed crosses, but recombination effects were not well estimated and small gains, not losses, were observed for yield traits in later generations. Heterosis for SCS was not significant. Estimated heterosis for PL was 1.2% of mean productive life and remained constant across the range of birth years. Protein yield of Brown Swiss x Holstein crossbreds (0.94 kg/d) equaled protein yield of purebred Holsteins. Fat yields of Jersey x Holstein and Brown Swiss x Holstein crossbreds (1.14 and 1.13 kg/d, respectively) slightly exceeded that of Holsteins (1.12 kg/d). With cheese yield pricing and with all traits considered, profit from these crosses exceeded that of Holsteins for matings at breed bases. For elite matings, Holsteins were favored because the range of evaluations is smaller and genetic progress is slower in breeds other than Holstein, in part because fewer bulls are sampled. A combined national evaluation of data for all breeds and crossbreds may be desirable but would require an extensive programming effort. Animals should receive credit for heterosis when considered as mates for another breed.     

Factors affecting length of herdlife in purebred and crossbred dairy cattle

The proportional hazards model with censoring was used to assess the effects of breeding value, disease, calving, size, and udder and lactation traits on length of herdlife of 3881 heifers in five herds. Data were recorded over 10 yr from three lines: a Holstein line, an Ayrshire-based line, and a crossbred line. Influences on survival were assessed from data collected at birth, 34, 50, and 82 wk, first freshening, and at 112 and 308 d postpartum. Median estimated herdlife (age at 50% culling) was 3.9 yr for animals alive at first freshening and increased to 4.3 yr for those that completed a first lactation (308 d postpartum). Herds differed greatly in the pattern of culling after freshening. Crossbred females had 21 wk longer median estimated herdlife than the mean of the purelines at 308 d postpartum. Individual milk yield was positively associated with longevity and had the greatest impact on length of herdlife. Abortion and fertility measured as days to last insemination were negatively associated with length of herdlife. Large heifers tended to have increased longevity. High feed intake postpartum was associated with reduced length of herdlife. Objective measures of conformation, which included measurements of the udder, were not important in determining herdlife.     

Body weight changes in lactating purebred and crossbred dairy cattle.

Body weights of 396 first and 205 second lactation cows in the first, second, third, and fourth generations of the dairy cattle crossbreeding project at the Illinois Agricultural Experiment Station were studied. Body weights were taken regularly on each animal during the first 9 mo of each lactation with the first weight being taken 3 to 4 days after parturition and subsequent weights at intervals of 30 days thereafter. Among least-squares means there was a decrease in body weight during the first 1 or 2 mo of lactation and a steady increase thereafter in all breed groups for both first and second lactations. There were differences between cows as well as between months for all breed groups in each generation for both lactations. Sums of squares for months were partitioned into linear, quadratic, and cubic components. A third degree polynomial was fitted for each breed group within each generation and separately for each lactation showing the changes in body weights.     

Indirect genomic predictions for milk yield in crossbred Holstein-Jersey dairy cattle

The objective of this study was to predict genomic breeding values for milk yield of crossbred dairy cattle under different scenarios using single-step genomic BLUP (ssGBLUP). The data set included 13,880,217 milk yield measurements on 6,830,415 cows. Genotypes of 89,558 Holstein, 40,769 Jersey, and 22,373 Holstein-Jersey crossbred animals were used, of which all Holstein, 9,313 Jersey, and 1,667 crossbred animals had phenotypic records. Genotypes were imputed to 45K SNP markers. The SNP effects were estimated from single-breed evaluations for Jersey (JE), Holstein (HO) and crossbreds (CROSS), and multibreed evaluations including all Jersey and Holstein (JE_HO) or approximately equal proportions of Jersey, Holstein, and crossbred animals (MIX). Indirect predictions (IP) of the validation animals (358 crossbred animals with phenotypes excluded from evaluations) were calculated using the resulting SNP effects. Additionally, breed proportions (BP) of crossbred animals were applied as a weight when IP were estimated based on each pure breed. The predictive ability of IP was calculated as the Pearson correlation between IP and phenotypes of the validation animals adjusted for fixed effects in the model. Regression of adjusted phenotypes on IP was used to assess the inflation of IP. The predictive ability of IP for CROSS, JE, HO, JE_HO, and MIX scenario was 0.50, 0.50, 0.47, 0.50, and 0.46, respectively. Using BP was the least successful, with a predictive ability of 0.32. The inflation of the IP for crossbred animals using CROSS, JE, HO, JE_HO, MIX, and BP scenarios were 1.17, 0.65, 0.55, 0.78, 1.00, and 0.85, respectively. The IP of crossbred animals can be predicted using single-step GBLUP under a scenario that includes purebred genotypes.     

Estimation of milk protein gene frequencies in crossbred cattle by maximum likelihood

A maximum likelihood method is presented to estimate the fraction of animals misclassified and breed effects for milk protein gene frequencies based on crossbred data. A simulation study indicates that the method provides estimates of gene frequencies that agree closely with the true values. Gene frequencies in the Dutch Black and White and the Dutch Red and White crossbred populations, based on data on 10,151 and 580 animals respectively, were estimated. Dutch Friesian and Holstein-Friesian breeds differ in gene frequencies for beta-casein and beta-lactoglobulin. Estimates for fractions misclassified are zero for alpha s1-casein, .09 for beta-casein and beta-lactoglobulin, and .12 for kappa-casein. Differences between Dutch Red and Whites and Red Holstein-Friesian breeds are small, and estimates for fractions misclassified are high but have high approximate standard errors. Compared with the Black and White breeds, the Red and Whites have a high kappa-casein B gene frequency.     

In vitro peripheral blood mononuclear cell proliferation in a crossbred cattle population

Immune function measured by Staphylococcus aureus- and phytohemagglutinin- (PHA-) induced cell proliferation was assessed in a population of 445 genetically defined, F2 and backcross Charolais-Holstein crossbred cattle when the animals were approximately 5 mo of age. Variation in Staph. aureus-induced, PHA-induced, and control proliferation [peripheral blood mononuclear cell (PBMC) and media only] was observed at d 2, 3, 4, 5, 9, and 10 of in vitro culture. The levels of Staph. aureus-induced, PHA-induced, and control proliferation were strongly positively correlated between days of culture within-assay (e.g., between d 2 and d 3 or between d 4 and d 5). Responses were also positively correlated when the same individuals were resampled and the assay repeated within 3 mo. Analyses fitting linear mixed models using REML showed that Staph. aureus-induced and PHA-induced proliferation was significantly associated with control proliferation and the year of birth. The age of the animal at sampling influenced only Staph. aureus-induced proliferation, with Staph. aureus-induced proliferation increasing with the age of the animal. Control proliferation was influenced by a sex × cross interaction, although in this study, sex was confounded by management, as female cattle were housed and reared differently from male cattle. All 3 measures of immune function were influenced by sire, demonstrating that these traits are partially under genetic control, and indicating that it may ultimately be possible to identify quantitative trait loci for these measures of immunity.     

Estimation of genetic parameters and heterosis for longevity in crossbred Danish dairy cattle

Crossbreeding has been shown to improve the longevity of dairy cattle in countries across the world. The aim of this study was to estimate heterosis, breed effects, and genetic parameters for longevity in crossbred dairy cattle among Danish Holstein (DH), Danish Red (DR), and Danish Jersey (DJ) breeds. Data were provided from 119 Danish commercial herds that use systematic crossbreeding (i.e., rotational crossbreeding). Additional data from 11 mixed-breed herds with DH and DJ were included to estimate reliable breed effects for DJ. Survival information on 73,741 cows was analyzed with a linear animal model using the artificial insemination–REML algorithm in the DMU package. Five longevity (L) traits were defined: days from first calving until the end of first lactation or culling (L1), days from first calving until the end of second lactation or culling (L2), days from first calving until the end of third lactation or culling (L3), days from first calving until the end of fourth lactation or culling (L4), and days from first calving until the end of fifth lactation or culling (L5). Heritabilities ranged between 0.022 and 0.090. Additive breed effects in units of days were estimated relative to DH for DR as ?0.5 (L1), +10.5 (L2), +18.5 (L3), +11.9 (L4), and +28.6 (L5), and corresponding figures for DJ were +2.0, +0.5, +14.2, +27.7, and +44.0. Heterosis effects in L1 were low (1.2%) but favorable in crosses between DH and DR, whereas negative heterosis effects were estimated for crosses between DH and DJ (?2.5%) and DR and DJ (?1.2%). The largest heterosis effects for L2, L3, L4, and L5 were found in DH × DR and were favorable (+3.3, +5.7, +7.7, and +8.5%, respectively). Corresponding figures for heterosis effects in DH × DJ and DR × DJ were favorable as well: +2.3, +4.1, +5.6, and +6.2% in DH × DJ and +3.1, +7.3, +6.9, and +7.2% in DR × DJ. The favorable heterosis effects show that crossbreeding is an efficient tool for improving longevity in Danish dairy cattle.     

Growth and reproduction characteristics of purebred and crossbred dairy cattle in first lactation

Breed additive, maternal, and heterozygotic effects on 11 monthly postpartum body weights, average size, weight gain, age at first calving, and days open were estimated by linear regression analyses from records of 680 purebred and crossbred animals. Calving year, age, and milk yield were significant environmental effects. Positive regressions of age on body weights indicated late calving cows were heaviest postpartum and had most days open. Negative regressions of milk yield on weight gain and postpartum weight showed greatest losses of weight associated with highest yields. There were breed differences in growth; purebreds highest to lowest were Brown Swiss, Holstein, Red Dane, Jersey, and Ayrshire and for weight gain, Brown Swiss, Ayrshire, and for weight gain, Brown Swiss, Ayrshire, Jersey, Holsteins, and Red Dane. Crosses were superior to purebreds in these traits. Additive effects of Holstein were greater than Ayrshire, Jersey, and Red Dane for postpartum body weights and average size. All constants for heterozygotic effect combinations were significant for postpartum weights and average size. Heterozygosity effects increased in magnitude with advancing lactation. Generally, age at first calving and postpartum interval to conception reflected little heterozygotic or maternal effects. There was some indication of breed differences in mean and additive effects for age at first calving.     

Genetic variability in the kappa‐casein gene in Sahiwal,Cholistani and Red Sindhi cattle breeds

Polymorphism of kappa‐casein (κ‐CN) gene in three Bos indicus cattle breeds was investigated using a polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) technique. Only genotypes AA and AB were observed, and no BB, AE, BE, EE, AC or BC genotypes were detected in the three cattle breeds. In the Sahiwal, Cholistani and Red Sindhi breeds, the frequencies of the allele A were 0.69, 0.90 and 0.86, and the frequencies of the allele B were 0.31, 0.10 and 0.14, respectively. The Sahiwal breed was found to have a higher frequency of the AB genotype as compared to the Cholistani and Red Sindhi breeds. The frequency of the κ‐CN alleles noted in the three cattle breeds was similar to those observed in other cattle breeds of B. indicus origin.     

Tissue growth patterns in the carcasses of water buffalo and Friesian crossbred cattle-part 1: Individual muscles and anatomical muscle groups

The left sides of the carcasses of twelve Egyptian buffalo, nine half Friesian (♂ Friesian x ♀ Egyptian Baladi) and nine three-quarter Friesian (♂ x ♀ half-Friesian) bulls, serially slaughtered between 161 and 560 kg for buffaloes and between 176 and 448 kg for cattle, were used to describe the growth and distribution of individual muscles and muscle groups.

Genotype-group differences in the relative rate of growth were not significant in 85 of 89 muscles and in 8 of 9 muscle groups. The pooled within-group growth coefficients of individual muscles revealed different increasing growth gradients, i.e. disto-proximal in both limbs, mediolateral in the proximal pelvic limb, from elbow flexors to shoulder flexors in the proximal thoracic limb, caudo-cranial in the trunk and from hypaxial to epaxial muscles around the spinal column. The relative growth was lowest in the distal part of the limbs and highest in the anterior part of the carcass (SMG 7 and 8), with the loin and abdominal muscle groups growing at a rate similar to that of the total muscle. The neck and thorax muscle group grew at a higher rate in Friesian crosses than in buffaloes.

Genotype-group differences in the weight of each muscle relative to total side muscle (TSM) were significant in 50 of 89 muscles. Of the 50 muscles (constituting around 59% of TSM), 24 (approximately 44% of TSM) were from the expensive muscle groups. As compared with the most different Friesian cross (base = 100) at equal TSM, buffaloes had higher weight of muscle in the hindlimb (107·5% proximally; 106·3% distally) and forelimb (120·0% proximally: 104·6% distally) and significantly less weight of the muscle groups forming the abdominal wall (79·8%) and connecting the forelimb to the thorax (89·1%) and to the neck (90·7%). The weight of the combined expensive groups was significantly greater in buffaloes than in cattle (maximum difference = 1·8 kg) with a tendency for buffaloes to have relatively less of the tender muscles surrounding the spinal column.     

不同杂交牛肝脏食用品质和营养品质分析

研究不同品种杂交牛肝脏食用品质和营养品质以及氨基酸组成和含量的差异。以安格斯牛×秦川牛杂交牛、安格斯牛×河西地区黄牛杂交牛和鲁西黄牛×利木赞牛杂交牛肝脏为原料,采用相关国标方法或常用方法对3种杂交牛肝脏食用品质和营养品质以及氨基酸含量进行测定,并进行必需氨基酸评分。结果表明,3种杂交牛肝脏色泽正常,pH分别为6.17、6.44和6.22,熟肉率分别为82.46%,77.03%和80.38%,加工性能良好,蛋白质含量分别为20.11、18.82、19.01g/100g,氨基酸含量分别为19.68、17.68、17.63g/100g,其中,必需氨基酸含量分别为7.30、6.46、6.44g/100g,且氨基酸种类齐全,氨基酸评分高于或接近FAO提出的标准模式。3种杂交牛肝脏食用品质和营养品质虽然存在一定的差异,但均可作为优质的牛副产物,有较大开发利用价值。      

Detection of QTL for milk protein percentage in Italian Friesian cattle by AFLP markers and selective genotyping

We targeted quantitative trait loci (QTL) for milk protein percentage (P%) in two Italian Holstein granddaughter design families using selective genotyping in combination with high throughput amplified fragment length polymorphism (AFLP) markers. A total of 64 extreme high and low sires in respect to estimated breeding value (EBV) for P% (EBVP%) were genotyped with 25 AFLP primer combinations that revealed 305 and 291 polymorphisms in the two families. Association between markers and EBVP% was investigated by a linear model only on bands having paternal origin (105 and 96 AFLP bands in family D and S, respectively). Although no marker was significantly associated with the target trait after correction for multiple comparisons, 17 AFLP markers, significant without correction for multiple tests, were considered suggestive of the presence of a QTL. Eleven of these were successfully located on six Bos taurus (BTA) chromosomes by radiation hybrid or in-silico mapping. Ten of these mapped in the immediate neighbourhood (less than 10 cM) of already described QTL for P%. Suggestive association was verified in four regions by microsatellites analysis: one on BTA 10; one on BTA 28; and two on BTA 18. Microsatellites identified significant effects by single marker and interval mapping analyses on BTA 10 and BTA 28, while they were only suggestive of the presence of QTL on BTA 18. In summary, our results firstly indicate that AFLP markers may be used to seek QTL exploiting a selective genotyping approach in GDD, a wide used experimental design in cattle; secondly, propose two approaches for AFLP mapping, namely in-silico mapping exploiting most updated release from the bovine whole genome sequencing project, and physical mapping exploiting a panel of Bovine/Hamster Radiation Hybrids; and thirdly, provide new information on QTLs for an economic important trait in a never investigated Holstein cattle population. AFLP in combination with selective genotyping can be a useful strategy for QTL searching in minor livestock species, sometimes having large economic impact in marginal areas, where more informative markers are still poorly developed.     

A genome-wide association study for susceptibility and infectivity of Holstein Friesian dairy cattle to digital dermatitis

Selection and breeding can be used to fight transmission of infectious diseases in livestock. The prevalence in a population depends on the susceptibility and infectivity of the animals. Knowledge on the genetic background of those traits would facilitate efficient selection for lower disease prevalence. We investigated the genetic background of host susceptibility and infectivity for digital dermatitis (DD), an endemic infectious claw disease in dairy cattle, with a genome-wide association study (GWAS), using either a simple linear mixed model or a generalized linear mixed model based on epidemiological theory. In total, 1,513 Holstein-Friesian cows of 12 Dutch dairy farms were scored for DD infection status and class (M0 to M4.1) every 2 wk for 11 times; 1,401 of these cows were genotyped with a 75k SNP chip. We performed a GWAS with a linear mixed model on 10 host disease status traits, and with a generalized linear mixed model with a complementary log-log link function (GLMM) on the probability that a cow would get infected between 2 scorings. With the GLMM, we fitted SNP effects for host susceptibility and host infectivity, while taking the variation in exposure of the susceptible cow to infectious herd mates into account. With the linear model we detected 4 suggestive SNP (false discovery rate < 0.20), 2 for the fraction of observations a cow had an active lesion on chromosomes 1 and 14, one for the fraction of observations a cow had an M2 lesion on at least one claw on chromosome 1 (the same SNP as for the fraction of observations with an active lesion), and one for the fraction of observations a cow had an M4.1 lesion on at least one claw on chromosome 10. Heritability estimates ranged from 0.09 to 0.37. With the GLMM we did not detect significant nor suggestive SNP. The SNP effects on disease status analyzed with the linear model had a correlation coefficient of only 0.70 with SNP effects on susceptibility of the GLMM, indicating that both models capture partly different effects. Because the GLMM better accounts for the epidemiological mechanisms determining individual disease status and for the distribution of the y-variable, results of the GLMM may be more reliable, despite the absence of suggestive associations. We expect that with an extended GLMM that better accounts for the full genetic variation in infectivity via the environment, the accuracy of SNP effects may increase.     

Apparent digestibility of nitrogen in rumen and whole tract of Friesian cattle fed direct-cut and wilted grass silages

Spring grass consisting of Lolium perene L. (81%), Poa pratensis L. (9%), and annual weeds (5%) was stored as direct-cut or as wilted silage and used in feeding trials to determine the effects of wilting on N utilization. Six mature Friesian cattle, fitted with rumen and simple duodenal cannulae, were fed the silages for ad libitum intake in a crossover design consisting of two 49-d periods. Wilting increased intake of organic matter and decreased ruminal apparent digestibility or organic matter and whole tract apparent digestibilities of organic matter, NDF, and total N. Rumen degradability of silage N was increased by wilting (.7 vs. .67). Direct-cut silage, in comparison with wilted silage, provide (g/d) less N intake (232 vs. 286) and lower duodenal flows of total N (215 vs. 293), non-NH3 N (202 vs. 280), microbial N (111 vs. 177), and total amino acids (1056.8 vs. 1342.7). Duodenal flows of NH3 N and undegraded N were not different between silages. Efficiency of bacterial N synthesis in rumen was higher for wilted than for direct-cut silage (32.3 vs. 21.4 g N/kg organic matter apparently digested in rumen). It was concluded that wilting increase silage intake, rumen bacterial synthetic efficiency, and duodenal flow of non-NH3 N in cattle.     

Genome-wide association study for age at puberty and resumption of cyclicity in a crossbred dairy cattle population

Fertility is of primary economic importance in dairy cattle and the most common reason for involuntary culling. However, standard fertility traits have very low heritability that renders genetic selection slow and difficult. In this study, we explored fertility from an endocrine standpoint. A total of 1,163 crossbred Holstein-Normande females in a 3-generation familial design were studied for progesterone level measured every 10 d to determine age at puberty (PUB) and commencement of postpartum luteal activity (CPLA). Genetic parameters were estimated using REML with WOMBAT software. The heritability estimates were 0.38 ± 0.10 and 0.16 ± 0.07 for PUB and CPLA, respectively. Moreover, the 2 traits were genetically correlated (0.45 ± 0.23), suggesting a partially common determinism. Because of the family structure, a linkage disequilibrium and linkage analysis approach was preferred over standard genome-wide association study to map genomic regions associated with these traits. Ten quantitative trait loci (QTL) were detected for PUB on chromosomes 1, 3, 11, 13, 14, 21, and 29, whereas 3 QTL were associated with CPLA on chromosomes 21 and 26. Only the QTL on chromosome 21 was common to both traits. Four functional candidate genes (NCOA2, GAS2, OVOL1, and FOSL1) were identified in the detected regions. These findings will contribute to a clearer understanding of fertility determinism and enhance the value of introducing endocrinological data in fertility studies.     

Genomic prediction of crossbred dairy cattle in Tanzania: A route to productivity gains in smallholder dairy systems

Selection based on genomic predictions has become the method of choice for genetic improvement in dairy cattle. This offers huge opportunity for developing countries with little or no pedigree data, and preliminary studies have shown promising results. The African Dairy Genetic Gains (ADGG) project initiated a digital system of dairy performance data collection, accompanied by genotyping in Tanzania in 2016. Currently, ADGG has the largest body of dairy performance data generated in East Africa from a smallholder dairy system. This study examines the use of genomic best linear unbiased prediction (GBLUP) and single-step (ss)GBLUP for the estimation of genetic parameters and accuracy of genomic prediction for daily milk yield and body weight in Tanzania. The estimates of heritability for daily milk yield from GBLUP and ssGBLUP were essentially the same, at 0.12 ± 0.03. The heritability estimates for daily milk yield averaged over the whole lactation from random regression model (RRM) GBLUP or ssGBLUP were 0.22 and 0.24, respectively. The heritability of body weight from GBLUP was 0.24 ± 04 but was 0.22 ± 04 from the ssGBLUP analysis. Accuracy of genomic prediction for milk yield from a forward validation was 0.57 for GBLUP based on fixed regression model or 0.55 from an RRM. Corresponding estimates from ssGBLUP were 0.59 and 0.53, respectively. Accuracy for body weight, however, was much higher at 0.83 from GBLUP and 0.77 for ssGBLUP. The moderate to high levels of accuracy of genomic prediction (0.53–0.83) obtained for milk yield and body weight indicate that selection on the basis of genomic prediction is feasible in smallholder dairy systems and most probably the only initial possible pathway to implementing sustained genetic improvement programs in such systems.